The Experts below are selected from a list of 1215 Experts worldwide ranked by ideXlab platform
Andrew M. Collins - One of the best experts on this subject based on the ideXlab platform.
-
a comparison of immunoglobulin ighv IGHD and ighj genes in wild derived and classical inbred mouse strains
Immunology and Cell Biology, 2019Co-Authors: Corey T Watson, Katherine J. L. Jackson, Justin T Kos, William S Gibson, Leah Newman, Gintaras Deikus, Christian E Busse, Melissa Smith, Andrew M. CollinsAbstract:The genomes of classical inbred mouse strains include genes derived from all three major subspecies of the house mouse, Mus musculus. We recently posited that genetic diversity in the immunoglobulin heavy chain (IGH) gene loci of C57BL/6 and BALB/c mice reflects differences in subspecies origin. To investigate this hypothesis, we conducted high-throughput sequencing of IGH gene rearrangements to document IGH variable (IGHV), joining (IGHJ) and diversity (IGHD) genes in four inbred wild-derived mouse strains (CAST/EiJ, LEWES/EiJ, MSM/MsJ and PWD/PhJ) and a single disease model strain (NOD/ShiLtJ), collectively representing genetic backgrounds of several major mouse subspecies. A total of 341 germline IGHV sequences were inferred in the wild-derived strains, including 247 not curated in the international ImMunoGeneTics information system. By contrast, 83/84 inferred NOD IGHV genes had previously been observed in C57BL/6 mice. Variability among the strains examined was observed for only a single IGHJ gene, involving a description of a novel allele. By contrast, unexpected variation was found in the IGHD gene loci, with four previously unreported IGHD gene sequences being documented. Very few IGHV sequences of C57BL/6 and BALB/c mice were shared with strains representing major subspecies, suggesting that their IGH loci may be complex mosaics of genes of disparate origins. This suggests a similar level of diversity is likely present in the IGH loci of other classical inbred strains. This must now be documented if we are to properly understand interstrain variation in models of antibody-mediated disease.
-
DJ Pairing during VDJ Recombination Shows Positional Biases That Vary among Individuals with Differing IGHD Locus Immunogenotypes
Journal of immunology (Baltimore Md. : 1950), 2015Co-Authors: Marie J. Kidd, Katherine J. L. Jackson, Scott D. Boyd, Andrew M. CollinsAbstract:Human IgH diversity is influenced by biases in the pairing of IGHD and IGHJ genes, but these biases have not been described in detail. We used high-throughput sequencing of VDJ rearrangements to explore DJ pairing biases in 29 individuals. It was possible to infer three contrasting IGHD-IGHJ haplotypes in nine of these individuals, and two of these haplotypes include deletion polymorphisms involving multiple contiguous IGHD genes. Therefore, we were able to explore how the underlying genetic makeup of the H chain locus influences the formation of particular DJ pairs. Analysis of nonproductive rearrangements demonstrates that 3' IGHD genes tend to pair preferentially with 5' IGHJ genes, whereas 5' IGHD genes pair preferentially with 3' IGHJ genes; the relationship between IGHD gene pairing frequencies and IGHD gene position is a near linear one for each IGHJ gene. However, striking differences are seen in individuals who carry deletion polymorphisms in the D locus. The absence of different blocks of IGHD genes leads to increases in the utilization frequencies of just a handful of genes, and these genes have no clear positional relationships to the deleted genes. This suggests that pairing frequencies may be influenced by additional complex positional relationships that perhaps arise from chromatin structure. In contrast to IGHD gene usage, IGHJ gene usage is unaffected by the IGHD gene-deletion polymorphisms. Such an outcome would be expected if the recombinase complex associates with an IGHJ gene before associating with an IGHD gene partner.
-
use of ighj and IGHD gene mutations in analysis of immunoglobulin sequences for the prognosis of chronic lymphocytic leukemia
Leukemia Research, 2007Co-Authors: Cindy E H Lee, Katherine J. L. Jackson, William A Sewell, Andrew M. CollinsAbstract:The level of somatic point mutation in immunoglobulin genes is an important prognostic indicator for patients with chronic lymphocytic leukemia (CLL). Mutation analysis presently focuses solely upon the heavy chain IGHV gene, however mutation is a stochastic process that also targets IGHD and IGHJ genes. Here, we evaluate the completeness and reliability of the reported IGHJ gene repertoire, and demonstrate the likely consequences of the inclusion of IGHD and IGHJ mutations in CLL analysis, using a dataset of 607 sequences. Inclusion of these mutations would lead to the re-classification of many sequences, which should significantly improve the prognostic value of mutation analysis.
