A protein selected from the amino acid sequence of the region valine Val(91) to glycine Gly(121) of the mature human tumor necrosis factor, or a portion thereof, with the proviso that the protein comprises at least the amino acid sequence of the region lysine Lys(98) to glutamic acid Glu(116), with the cysteine Cys(101) being replaced by a glycine and an amide bond being formed between the amino group of the side chain of the lysine Lys(98) and the carboxyl group of the side chain of the glutamic acid Glu(116), which activates epithelial ion channels and improves the lung function and which can be used for the manufacture of medicaments for the treatment of diseases associated with the lung function, such as oedemas.