Association of vitamin D status & miRNA-155 levels with disease severity in patients with dengue

Background & objectives The clinical manifestation of dengue results from a complex and finely balanced interaction between the dengue virus (DENV) and the host immune responses, particularly excessive inflammation driven by pro-inflammatory cytokines. Vitamin D is an essential modulator of antiviral innate immunity, capable of reducing cytokine production and viral replication in vitamin D3-differentiated monocyte-derived macrophages (D3-MDM). It also downregulates inflammatory miRNAs, including miRNA-155. This study aimed to investigate serum levels of 25-hydroxyvitamin D [25(OH)D], cytokine production, and the expression of microRNA-155 (miRNA-155) in patients with dengue. Methods Serum samples were collected from 98 dengue-positive patients categorised as dengue without warning signs, dengue with warning signs, or severe dengue, along with 10 healthy individuals as controls. Clinical and laboratory data were also analysed. Results Serum 25(OH)D levels were significantly higher in dengue without warning as compared to other two categories. Although dengue with warning signs patients exhibited higher 25(OH)D levels than those with severe dengue, both groups showed a significant reduction compared to healthy controls. In contrast, miRNA-155 expression was highest in the severe dengue group, followed by dengue with warning signs, dengue without warning signs, and controls. A significant negative correlation was observed between serum 25(OH)D levels and miRNA-155 expression. Lower 25(OH)D concentrations were associated with elevated TNF-α, IL-6, and IFN-γ levels, particularly in patients with warning signs and severe dengue. Interpretation & conclusions These findings suggest a relationship between vitamin D status, miRNA-155 expression, and immune activation during dengue infection. The inverse correlation between 25(OH)D and miRNA-155 highlights their potential as disease severity and progression biomarkers in patients infected by dengue virus.