N-Acetylcysteine (NAC) and its Immunomodulatory Properties

N-acetylcysteine (NAC), an acetylated derivative of the amino acid L-cysteine has been widely used as a mucolytic agent and antidote for acetaminophen overdose since the 1960s and the 1980s respectively. NAC possesses antioxidant, cytoprotective, anti-inflammatory, antimicrobial and mucolytic properties, making it a promising therapeutic agent for a wide range of diseases in both humans and livestock in which oxidative stress and inflammation plays a major role in the onset and progression of the disease. NAC’s primary role is to replenish glutathione (GSH) stores; the master antioxidant in all tissues, however it can also reduce levels of pro-inflammatory tumor necrosis factor-alpha (TNF-) and interleukins (IL-6 and IL-1), inhibit formation of microbial biofilm, destroy biofilms, and break down disulfide bonds between mucin molecules. Many experimental studies have been conducted on the use of NAC in addressing a wide range of pathological conditions, however, its effectiveness in addressing different pathological conditions in clinical trials remains limited and studies often have conflicting results. The purpose of this review is to provide a concise overview of promising NAC usages for treatment of different human and livestock disorders.