masoumeh beheshti

Epstein-Barr virus (EBV) and Human Herpes virus 6 (HHV-6) are believed to involve in multiple sclerosis (MS) pathogenesis. Natural killer (NK) and CD8+ T cells have essential roles in handling viral infections and their phenotypic and functional properties may be influenced following exposure to viral infections. Here, we investigated the association of NK and CD8+ T cells subpopulations frequency with EBV and HHV-6 viral load in MS patients.

In this case-control study, EBV and HHV-6 viral load were evaluated in plasma of newly diagnosed relapsing-remitting MS (RRMS) patients at relapse phase (n=23), who were not on disease-modifying therapy (DMT), and sex- and age-matched healthy controls (n=19) using real-time polymerase chain reaction (PCR). The frequency of NK and CD8+ T cells subsets were assessed by CD27, CD28, CD45RO, CD56, and CD57 markers using flow cytometry.

Despite the increased level of EBV viral load in RRMS patients compared to the control group, there was no statistically significant difference in EBV and HHV-6 copy numbers between the studied groups. In addition, a significant decrease was observed in the percentages of CD56bright CD57- and CD56dim CD57+ CD8low CD45RO- NK cells in RRMS patients in comparison to healthy controls. Analysis of CD8+ T cell subsets showed a substantially high proportion of CD27+ CD28+ CD45RO+ CD57- CD8hi T cells in patients at relapse phase compared to controls. The frequency of NK and T cells subtypes was not associated with EBV and HHV6 plasma viral loads.

These findings further highlight the variation of NK and CD8+ T cells subsets frequency in clinically active RRMS patients. Since the composition of cells was not associated with EBV and HHV-6 viral load, perhaps other viral infections may be involved in altered NK and CD8+ T cells subpopulation. Larger cohort studies are needed to confirm these results.

Multiple sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system, in which proinflammatory cytokines play a critical role in the pathogenic formation of lesions. Caspase-1 is a cysteine protease that proteolytically cleaves precursors of interleukin (IL)-18 and IL-1β and turns them into their active forms. These inflammatory cytokines play an important role in the development of MS. The aim of the present study was the investigation of caspase-1 and its downstream products, IL-18 and IL-1β, in relapsing-remitting MS (RRMS) patients. In this study, we used an ELISA assay to measure serum and cellular caspase-1 and serum levels of IL-18 and IL-1β in RRMS patients in the relapse phase (n=23) and healthy age-and gender-matched controls (n=19). We observed that the caspase-1 level was significantly increased in the serum of MS patients compared to the healthy controls (p=0.03). Although caspase-1 concentration in the lysate of peripheral blood mononuclear cells (PBMCs) was higher than serum among patients and controls (p<0.001), no significant difference was found in cellular levels of caspase-1 between the two groups. There was no significant difference in serum levels of IL-18 and IL-1β between patients and controls. In this study, we found an elevation of extracellular caspase-1, as a reflection of its intracellular level, in the serum of RRMS patients during the relapse phase. Therefore, it suggests being a suitable peripheral biomarker of disease activity in multiple sclerosis.