RESUMO
Anti-inflammatory effect of soluble secreted compounds of probiotic bacteria was widely demonstrated as therapy for different inflammatory diseases, but was not investigated in inflammatory eye disorders. The aim of this study was to determine whether Lactiplantibacillus plantarum CRL759 cell-free supernatant reduced inflammatory parameters and clinical signs in ocular inflammations. First, we evaluated the effect of L. plantarum CRL759 supernatant in vitro on human retinal cell line, ARPE-19 cells, stimulated with lipopolysaccharide (LPS). Then, we investigated in vivo its capacity to decrease inflammation by local administration on the eyes of mice with endotoxin induced inflammation. In vitro assays demonstrated that L. plantarum CRL759 supernatant reduced the production of interleukin (IL)-6, IL-8, nitric oxide and thiobarbituric acid reactive substances in LPS-stimulated ARPE-19 cells. Our in vivo data proved that L. plantarum supernatant significantly reduced the clinical score of endotoxin treated mice and diminished levels of tumour necrosis factor alpha, interferon gamma and protein concentration in aqueous humour. Histological examination showed reduction of infiltrating inflammatory cells in the posterior segment of the eyes. As far as we know, this is the first report showing that Lactobacillus spp. supernatant administered as drops reduces some parameters of ocular inflammation. This promising strategy is safe and could alleviate symptoms and signs of ocular inflammation in people that are refractories to the conventional therapies.