Molecular characterization of Enterococcus faecalis isolates from urinary tract infection and interaction between Enterococcus faecalis encountered Dendritic and Natural Killer cells.

PURPOSE: Enterococcus faecalis is an emerging nosocomial pathogen. The study investigates the E. faecalis specific innate immune cells interplay between Natural Killer cells (NK) and Dendritic cells (DCs) in vitro. The present study also determines the prevalence, phenotype, and genotype of Enterococcus faecalis isolated from paediatric patients with urinary tract infection. MATERIALS AND METHODS: A total of 14 clinical isolates of Enterococcus spp were characterized using standard phenotypic tests and virulence factors were determined by polymerase chain reaction (PCR). Immature monocyte-derived DCs were cultured in the presence of six pathogenic E. faecalis isolates infected DCs were co-cultured with NK cells. Bacteria induced matured DCs and activated NK cells were evaluated by polychromatic flow cytometry. RESULTS: Out of 14 isolates, 13 were identified as E. faecalis. E. faecalis infected DCs differentiated into inflammatory and CD141 + DCs that promote NK cell activation. Activated NK cells significantly elevated the secretion of cytokines and chemokines in infected DCs during E. faecalis. This suggests that DC induced NK cell activation is effectively enhanced by the presence of E. faecalis. CONCLUSIONS: Studies on virulence determinants are necessary to understand the pathogenesis of E. faecalis. DC/NK cross-talk is of particular importance at mucosal surfaces such as the intestine, urinary tract where the immune system exists in intimate association with commensal bacteria. We found E. faecalis specific NK cells activation by infected DC-derived effector signals may involve in the killing of transformed or infected cells, thus coordinating innate and adaptive immune responses. E. faecalis specific DC/NK interaction is necessary for DC maturation and modulation of innate effector functions. Similarly, activated NK cells that induce- maturation of DC by pattern recognition receptors are also required for the generation of bacterial specific adaptive immunity.

Elevated Numbers of HIV-Specific Poly-Functional CD8+ T Cells With Stem Cell-Like and Follicular Homing Phenotypes in HIV-Exposed Seronegative Individuals.

HIV-specific CD8+ T cells are known to play a key role in viral control during acute and chronic HIV infection. Although many studies have demonstrated the importance of HIV-specific CD8+ T cells in viral control, its correlation with protection against HIV infection remains incompletely understood. To better understand the nature of the immune response that contributes to the early control of HIV infection, we analyzed the phenotype, distribution and function of anti-viral CD8+ T cells in a cohort of HIV-exposed seronegative (HESN) women, and compared them with healthy controls and HIV-infected individuals. Further, we evaluated the in vitro viral inhibition activity of CD8+ T cells against diverse HIV-1 strains. We found that the HESN group had significantly higher levels of CD8+ T cells that express T-stem cell-like (TSCM) and follicular homing (CXCR5+) phenotype with more effector like characteristics as compared to healthy controls. Further, we observed that the HESN population had a higher frequency of HIV-specific poly-functional CD8+ T cells with robust in vitro virus inhibiting capacity against different clades of HIV. Overall, our results demonstrate that the HESN population has elevated levels of HIV-specific poly-functional CD8+ T cells with robust virus inhibiting ability and express elevated levels of markers pertaining to TSCM and follicular homing phenotype. These results demonstrate that future vaccine and therapeutic strategies should focus on eliciting these critical CD8+ T cell subsets.

Binding property of HIV p24 and Reverse transcriptase by chalcones from Pongamia pinnata seeds.

HIV remains a challenging life threatening viral agent for humans despite available anti HIV drugs. The known effective drug named HAART clears the circulating viruses but not the intracellular viruses. Therefore, it is of interest to identify molecules with improved anti-HIV activity from natural plant sources. Hence, we studied the anti-HIV potency of an Indian medicinal plant named Pongamia pinnata. Aqueous extracts were made from leaf, seed and roots of Pongmia pinnata and screened for anti HIV-1 activity using HIV-1 p24 and reverse transcriptase (RT) inhibition assays. Further, the active chalcone derivatives namely, P24 protein and RT enzymes showed promising binding score against Glabarachalcone and Karanijin. Among these extracts, P. pinnta aqueous seed extracts have shown HIV-1 p24 inhibition at 66.9 ± 4.4 percentage. However, RT inhibition assay showed only 36.8%. Hence, the HIV-1 p24 inhibition infers either the prevention of virus entry or inhibits other enzymes and or interferes with virion assembly.