Nod2, also known as nucleotide-binding oligomerization domain 2, is an intracellular pattern recognition receptor belonging to the NOD-like receptor family. It senses conserved motifs in bacterial peptidoglycan, such as muramyl dipeptide (MDP), and induces pro-inflammatory and antimicrobial responses. Nod2 activation leads to the activation of the NF-κB pathway, which upregulates pro-inflammatory cytokines, playing a crucial role in host defense and maintaining immune system homeostasis [1,3,5,6].

Loss-of-function mutations in Nod2 are primary risk factors for Crohn's disease. In mouse models, absence of Nod2 during mycobacterial infection can be detrimental, although the mechanism remains unclear. Nod2-related disease in humans shows a distinct ileal stricturing phenotype, suggesting its potential for personalized diagnosis and targeted therapy. Nod2 also plays a role in Blau Syndrome, a hereditary juvenile-onset systemic granulomatosis caused by heterozygous mutations in Nod2 [2,3,4].

In conclusion, Nod2 is essential for host defense against pathogens and immune system regulation. Model-based research, especially studies using gene knockout mouse models, has revealed its significant role in diseases like Crohn's disease and Blau Syndrome. Understanding Nod2 provides insights into disease pathogenesis and may lead to the development of new treatment strategies for inflammatory and infectious disorders.