-
identifying highly mutated IGHD genes in the junctions of rearranged human immunoglobulin heavy chain genes
Journal of Immunological Methods, 2007Co-Authors: Katherine J. L. Jackson, Bruno A Gaeta, Andrew M. CollinsAbstract:The reliable identification of IGHD genes within human immunoglobulin heavy chains is challenging with up to one third of rearrangements having no identifiable IGHD gene. The short, mutated IGHD genes are generally assumed to be indistinguishable from the N-REGIONS of non-template encoded nucleotides that surround them. In this study we have characterised N-REGIONS, demonstrating the importance of nucleotide composition biases in the addition process, including the formation of homopolymer tracts. We then use a simulation approach to determine the likelihood of misidentification of highly mutated IGHD genes among the JUNCTION nucleotides. These likelihoods provide general rules for the identification of mutated D-REGIONs, and suggest that longer D-REGIONs (>25 nucleotides) with as many as ten mutations can be identified with a low risk of error. Shorter D-REGIONs (>16 nucleotides) with as many as four mutations are also identifiable. The reliability of different alignments is dependent upon the junction length (combined N-REGIONs and D-REGION). Data is presented that can guide the alignment of sequences with junction lengths from 5 to 50 nucleotides, including explicit selection between two D-REGION possibilities. The use of such a statistically-based approach to the alignment of IGHD genes will improve the reliability of the partitioning of immunoglobulin sequences, and this in turn will facilitate the study of the many processes that contribute to the diversity of the immunoglobulin repertoire.
-
reconsidering the human immunoglobulin heavy chain locus 1 an evaluation of the expressed human IGHD gene repertoire
Immunogenetics, 2006Co-Authors: C E H Lee, Bruno A Gaeta, H R Malming, Michael Bain, William A Sewell, Andrew M. CollinsAbstract:We have used a bioinformatics approach to evaluate the completeness and functionality of the reported human immunoglobulin heavy-chain IGHD gene repertoire. Using the hidden Markov-model-based iHMMune-align program, 1,080 relatively unmutated heavy-chain sequences were aligned against the reported repertoire. These alignments were compared with alignments to 1,639 more highly mutated sequences. Comparisons of the frequencies of gene utilization in the two databases, and analysis of features of aligned IGHD gene segments, including their length, the frequency with which they appear to mutate, and the frequency with which specific mutations were seen, were used to determine the reliability of alignments to the less commonly seen IGHD genes. Analysis demonstrates that IGHD4-23 and IGHD5-24, which have been reported to be open reading frames of uncertain functionality, are represented in the expressed gene repertoire; however, the functionality of IGHD6-25 must be questioned. Sequence similarities make the unequivocal identification of members of the IGHD1 gene family problematic, although all genes except IGHD1-14*01 appear to be functional. On the other hand, reported allelic variants of IGHD2-2 and of the IGHD3 gene family appear to be nonfunctional, very rare, or nonexistent. Analysis also suggests that the reported repertoire is relatively complete, although one new putative polymorphism (IGHD3-10*p03) was identified. This study therefore confirms a surprising lack of diversity in the available IGHD gene repertoire, and restriction of the germline sequence databases to the functional set described here will substantially improve the accuracy of IGHD gene alignments and therefore the accuracy of analysis of the V–D–J junction.
Primus E Mullis - One of the best experts on this subject based on the ideXlab platform.
-
autosomal dominant isolated growth hormone deficiency IGHD type ii with normal gh 1 gene
Hormone Research in Paediatrics, 2006Co-Authors: Danilo Fintini, Roberto Salvatori, Souzan Salemi, Barto J Otten, Grazia Maria Ubertini, Paola Cambiaso, Primus E MullisAbstract:BACKGROUND: Autosomal-dominant isolated GH deficiency (IGHD) is a rare disorder that is commonly believed to be due to heterozygous mutations in the GH-1 gene (GH-1). These mutations cause the production of a protein that affects the release of the product of the normal allele. Rarely, heterozygous mutations in the gene encoding for HESX-1 gene (HESX-1) may cause autosomal-dominant IGHD, with penetrance that has been shown to be variable in both humans and mice. SUBJECTS AND METHODS: We have sequenced the whole GH-1 in the index cases of 30 families with autosomal-dominant IGHD. In all the families other possible causes of GH deficiency and other pituitary hormones deficits were excluded. We here describe the clinical, biochemical and radiological picture of the families without GH-1 mutations. In these families, we also sequenced the HESX-1. RESULTS: The index cases of the five families with autosomal-dominant IGHD had normal GH-1, including the intronic sequences. They had no HESX-1 mutations. CONCLUSION: This study shows that GH-1 mutations are absent in 5/30 (16.6%) of the families with autosomal-dominant IGHD and raises the possibility that mutations in other gene(s) may be involved in IGHD with this mode of transmission.
