Lrba, also known as lipopolysaccharide-responsive and beige-like anchor protein, is a cytoplasmic protein with a scaffolding function [3]. It is involved in multiple biological processes, especially in the immune system and renal function. In the immune system, it is thought to regulate CTLA4, an inhibitory immunoreceptor, and is associated with immune-related pathways. In the kidneys, it plays a role in the regulation of water reabsorption [2,4].

In Lrba -deficient patients, there is increased CTLA4 turnover, leading to reduced CTLA4 protein levels in regulatory and activated T cells, resulting in immune dysregulation, autoimmunity, lymphoproliferation, and humoral immune deficiency. Abatacept, a CTLA4 -immunoglobulin fusion drug, can improve the condition of these patients [1]. In Lrba knockout mice, vasopressin-induced AQP2 phosphorylation is impaired, causing AQP2 retention at the recycling endosome and resulting in low urinary concentrating ability, indicating its importance in renal water reabsorption [2].

In conclusion, Lrba is essential for maintaining immune homeostasis and renal water balance. Studies on Lrba -deficient patients and knockout mouse models have revealed its key role in immune-related diseases such as autoimmunity and in conditions related to abnormal water reabsorption in the kidneys. These findings provide important insights into potential therapeutic strategies for these diseases [1,2].