ABSTRACT
A Pseudomonas aeruginosa quorum-sensing system, which produces N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12 -HSL) and N-butanoyl-l-homoserine lactone (C4 -HSL), regulates the virulence factors. In our previous study, 3-oxo-C12 -HSL, encoded by lasI gene, was shown to promote wound healing. However, the effect of C4 -HSL, encoded by rhlI gene, remains to be elucidated. We addressed the effect of C4 -HSL on wounds in P. aeruginosa infection. Wounds were created on the backs of Sprague-Dawley SD rats, and P. aeruginosa PAO1 (PAO1) or its rhlI deletion mutant (ΔrhlI) or lasI deletion mutant (ΔlasI) was inoculated onto the wound. Rats were injected intraperitoneally with anti-C4 -HSL antiserum or treated with C4 -HSL at the wound surface. PAO1 inoculation led to significant acceleration of wound healing, which was associated with neutrophil infiltration and TNF-α synthesis. These responses were reversed, except for TNF-α production, when ΔrhlI was inoculated instead of PAO1 or when rats were co-treated with PAO1 and anti-C4 -HSL antiserum. In contrast, the healing process and neutrophil infiltration, but not TNF-α synthesis, were accelerated when C4 -HSL was administered in the absence of PAO1. This acceleration was not affected by anti-TNF-α antibody. These results suggest that C4 -HSL may be involved in the acceleration of acute wound healing in P. aeruginosa infection by modifying the neutrophilic inflammation.
Subject(s)
4-Butyrolactone/analogs & derivatives , Pseudomonas aeruginosa/enzymology , Wound Healing/physiology , Wounds and Injuries/pathology , Wounds and Injuries/therapy , 4-Butyrolactone/pharmacology , Acute Disease , Analysis of Variance , Animals , Biopsy, Needle , Disease Models, Animal , Female , Homoserine/analogs & derivatives , Homoserine/pharmacology , Immunohistochemistry , Neutrophils/metabolism , Random Allocation , Rats , Rats, Sprague-Dawley , Statistics, Nonparametric , Tumor Necrosis Factor-alpha/metabolismABSTRACT
In the present study, we determined the contribution of invariant natural killer T (iNKT) cells to the skin wound healing process. In iNKT cell-deficient (Jα18KO) mice lacking iNKT cells, wound closure was significantly delayed compared with wild-type mice. Collagen deposition, expression of α-smooth muscle actin and CD31, and wound breaking strength were significantly attenuated in Jα18KO mice. The adoptive transfer of liver mononuclear cells from wild-type but not from Jα18KO or interferon (IFN)-γ gene-disrupted (IFN-γKO) mice resulted in the reversal of this impaired wound healing in Jα18KO mice. IFN-γ expression was induced in the wounded tissues, which was significantly decreased at 6, 12, and 24 hours, but increased on day 3 after wounding in Jα18KO mice. The main source of the late-phase IFN-γ production in Jα18KO mice were neutrophils rather than NK cells and T cells. Administration of α-galactosylceramide, an activator of iNKT cells, resulted in the acceleration of wound healing on day 3 in wild-type mice. This effect was not observed in IFN-γKO mice. These results indicate that iNKT cells play important roles in wound healing. The iNKT cell-induced IFN-γ production may regulate the wound healing process in the early phase.