-
variability of isolated autosomal dominant gh deficiency IGHD ii impact of the p89l gh mutation on clinical follow up and gh secretion
European Journal of Endocrinology, 2005Co-Authors: Souzan Salemi, Gerhard Binder, Iain C A F Robinson, Shida Yousefi, Kurt Baltensperger, Andree Eble, Dominique Simon, Paul Czernichow, E Sonnet, Primus E MullisAbstract:Objective: Four distinct familial types of isolated GH deficiency (IGHD) are classified, of which type II, IGHD II, is the autosomal dominant inherited form. Based on clinical data, it became evident that there is a wide variability in phenotype among the various GH-1 gene alterations leading to the disorder. As subjects suffering from IGHD II caused by the specific missense mutated P89L GH (C6129T) have never been reported in detail, the aim was to analyse the impact of this mutated GH form on its clinical follow-up as well as to study its effect at the cellular level in comparison with the most common missense mutation R183H GH (G6664A). Methods: Twelve subjects belonging to four families presenting with P89L GH were clinically compared with 17 subjects from 5 families with the R183H GH missense mutation. Further, co-localization of the wild-type (wt-type) and mutant GH forms was studied in AtT-20 cells, mouse pituitary gland, applying quantitative confocal microscopy analysis. Using immunofluorescent techniques, cells were double stained for GH and one of the following organelles: endoplasmic reticulum (antiGrp94), Golgi (anti-bCOP) and secretory granules (anti-Rab3a). In addition, GH secretion and cell viability was analysed in detail. Results: Importantly, as well as growth hormone deficiency, eight out of twelve subjects with the P89L mutated GH form developed other endocrine deficits and the pituitary gland became smaller over time (P , 0.05). At the cellular level, quantitative analysis of the variable mutants expressed in AtT-20 cells revealed a different extent of co-localization, different effects on GH secretion, and, therefore, a different impact on the secretory pathway which might be caused by different folding or aggregation problems necessary for sorting, packaging and/or secretion through the regulated secretory pathway. Conclusions: Our results show that specific and detailed analyses of the different mutations identified in IGHD II may shed light on the different mechanisms of secretory pathophysiology, and may provide a better explanation of the range of clinical features associated with GH missense isoforms. Importantly, the findings in patients with P89L GH extend beyond classical IGHD and stress the need for continued clinical vigilance in IGHD II patients for the development of other hormonal deficiencies.
-
isolated gh deficiency IGHD type ii imaging of the pituitary gland by magnetic resonance reveals characteristic differences in comparison with severe IGHD of unknown origin
European Journal of Endocrinology, 2002Co-Authors: Gerhard Binder, B H P Nagel, Michael B Ranke, Primus E MullisAbstract:Objective: To determine the specific morphology of the pituitary gland in children with severe isolated GH deficiency due to GH-1 gene mutations (IGHD type II). Design: The pituitary gland morphology in magnetic resonance imaging (MRI) of children with IGHD type II was analyzed and compared with the findings in a group of children with comparably severe IGHD of unknown origin. In addition, the birth histories of both groups were studied. Subjects: Thirteen children with IGHD type II were diagnosed in seven European children’s hospitals and they carried a corresponding GH-1 gene mutation. For comparison, we selected from a group of 66 MRI-studied GH-insufficient subjects diagnosed in our clinic, all children with severe IGHD (all GH peaks , 4mg/l) who had no GH-1 gene mutation, no first-grade relative with IGHD and no septo-optic dysplasia. Methods: Sagittal and coronal images of the brain were analyzed for the presence of any malformation of the pituitary gland and the intracranium. The height of each adenohypophysis was measured in a strict midline sagittal image for quantification of the gland’s size. In addition, patients’ files were reviewed for birth trauma or breech delivery. Results: Normal MRI morphology of the pituitary gland was observed in all patients of the familial IGHD type II group ðP , 0:003Þ in which, however, five of thirteen patients (38%) exhibited a mild hypoplasia of their gland (mean sagittal adenohypophysial height 21:0^0:03 SD score (SDS)). In contrast, the pituitary gland in the idiopathic group showed a definitive malformation with hypoplasia of pituitary stalk and adenohypophysis in all cases, while ectopia of the neurohypophysis was present in nine of the ten cases. The adenohypophysis was significantly smaller in the idiopathic group (mean sagittal adenohypophysial height 23:2^0:3 SDS) ðP , 0:0001Þ: All thirteen birth histories in the familial group (IGHD type II) were unremarkable while, in the idiopathic group, three of eight available birth histories recorded a breech delivery or traumatic birth (37.5%) ðP , 0:05Þ: Conclusions: This study shows for the first time that MRI pituitary morphology may correlate with the etiology of severe IGHD: normal morphology suggests the presence of GH-1 gene mutations, while severe hypoplasia with malformation have other causes which might include so far unknown genetic defects as well as traumatic insults.
-
molecular and cellular basis of isolated dominant negative growth hormone deficiency IGHD type ii insights on the secretory pathway of peptide hormones
Hormone Research in Paediatrics, 2002Co-Authors: Primus E Mullis, Johnny Deladoey, Priscilla S DanniesAbstract:Estimates of the frequency of GH deficiency range from 1:4,000 to 1:10,000. Most cases are sporadic and presumed to be secondary to a wide variety of aetiologies. However, in families with consanguinity, or when a second case occurs in the same family, a genetic cause may be suspected. Given that the patient is isolated GH deficient four distinct familial types of isolated GH deficiencies (IGHD) are well-differentiated on the basis of inheritance, hormonal deficiencies as well as molecular analyses. Two forms are autosomal recessively (IGHD type IA and IB), one is autosomal dominantly (IGHD type II) and one X-linked inherited. In this review, we focus on the secretory pathway of peptide hormones in general and on the possible mechanisms causing IGHD type II in detail. Most interestingly, in IGHD type II the apparently same phenotype of IGHD is caused by distinct GH-1 gene alterations leading to different blockades within the secretory pathway. Furthermore, this type of IGHD, in addition to some other specific GH-1 gene mutations, provides the most important opportunity to shed light on cell-biological mechanisms far beyond its pure description at the DNA/RNA level.
