LCN2 and alcohol dependence: Major factors that lead to microbiota dysbiosis include the early exposure to antibiotics in life, or the too-frequent use of broad-spectrum antibiotics [22,23,24], unhealthy habits like alcoholism and smoking [25], excessive consumption of a modern high-fat and high-protein and low-fibre diet (referred to as the westernised diet), and genetic mutations in regulatory genes such as sirtuins [26], nucleotide-binding oligomerisation-domain (NLRP) genes [27], mucin 2 [28,29,30], and lipocalin 2 (Lcn2) [31] (Figure 1).