No abstract

Toll-like receptors (TLRs) are a class of receptors of the innate immune system which detect pathogen-associated and danger-associated molecular patterns in order to initiate an inflammatory response. TLR2 and TLR4 downward signaling causes the production of proinflammatory cytokines that can induce insulin resistance and cardiovascular damage in obesity and type 2 diabetes mellitus. In diabetic nephropathy, TLR4, nucleotide-binding oligomerization domain-containing protein 2 (NOD2), and NLRP3 inflammasome are involved in the production and persistence of inflammation. The activation of TLRs stimulates the expression of several inflammatory cytokines and chemokines such as CCL2 and tumor necrosis factor (TNF)-α, which are associated with the progression of diabetic nephropathy. Different inflammatory mechanisms seem to take place in the early and late stages of diabetic kidney disease, with activation of the innate immunity response and enhanced chemiotactic effects in native kidney cells at an early stage, followed by tubulointerstitial monocyte infiltration at a more advanced disease state. Overall, available data indicate that the upregulated TLR4 response in the kidney translates the metabolic alterations of diabetes into kidney damage.

A low protein diet (LPD) has historically been used to delay uremic symptoms and decrease nitrogen (N)-derived catabolic products in patients with chronic kidney disease (CKD). In recent years it has become evident that nutritional intervention is a necessary approach to prevent wasting and reduce CKD complications and disease progression. While a 0.6 g/kg, high biological value protein-based LPD has been used for years, recent observational studies suggest that plant-derived LPDs are a better approach to nutritional treatment of CKD. However, plant proteins are less anabolic than animal proteins and amino acids contained in plant proteins may be in part oxidized; thus, they may not completely be used for protein synthesis. In this review, we evaluate the role of LPDs and plant-based LPDs on maintaining skeletal muscle mass in patients with CKD and examine different nutritional approaches for improving the anabolic properties of plant proteins when used in protein-restricted diets.