Roberto Salvatori - One of the best experts on this subject based on the ideXlab platform.
-
Walking and postural balance in adults with severe short stature due to isolated GH deficiency
'Bioscientifica', 2019Co-Authors: Ananda A Santana-ribeiro, Roberto Salvatori, Giulliani A Moreira-brasileiro, Manuel H Aguiar-oliveira, Vitor O Carvalho, Claudia K Alvim-pereira, Carlos R Araújo-daniel, Júlia G Reis-costa, Alana L Andrade-guimarães, Alécia A Oliveira-santosAbstract:Objectives: Walking and postural balance are extremely important to obtain food and to work. Both are critical for quality of life and ability to survive. While walking reflects musculoskeletal and cardiopulmonary systems, postural balance depends on body size, muscle tone, visual, vestibular and nervous systems. Since GH and IGF-I act on all these systems, we decided to study those parameters in a cohort of individuals with severe short stature due to untreated isolated GH deficiency (IGHD) caused by a mutation in the GHRH receptor gene. These IGHD subjects, despite reduction in muscle mass, are very active and have normal longevity. Methods: In a cross-sectional study, we assessed walking (by a 6-min walk test), postural balance (by force platform) and fall risk (by the 'Timed Up and Go' test) in 31 IGHD and 40 matched health controls. Results: The percentage of the walked distance measured in relation to the predicted one was similar in groups, but higher in IGHD, when corrected by the leg length. Absolute postural balance data showed similar velocity of unipodal support in the two groups, and better values, with open and closed eyes and unipodal support, in IGHD, but these differences became non-significant when corrected for height and lower-limb length. The time in 'Timed Up and Go' test was higher in IGHD cohort, but still below the cut-off value for fall risk. Conclusion: IGHD subjects exhibit satisfactory walking and postural balance, without increase in fall risk
-
voice formants in individuals with congenital isolated lifetime growth hormone deficiency
Journal of Voice, 2016Co-Authors: Eugenia H O Valenca, Roberto Salvatori, Anita H O Souza, Luiz A Oliveiraneto, Alaide H A Oliveira, Maria Ines Rebelo Goncalves, Carla R P Oliveira, Jeferson Sampaio Davila, Valdinaldo Aragao De Melo, Susana De CarvalhoAbstract:Summary Objective To analyze the voice formants (F1, F2, F3, and F4 in Hz) of seven oral vowels, in Brazilian Portuguese, [a, e, e, i, ɔ, o, and u] in adult individuals with congenital lifetime untreated isolated growth hormone deficiency (IGHD). Study Design This is a cross-sectional study. Methods Acoustic analysis of isolated vowels was performed in 33 individuals with IGHD, age 44.5 (17.6) years (16 women), and 29 controls, age 51.1 (17.6) years (15 women). Results Compared with controls, IGHD men showed higher values of F3 [i, e, and e], P = 0.006, P = 0.022, and P = 0.006, respectively and F4 [i], P = 0.001 and lower values of F2 [u], P = 0.034; IGHD women presented higher values of F1 [i and e] P = 0.029 and P = 0.036; F2 [ɔ] P = 0.006; F4 [ɔ] P = 0.031 and lower values of F2 [i] P = 0.004. IGHD abolished most of the gender differences in formant frequencies present in controls. Conclusions Congenital, severe IGHD results in higher values of most formant frequencies, suggesting smaller oral and pharyngeal cavities. In addition, it causes a reduction in the effect of gender on the structure of the formants, maintaining a prepubertal acoustic prediction.
-
increased visceral adiposity and cortisol to cortisone ratio in adults with congenital lifetime isolated gh deficiency
The Journal of Clinical Endocrinology and Metabolism, 2014Co-Authors: Elenilde Gomessantos, Roberto Salvatori, Anita H O Souza, Carla R P Oliveira, Thiago De Oliveira Ferrao, Rachel D C A Diniz, Joao A M Santana, Francisco A Pereira, Rita A A Barbosa, Enaldo Vieira De MeloAbstract:Context: Adult-onset GH deficiency (GHD) increases visceral adiposity and the activity of the enzyme 11β-hydroxysteroid dehydrogenase, which converts cortisone (E) to cortisol (F), both linked to insulin resistance and increased cardiovascular risk. Conversely, we reported that adults with congenital isolated GHD (IGHD) have increased insulin sensitivity. Objective: To assess the type of fat distribution and the amount of visceral and sc fat and to correlate them to the F/E ratio in adults with untreated IGHD due to a mutation in the GHRH receptor gene. Methods: Body composition was assessed by dual-energy x-ray absorptiometry, thickness of sc and visceral fat was measured by sonography, and serum F and E were measured in 23 IGHD subjects and 21 age-matched controls. Results: Waist/hip ratio (WHR), trunk fat, and trunk/extremity fat (TR/EXT) ratio were higher in IGHD subjects. Visceral fat index (VFI) (but not sc fat index [SFI]) was higher in IGHD. F and F/E ratio were also higher in IGHD. In all 44 indi...
