Abstract
Vitamin D (VD), a crucial micronutrient, regulates bone health and immune responses. Recent studies suggest that VD may confer protective effects against chronic inflammatory diseases. Additionally, plant-based peptides can show biological activities. Furthermore, the supplementation of protein hydrolysates with VD could potentially enhance the bioactivity of peptides, leading to synergistic effects. In this study, THP-1 cells were exposed to low concentrations of Lipopolysaccharide (LPS) to induce inflammation, followed by treatment with vitamin D at different concentrations (10, 25, or 50 nM) or a chickpea protein hydrolysate ("H30BIO") supplemented with VD. The cytotoxicity of VD was evaluated using viability assay to confirm its safety. The cytokine secretion of TNF-α, IL-1β, and IL6 was assessed in the cell supernatant, and the gene expression of TNF-α, IL-1β, IL6, IL8, CASP-1, COX2, NRF2, NF-ĸB, NLRP3, CCL2, CCR2, IP10, IL10, and RANTES was quantified by qRT-PCR. Treatment with VD alone significantly decreased the expression of the pro-inflammatory genes TNF-α and IL6, as well as their corresponding cytokine levels in the supernatants. While IL-1β gene expression remained unchanged, a reduction in its cytokine release was observed upon VD treatment. No dose-dependent effects were observed. Interestingly, the combination of VD with H30BIO led to an increase in TNF-α expression and secretion in contrast with the LPS control, coupled with a decrease in IL-1β levels. Additionally, genes such as IP10, NF-κB, CCL2, COX2, NRF2, and CASP-1 exhibited notable modulation, suggesting that the combination treatment primarily downregulates NF-κB-related gene activity. This study demonstrates a synergistic interaction between VD and H30BIO, suggesting that this combination may enhance pathways involving TNF-α, potentially aiding in the resolution and modulation of inflammation through adaptive processes. These findings open new avenues for research into the therapeutic applications of enriched protein hydrolysates with VD to manage low-grade inflammatory-related conditions.