Fig. 3.

Synergistic role of vitamin D and melatonin in mediating anti-inflammatory, antioxidant and anti-apoptotic actions, as well as preventing immune cell infiltration in mitigating COVID-19 infection. The solid lines indicate stimulatory, while the dashed lines indicate inhibitory actions; [MMP = matrix metalloproteinases, NLPR3 = nod like receptor protein-3, COX-2 = cyclooxygenase-2, VEGF = vascular endothelial growth factor, NF-κB = nuclear factor kappa-light-chain-enhancer of activated B cells, CRP = C-reactive protein, TLR4 = toll-like receptor 4, HMGB1 = high mobility group box 1, HSP70e/i = heat shock protein 70e/i, PD-1 = programmed cell death protein 1, IL-8/6/4/10/1β = interleukin-8/6/4/10/1β, INF-1 = interferon-1, iNOS = inducible nitric oxide synthase, CXCL = chemokine (C-X-C motif) ligand, TNF-α = tumor necrosis factor-alpha, RANTES = regulated on activation, normal T cell expressed and secreted, IgE = immunoglobulin E, TGF-β1 = transforming growth factor-β1, SIRT1 = sirtuin 1, NO = nitric oxide, MDA = malondialdehyde, +OH = hydroxide, GSH = glutathione, SOD = superoxide dismutase, G6PD = glucose-6-phosphate dehydrogenase, Nrf2 = nuclear factor erythroid 2-related factor 2, CASP3/1 = caspase 3/1, AIF = apoptosis-inducing factor, p38 = p38 mitogen activated protein kinases, JNK = c-Jun N-terminal kinases, Bax/Bcl-2/Bad = Bcl-2 family of apoptotic proteins].