-
isolated gh deficiency due to a ghrh receptor mutation causes hip joint problems and genu valgum and reduces size but not density of trabecular and mixed bone
The Journal of Clinical Endocrinology and Metabolism, 2013Co-Authors: Carlos C Epitaciopereira, Roberto Salvatori, Anita H O Souza, Carla R P Oliveira, Joao A M Santana, Miburge B Goisjunior, Gabriella M F Silva, Francisco De Assis Pereira, Allan V O Britto, Elenilde G SantosAbstract:Context: The GH/IGF-I axis is important for bone growth, but its effects on joint function are not completely understood. Adult-onset GH-deficient individuals have often reduced bone mineral density (BMD). However, there are limited data on BMD in adult patients with untreated congenital isolated GH-deficient (IGHD). We have shown that adult IGHD individuals from the Itabaianinha, homozygous for the c.57+1G>A GHRHR mutation, have reduced bone stiffness, but BMD and joint status in this cohort are unknown. Objective: The goal is to study BMD, joint function, and osteoarthritis score in previously untreated IGHD adults harboring the c.57+1G>A GHRHR mutation. Design: This is a cross-sectional study. Methods: Areal BMD by dual-energy X-ray absorptiometry was measured in 25 IGHD and 23 controls (CO). Volumetric BMD (vBMD) was calculated at the lumbar spine and total hip. Joint function was assessed by goniometry of elbow, hips, and knees. X-rays were used to measure the anatomic axis of knee and the severity o...
-
a novel frame shift mutation in the ghrh receptor gene in familial isolated gh deficiency early occurrence of anterior pituitary hypoplasia
The Journal of Clinical Endocrinology and Metabolism, 2011Co-Authors: Rugia Shohreh, Rosa Sherafatkazemzadeh, Youn Hee Jee, Ari M Blitz, Roberto SalvatoriAbstract:Background: Mutations in the genes encoding for GHRH receptor (GHRHR) and GH (GH1) are the most common cause of familial isolated GH deficiency (IGHD). GHRHR mutations are often associated with anterior pituitary hypoplasia (APH), but this has been reported almost exclusively in children older than 8 yr. We analyzed the GHRHR and measured pituitary size in a consanguineous family with the father and three of the five siblings with IGHD. Objective: The aim of the study was to find the mutated gene in a family with severe IGHD. Methods: We sequenced the whole GHRHR coding regions and the intron-exon boundaries from peripheral DNA of the index patient. After identifying the novel mutation, we sequenced the region of interest in the other members of the family. We measured the anterior pituitary volume from magnetic resonance imaging (MRI). Results: The father and the three affected children were homozygous for a new frame-shift mutation in the coding sequence of exon 4 (corresponding to the extracellular dom...
Guy Bordenave - One of the best experts on this subject based on the ideXlab platform.
-
Mechanisms of mouse T lymphocyte-induced suppression of the IgG2ab allotype and T lymphocyte tolerance to IgG2ab.
