BACKGROUND

Expression of multiple graft-protective proteins targeted to different locations (i.e., intracellular, cell surface, and secreted) has become an increasingly important goal in xenotransplantation. The 2A "ribosome skip" signal is used as a linker to enable transgene co-expression, but some studies have shown that post-translational modification and trafficking of 2A-linked proteins may be adversely affected depending on their position relative to 2A. We tested whether several relevant proteins, subject to a range of processing and localization mechanisms, could be efficiently co-expressed using the 2A system.

METHODS

Six expression cassettes were constructed, each containing up to four 2A-linked open reading frames, encoding combinations of human CD55, thrombomodulin (TBM), CD39, CTLA4-Ig and hygromycin resistance. Each linker incorporated a furin cleavage site to remove the carboxy-terminal extension that remains on upstream proteins after 2A processing. The cassettes were used to produce vectors for transfection, adenoviral transduction and transgenesis. Expression was detected by flow cytometry and/or Western blotting.

RESULTS

All proteins were expressed in the appropriate location following transient transfection of COS-7 cells, irrespective of the number of linked genes. The percentage of stable transfectants expressing a linked gene was increased 10-fold (from 4-5% to 58-67%) by incorporating the hygromycin resistance gene into the cassette. Stable transfection of transgenic GalT KO pig fibroblasts with a hygromycin- TBM-CD39 construct resulted in surface expression of both TBM and CD39 by the majority of hygromycin-resistant cells. Expression was maintained after flow cytometric sorting and expansion. Adenoviral transduction of NIT-1 mouse insulinoma cells with a TBM-CD39 construct resulted in strong expression of both genes on the cell surface. Mice transgenic for 3-gene (CD55- TBM-CD39) or 4-gene (CD55- TBM-CTLA4Ig-CD39) constructs expressed all genes except CD55.

CONCLUSIONS

These results confirm the versatility of the 2A system, and demonstrate that careful construct design can minimize potential problems with post-translational modification and trafficking. In addition, incorporation of a selection marker into the 2A-linked chain can dramatically increase the proportion of stable transfectants expressing proteins of interest. This provides a powerful method for the rapid modification of existing genetically modified pigs.

OBJECTIVE

The objective of this study was to determine whether there was any association between the peripheral blood CD4(+) CD25(+) Foxp3(+) regulatory T cells (Treg cells) and implantation success in patients undergoing in vitro fertilization (IVF) treatment.

METHODS

Prospective observational study of 101 randomly selected women who underwent IVF treatment for tubal factor from May 2011 to June 2011. The percentage of peripheral blood Treg cells and the expression levels of Foxp3 and CTLA4 mRNA in peripheral blood mononuclear cells (PBMCs) were recorded and their relations to IVF treatment outcomes were analyzed.

RESULTS

Treg cells were significantly elevated in the pregnant group ( P = 0.03). The expression level of Foxp3 mRNA in PBMCs from pregnant group also significantly increased ( P = 0.02). A receiver operating characteristic analysis (area under curve = 0.631) found that those women with Treg cells >0.6%, the pregnancy rate and live birth rate were much higher as compared to women with Treg cells below this level ( P < 0.05). An increase of Treg cells in the peripheral blood was associated with a better IVF treatment outcome (OR 4.3, 95% CI = 1.76-10.48), with a sensitivity of 64%, specificity of 71%.

CONCLUSIONS

An elevated level of circulating Treg cells was associated with increased rates of pregnancy and live birth in IVF treatment.

The development of cytotoxic CD4+ T lymphocytes that can kill target cells in a MHC class II-restricted manner was evaluated by comparing different APCs. B-lymphoblasts (B-LCL) pulsed with the superantigen staphylococcus enterotoxin B or allogeneic B-lymphoblasts induce CD4+ T cells without cytotoxic activity. In contrast, superantigen-pulsed, MHC class II+ T cell blasts or allogeneic T cell blasts preferentially induce the development of specific, MHC class II-restricted CD4+ cytotoxic effector cells. CD4+ T cell clones generated with T or B cell blasts as APCs (T- or B-APCs) differ in their cytolytic potential, but secrete a similar cytokine pattern. Our data implicate that activated T-APCs preferentially induce a cytotoxic, CD8+ and CD4+ T cell response. Because the density of CD80 expression is lower on activated T-APCs than on B-APCs, we studied the involvement of CD28 and CD80 adhesion molecules in the generation of CD4+ CTLs. Partial blockade of the CD80 molecule with a CTLA4-Ig fusion protein and with specific anti-CD80 mAbs on B-APCs enhanced the generation of CD4+ CTLs. Specific anti-CD86 mAbs, on the contrary, had no effect on the generation of CD4+ CTLs. In contrast, stimulation of CD28, the CD80 counter-receptor, with a cross-linked B7-Ig fusion protein or with an anti-CD28 mAb, inhibited the generation of CD4+ CTLs. Thus, a reduced interaction between CD80 and CD28 may be relevant for the induction of CD4+ CTLs. This shows a new and not yet described function of these adhesion molecules. This induction of a cytotoxic immune response by T cells as APCs may be relevant for the anticlonotypic regulation of T cells and for the depletion of CD4+ T cells in HIV infection.

