No abstract

Rheumatoid arthritis (RA) is the most common systemic autoimmune disease, affecting approximately 1% of the adult population worldwide, with an estimated heritability of 60%. To identify genes involved in RA susceptibility, we investigated the association between putative functional single-nucleotide polymorphisms (SNPs) and RA among white individuals by use of a case-control study design; a second sample was tested for replication. Here we report the association of RA susceptibility with the minor allele of a missense SNP in PTPN22 (discovery-study allelic P=6.6 x 10(-4); replication-study allelic P=5.6 x 10(-8)), which encodes a hematopoietic-specific protein tyrosine phosphatase also known as "Lyp." We show that the risk allele, which is present in approximately 17% of white individuals from the general population and in approximately 28% of white individuals with RA, disrupts the P1 proline-rich motif that is important for interaction with Csk, potentially altering these proteins' normal function as negative regulators of T-cell activation. The minor allele of this SNP recently was implicated in type 1 diabetes, suggesting that the variant phosphatase may increase overall reactivity of the immune system and may heighten an individual carrier's risk for autoimmune disease.

We performed a multitiered, case-control association study of psoriasis in three independent sample sets of white North American individuals (1,446 cases and 1,432 controls) with 25,215 genecentric single-nucleotide polymorphisms (SNPs) and found a highly significant association with an IL12B 3'-untranslated-region SNP (rs3212227), confirming the results of a small Japanese study. This SNP was significant in all three sample sets (odds ratio [OR](common) 0.64, combined P [Pcomb]=7.85x10(-10)). A Monte Carlo simulation to address multiple testing suggests that this association is not a type I error. The coding regions of IL12B were resequenced in 96 individuals with psoriasis, and 30 additional IL12B-region SNPs were genotyped. Haplotypes were estimated, and genotype-conditioned analyses identified a second risk allele (rs6887695) located approximately 60 kb upstream of the IL12B coding region that exhibited association with psoriasis after adjustment for rs3212227. Together, these two SNPs mark a common IL12B risk haplotype (OR(common) 1.40, Pcomb=8.11x10(-9)) and a less frequent protective haplotype (OR(common) 0.58, Pcomb=5.65x10(-12)), which were statistically significant in all three studies. Since IL12B encodes the common IL-12p40 subunit of IL-12 and IL-23, we individually genotyped 17 SNPs in the genes encoding the other chains of these cytokines (IL12A and IL23A) and their receptors (IL12RB1, IL12RB2, and IL23R). Haplotype analyses identified two IL23R missense SNPs that together mark a common psoriasis-associated haplotype in all three studies (OR(common) 1.44, Pcomb=3.13x10(-6)). Individuals homozygous for both the IL12B and the IL23R predisposing haplotypes have an increased risk of disease (OR(common) 1.66, Pcomb=1.33x10(-8)). These data, and the previous observation that administration of an antibody specific for the IL-12p40 subunit to patients with psoriasis is highly efficacious, suggest that these genes play a fundamental role in psoriasis pathogenesis.

Protective immunity against Mycobacterium tuberculosis requires the generation of cell-mediated immunity. We investigated the expression and role of programmed death 1 (PD-1) and its ligands, molecules known to modulate T cell activation, in the regulation of IFN-γ production and lytic degranulation during human tuberculosis. We demonstrated that specific Ag-stimulation increased CD3+PD-1+ lymphocytes in peripheral blood and pleural fluid from tuberculosis patients in direct correlation with IFN-γ production from these individuals. Moreover, M. tuberculosis-induced IFN-γ participated in the up-regulation of PD-1 expression. Blockage of PD-1 or PD-1 and its ligands (PD-Ls: PD-L1, PD-L2) enhanced the specific degranulation of CD8+ T cells and the percentage of specific IFN-γ-producing lymphocytes against the pathogen, demonstrating that the PD-1:PD-Ls pathway inhibits T cell effector functions during active M. tuberculosis infection. Furthermore, the simultaneous blockage of the inhibitory receptor PD-1 together with the activation of the costimulatory protein signaling lymphocytic activation molecule led to the promotion of protective IFN-γ responses to M. tuberculosis, even in patients with weak cell-mediated immunity against the bacteria. Together, we demonstrated that PD-1 interferes with T cell effector functions against M. tuberculosis, suggesting that PD-1 has a key regulatory role during the immune response of the host to the pathogen.

