Biomedical subjects

Subhasis Mohanty

Publications and source records attributed to Subhasis Mohanty.

4 recordsLinked to original sources

PubMed2007

Age-associated defect in human TLR-1/2 function.

The effects of aging on human TLR function remain incompletely understood. We assessed TLR function and expression in peripheral blood monocytes from 159 subjects in 2 age categories, 21-30 and >65 years of age, using a multivariable mixed effect model. Using flow cytometry to assess TLR-induced cytokine production, we observed a substantial, highly significant defect in TLR1/2-induced TNF-alpha (p = 0.0003) and IL-6 (p < 0.0001) production, in older adults compared with young controls. In contrast to findings in aged mice, other TLR (including TLR2/6)-induced cytokine production appeared largely intact. These differences were highly significant even after correcting for covariates including gender, race, medications, and comorbidities. This defect in TLR1/2 signaling may result from alterations in baseline TLR1 surface expression, which was decreased by 36% in older adults (p < 0.0001), whereas TLR2 surface expression was unaffected by aging. Production of IL-6 (p < 0.0001) and TNF-alpha (p = 0.003) after stimulation by N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2R,S)-propyl]-Cys-[S]-Ser1-[S]-Lys(4) trihydrochloride was strongly associated with TLR1 surface expression. Diminished TLR1/2 signaling may contribute to the increased infection-related morbidity and mortality and the impaired vaccine responses observed in aging humans.

Adult↗

PubMed2003

Generation of three-dimensional pannus-like tissues in vitro from single cell suspensions of synovial fluid cells from arthritis patients.

Using single cell suspensions from synovial fluid cells of arthritis patients, we observed differentiation of three-dimensional tissues in vitro. This new model of pannus-like tissue (PLT) might be useful to study pannus tissue formation and differentiation. In the PLT cultures, we observed two cell types, fibroblast-like and macrophage-like cells, defined by their distinct morphology and major histocompatibility complex (MHC) by human leukocyte antigen (HLA) class II expression. We could discriminate several intermediate steps of differentiation which finally led to 3D villi-like structures. Secretion of interferon gamma, interleukin-10, and tumor necrosis factor alpha was measured in the culture supernatants. Using methotrexate at various concentrations, the growth of PLT could be inhibited. We describe definite intermediate steps of differentiation. The present approach could be a suitable model for the in vitro study of pannus tissue formation.

Arthritis, Reactive↗

PubMed2003

Human IgG1/IgG3 cryoglobulin suggesting lack of allelic exclusion.

Immunoglobulins undergoing cold-dependent precipitation are known as cryoglobulins. A type I cryoglobulin after Brouet et al. from serum of a patient with severe cutaneous vasculitis and membranoproliferative glomerulonephritis was purified by reversible temperature-dependent precipitation and analyzed using FPLC, Western blotting and peptide sequencing. The isolated cryoglobulin consisted of a single complex of a molecular weight of above 210kDa observed under non-reducing conditions in SDS-polyacrylamide gel electrophoresis (PAGE). Under reducing conditions, this complex resolved into three bands, two of which were reminiscent of Ig heavy (HC) chains and one of Ig-light chains (LC). The FPLC-purified type I cryoglobulin showed reversible precipitation analyzed by spectrophotometry. Delineation of the peptides involved in complex formation by immunoblot analysis and peptide sequencing revealed IgG3-V(H)4/Igkappa-VkappaIII/JkappaII and IgG1/V(H)3 molecules with evidence of somatic mutation. Coomassie blue-staining suggested that molar amounts of the IgG3-heavy chain were much higher than that of the IgG1-heavy chain. Treatment with SDS and boiling did not disrupt the unusually high molecular weight Ig complex. Pre-treatment of the cryoglobulin in 6M guadinium hydrochloride followed by gel filtration chromatography suggested covalent association of the IgG3, IgG1 and Igkappa molecules. Therefore, it might be that the cryoglobulin was produced by a single plasma B cell clone which passed immunological check-points in terms of B cell selection in the bone marrow in the absence of allelic exclusion, class switching and affinity maturation by somatic mutation.

Aged↗

PubMed2002

Transmission of antibody-induced arthritis is independent of complement component 4 (C4) and the complement receptors 1 and 2 (CD21/35).

The K/BxN murine model of rheumatoid arthritis (RA) is dependent on the specificity of the KRN alpha beta-TCR, to recognize glucose-6-phosphate-isomerase (GPI) on the NOD MHC class II A(g7) allele and production of GPI-specific autoantibodies. Transfer of K/BxN serum into MHC-unrelated and lymphocyte-deficient mice induces RA. To investigate whether K/BxN serum-induced RA involves complement activation and/or the complement receptors (CR) 1 and 2, we analyzed the role of complement C4 and of CR1 and CR2. For this purpose we used C4(-/-) mice impaired in the classical and the lectin complement pathways; Cr2(-/-) mice lacking CR1 and CR2 and, as control strains, BALB/c, C57BL/6, KRN and NOD. RA was assessed by caliper measurement of ankle thickness, clinical index and joint histology. We found that all mouse strains except NOD developed RA. The lack of protection in C4(-/-) mice suggests that antibody-mediated RA is independent of the classical as well as the lectin complement pathways and the split complement product C4b. The lack of protection in Cr2(-/-) mice suggests that absence of CR1 had no significant affect, considering its role in immune complex clearance, inhibition of C3 and C5 convertase and as receptor for C3b/C4b. Also, CR2 lacks a role in disease as analyzed here, in its possible functions as receptor for C3dg, germinal center reaction and activation of alternative pathway on binding iC3. Hence we conclude that the transmission of K/BxN serum-induced RA is independent of the classical and the lectin complement pathways and CR1 and CR2. The crucial role of complement C5, while neither classical nor lectin pathway is necessary, indicates that the alternative complement pathway may have a role in the K/BxN serum-induced RA model.

Animals↗