Here we examined whether the expression of a novel immunoregulatory gene set could be used to predict outcomes in murine models of rapamycin-induced cardiac tolerance, spontaneous hepatic tolerance, and cardiac rejection. The expression of the immunoregulatory gene set was assessed with the GeXP multiplex reverse-transcription polymerase chain reaction (RT-PCR) analysis system, and it was correlated to the pathological and biochemical parameters of the allografts. In rejecting cardiac grafts, the increased expression of an inflammatory set of genes, which included CD45, CD4, CD25, suppressor of cytokine signaling 2, cytotoxic T lymphocyte-associated protein 4 (CTLA4), selectin lymphocyte, interferon-γ (IFN-γ), programmed cell death 1 (Pdcd1), and granzyme B (Gzmb), was seen 8 days after transplantation along with histological evidence of severe allograft rejection. In tolerant cardiac allografts, the expression of fibrinogen-like protein 2 (Fgl2), Pdcd1, killer cell lectin-like receptor G1 (Klrg1), CTLA4, and lymphocyte-activation gene 3 was associated with tolerance. In a model of liver allograft tolerance, the increased expression of lectin galactose-binding soluble 1, Fgl2, CD39, phosphodiesterase 3B, Klrg1, forkhead box P3 (Foxp3), and transforming growth factor β as well as the inflammatory set of genes was observed 8 to 14 days after transplantation (ie, when there was severe inflammatory injury). At a later time when the liver allografts had been fully accepted and were histologically normal, the expression of the inflammatory set of genes returned to the baseline, but the expression of the tolerogenic set of genes was still increased. Genes that were expressed in tolerant cardiac and liver allografts included Fgl2, Klrg1, and Foxp3, whereas genes associated with rejection included CD25, Gzmb, and IFN-γ. Our data indicate that monitoring the graft expression of a novel biomarker gene set with the GeXP multiplex RT-PCR analysis system may allow differentiation between rejection and tolerance.

We investigated whether CTLA4-Ig can reverse established asthma manifestations in a novel murine model of ongoing disease. In BALB/c mice, sensitized to ovalbumin (OVA) without adjuvant, airway inflammation was induced by a first series of OVA aerosol challenges. Murine CTLA4-IgG was then administered, followed by a second series of OVA inhalations. In control-treated mice, two series of OVA challenges induced upregulation of OVA-specific IgE in serum, eosinophils in the bronchoalveolar lavage fluid (BALF), and IL-5 production by lung lymphocytes upon OVA restimulation in vitro, compared with saline-challenged mice. CTLA4-IgG significantly inhibited all of these parameters in OVA-challenged mice. Importantly, mCTLA4-IgG performed better than the gold-standard dexamethasone because this corticosteroid did not inhibit the upregulation of OVA-specific IgE in serum. In a more "severe" ongoing model, induced by sensitization to OVA emulsified in aluminum hydroxide, resulting in airway hyperresponsiveness to methacholine and stronger inflammatory responses, mCTLA4-IgG was less effective in that only the number of eosinophils in the BALF was reduced (P = 0.053), whereas dexamethasone inhibited both BALF eosinophilia and cytokine production by lung lymphocytes. Thus, CTLA4-Ig might be an effective alternative therapy in established allergic asthma, especially in situations of mild disease.

BACKGROUND

Allergen-specific T lymphocytes biased to the production of type 2 cytokines play an important role in the pathophysiology of atopic disease. It is not known whether optimal activation of these T cells requires costimulation via interaction of B7 (CD86/CD80) with CD28.

