Influence of homocysteine on regulating immunothrombosis: mechanisms and therapeutic potential in management of infections

Mechanisms controlling innate immune responses and coagulation are interdependent, evolutionarily entangled and make a complex network to form immuno-thrombosis axis which is an integral part of host-defence response. During infections, immunothrombosis generates intravascular scaffold enabling recognition, trap and destruction of pathogens facilitating tissue integrity. However, the accompanying dysregulation fosters into pathologies associated with thrombosis and regulates severity, morbidity and mortality in infections. Several extrinsic and intrinsic factors such as (epi)genetic mechanisms, age, metabolism and lifestyle regulate immunothrombosis during infections. Mounting evidence demonstrates that homocysteine, a metabolic intermediate of methionine synthesis pathway activate cells participating in immuno-thrombosis such as neutrophils, platelets, monocytes and endothelial cells. Interestingly, multiple infections are significantly associated with perturbed homocysteine metabolism. In the present review, we describe mechanistic insights into how homocysteine drives immuno-thrombotic crosstalk that generate a vicious cycle of inflammation and coagulation that fuels organ failure during infections with an emphasis on sepsis, COVID-19, and other infectious diseases caused by parasites, viral, and bacterial pathogens. Subsequently, we discuss therapeutic strategies targeting homocysteine metabolism that may improve clinical outcomes in infections.