Histatin-1 Attenuates LPS-Induced Inflammatory Signaling in RAW264.7 Macrophages.

Sang Min Lee,Vinay Kumar Aakalu,Kyung-No Son,Arun Balasubramaniam,Marwan Ali,Deepak Shukla,Dhara Shah

doi:10.3390/ijms22157856

Abstract

Macrophages play a critical role in the inflammatory response to environmental triggers, such as lipopolysaccharide (LPS). Inflammatory signaling through macrophages and the innate immune system are increasingly recognized as important contributors to multiple acute and chronic disease processes. Nitric oxide (NO) is a free radical that plays an important role in immune and inflammatory responses as an important intercellular messenger. In addition, NO has an important role in inflammatory responses in mucosal environments such as the ocular surface. Histatin peptides are well-established antimicrobial and wound healing agents. These peptides are important in multiple biological systems, playing roles in responses to the environment and immunomodulation. Given the importance of macrophages in responses to environmental triggers and pathogens, we investigated the effect of histatin-1 (Hst1) on LPS-induced inflammatory responses and the underlying molecular mechanisms in RAW264.7 (RAW) macrophages. LPS-induced inflammatory signaling, NO production and cytokine production in macrophages were tested in response to treatment with Hst1. Hst1 application significantly reduced LPS-induced NO production, inflammatory cytokine production, and inflammatory signaling through the JNK and NF-kB pathways in RAW cells. These results demonstrate that Hst1 can inhibit LPS-induced inflammatory mediator production and MAPK signaling pathways in macrophages.

Highlights

Responses to environmental triggers, such as bacterial lipopolysaccharide (LPS), by the immune system play a critical role in both acute and chronic conditions
To test whether Hst1 could reduce nitric oxide (NO) production by RAW cells, in response to LPS stimulation, we performed a series of experiments
We tested whether Hst1 was toxic to RAW cells and determined that Hst1 application did not demonstrate statistically significant toxicity up to 200 μM (Figure 1A)

Summary

Introduction

Responses to environmental triggers, such as bacterial lipopolysaccharide (LPS), by the immune system play a critical role in both acute and chronic conditions. Monocyte and macrophage activation is demonstrably important in a number of diseases such as dry eye disease (DED) and periodontitis [1,2,3,4,5,6,7,8,9]. Innate immune signaling and activation of Toll-like receptors (TLRs) are increasingly thought to play a role in these chronic diseases. Antimicrobial peptides (AMPs) are multi-functional endogenous components of mucosal and other tissue defense systems that play a role in both innate immune signaling and disease processes. Synthesis and release of nitric oxide (NO) and other inflammatory cytokines such as IL-1β, IL-6, and TNF-α underpin the propagation of the immune response to environmental triggers. Cell-level regulation of these processes is driven by a number of signal transduction pathways, including NF-kB and MAPKs [1,10,11,12,13,14]

Methods

Results

Discussion

Conclusion