METHODS

Peripheral blood mononuclear cells (PBMC), isolated from 10 house dust mite Dermatophagoides pteronyssinus (Der p)-allergic asthma patients and 10 non-allergic control individuals, were stimulated with house dust mite (Der p) and the control antigens Candida albicans (CA) and tetanus toxoid (TT). The role of costimulation in activation for proliferation and cytokine mRNA production of peripheral blood T cells was studied by blocking CD28, CTLA-4, and their ligands CD80 (B7-1) and CD86 (B7-2).

RESULTS

The proliferation and the production of type 1 and 2 cytokine mRNA by T cells in response to Der p as well as the control antigens TT and CA was inhibited by simultaneously masking CD80 and CD86 using CTLA4-Ig, a soluble form of CTLA-4. Notably, Der p-specific proliferation of T cells from Der p-allergic asthma patients and non-allergic controls were inhibited equally well. Additional experiments with MoAbs revealed that activation of these T cells was optimally inhibited by blocking the interaction of CD28 with CD86.

CONCLUSIONS

In vitro responses of allergen- and antigen-specific T cells of allergic patients and non-allergic control persons are equally dependent on costimulation via the CD28-CD86 pathway, suggesting that inhibition of this pathway may prevent complete activation of allergen-specific T cells in allergic individuals in vivo.

Selection and genetic drift can create genetic differences between populations. Cytokines and chemokines play an important role in both hematopoietic development and the inflammatory response. We compared the genotype frequencies of 45 SNPs in 30 cytokine and chemokine genes in two healthy Chinese populations and one Caucasian population. Several SNPs in IL4 had substantial genetic differentiation between the Chinese and Caucasian populations (F ST approximately 0.40), and displayed a strikingly different haplotype distribution. To further characterize common genetic variation in worldwide populations at the IL4 locus, we genotyped 9 SNPs at the IL4 gene in the Human Diversity Panel's (N = 1056) individuals from 52 world geographic regions. We observed low haplotype diversity, yet strikingly different haplotype frequencies between non-African populations, which may indicate different selective pressures on the IL4 gene in different parts of the world. SNPs in CSF2, IL6, IL10, CTLA4, and CX3CR1 showed moderate genetic differentiation between the Chinese and Caucasian populations (0.15 < F ST < 0.25). These results suggest that there is substantial genetic diversity in immune genes and exploration of SNP associations with immune-related diseases that vary in incidence across these two populations may be warranted.

We previously selected a group of hypertension candidate genes by a key word search using the OMIM database of NCBI and validated 525 coding single nucleotide polymorphisms (SNPs) in 179 hypertension candidate genes by DNA sequencing in a Japanese population. In the present study, we examined the association between 61 non-synonymous SNPs and blood pressure variations and hypertension. We used DNA samples taken from 1,880 subjects in the Suita study, a population-based study using randomly selected subjects. Analyses of covariance adjusting for age, body mass index, hyperlipidemia, diabetes, smoking, drinking, and antihypertensive medication revealed that 17 polymorphisms in 16 genes (APOB, CAST, CLCNKB, CTNS, GHR, GYS1, HF1, IKBKAP, KCNJ11, LIPC, LPL, P2RY2, PON2, SLC4A1, TRH, VWF) were significantly associated with blood pressure variations. Multivariate logistic regression analysis with adjustment for the same factors revealed that 11 polymorphisms in 11 genes (CAST, CTLA4, F5, GC, GHR, LIPC, PLA2G7, SLC4A1, SLCI8A1, TRH, VWF) showed significant associations with hypertension. Five polymorphisms in five genes, CAST(calpastatin), LIPC (hepatic lipase), SLC4A1 (band 3 anion transporter), TRH (thyrotropin-releasing hormone), and VWF (von Willebrand factor), were significantly associated with both blood pressure variation and hypertension. Thus, our study suggests that these five genes were susceptibility genes for essential hypertension in this Japanese population.

OBJECTIVE

To examine the contribution of the CTLA4 gene in the susceptibility to fulminant type 1 diabetes and compare it with classic type 1A diabetes.

METHODS

We genotyped the +49G>A and CT60G>A variants of the CTLA4 gene in fulminant type 1 diabetic patients (n = 55), classic type 1A diabetic patients (n = 91), and healthy control subjects (n = 369). We also assessed serum levels of the soluble form of CTLA4 (sCTLA4).

RESULTS

The +49GG and CT60GG genotypes were associated with type 1A diabetes (P < 0.001). In contrast, the CT60AA genotype, but not the +49G>A variation, was associated with fulminant type 1 diabetes (P < 0.05), especially in patients carrying HLA-DR4 (P < 0.01). Serum levels of sCTLA4 were significantly decreased in patients with fulminant type 1 diabetes (P < 0.05).

