A Preliminary Study Of Immunomodulatory Activity Of Antimicrobial Peptides From The Skin Of Rana Chensinensis In Vivo

Natural cationic antimicrobial peptides are conserved component of the innate immune system present among all classes of life.These peptides show potent,broad spectrum antimicrobial activities.Recent studies have found that part of antimicrobial peptides in host defense system,not only non-specifically act on the bacterial cell membrane that play direct antibacterial effects,but also inhibit the inflammatory cytokines,TNF-?,IL-6,NO,and etc,overproduction and release,even selectively modulate the inflammatory response induced by pathogens,and reducing tissue damage caused by inflammation.In addition,some peptides could be involved in the wound healing,angiogenesis,and et al.Now the antimicrobial peptides mediated immune regulation have attracted more attention.Temporin-1CEa and chensinin-1b are two kinds of antimicrobial peptides derived from the Chinese forest frog(Rana chensinensis)skin secretions.Previous results show that the two antimicrobial peptides exhibit broad-spectrum bactericidal activities,especially chensinin-1b have strong antibacterial activity against Gram-positive bacteria and negative bacteria at low concentrations,and can inhibit the release inflammatory cytokines TNF-? and IL-6 from LPS-induced human monocytes / macrophage U937 cells,THP-1 cells and murine macrophages RAW264.7 cells.The main purpose of this research is to study the in vivo immunomodulatory activity of the two kinds of antimicrobial peptides,Temporin-1CEa and chensinin-1b,based on the previous in vitro experiments.Firstly,the effects of Temporin-1CEa and chensinin-1b on a endotoxemia mouse model of LPS-induced and septic shock model induced by the(sensitive / resistant)Pseudomonas aeruginosa were studied.The results showed that both antimicrobial peptides have shown a good protective effect in endotoxemia and septic shock in mice,increased the survival rate of mice,and inhibited TNF-? and IL-6 and other inflammatory cytokines excessive produced via the immunomodulatory,also can reduce the damage of liver and lung and other organs that caused by LPS or bacteria.Secondly,the wound infection mouse model was established to investigate the effects of Temporin-1CEa and chensinin-1b in traumatic infection mice.The skin permeability experiments found that Temporin-1CEa and chensinin-1b could quickly penetrate into the mouse dermis,and maintain their structures stable,and demonstrated that both of them can be as a potential topical anti-infective agents.In wound healing experiments,we have established a mouse healing mode via excision full-thickness skin.The study foundthat high doses of these peptides can promote wound granulation tissue formation and reepithelialization,and increase wound healing rate.In summary,Temporin-1CEa and chensinin-1b show immune modulating activities in vivo,can inhibit the harmful excessive cytokine production,protected the organs from damage by LPS/ Pathogens in mice,and increase the survival rate of mice.In addition,they have significant skin permeability and stability,and can accelerate wound healing.