Anti-inflammatory activities of Waltheria indica extracts by modulating expression of IL-1B, TNF-α, TNFRII and NF-κB in human macrophages

Abstract

In Hawaiian traditional medicinal practices, the indigenous 'uhaloa, Waltheria indica var. Americana is one of the most recognized plants. Waltheria is also known in various cultures as a medicinal plant for the treatment of inflammatory conditions. Results in human subjects and cell and animal models supported anti-inflammatory activity for the Waltheria flavonoid quercetin, and for crude plant extracts, limited animal studies also confirmed anti-inflammatory effects. Yet no systematic studies have examined immune or inflammatory responses affected by these extracts. In order to gain insight into inflammatory cascades modulated by Waltheria extracts, and to uncover the mechanistic bases for the effective use of this medicinal plant as a natural anti-inflammatory agent, we have undertaken analyses of LPS and TNF-α/IF-γ-stimulated human macrophages treated with Waltheria extracts using targeted qRT-PCR and Inflammation Panels to test differential mRNA expression of two hundred immune-related genes, furthermore, ELISA assays and Inflammatory Protein arrays to determine extracts-modulated intracellular and secreted levels of prominent cytokines. Results demonstrate that Waltheria extracts inhibit key inflammatory cytokines and cytokine receptors including protein levels of IL-1B, IL-1ra, IL-8 and IL-6, reduce both mRNA and protein levels of TNF-α and protein levels of its receptor, TNF RII, predicting diminished TNF-α-associated inflammatory signaling that, together with significant reduction of NF-κB mRNA and protein, can effectively diminish activities of multiple pro-inflammatory signaling pathways and mitigate key processes in diseases with inflammatory components.

Keywords: Human macrophages; IL-1B; IL-8; NF-κB; TNF-α; Waltheria.