CONCLUSIONS

These results suggest that CTLA4 CT60 affects the genetic susceptibility to fulminant type 1 diabetes. Furthermore, the contribution of CTLA4 to disease susceptibility is distinct between fulminant type 1 diabetes and classic type 1A diabetes.

Vitiligo is a common skin disorder characterized by patterned depigmentation, because of a decrease of melanin pigment resulting from apparent melanocyte loss. The aim of this study was to investigate interleukin 4 (IL4), Angiotensin Converting Enzyme (ACE), C-C Chemocine Receptor 5 (CCR5), Cytotoxic T Lymphocyte-associated Antigen Receptor 4 (CTLA4) and Interleukin 1 Receptor Antagonist (IL1-RN) gene polymorphisms in 48 Turkish vitiligo patients and 50 healthy controls. Polymorphisms for the genes ACE insertion(I)/deletion(D), CCR5 (Delta32), IL1-RN (VNTR in intron 2) were detected by PCR methods. IL4 (-590) and CTLA4 (+49) gene polymorphisms were typed using PCR-RFLP methods. No significant differences in either the genotype distribution or allele frequencies of IL4, CCR5 and ACE gene polymorphisms were observed. GG genotype and G allele in CTLA4 genes were found to be significantly higher in vitiligo patients compared to the controls. (0.002, 0.000). CTLA4 (AA) and IL1-RN (1/5) genotypes and 5 allele frequency in the IL1-RN gene were found to be significantly lower in vitiligo patients compared to healthy controls (p: 0.014, 0.015, 0.016, respectively). As a conclusion, CTLA4 and IL1-RN genes might play roles in the genetic etiology of vitiligo.

Autism has a strong and complex genetic component, involving several genes. Genomic screens, including our own, have shown suggestive evidence for linkage over a 20-30 cM region on chromosome 2q31-q33. Two subsequent reports showed that the linkage evidence increased in the subset of families with phrase speech delay (PSD), defined as onset of phrase speech later than 3 years of age. To further investigate the linkage in the presumptive candidate region, microsatellite markers in a 2 cM grid covering the interval from 164 to 203 cM were analyzed in 110 multiplex (2 or more sampled autism patients) families. A maximum heterogeneity LOD (HLOD) score of 1.54 was detected at D2S1776 (173 cM) in the overall dataset (dominant model), increasing to 1.71 in the PSD subset. While not conclusive, these data continue to provide suggestive evidence for linkage, particularly considering replication by multiple independent groups. Positive LOD scores extended over the entire region, continuing to define a broad candidate interval. Association studies were performed on several functional candidates mapping within the region. These included GAD1, encoding GAD67, whose levels are reduced in autopsy brain material from autistic subjects, and STK17B, ABI2, CTLA4, CD28, NEUROD1, PDE1A, HOXD1 and DLX2. We found no evidence for significant allelic association between autism and any of these candidates, suggesting that they do not play a major role in the genetics of autism or that substantial allelic heterogeneity at any one of these loci dilutes potential disease-allele association.

Tolerance-inducing strategies that infuse donor bone marrow cells in conjunction with costimulation blockade have not been applied to intestinal transplantation. Intestines from BALB/c mice were transplanted into C57BL/6 recipients treated with anti-CD40L mAb, CTLA4-Ig, donor bone marrow, and busulfan. The majority of mice transplanted after completion of this regimen developed hematopoietic macrochimerism, although the degree of chimerism varied widely between recipients, and experienced long-term allograft survival. T cells from these mice demonstrated donor-specific hyporesponsiveness in vitro. However, T cells from chimeric mice proliferated to donor alloantigen in vivo. Furthermore, chimeric mice bearing intestinal allografts were capable of rejecting subsequently placed donor-strain skin grafts. These data suggest that although long-term allograft survival occurs in the absence of acute or chronic rejection, recipient mice are not completely unresponsive to donor alloantigens. When intestinal transplantation was performed at the time of initial bone marrow infusion (initiation of the chimerism protocol), most recipients failed to develop chimerism and promptly rejected the intestinal allograft. Although this is the most effective protocol that we have tested using this stringent model of transplantation, our observations suggest that modifications will be necessary before it can be reliably applied to the transplantation of highly immunogeneic organs like the intestine.

BACKGROUND

Cytokines and T cell regulatory proteins play an important role in the pathogenesis of Wegener's granulomatosis (WG).

