Promotion of the inflammatory response in mid colon of complement component 3 knockout mice

Yun Ju Choi,Ho Lee,Dae Youn Hwang,Jeong Eun Gong,Ji Eun Kim,You Jeong Jin,Su Jin Lee

doi:10.1038/s41598-022-05708-8

Abstract

To determine whether complement component 3 (C3) deficiency affects its receptor downstream-mediated inflammatory response, the current study was undertaken to measure alterations in the inducible nitric oxide synthase (iNOS)‑mediated cyclooxygenase‑2 (COX‑2) induction pathway, inflammasome pathway, nuclear factor-κB (NF-κB) activation, and inflammatory cytokine expressions in the mid colon of C3 knockout (KO) mice. Significant enhancement was observed in expressions of key components of the iNOS‑mediated COX‑2 induction pathway, and in the phosphorylation of mitogen‑activated protein (MAP) kinase members. A similar pattern of increase was also observed in the expression levels of inflammasome proteins in C3 KO mice. Moreover, compared to WT mice, C3 KO mice showed remarkably enhanced phosphorylation of NF-κB and Inhibitor of κB-α (IκB-α), which was reflected in entirety as increased expressions of Tumor necrosis factor (TNF), IL-6 and IL-1α. However, the levels of E-cadherin, tight junction channels and ion channels expressions were lower in the C3 KO mice, although myeloperoxidase (MPO) activity for neutrophils was slightly increased. Taken together, results of the current study indicate that C3 deficiency promotes inflammatory responses in the mid colon of C3 KO mice through activation of the iNOS‑mediated COX‑2 induction pathway, Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)-inflammasome pathway and NF-κB signaling pathway, and the enhancement of inflammatory cytokine expressions.

Highlights

To determine whether complement component 3 (C3) deficiency affects its receptor downstreammediated inflammatory response, the current study was undertaken to measure alterations in the inducible nitric oxide synthase‐mediated cyclooxygenase‐2 (COX‐2) induction pathway, inflammasome pathway, nuclear factor-κB (NF-κB) activation, and inflammatory cytokine expressions in the mid colon of C3 knockout (KO) mice
Compared to levels obtained in wild type (WT) mice, we obtained decreased expression levels of the C3 protein (Supplementary Fig. 1C), indicating that expression of the C3 protein is successfully inhibited in the kidney, spleen and thymus of C3 KO mice generated using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9-mediated technique
To investigate whether C3 deficiency in the mid colon is similar to the levels observed in major C3 producing organs, we measured for expression levels of the C3 protein and mRNA in mid colon samples harvested from C3 KO mice

Summary

Introduction

To determine whether complement component 3 (C3) deficiency affects its receptor downstreammediated inflammatory response, the current study was undertaken to measure alterations in the inducible nitric oxide synthase (iNOS)‐mediated cyclooxygenase‐2 (COX‐2) induction pathway, inflammasome pathway, nuclear factor-κB (NF-κB) activation, and inflammatory cytokine expressions in the mid colon of C3 knockout (KO) mice. Results of the current study indicate that C3 deficiency promotes inflammatory responses in the mid colon of C3 KO mice through activation of the iNOS‐mediated COX‐2 induction pathway, Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)inflammasome pathway and NF-κB signaling pathway, and the enhancement of inflammatory cytokine expressions. The complement system plays a key role in the opsonization of pathogens and injured cells, induction of inflammation, and destruction of microorganisms in the innate immune system of various organs, including the heart, lung, liver, kidney and gut[1,2] These responses of the complement are mediated via four routes, viz., the classical, lectin, alternative and thrombin mediated pathways, subsequently resulting in elimination of the antigenic agent and activation of the inflammatory r esponse[2,3]. Our study especially focuses on regulation of the iNOS‐mediated COX‐2 induction pathway, ASC-inflammasome pathway, NF-κB phosphorylation, and inflammatory cytokine expression in the mid colon of C3 KO mice

Methods

Results

Conclusion