Creatinine downregulates TNF-α in macrophage and T cell lines

[Display omitted] •Creatinine exposure decreases TNF-α mRNA levels in a macrophage and T cell line.•TNF-α mRNA stability is not affected by exposure to creatinine.•Creatinine exposure decreases TNF-α staining intensity and secretion in a macrophage cell line.•Creatinine exposure reduces NF-κB levels in the nucleus. Creatinine is the breakdown product of creatine, a key participant in the generation of ATP and is traditionally considered to be a biologically inert waste product. Based on our earlier work, we analyzed the effects of creatinine hydrochloride on the expression of tumor necrosis factor-alpha (TNF-α), a pro-inflammatory cytokine, in a human T cell line, as well as human and mouse macrophage cell lines. Exposing cells to creatinine hydrochloride significantly reduced TNF-α mRNA and protein levels compared to control-treated cultures in all cell lines tested. Lipopolysaccharide (LPS), a potent inducer of inflammation, was employed with in mouse macrophage cell lines to induce high levels of TNF-α in order to determine whether creatinine hydrochloride could reduce preexisting inflammation. Cells treated with LPS and creatinine hydrochloride had significantly reduced TNF-α levels compared to cells treated with LPS alone. As the NF-κB signaling pathway represents a major mechanism of TNF-α generation, nuclear extracts were examined for NF-κB pathway activation. Cells exposed to CRN had significantly lower levels of NF-κB in the nucleus compared to control-treated cells. Together, these results support the hypothesis that CRN can alter anti-inflammatory responses by interfering with the activation of the NF-κB pathway.