OBJECTIVE

To investigate cytokine and cytotoxic T cell antigen-4 (CTLA4) gene polymorphisms and HLA class II alleles in generalised WG.

METHODS

The distribution of cytokine and cytotoxic T cell antigen 4 (CTLA4) gene polymorphisms and HLA class II alleles was analysed in 32 patients with generalised WG and 91 healthy controls. Genotyping was carried out for HLA-DRB1 and HLA-DQB1 and for polymorphism of the genes encoding TNF alpha (-238, -308, -376), TGF beta (codon 10 and 25), IFN gamma (+874), IL6 (-174), IL10 (-592, -819, -1082), CTLA4 (-318, +49), and the (AT)(n) repeats of the CTLA4 gene. In addition, stratification analysis was carried out according to the presence (n = 15) or absence (n = 17) of end stage renal disease.

RESULTS

An increase in the IFN gamma +874 T/T (odds ratio (OR) = 3.14) and TNF alpha -238 G/A (OR = 5.01) genotypes was found in WG patients. When ESRD positive and negative patients were compared, the IFN gamma +874 A/A and the CTLA4 -318 C/C genotypes were found more often in the ESRD subgroup (OR = 10.6 and OR = 2.25). WG patients without ESRD had a higher frequency of the IL10 GCC/ACC promotor genotype (OR = 0.13) and long CTLA4 (AT)(n) repeats (OR = 0.4). No effect was seen for HLA-DR and -DQ markers.

CONCLUSIONS

Disease susceptibility and clinical course in WG may be associated with distinct polymorphisms of cytokine and CTLA4 genes.

The presence of CD28(-) memory CD8 T cells in the peripheral blood of renal transplant patients is a risk factor for graft rejection and resistance to CTLA-4Ig induction therapy. In vitro analyses have indicated poor alloantigen-induced CD28(-) memory CD8 T cell proliferation, raising questions about mechanisms mediating their clonal expansion in kidney grafts to mediate injury. Candidate proliferative cytokines were tested for synergy with alloantigen in stimulating CD28(-) memory CD8 T cell proliferation. Addition of IL-15, but not IL-2 or IL-7, to co-cultures of CD28(-) or CD28(+) memory CD8 T cells and allogeneic B cells rescued proliferation of the CD28(-) and enhanced CD28(+) memory T cell proliferation. Proliferating CD28(-) memory CD8 T cells produced high amounts of interferon gamma and tumor necrosis factor alpha and expressed higher levels of the cytolytic marker CD107a than CD28(+) memory CD8 T cells. CTLA-4Ig inhibited alloantigen-induced proliferation of CD28(+) memory CD8 T cell proliferation but had no effect on alloantigen plus IL-15-induced proliferation of either CD28(-) or CD28(+) memory CD8 T cells. These results indicate the ability of IL-15, a cytokine produced by renal epithelial during inflammation, to provoke CD28(-) memory CD8 T cell proliferation and to confer memory CD8 T cell resistance to CTLA-4Ig-mediated costimulation blockade.

OBJECTIVE

Colorectal cancer is a major health problem. Colonoscopic colorectal cancer screening is cumbersome and expensive. Identification of genetic risk of colorectal cancer may help to select the subjects who could benefit from colonoscopy. The immune system plays a fundamental role in the human-environment interaction, and the carcinogenic effects of many environmental factors are mediated by the chronic activation of the immune system in a genetic-controlled fashion. Cytotoxic T lymphocyte associated antigen 4 (CTLA4) plays an inhibitory role in regulating lymphocyte functions. The loss of CTLA4 function is responsible for loss of mucosal lymphocyte tolerance. The G allele at position +49 of exon 1 of the CTLA4 gene affects the CTLA4 function. We evaluated in an association study the role of CTLA4 A+49G polymorphism as a risk factor for colorectal neoplasm.

METHODS

Five hundred and fifty-six patients (male 295; female 261) who underwent colonoscopy at our Centre were enrolled in the study and divided into three groups: Colorectal cancer (132 patients, M/F 68/64, mean age 66+/-11 years); Colorectal adenoma (186 patients, M/F 110/76, mean age 65+/-11 years); Healthy controls (238 patients, M/F 117/121, mean age 63+/-10 years). DNA was extracted from peripheral blood, CTLA4 gene was amplified by using specific primers, and A+49G polymorphism was analysed by restriction enzyme digestion.

RESULTS

No statistically significant differences in the genotype distribution among Control and Adenoma groups (p=0.93), Control and Carcinoma groups (p=0.52), and Adenoma and Carcinoma groups (p=0.53) were observed.

