Aspects of the disclosure concern methods and compositions related to recombinant microorganisms expressing one or more biologically active peptides that are heterologous to the microorganism, wherein the one or more biologically active peptides comprise a potassium channel blocker. In particular aspects, recombinant microorganisms are generated by introducing into the microorganism one or more polynucleotides encoding one or more biologically active peptides. In specific aspects, a subject having one or more diseases or conditions mediated by cells of the immune system and/or fibroblasts or fibroblast-like cells is administered a therapeutically effective amount of a recombinant microorganism or composition thereof, wherein the recombinant microorganism is capable of producing a therapeutically effective amount of the one or more biologically active polypeptides to treat or prevent the one or more diseases or conditions mediated by cells of the immune system and/or fibroblasts or fibroblast-like cells.