No abstract

No abstract

Lsr2 protein of Mycobacterium leprae was shown earlier to elicit B and T cell responses in leprosy patients (20, 28). Lymphoproliferation to M. leprae and Lsr2 antigens was observed in >70% of tuberculoid (T) patients and in 16 and 34% of lepromatous (L) patients, respectively. We focused on the M. leprae nonresponders in the lepromatous group using 22 synthetic Lsr2 peptides (end-to-end peptides A to F and overlapping peptides p1 to p16) in in vitro T cell responses. A total of 125 leprosy and 13 tuberculosis patients and 19 healthy controls from the area of endemicity (here, healthy controls, or HC) were investigated. The highest responses were observed (67 to 100%) in HC for all peptides except p1 to p3, and the lowest was observed in tuberculosis patients. Significant differences in lymphoproliferation were observed in T, L, and HC groups (analysis of variance [ANOVA], P ‫؍‬ 0.000 to 0.015) for all end-to-end peptides except B and for p5 and p7 to p10. Hierarchical recognition between lepromatous and tuberculoid leprosy was noted for p8 (P < 0.05) and between the HC and L groups for p7 to p10, p15, and p16 (P < 0.005 to P < 0.02). Significant lymphoproliferation was observed to peptides A to F and p1 to p9, p11, p12, p15, p16 (P ‫؍‬ 0.000 to 0.001) with 40% responding to peptides C and p16 in L patients. Lepromatous patients also showed significantly higher levels of a gamma interferon (IFN-␥) response to peptide C than to other peptides (P < 0.05). Major histocompatibility complex (MHC) class II bias for peptide recognition was not observed. These studies indicate that Lsr2 has multiple T cell epitopes that induce in vitro T cell responses in the highly infective lepromatous leprosy patients. Though the prevalence of leprosy has been reduced due to multidrug therapy regimens, the incidence continues to be a public health worry in some countries (40). Leprosy is caused by the noncultivable Mycobacterium leprae and is defined by distinct clinical-pathological types in humans (29), with the paucibacillary localized tuberculoid forms (borderline tuberculoid/tuberculoid [BT/TT]) having good in vitro and in vivo T cell functions and low levels of antibodies. In contrast, the multibacillary generalized lepromatous leprosy patients (borderline leprosy/lepromatous leprosy [BL/LL]) show abundant antibody responses and T cell unresponsiveness unique to the leprosy bacillus and not to other antigenically related mycobacteria such as Mycobacterium tuberculosis. Moreover, 10 to 15% of stable leprosy patients undergo inflammatory episodes of types 1 (reversal reactions [RR]) and 2 (erythema nodosum leprosum [ENL]) which are localized to the lesion or produce systemic signs of fever, joint pains, and skin nodules. The inverse relationship between cellular and humoral immunity as well as the dichotomy in the leprosy types has been intensely investigated (21,30). The mechanisms underlying the antigen-specific anergy are not completely understood as it is long-lasting and not reversed by conventional therapy. Attempts to impr...

Single-nucleotide polymorphisms (SNPs) are implicated in the complexity of understanding the genetics of diseases and their therapeutics. Here we have attempted to determine the impact of nonsynonymous SNPs (nsSNPs) on structure, dynamics, and ligand-binding properties of the human acetylcholinesterase (hAChE) protein, which has been targeted in the treatment of Alzheimer's disease. Of the reported 153 SNPs, 4 nsSNPs, namely, A415G, P104A, V302E, and Y119H, were prioritized to be functionally unfavorable by SIFT and PolyPhen algorithms. Molecular dynamics simulation revealed these nsSNP forms to be structurally stable, and they are also considered functionally active as they lie away from the catalytic triad. However, the aromatic amino acids lining the active-site gorge exhibited altered degrees of side chain dihedral angles. Such conformational alterations were evaluated for their ability to interfere with binding of hAChE inhibitors. The inhibitors (donepezil, galantamine, rivastigmine, and tacrine) were oriented differently in comparison to the native because of the steric hindrance offered by the altered dihedral angles. Interestingly, huperzine A alone exhibited higher efficiency in its binding to the AChE and retained similar orientation irrespective of the polymorphisms since the orientation of Asp74 involved in its binding and trafficking remained unaltered in all protein forms. Therefore, we conclude that nsSNPs confer changes to the dynamicity of proteins, which in turn affects their ligand-binding properties rather than their stability. Considering the diverse polymorphic nature of hAChE, while contemplating any structure-based drug design, the common, nonpathogenic nsSNPs should be considered for the utmost efficacy of drugs.