Kidney injury: the spleno-renal connection and splenic tyrosine kinase.

Kidney injury is a major medical burden and one of the most common reasons for hospitalization and poor life quality. Kidney injury can include acute kidney injury, chronic kidney disease, and immune-mediated kidney diseases most of which have no definitive therapy. The spleen is a secondary lymphoid organ in the reticuloendothelial system that plays an important role in protecting the body from various diseases. Notably, spleen tyrosine kinase, a non-receptor tyrosine kinase, is a crucial player that aids in immunity and protection and is highly expressed in the kidney and hematopoietic cells. It has been shown that alterations in spleen tyrosine kinase function or expression could lead to a wide range of diseases and abnormalities. Over the past decade, the role of spleen and spleen tyrosine kinase in multiple kidney diseases has emerged. Evidence suggests that modulating the spleno-renal connection through activation of the cholinergic anti-inflammatory pathway can be a promising strategy for protecting against kidney injury. Imitating the protective function of the spleen through interleukin-10-extracellular vesicles can also be of therapeutic value. In addition, evidence showed that inhibition of the spleen tyrosine kinase leads to amelioration of the kidney injury. However, further exploration and long-term studies are needed to unravel the spleno-renal connection, as well as the efficacy of spleen tyrosine kinase inhibitors, before they can be used as means for treatment of kidney injury.