CONCLUSIONS

There is no significant correlation between CTLA4 A+49G polymorphism and the risk of colorectal neoplasm among Italian Caucasians.

BACKGROUND

The effects on cell signalling networks upon blockade of cytotoxic T lymphocyte-associated antigen-4 (CTLA4) using the monoclonal antibody tremelimumab were studied in peripheral blood mononuclear cell (PBMC) samples from patients with metastatic melanoma.

RESULTS

Findings Intracellular flow cytometry was used to detect phosphorylated (p) signaling molecules downstream of the T cell receptor (TCR) and cytokine receptors. PBMC from tremelimumab-treated patients were characterized by increase in pp38, pSTAT1 and pSTAT3, and decrease in pLck, pERK1/2 and pSTAT5 levels. These changes were noted in CD4 and CD8 T lymphocytes but also in CD14 monocytes. A divergent pattern of phosphorylation of Zap70, LAT, Akt and STAT6 was noted in patients with or without an objective tumor response.

CONCLUSIONS

The administration of the CTLA4-blocking antibody tremelimumab to patients with metastatic melanoma influences signaling networks downstream of the TCR and cytokine receptors both in T cells and monocytes. The strong modulation of signaling networks in monocytes suggests that this cell subset may be involved in clinical responses to CTLA4 blockade.

BACKGROUND

clinicaltrials.gov; Registration numbers NCT00090896 and NCT00471887.

Canine diabetes is a complex genetic disease of unknown aetiology. It affects 0.005-1.5% of the canine population and shows a clear breed predisposition with the Samoyed being at high risk and the Boxer being at low risk of developing the disease. Canine diabetes is considered to be a disease homologue for human type 1 diabetes (T1D). It results in insulin deficiency as a consequence of autoimmune destruction of islet beta-cells in the pancreas and is believed to be mediated by Th1 cytokines (IFNgamma, TNFalpha, and IL-2). A number of genes have been associated with type 1 diabetes in humans, including the human leukocyte antigen region, the insulin variable number tandem repeat, PTPN22, CTLA4, IL-4, and IL-13. As yet, these genes have not been evaluated in canine diabetes. In this study, 483 cases of canine diabetes and 869 controls of known breed were analyzed for association with IFNgamma, IGF2, IL-10, IL-12beta, IL-6, insulin, PTPN22, RANTES, IL-4, IL-1alpha and TNFalpha. Minor allele frequencies were determined for these genes in each breed. These data were used for comparative analyses in a case-control study, and clear associations with diabetes were identified in some breeds with certain alleles of candidate genes. Some associations were with increased susceptibility to the disease (IFNgamma, IL-10, IL-12beta, IL-6, insulin, PTPN22, IL-4, and TNFalpha), whereas others were protective (IL-4, PTPN22, IL-6, insulin, IGF2, TNFalpha). This study demonstrates that a number of the candidate genes previously associated with human T1D also appear to be associated with canine diabetes and identifies an IL-10 haplotype which is associated with diabetes in the Cavalier King Charles Spaniel. This suggests that canine diabetes is an excellent comparative and spontaneously occurring disease model of human T1D.

The Idd5 locus for autoimmune diabetes in nonobese diabetic (NOD) mice has been mapped to the proximal half of chromosome 1 and appears to include two loci, Idd5.1 and Idd5.2, Idd5.1 being a candidate homolog of the human IDDM12 locus. Using new recombinant congenic lines, we have reduced the Idd5.1 interval to 5 cM at most, between D1Mit279 and D1Mit19 (not included). This interval now excludes the Casp8 and Cflar (Flip) candidate genes. It still retains Cd28 and Ctla4 and also includes Icos (inducible costimulator). The previously reported differential expression of Ctla4, which is induced at a lower level in NOD than in B6-activated T-cells, was found independent of Idd5.1 itself because Ctla4 expression was induced at a low level in T-cells from Idd5.1-congenic mice. The Idd5.1 locus protected against both spontaneous and cyclophosphamide-induced diabetes, but it did not prevent inflammatory infiltration of the islets of Langerhans. Furthermore, diabetogenic precursor spleen cells from prediabetic NOD and Idd5.1-congenic mice were equally capable of transferring diabetes to immunodeficient NOD.scid/scid recipient mice. The Idd5.1 locus might affect a late event of disease development, subsequent to the onset of insulitis and possibly taking place in the islets of Langerhans.

