LCN2 and obesity due to melanocortin 4 receptor deficiency: Given the suggested role of Lcn2 in metabolic disorders and obesity (36) and the correlation between IPF and obesity in patients (37), the effect of obesity-driven microbiome changes in the lungs (38), as well as the suggested role of Lcn2 in iron sequestration and microbiome regulation, we next investigated the role of Lcn2 in the pathogenesis of pulmonary fibrosis in obese mice, following the high-fat diet (HFD) feeding for 13 weeks, in comparison with mice fed a matched control diet.