Transcriptomic analysis of the anti-inflammatory effect of Cordyceps militaris extract on acute gouty arthritis

Abstract

Background: Gouty arthritis (GA) is a common inflammatory disease that causes pain due to the deposition of monosodium urate (MSU) crystals into joints and surrounding tissues. Anti-inflammatory drugs have significant clinical anti-inflammatory and analgesic effects, but they have many side effects. Cordyceps militaris is an edible and medicinal fungus, and its extract (CME) has good anti-inflammatory and analgesic effects. This study aimed to investigate the anti-inflammatory effect of CME on GA and its underlying mechanism. Methods: The effect of CME on the expression of related inflammatory factors and histopathological changes in the MSU-induced acute inflammatory gout model in rats was studied by ELISA and HE, and its anti-inflammatory mechanism was analyzed by transcriptome combined with RT-qPCR. Results: CME significantly improved gait scores and joint swelling in GA rats, and reduced MSU-induced inflammatory cell infiltration. CME inhibited MSU-induced inflammatory responses by reducing the levels of pro-inflammatory factors TNF-α, IL-1β, IL-6, and Caspase-1 and increasing the anti-inflammatory factor IL-10. Transcriptome analysis showed that CME significantly altered inflammation-related cytokine pathways, and identified four major genes involved in regulation of inflammation, CCL7, CSF2RB, LIF, and IL-1β. In addition, RT-qPCR was performed to verify these differential genes. Conclusion: CME significantly alleviated the inflammatory progression of GA and ameliorated the onset of GA. The underlying mechanism may be related to triggering the cytokine-cytokine receptor interaction signaling pathway to inhibit the activation of the inflammasome and regulate the immune system. And it regulates the inflammatory response induced by MSU crystals through the genes CCL7, CSF2RB, and IL-1β.

Keywords: Cordyceps militaris extract; gouty arthritis; inflammation; monosodium urate; transcriptomics.

FIGURE 1

The effect of CME on MSU-induced naked joints in rats (A)Representative photographs of the ankle joints of rats after 24 h of MSU injection. (B)Ankle girth according to time after MSU crystal injection (n = 8/group). (C)MSU-induced ankle dysfunction index (n = 8/group). (D)The mean ankle temperature of MSU-induced gout model (n = 8/group). (E)Hematoxylin and eosin-stained sections of ankle joints after MSU induction for 24 h (200x). Data are expressed as mean ± SD (two‐way ANOVA), *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 vs. Gout.

FIGURE 2

Analysis of the effect of CME on the levels of gout inflammatory factors by ELISA (n = 8/group). Data are expressed as mean ± SD (one‐way ANOVA), *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 vs. Control; #p < 0.05, ##p < 0.01, ###p < 0.001, ####p < 0.0001 vs. Gout.

FIGURE 3

Effects of CME on the transcriptomic profile of MSU-induced acute gout. (A) Correlation heat map of differential genes between groups (B) Statistics of differential expression results (C) Volcano plot of differential genes between control and gout groups (n = 3/group) (D) Volcano plot of differential genes between CME and gout groups (n = 3/group) (E) Control and gout groups GO enrichment analysis (F) GO enrichment analysis of CME and gout group (G) KEGG enrichment analysis of control and gout group (H) KEGG enrichment analysis of CME and gout group.

FIGURE 4

Comparison of relative expression levels between RNA-Seq and RT-qPCR results. (A) Detection of expression of four differential genes from RNA-Seq (n = 3/group). (B) Detection of expression of four differential genes by RT-qPCR (n = 3/group). Data are expressed as mean ± SD (one‐way ANOVA), *p < 0.05, **p < 0.01 vs. Control; #p < 0.05, ##p < 0.01 vs. Gout.