Inhibitory Effects of Antimicrobial Peptide JH-3 on Salmonella enterica Serovar Typhimurium Strain CVCC541 Infection-Induced Inflammatory Cytokine Release and Apoptosis in RAW264.7 Cells

Abstract

The antibiotic resistance of Salmonella has become increasingly serious due to the increased use of antibiotics, and antimicrobial peptides have been considered as an ideal antibiotic alternative. Salmonella can induce macrophage apoptosis and thus further damage the immune system. The antimicrobial peptide JH-3 has been shown to have a satisfactory anti-Salmonella effect in previous research, but its mechanism of action remains unknown. In this study, the effects of JH-3 on macrophages infected with Salmonella Typhimurium CVCC541 were evaluated at the cellular level. The results showed that JH-3 significantly alleviated the damage to macrophages caused by S. Typhi infection, reduced the release of lactic dehydrogenase (LDH), and killed the bacteria in macrophages. In addition, JH-3 decreased the phosphorylation level of p65 and the expression and secretion of interleukin 2 (IL-2), IL-6, and tumor necrosis factor-α (TNF-α) by inhibiting the activation of the mitogen-activated protein kinase (MAPK) (p38) signaling pathway and alleviating the cellular inflammatory response. From confocal laser scanning microscopy and flow cytometry assays, JH-3 was observed to inhibit the release of cytochrome c in the cytoplasm; the expression of TNF-αR2, caspase-9, and caspase-8; to further weaken caspase-3 activation; and to reduce the S.-Typhi-induced apoptosis of macrophages. In summary, the mechanism by which JH-3 inhibits Salmonella infection was systematically explored at the cellular level, laying the foundation for the development and utilization of JH-3 as a therapeutic alternative to antibiotics.

The Antimicrobial Peptide Mastoparan X Protects Against Enterohemorrhagic Escherichia coli O157:H7 Infection, Inhibits Inflammation, and Enhances the Intestinal Epithelial Barrier

“…Mitogen-activated protein kinase (MAPKs), including JNK, ERK1/2, and p38, are a group of serine/threonine proteins and are involved in the final step of cytoplasmic signal transduction pathways that are activated by multiple extracellular signal pathways. These proteins play a role in the activation of nuclear transcription factor p65, regulating gene expression, and participating in cytokine secretion and apoptosis after activation ( Wang et al, 2019b ). Immunohistochemistry and immunofluorescence were used to further explore the mechanism by which MPX inhibits the secretion of inflammatory factors.…”

Bee venom-derived antimicrobial peptide melectin has broad-spectrum potency, cell selectivity, and salt-resistant properties

“…www.nature.com/scientificreports www.nature.com/scientificreports/ AMPs not only have antibacterial activity but also modulate bacterial-induced inflammatory responses 32 . Infection with bacteria increases the expression of pro-inflammatory cytokines including TNFα, IL-8, IL-6, and IL-1β, and cytokine overexpression causes inflammation and organ damage 33 . We found that pro-inflammatory cytokines were significantly increased when cells were treated with S. aureus.…”

Salmonella Virulence and Immune Escape

“…This peptide helps stabilize the intestinal barrier, while promoting the stability of intestinal microbial flora. Musca domestica cecropin and JH-3 (an analog of hemoglobin peptide P3), as the novel AMPs, were recently found to have an obvious inhibitive effect on S. Typhimurium [155,156]. However, the presence of host AMPs activates the PbgA which is required to maintain PhoPQ system of S. Typhimurium, promoting remodeling of outer membrane and resistance to innate immune AMPs [157].…”