C-Type Natriuretic Peptide Plays an Anti-Inflammatory Role in Rat Epididymitis Induced by UPEC

Abstract

Human epididymitis is mainly caused by retrograde urinary tract infection with uropathogenic Escherichia coli (UPEC). This disease is an important factor (accounting for 20–30%) causing male infertility. C-type natriuretic peptide (CNP), a protein composed of 22 amino acids, is proved to play an immunoregulatory role in respiratory and cardiovascular systems. CNP is expressed extremely high in the epididymis, but whether CNP plays the same role in acute epididymitis is unclear. At first, we established an acute caput epididymitis model in rats with UPEC and treated them with CNP to measure inflammatory damage. Then RNA-seq transcriptome technology was used to reveal potential signal pathways. Secondly, the turbidity and activity of UPEC were assessed using a microplate reader and the amount of UPEC by agar plates after incubation with CNP. Thirdly, macrophages in caput epididymis were tested by immunohistochemistry (IHC). Meanwhile, lipopolysaccharide (LPS) with or without CNP was used to stimulate the macrophage (RAW264.7) in vitro and to detect the expression level of pro-inflammatory factors. Finally, the macrophage (RAW264.7) was treated with CNP, 8-Br-cGMP [cyclic guanosinc monophosphate (cGMP) analog] and KT5823 [protein kinase G (PKG) inhibitor], and the expression level of nuclear factor-k-gene binding (NF-kB) signal pathway was examined. The results showed that the damage of epididymis induced by UPEC as well as the pro-inflammatory factors could be alleviated significantly with CNP treatment. CNP could inhibit the activity and numbers of bacteria in both in vivo and in vitro experiments. Moreover, CNP repressed the invasion, and the expression of pro-inflammatory factors (such as NF-kB, IL-1β, IL-6, TNF-α) in macrophages and its effect could be inhibited by KT5823. Therefore, we drew a conclusion from the above experiments that CNP alleviates the acute epididymitis injury induced by UPEC. On one hand, CNP could inhibit the growth of UPEC. On the other hand, CNP could decrease invasion and inflammatory reaction of macrophages; the mechanism was involved in inhibiting NF-kB signal pathway through the cGMP/PKG in macrophages. This research would open up the possibility of using CNP as a potential treatment for epididymitis.

C-Type Natriuretic Peptide (CNP) Could Improve Sperm Motility and Reproductive Function of Asthenozoospermia

“…Chen et al found that CNP effectively attenuated LPS-induced endothelial activation by inhibiting the NF-κB and p38 signaling pathways [ 44 ]. Our previous studies also showed that CNP plays a protective anti-inflammatory effect in the epididymitis mouse model by NF-kB signal pathway, inhibiting NF-κB and P38 signaling pathways [ 45 ]. In this study, the mRNA expression levels of TNF-α and IL-6 were increased in the CTX group and decreased after being treated with CNP in a dose-dependent trend.…”

Comprehensive Analysis of m6A Modification in Lipopolysaccharide-induced Acute Lung Injury in Mice

“…Our data demonstrated that these genes were primarily related to the calcium signaling pathway, protein digestion and absorption, cGMP-PKG signaling pathway. cGMP-PKG signaling pathway has been found to in uence the release of pro-in ammatory cytokines in macrophages, which might participate in the development of ALI (Mei et al 2021;Sun et al 2023). PPI network analysis further revealed that Flrt3 was located at the core position of the whole regulatory pathway.…”

C‐type natriuretic peptide (CNP) inhibits 7,12‐Dimethylbenz[a]anthracene (DMBA)/Croton oil‐induced skin tumor growth by modulating inflammation in Swiss albino mice

“…[ 56 ] It has been shown that exogenous CNP administration suppresses inflammation in various tissues. [ 12 ] Moreover, reports have shown that CNP effectively inhibits NF‐κB activation by the suppression of p65 phosphorylation in LPS‐stimulated HUVECs [ 57 ] ; Mei et al [ 58 ] demonstrated that CNP inhibits the expression of pro‐inflammatory factors (such as NF‐kB, IL‐1β, IL‐6, TNF‐α) by the suppression of NF‐kB signal pathway through the cGMP/PKG signaling mechanisms in Rat epididymitis. The present study shows that CNP significantly downregulates the inflammatory/cytokines genes such as, Ptgs2, Nos2, Nfκb1, Tnf, Il1a, Il1b, Il2, Il6 , and Vegfa and proliferating/proto‐oncogene such as Activation protein‐1 ( Fos , and Jun ), and Myc expressions in DMBA/Croton oil‐induced group of mice (Figures 5 and 6).…”

“…Mei et al [58] demonstrated that CNP inhibits the expression of pro- showed a more prominent reduction in the genes and proteins expression of inflammatory/cytokines and proliferating/protooncogenes as compared to the CNP or CDDP alone treatment mice (Figures 5 and 6).…”