Efeitos de uma dieta rica em fibras solúveis na cicatrização de feridas cutâneas infectadas por Pseudomonas aeruginosa em camundongos diabéticos

Abstract

Diabetic wounds have impaired healing dynamics and are often colonized by bacteria, which further compromise the healing process. Oour group has studied the use of soluble fibers as healing stimulators. We hypothesized that the local actions of soluble fibers in the intestinal microbiota have a systemic impact on skin healing. We evaluated the effects of a pectin-enriched diet on the healing of excisional wound cells using an experimental murine model of a diabetic wound infected with Pseudomonas aeruginosa. C57BL6 mice received a standard diet supplemented with pectin and were divided into the following groups: healthy, diabetic, and diabetic with infected wounds. Diabetes was induced using streptozotocin and confirmed by the presence of glycosuria and intraperitoneal glucose intolerance. Immediately thereafter, experimental diets were provided. Then, after 14 days, wounds were prepared and inoculated with P. aeruginosa. After 7 and 14 days of wounding, the animals were euthanized and the wounds, blood, and feces were collected. Pectin did not alter weight. The survival rate of the healthy mice was 100%, and that of the other groups was much lower, with the exception of the diabetic group that received pectin and had a survival rate of approximately 60%. Pectin optimized wound closure in both healthy and diabetic groups, even in the presence of infection. Even so, regardless of the applied diet, the infected diabetic wounds showed the same bacterial load. Corroborating this data, in vitro growth of P. aeruginosa was not affected by the aerobic skin microbiota, regardless of whether the skin was obtained from animals that received or not a diet rich in pectin. Histologically, pectin promoted the reduction of granulation tissue in the wounds of healthy animals (7th day) and diabetic animals without infection (14th day), but not in infected wounds, and stimulated epithelialization and improved the total score of the wounds of all groups, regardless of the presence of infection. Interestingly, only in the infected diabetic group supplemented with pectin, an increase in the inflammatory infiltrate was observed on the 7th day after the injury. The pectin-rich diet provided higher capillary counts in the wounds of diabetic groups, regardless of the presence of infection. Systemically, the pectin-rich diet did not influence the serum levels of total proteins, albumin, and creatinine of any group. However, it promoted a significant increase in triglyceride and VLDL levels in diabetic animals with uninfected wounds. The 16S rRNA-based metagenomic sequencing analyses showed relevant changes in the local colonic and remote skin microbial communities. The pectin-rich diet increased the phylum Bacterioidetes and reduced Firmicutes in the intestine of both healthy and diabetic animals. In the presence of skin wounds, pectin maintained this effect only in healthy mice. Interestingly, under wound infection, pectin again promoted the increase in the phylum Bacterioidetes and reduced Firmicutes in the feces of diabetic animals. Considering the remote effects on cutaneous microbiota, pectin increased the phylum Proteobacteria and reduced Firmicutes in the intact diabetic skin, but not in the wounds from these animals. However, in sharp contrast, in the presence of infection, pectin reduced the phylum Proteobacteria and increased Firmicutes in the wounds of diabetic mice. Overall, our data suggest that a pectin-rich diet increases the survival of diabetic animals and accelerates the closure of their skin wounds, even in the presence of infection. The modulatory effect of oral-supplemented pectin on the colonic and skin microbiota was also evidenced. These data suggest a potential prebiotic effect of this soluble fiber on cutaneous wound healing.