Archivum immunologiae et therapiae experimentalis, 2001Co-Authors: Laleh Majlessi, Guy BordenaveAbstract:In mice of the Igha immunoglobulin allotypic haplotype we found, the presence of T lymphocytes with an inherent inhibitory activity against the expression of the IgG2a(b) allotype (IgG2a of the Ighb immunoglobulin allotypic haplotype). This constitutive anti-IgG2a(b) T lymphocyte activity can be enhanced in vivo by what we called "sensitization", which usually consists of one or two intravenous injections of B splenocytes from Ighb congenic mice. When injected at birth, the resulting anti-IgG2a(b) T splenocytes induce, with 100% success, total, specific and chronic (but experimentally reversible) suppression of IgG2a(b) in Igh(a/b) F1 hybrid mice prepared by mating Igh congenic mice. Even if restricted to IgG2a(b) expression, this experimental model, which deals with an unambiguous case of T cell-mediated down-regulation of immunoglobulin production, provides a clear and powerful tool to dissect finely the behavior of the partners (T and B lymphocytes) intervening in regulation within the immune system. For example, we observed that CD4 T lymphocytes were necessary to obtain full recruitment of anti-IgG2a(b) CD8 T lymphocytes during the sensitization, that suppression induction in anti-IgG2a(b) T splenocytes of newborn recipients required cooperation between CD4 and CD8 T lymphocytes, and that CD8 T lymphocytes were essential for suppression maintenance. We showed that this suppression was not characterized by an accumulation of B lymphocytes containing the allotype they could not secrete or Cgamma2a(b) mRNA they could not translate. The recipient's immune system was not involved in the suppession maintenance; this was done by donor T lymphocytes, which ensured the chronicity of IgG2a(b) suppression throughout the recipient's life. We demonstrated that the mechanism of this suppression implied an MHC-restricted presentation by target B lymphocytes of Cy2a(b) peptides to the T cell receptor (TCR) of anti-IgG2a(b) T lymphocytes. Notwithstanding the requirement of a CD4-CD8 T lymphocyte cooperation during the induction phase, we functionally determined that the suppression induction implicated an MHC class I-, but not class II-restricted interaction. We also demonstrated the existence in vivo of alternative or concomitant use of perforine- and Fas-mediated cytotoxicity pathways in this T cell-induced IgG2a(b) suppression. Thus this suppression did not imply silencing IgG2a(b) production, but B lymphocyte destruction by CD8 T lymphocytes. Always using our suppression model, we demonstrated that an agonistic anti-CD40 treatment helps in recruiting CD8 cytotoxic T lymphocytes, involved in immune regulatory functions and that CD40 expression on Ighb B lymphocytes confronted with CD8 T lymphocyte effectors only operating via the Fas pathway was involved in the total suppression of IgG2a(b) expression. The selection and maintenance of such normal T cell activity against the IgG2a(b) allotype in mice of different genetic backgrounds remain somewhat enigmatic. Indeed, we did not observe any similar activity against other immunoglobulin allotypes or isotypes. The intestinal flora had no influence on the emergence of this anti-IgG2a(b) T lymphocyte activity, as it was untouched in germ-free-Igha mice when compared with normal Igha mice. More recently, this model offered an opportunity to study problems pertaining to immune tolerance. For instance, we showed that the genetic elements involved in the building of anti-IgG2a(b) TCR were available in Igha and Ighb mice of different genetic backgrounds, but that somatic constraints, namely the perinatal presence of IgG2a(b), effectively prevented their acquisition, while its absence led to their spontaneous emergence. Consequently, we were able to induce anti-IgG2a(b) T lymphocytes into a tolerance state by injecting Igha mice with soluble IgG2a(b) during the perinatal period. However, the full T lymphocyte tolerance obtained in this manner was not definitively acquired, as it had reversed spontaneously when investigated 3 to 6 months after the end of tolerogen treatment, even when this treatment had been prolonged from the perinatal period to 9 months of age. The mechanisms (induction and reversion) of this tolerance involves the physical elimination or the irreversible inactivation of the natural anti-IgG2a(b) T lymphocyte clones and their resurgence, from bone-marrow precursors, as long as the thymus remains operational, but not the establishment of a reversible, functional unresponsiveness (anergy) or an active, cell-mediated inhibition of anti-IgG2a(b) T clones. We attempted to elucidate, in Ighb mice, whether the natural T lymphocyte unresponsiveness to IgG2a(b) involved a central tolerance mechanism and to identify the type of tolerogen implicated in this tolerogenesis. The experiments principally showed that this natural T lymphocyte tolerance to IgG2a(b) was mediated by a thymic mechanism; that the capacity to induce it was gradually acquired by Ighb thymuses and was most probably due to potentially IgG2a(b)-producing/presenting cells, progressively colonizing the developing thymus; and that a significantly decreased postnatal Cy2a(b) gene transcription correlated with the emergence of anti-IgG2a(b) T lymphocytes in Igh(a/b) F1 (postnatally deprived of their B lymphocyte compartment), which subjected them to autoimmune IgG2a(b)-allotype suppression.
-
t cell induced ig allotypic suppression in mice basis for emergence or tolerization during the perinatal period of natural t cells specific to the igg2ab allotype
Journal of Immunology, 1994Co-Authors: Laleh Majlessi, P Benaroch, C Denoyelle, M A R Marcos, Guy BordenaveAbstract:We have previously described an anti-IgG2ab T cell activity in normal Igha/a mice. Their congenic partner at the Igh locus (Ighb/b) and Igha/b hybrids bred from them, do not display this T cell activity but express IgG2ab. As these mice are supposed to possess the same genetic elements related to this potential T cell repertoire, only somatic selection mechanisms could be responsible for their different behavior. In this study, we investigated the basis for the emergence (in Igha/a mice) or tolerization (in Ighb/b-congenic mice and in Igha/b hybrids) of these natural anti-IgG2ab T cells. Stringent perinatal B cell deprivation in Ighb/b and Igha/b mice resulted in the emergence of anti-IgG2ab T cells, as these individuals could be subjected to autoimmune, T cell-mediated IgG2ab suppression. Furthermore, the acquisition of anti-IgG2ab T cell activity was drastically reduced in Igha/a mice, perinatally exposed to IgG2ab; thus, the presence of this allotype leads to tolerization of these specific T cells.
