ACSL4 and chronic obstructive pulmonary disease: Forty-six participants in the COPD group walked less than 350 m in the 6MWD test, including 35 individuals with low serum GPX4 levels, 30 with high serum sTfR1 levels, 25 with high serum AIFM2 levels, 25 with high serum ACSL4 levels, and 35 with high sTfR1/GPX4.