Association of increased risk of asthma with elevated arginase & interleukin-13 levels in serum & rs2781666 G/T genotype of arginase I.

BACKGROUND & OBJECTIVES: High expression of arginase gene and its elevated level in serum and bronchial lavage reported in animal models indicated an association with the pathogenesis of asthma. This study was undertaken to assess the serum arginase activity in symptomatic asthma patients and healthy controls and to correlate it with cytokine levels [interleukin (IL)-4 and IL-13] and arginase I (ARG1) gene polymorphism. METHODS: Asthma was confirmed by lung function test according to the GINA guidelines in patients attending Allergy and Pulmonology Clinic, Bhagwan Mahavir Hospital and Research Centre, Hyderabad, India, a tertiary care centre, during 2013-2015. Serum arginase was analyzed using a biochemical assay, total IgE and cytokine levels by enzyme-linked immunosorbent assay and genotyping of ARG1 for single-nucleotide polymorphisms (SNPs) rs2781666 and rs60389358 using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. RESULTS: There was a significant two-fold elevation in the arginase activity in asthmatics as compared to healthy controls which correlated with disease severity. Non-atopic asthmatics showed elevated activity of arginase compared to atopics, indicating its possible role in intrinsic asthma. Levels of serum IL-13 and IL-4 were significantly high in asthma group which correlated with disease severity that was assessed by spirometry. A positive correlation was observed between arginase activity and IL-13 concentration. Genetic analysis of ARG1 SNPs revealed that rs2781666 G/T genotype, T allele and C-T haplotype (rs60389358 and rs2781666) were associated with susceptibility to asthma. INTERPRETATION & CONCLUSIONS: This study indicated that high arginase activity and IL-13 concentration in the serum and ARG1 rs2781666 G/T genotype might increase the risk of asthma in susceptible population. Further studies need to be done with a large sample to confirm these findings.

Influence of Intron II microsatellite polymorphism in human toll-like receptor 2 gene in leprosy.

Leprosy is a chronic granulomatous infection caused by the obligate intracellular organism Mycobacterium leprae. TLR2 plays a key role when activated by M. leprae lipoproteins initiating protective responses which induce bacterial killing and therefore control of disease spread. Microsatellite polymorphisms in intron2 of TLR2 gene have been reported to be associated with development of clinical features of several infectious diseases. The study aims to evaluate the influence of GT microsatellite on the expression of TLR2 which could make humans prone to M. leprae infections. A total of 279 individuals were enrolled in the study, 88 were leprosy patients, 95 were house hold contacts (HHC) and 96 were healthy controls (HC). Genotyping was done using PCR-Sequencing method. TLR2 mRNA expression was analyzed by RT-PCR. IL-10 and IFN-γ levels were measured using ELISA in MLSA stimulated cell culture supernatants. Statistical analysis was performed using Chi-Square (χ(2)) test and t-tests. Allele/genotype of TLR2 microsatellite which includes longer GT repeats was associated with low TLR2 mRNA expression and high IL-10 production while that including shorter GT repeats was associated with high TLR2 mRNA expression and low IL-10 production. High IL10 producing allele of TLR2 microsatellite might predispose house hold contacts to leprosy.

Indirect recognition and antibody production against a single mismatched HLA-A2-transgenic molecule precede the development of obliterative airway disease in murine heterotopic tracheal allografts.

BACKGROUND: Previous studies have implicated the allogeneic immune response in the development of obliterative bronchiolitis after lung transplantation. However, the progression of specific pathogenic events leading to this form of chronic allograft dysfunction have not been well characterized. We used a murine tracheal transplantation model in which a single mismatched HLA-A2-transgenic molecule is indirectly recognized by the recipient CD4(+) T cells to show that obliterative airway disease (OAD) that developed in these allografts was preceded by indirect recognition of the HLA-A2 molecule and subsequent development of anti-HLA-A2 antibodies. METHODS: Tracheas from HLA-A2(+) C57BL/6 mice were heterotopically transplanted into C57BL/6 mice. Allograft histopathology as well as anti-HLA-A2 T-cell proliferative responses and anti-HLA-A2 antibody development were determined at days 5, 10, 20, and 28 after transplantation. RESULTS: All of the HLA-A2(+) tracheal allografts transplanted into C57BL/6 recipients demonstrated complete development of OAD by day 20. Spleen cells from the mice that underwent transplantation demonstrated significant proliferation against HLA-A2(+) cells by day 5. Indirect recognition of HLA-A2-derived peptides by spleen cells from allograft recipients was also higher on days 5 and 10 as compared with irrelevant peptides derived from HLA-A1, HLA-A3, and HLA-B44. Allograft recipients showed detectable levels of anti-HLA-A2 antibodies by day 5 and full development of anti-HLA-A2 antibodies by day 20. CONCLUSION: These results show that sensitization of CD4+ T cells against the mismatched HLA-A2 alloantigen precedes the development of anti-HLA antibodies as well as OAD, suggesting an important role for alloreactive CD4(+) T-cell activation and alloantibody development in the immunopathogenesis of OAD.