NRTN and idiopathic pulmonary fibrosis: The IVW way illustrated 12 taxa (Bacillales, Gastranaerophilales, Selenomonadales, Family XIII, Bacteroidaceae, Bacteroides, and Actinomyces, Bifidobacterium, Oscillibacter, Ruminococcus gnavus, Subdoligranulum, Veillonella) of GM and 8 circulating inflammatory proteins (CCL11, CXCL6, CXCL9, CCL8, CCL7, NRTN, STAMPB, and TGFa) had suggestive evidence of causality on IPF.