TNF and amyotrophic lateral sclerosis: Interestingly, a recent population study has provided evidence for selective hormonal and adipokine alterations in ALS patients and in particular lower ghrelin, glucagon-like peptide-1 (GIP), and pancreatic polypeptide (PP) plasma levels as well as increased metabolic disease-associated adipokines such as interleukin-6 (IL-6), interleukin-8 (IL-8), lipocalin-2 (LCN-2), tumor necrosis factor alpha (TNFα), and plasminogen activator inhibitor-1 (PAI-1) [97].