-
role of cd4 and cd8 cell subsets during amplification of natural t cell activity against igg2ab in igha mice and during induction of igg2ab allotype suppression in igha b mice
Journal of Immunology, 1993Co-Authors: Laleh Majlessi, P Benaroch, C Denoyelle, Guy BordenaveAbstract:Transfer into F1 Igha/b mice of splenocytes from Igha mice sensitized once against B cells from an Ighb congenic strain induces total, chronic, and IgG2ab (IgG2a of the Ighb haplotype)-specific allotype suppression in these recipients. We previously demonstrated that both the CD4+ and CD8+ T subsets were necessary for inducing suppression, but that CD8+, cells by themselves were sufficient for maintaining suppression. We have studied the suppression induction capacity of different mixtures of CD4+ and CD8+ subsets obtained by in vitro cytotoxic treatment of T splenocytes from normal or sensitized Igha mice, and we have established that suppression induction requires the cooperation between CD4+ and CD8+ populations, both of which have to be IgG2ab specific. In addition, Igha mice were sensitized in the absence of CD4+ or CD8+ cells by in vivo cytotoxic treatment performed before and after the sensitization in order to obtain an IgG2ab-specific CD4+ population that has arisen in the absence of CD8+ cells, and vice versa. We found that only IgG2ab-specific CD4+ cells from anti-CD8-treated mice (T'sens CD4+) had the ability to induce suppression in F1 Igha/b hosts. Nevertheless, the real effector cells in this suppression model display the CD8+ phenotype, as in vivo cytotoxic anti-CD8 treatment of Igha/b recipients of T'sens CD4+ abrogates the suppression induction capacity. Taken together, these results show that T'sens CD4+ have an important capacity to recruit CD8+ anti-IgG2ab effector cells from precursors that have been transferred with them into Igha/b hosts. These precursors are actually derived from the T'sens CD4+ cell preparation, because we have recently demonstrated that suppression is maintained by donor T cells throughout the recipient's life. CD4+ cells can have their anti-IgG2ab activity amplified only by means of target cells (i.e., B cells from Ighb congenic mice), whereas, in the absence of CD4+ cells, and despite the presence of target cells, CD8+ cells seem unable to acquire this amplified activity.
Katherine J. L. Jackson - One of the best experts on this subject based on the ideXlab platform.
-
a comparison of immunoglobulin ighv IGHD and ighj genes in wild derived and classical inbred mouse strains
Immunology and Cell Biology, 2019Co-Authors: Corey T Watson, Katherine J. L. Jackson, Justin T Kos, William S Gibson, Leah Newman, Gintaras Deikus, Christian E Busse, Melissa Smith, Andrew M. CollinsAbstract:The genomes of classical inbred mouse strains include genes derived from all three major subspecies of the house mouse, Mus musculus. We recently posited that genetic diversity in the immunoglobulin heavy chain (IGH) gene loci of C57BL/6 and BALB/c mice reflects differences in subspecies origin. To investigate this hypothesis, we conducted high-throughput sequencing of IGH gene rearrangements to document IGH variable (IGHV), joining (IGHJ) and diversity (IGHD) genes in four inbred wild-derived mouse strains (CAST/EiJ, LEWES/EiJ, MSM/MsJ and PWD/PhJ) and a single disease model strain (NOD/ShiLtJ), collectively representing genetic backgrounds of several major mouse subspecies. A total of 341 germline IGHV sequences were inferred in the wild-derived strains, including 247 not curated in the international ImMunoGeneTics information system. By contrast, 83/84 inferred NOD IGHV genes had previously been observed in C57BL/6 mice. Variability among the strains examined was observed for only a single IGHJ gene, involving a description of a novel allele. By contrast, unexpected variation was found in the IGHD gene loci, with four previously unreported IGHD gene sequences being documented. Very few IGHV sequences of C57BL/6 and BALB/c mice were shared with strains representing major subspecies, suggesting that their IGH loci may be complex mosaics of genes of disparate origins. This suggests a similar level of diversity is likely present in the IGH loci of other classical inbred strains. This must now be documented if we are to properly understand interstrain variation in models of antibody-mediated disease.
-
DJ Pairing during VDJ Recombination Shows Positional Biases That Vary among Individuals with Differing IGHD Locus Immunogenotypes
Journal of immunology (Baltimore Md. : 1950), 2015Co-Authors: Marie J. Kidd, Katherine J. L. Jackson, Scott D. Boyd, Andrew M. CollinsAbstract:Human IgH diversity is influenced by biases in the pairing of IGHD and IGHJ genes, but these biases have not been described in detail. We used high-throughput sequencing of VDJ rearrangements to explore DJ pairing biases in 29 individuals. It was possible to infer three contrasting IGHD-IGHJ haplotypes in nine of these individuals, and two of these haplotypes include deletion polymorphisms involving multiple contiguous IGHD genes. Therefore, we were able to explore how the underlying genetic makeup of the H chain locus influences the formation of particular DJ pairs. Analysis of nonproductive rearrangements demonstrates that 3' IGHD genes tend to pair preferentially with 5' IGHJ genes, whereas 5' IGHD genes pair preferentially with 3' IGHJ genes; the relationship between IGHD gene pairing frequencies and IGHD gene position is a near linear one for each IGHJ gene. However, striking differences are seen in individuals who carry deletion polymorphisms in the D locus. The absence of different blocks of IGHD genes leads to increases in the utilization frequencies of just a handful of genes, and these genes have no clear positional relationships to the deleted genes. This suggests that pairing frequencies may be influenced by additional complex positional relationships that perhaps arise from chromatin structure. In contrast to IGHD gene usage, IGHJ gene usage is unaffected by the IGHD gene-deletion polymorphisms. Such an outcome would be expected if the recombinase complex associates with an IGHJ gene before associating with an IGHD gene partner.