CTLA-4 is a potent inhibitor of T cell activation, primarily upon binding to its costimulatory ligands (B7.1 and B7.2) expressed on APCs. However, variants of CTLA-4 can also function independently of B7 molecules. 1/4CTLA-4 is a highly conserved isoform encoded by exons 1 and 4 of the Ctla4 gene that lacks the ligand-binding and the transmembrane domains, and as yet, its function is not known. To investigate the function of 1/4CTLA-4, we generated transgenic (Tg) mice overexpressing this variant. Cytokine production by 1/4CTLA-4 Tg T cells was elevated compared with wild type T cells. The frequency of CD44(high) memory T cells in 1/4CTLA-4 Tg mice was increased, and as the mice aged, the frequency further increased. 1/4CTLA-4 Tg mice >1 y old had increased expression of T cell activation markers and developed spontaneous autoimmunity, including elevated production of autoantibodies. In contrast with young 1/4CTLA-4 Tg mice, aged 1/4CTLA-4 Tg mice had elevated frequencies of Foxp3(+) regulatory T cells, but the regulatory T cells from these mice were not able to inhibit colitis development. Collectively, these data suggest that the function of the 1/4CTLA-4 isoform is distinct from that of CTLA-4 in that it enhances T cell activation and promotes autoimmunity rather than inhibiting immune responses.

Atopic allergic asthma is characterized by activation of Th2-type T cells in the bronchial mucosa. Previous reports have suggested an important role for costimulation through the CD28/CTLA4-CD80/CD86 pathway in allergen activation of T cells in animal models of inhaled allergen challenge. However, human allergen-specific lines and clones were reported to be costimulation independent. We therefore examined CD80 and CD86 dependence of allergen-induced T cell proliferation and cytokine production in peripheral blood and bronchoalveolar lavage from atopic asthmatic subjects and controls. Both allergen-induced proliferation and IL-5 production from PBMC were inhibited by CTLA4-Ig fusion protein and anti-CD86, but not anti-CD80 mAbs. When allergen-specific CD4+ T cell lines from peripheral blood were examined, proliferation and cytokine production were found to be independent of CD80 or CD86 costimulation. However, when cells obtained directly from the airways were examined, allergen-induced proliferation of bronchoalveolar lavage T cells from atopic asthmatic subjects was inhibited by anti-CD86 but not anti-CD80. In addition, bronchoalveolar lavage-adherent cells from asthmatic, but not control subjects showed APC activity to autologous T cells. This was also inhibited by anti-CD86 but not anti-CD80. Thus allergen-induced T cell activation and IL-5 production in the airway in asthmatic subjects is susceptible to blockade by agents interfering with costimulation via CD86, and this may hold therapeutic potential in asthma.

Autoimmune thyroid disease (AITD) is a multifactorial disease in which autoimmunity against thyroid antigens develops against a particular genetic background facilitated by exposure to environmental factors. Immunogenicity of the major thyroid antigens thyroid peroxidase, thyroglobulin (TG) and thyrotropin receptor (TSHR) is increased by genetic polymorphisms, a high number of antigenic peptides available for binding to human leukocyte antigen (HLA), and a high degree of glycosylation. Antigens bound to HLA are presented by antigen-presenting cells to T cell receptors. Further interaction between both cells is required via binding of CD40 ligand to CD40 and of B7-1/2 to CD28 for activation of T cells. Complex regulatory mechanisms serve to prevent an immune response directed against 'self'-antigens in the thymus (central tolerance) and in peripheral tissues (peripheral tolerance) with the help of regulatory T cells. Breakdown of tolerance to thyroid antigens can result in thyroid autoimmunity, which may happen in subjects who have the wrong genes and who are exposed to the wrong environment. Polymorphisms in thyroid genes (TG, TSHR) and immunoregulatory genes (HLA, CTLA4, PTPN22, CD40, FCRL3, IL2RA, FOXP3) would contribute for about 70% to AITD, and environmental exposures (like iodine, smoking, infections, parity) for the remaining 30%. Thyroid-infiltrating activated T cells may lead to cell-mediated immunity, thyroid injury and eventually hypothyroidism, whereas humoral immunity via TSHR-stimulating antibodies may give rise to hyperthyroidism. Pediatric Hashimoto's and Graves' disease are less prevalent than in adults, and the female preponderance is also less marked in children. The discrepancy is probably due to relatively less involvement of environmental insults in children, whereas the prevalence of risk alleles in AITD children is higher than in AITD adults.