We tested six single nucleotide polymorphisms (SNPs) in the alpha4 subunit gene (CHRNA4) and four SNPs in the beta2 subunit gene (CHRNB2) of nicotinic acetylcholine receptors (nAChRs) for association with nicotine dependence (ND), which was assessed by smoking quantity (SQ), the heaviness of smoking index (HSI) and the Fagerstrom test for ND (FTND) in 2037 subjects from 602 nuclear families of either European-American (EA) or African-American (AA) ancestry. Analysis of the six SNPs within CHRNA4 demonstrated that in the EA sample SNPs rs2273504 and rs1044396 are significantly associated with the adjusted SQ and FTND score, respectively. In the AA samples, SNPs rs3787137 and rs2236196 are each significantly associated with at least two adjusted ND measures. Association of rs2236196 with the adjusted HSI and FTND scores in the AA samples remained significant after correction for multiple testing. Furthermore, analysis revealed gender- and ethnic-specific associations for several SNPs with ND measures in both ethnic samples; however, only the association of SNP rs2236196 with the three adjusted ND measures remained significant after correcting for multiple testing in the AA female samples. Haplotype analysis of rs2273505-rs2273504-rs2236196 showed significant association after Bonferroni correction of a C-G-G haplotype (53.4%) with three adjusted ND measures in samples from the AA females. A similar analysis for the four SNPs within CHRNB2 did not reveal significant association with the three ND measures. In summary, our findings provide convincing evidence for the involvement of the nAChR alpha4 subunit, but not of the nAChR beta2 subunit, in nicotine addiction.

Th1 lymphocytes are crucial in the immune response against Mycobacterium tuberculosis. Nevertheless, IFN-␥ alone is not sufficient in the complete eradication of the bacteria, suggesting that other cytokines might be required for pathogen removal. Th17 cells have been associated with M. tuberculosis infection, but the role of IL-17-producing cells in human TB remains to be understood. Therefore, we investigated the induction and regulation of IFN-␥ and IL-17 during the active disease. TB patients were classified as High and Low Responder individuals according to their T cell responses against the antigen, and cytokine expression upon M. tuberculosis stimulation was investigated in peripheral blood and pleural fluid. Afterwards, the potential correlation among the proportions of cytokine-producing cells and clinical parameters was analyzed. In TB patients, M. tuberculosis induced IFN-␥ and IL-17, but in comparison with BCG-vaccinated healthy donors, IFN-␥ results were reduced significantly, and IL-17 was markedly augmented. Moreover, the main source of IL-17 was represented by CD4 ϩ IFN-␥ ϩ IL-17 ϩ lymphocytes, a Th1/Th17 subset regulated by IFN-␥. Interestingly, the ratio of antigen-expanded CD4 ϩ IFN-␥ ϩ IL-17 ϩ lymphocytes, in peripheral blood and pleural fluid from TB patients, was correlated directly with clinical parameters associated with disease severity. Indeed, the highest proportion of CD4 ϩ IFN-␥ ϩ IL-17 ϩ cells was detected in Low Responder TB patients, individuals displaying se-vere pulmonary lesions, and longest length of disease evolution. Taken together, the present findings suggest that analysis of the expansion of CD4 ϩ IFN-␥ ϩ IL-17 ϩ T lymphocytes in peripheral blood of TB patients might be used as an indicator of the clinical outcome in active TB.

During development, control of proliferation of neuronal precursor cells plays a crucial role in determining the number of neurons. Proliferation is driven by mitogens, but how it is terminated remains a mystery. In this study, we examined the role of cyclin-dependent kinase inhibitors in the control of proliferation of cerebellar granule cell precursors (GCPs). Among the inhibitors we examined, only p27/Kip1 (p27) was expressed at significant levels in cells of the granule cell lineage in the developing and adult cerebellum. In developing cerebella, p27 was expressed in the external germinal layer (the deeper regions), the molecular layer, and the granule layer. In adult cerebella, p27 was expressed in the cells of the granule layer. We isolated and purified GCPs from cerebella of developing mice and examined their bromodeoxyuridine (BrdU) uptake and p27 expression at various times. We found that there was an inverse correlation between BrdU uptake and p27 expression. Even in the presence of saturating amounts of Sonic hedgehog, a potent mitogen, the cells eventually stopped dividing and differentiated, expressing p27 strongly. We also examined mice in which one or both copies of the p27 gene have been inactivated by targeted gene disruption and found that their cerebella were larger than those of wild-type mice. In cell cultures, GCPs prepared from p27-deficient mice showed enhanced proliferation compared with GCPs from wild-type mice. Taken together, these results suggest that there is an intracellular mechanism that stops GCP division and causes GCPs to differentiate and that p27 is part of this mechanism.

Production of the Th1 cytokine IFN-γ by T cells is considered crucial for immunity against Mycobacterium tuberculosis infection. We evaluated IFN-γ production in tuberculosis in the context of signaling molecules known to regulate Th1 cytokines. Two populations of patients who have active tuberculosis were identified, based on their T cell responses to the bacterium. High responder tuberculosis patients displayed significant M. tuberculosis-dependent T cell proliferation and IFN-γ production, whereas low responder tuberculosis patients displayed weak or no T cell responses to M. tuberculosis. The expression of the signaling lymphocytic activation molecule (SLAM)-associated protein (SAP) on cells from tuberculosis patients was inversely correlated with IFN-γ production in those individuals. Moreover, patients with a nonfunctional SAP gene displayed immune responses to M. tuberculosis similar to those of high responder tuberculosis patients. In contrast to SAP, T cell expression of SLAM was directly correlated with responsiveness to M. tuberculosis Ag. Our data suggest that expression of SAP interferes with Th1 responses whereas SLAM expression contributes to Th1 cytokine responses in tuberculosis. The study further suggests that SAP and SLAM might be focal points for therapeutic modulation of T cell cytokine responses in tuberculosis.