-
individual variation in the germline ig gene repertoire inferred from variable region gene rearrangements
Journal of Immunology, 2010Co-Authors: Scott D. Boyd, Katherine J. L. Jackson, Bruno A Gaeta, Andrew Fire, Eleanor L Marshall, Jason D Merker, Jay M Maniar, Lyndon N Zhang, Bita Sahaf, Carol JonesAbstract:Individual variation in the Ig germline gene repertoire leads to individual differences in the combinatorial diversity of the Ab repertoire, but the study of such variation has been problematic. The application of high-throughput DNA sequencing to the study of rearranged Ig genes now makes this possible. The sequencing of thousands of VDJ rearrangements from an individual, either from genomic DNA or expressed mRNA, should allow their germline IGHV, IGHD, and IGHJ repertoires to be inferred. In addition, where previously mere glimpses of diversity could be gained from sequencing studies, new large data sets should allow the rearrangement frequency of different genes and alleles to be seen with clarity. We analyzed the DNA of 108,210 human IgH chain rearrangements from 12 individuals and determined their individual IGH genotypes. The number of reportedly functional IGHV genes and allelic variants ranged from 45 to 60, principally because of variable levels of gene heterozygosity, and included 14 previously unreported IGHV polymorphisms. New polymorphisms of the IGHD3-16 and IGHJ6 genes were also seen. At heterozygous loci, remarkably different rearrangement frequencies were seen for the various IGHV alleles, and these frequencies were consistent between individuals. The specific alleles that make up an individual's Ig genotype may therefore be critical in shaping the combinatorial repertoire. The extent of genotypic variation between individuals is highlighted by an individual with aplastic anemia who appears to lack six contiguous IGHD genes on both chromosomes. These deletions significantly alter the potential expressed IGH repertoire, and possibly immune function, in this individual.
-
use of ighj and IGHD gene mutations in analysis of immunoglobulin sequences for the prognosis of chronic lymphocytic leukemia
Leukemia Research, 2007Co-Authors: Cindy E H Lee, Katherine J. L. Jackson, William A Sewell, Andrew M. CollinsAbstract:The level of somatic point mutation in immunoglobulin genes is an important prognostic indicator for patients with chronic lymphocytic leukemia (CLL). Mutation analysis presently focuses solely upon the heavy chain IGHV gene, however mutation is a stochastic process that also targets IGHD and IGHJ genes. Here, we evaluate the completeness and reliability of the reported IGHJ gene repertoire, and demonstrate the likely consequences of the inclusion of IGHD and IGHJ mutations in CLL analysis, using a dataset of 607 sequences. Inclusion of these mutations would lead to the re-classification of many sequences, which should significantly improve the prognostic value of mutation analysis.
-
identifying highly mutated IGHD genes in the junctions of rearranged human immunoglobulin heavy chain genes
Journal of Immunological Methods, 2007Co-Authors: Katherine J. L. Jackson, Bruno A Gaeta, Andrew M. CollinsAbstract:The reliable identification of IGHD genes within human immunoglobulin heavy chains is challenging with up to one third of rearrangements having no identifiable IGHD gene. The short, mutated IGHD genes are generally assumed to be indistinguishable from the N-REGIONS of non-template encoded nucleotides that surround them. In this study we have characterised N-REGIONS, demonstrating the importance of nucleotide composition biases in the addition process, including the formation of homopolymer tracts. We then use a simulation approach to determine the likelihood of misidentification of highly mutated IGHD genes among the JUNCTION nucleotides. These likelihoods provide general rules for the identification of mutated D-REGIONs, and suggest that longer D-REGIONs (>25 nucleotides) with as many as ten mutations can be identified with a low risk of error. Shorter D-REGIONs (>16 nucleotides) with as many as four mutations are also identifiable. The reliability of different alignments is dependent upon the junction length (combined N-REGIONs and D-REGION). Data is presented that can guide the alignment of sequences with junction lengths from 5 to 50 nucleotides, including explicit selection between two D-REGION possibilities. The use of such a statistically-based approach to the alignment of IGHD genes will improve the reliability of the partitioning of immunoglobulin sequences, and this in turn will facilitate the study of the many processes that contribute to the diversity of the immunoglobulin repertoire.