The autoimmune response is executed via cognate interactions between effector immune cells and antigen presenting cells. Cognate interactions provide the immune effectors with specific signals generated through the antigen receptor as well as with second, non-specific signals, generated from the interaction of pairs of cell-surface molecules (costimulatory molecules) present on their plasma membrane. Disruption of this second, non-specific costimulatory signal results in the interruption of the productive (auto)immune response, leading to anergy, a state of immune unresponsiveness. The CD28:B7 families of molecules and the CD40:CD40L pair of molecules are considered as critical costimulatory elements. Disruption of the CD28:B7 interaction using a genetically engineered soluble form of the inhibitory molecule CTLA4 in vitro, as well as in experimental models of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), led to the inhibition of the autoimmune response. Similarly, promising data stem from the use of an anti-CD40L monoclonal antibody (mAb) in murine SLE. While such treatments prevent the development of autoimmunity in animal models, this preventive approach is inapplicable to human diseases. However, the rational bench-to-bedside approach led investigators to clinical trials of CTLA4-Ig and of two different humanized anti-human CD40L mAbs in patients with RA and SLE, respectively. Initial experience with the use of CTLA4-Ig in patients with RA is encouraging, since in one short-term trial the construct was well-tolerated and produced clinically meaningful improvement of the disease in a significant proportion of those treated. Surprisingly, the anti-CD40L mAb treatment approach in human lupus was not fruitful, since short-term administration of the anti-CD40L mAb ruplizumab in lupus nephritis was correlated with life-threatening prothrombotic activity despite initial encouraging data in the serology and renal function of the patients. Also, IDEC-131 anti-CD40L mAb treatment did not prove to be clinically effective in human SLE, despite being well tolerated. Precise tailoring of the administration schemes for these novel therapeutic modalities is awaited.Finally, conceptually different approaches to block costimulation by inhibiting the induced expression of costimulatory molecules or the transmission of their specific intracytoplasmic signal have already produced encouraging preliminary results.

Type 1 diabetes (T1D) is a polygenic autoimmune disease. Susceptibility to T1D is strongly linked to a major genetic locus that is the major histocompatibility complex (MHC) and several other minor loci including insulin, CTLA4 that contribute to diabetes risk in an epistatic way. MHC harbours genes whose primary function is to govern immune responsiveness. Being the most polymorphic genomic region known in humans, MHC serves as a very exciting minigenome model for studying susceptibility to T1D. We have observed enormous diversity in HLA class I and class II genes in the north Indian population and identified several 'novel alleles' and 'unique haplotypes'. For example, multiple DR3+ve autoimmunity favouring haplotypes have been identified, some of which are unique to the Asian north Indian T1D patients. Our molecular studies have revealed that (i) the classical Caucasian autoimmunity favouring AH8.1 (HLA-A1 B8 DR3) is rare in the Indian population and has been replaced by a variant AH8.1v that differs from the Caucasian AH8.1 at several gene loci, (ii) AH8.2 (HLA-A26 B8 DR3) is the most common DR3 positive haplotype in this population and resembles the Indian AH8.1v rather than Caucasian AH8.1, and (iii) there are additional HLA-DR3 haplotypes HLA-A24 B8 DR3 (AH8.3), A3 B8 DR3 (AH8.4) and A31 B8 DR 3 (AH 8.5) that occur in the Indian population. The studies have led to a hypothesis that AH8.1 and AH8.1v might have co-evolved from a common ancestor but preferential divergence of AH8.2 over AH8.1 leading to survival advantage might have been driven by vigorous pathogenic challenges encountered by the Indian population. These studies have important implications in our understanding of disease pathogenesis, identification of high risk individuals, disease diagnosis, disease management and immunological therapeutic approaches.

Blockade of IFN-α but not IFN-β signaling using either an antibody or a selective S1PR1 agonist, CYM-5442, prevented type 1 diabetes (T1D) in the mouse Rip-LCMV T1D model. First, treatment with antibody or CYM-5442 limited the migration of autoimmune "antiself" T cells to the external boundaries around the islets and prevented their entry into the islets so they could not be positioned to engage, kill, and thus remove insulin-producing β cells. Second, CYM-5442 induced an exhaustion signature in antiself T cells by up-regulating the negative immune regulator receptor genes Pdcd1, Lag3, Ctla4, Tigit, and Btla, thereby limiting their killing ability. By such means, insulin production was preserved and glucose regulation maintained, and a mechanism for S1PR1 immunomodulation described.