Structure-activity relationships and mechanisms of natural polysaccharides in modulating kidney diseases via the microbiota-gut-kidney axis: A review.

Natural polysaccharides are biocompatible high molecular compounds with low toxicity and have many biological activities. But their therapeutic effect on kidney diseases is not fully exploited at present. Generally, kidney diseases develop slowly, need a large sum of medical fees and are often associated with other chronic diseases. In this paper, we concentrate on an important scientific issue: what kinds of structural features of polysaccharides, such as molecular weight, types of glycosidic bonds and branching degree, affect the microflora-intestine-kidney link in order to prevent renal damage. Recently, it has been found that polysaccharides show renoprotective effects mainly by changing the microflora in the intestine, reducing the intestinal wall permeability and decreasing the levels of uremic toxins absorbed into the blood. Thus, they can inhibit oxidative stress, cell apoptosis, inflammation and fibrosis in kidney tissues. At first, these effects were considered to be produced directly, but now they are recognized to be mainly regulated by the gut-kidney link. Based on the present structure-activity relationship research, this review shows that the structural properties of polysaccharides can improve the intestinal microflora function and be beneficial to the kidneys. This provides a hopeful way to regulate and prevent chronic kidney diseases.