tacrolimus and Pneumonia--Staphylococcal

Topics: Adult; Atrioventricular Block; Bone Marrow Transplantation; Bradycardia; Electrocardiography; Female; Graft vs Host Disease; Heart Block; Hemorrhage; Humans; Immunosuppressive Agents; Leukemia, Lymphocytic, Chronic, B-Cell; Liver Diseases; Lung Diseases; Methicillin-Resistant Staphylococcus aureus; Methylprednisolone; Mycophenolic Acid; Pneumonia, Staphylococcal; Skin Diseases; Tacrolimus; Transplantation, Homologous

Staphylococcal superantigens (SAg) are a family of potent exotoxins produced by Staphylococcus aureus. They play an important role in the pathogenesis of staphylococcal shock and pneumonia by causing a robust activation of the immune system and eliciting a strong surge in systemic cytokine and chemokine levels. Given the biological functions of SAg, we evaluated the efficacy of tacrolimus, a potent immunosuppressive agent, in the prophylaxis and therapy of staphylococcal TSS and pneumonia using human leukocyte antigen (HLA)-DR3 transgenic mice. Tacrolimus significantly inhibited staphylococcal SAg induced T cell activation in vitro. In vivo, tacrolimus significantly suppressed the SAg-induced elevation in serum cytokine and chemokine levels when given prophylactically, when administered immediately or even 2 h following systemic SAg challenge. Paradoxically, neither the prophylactic nor post-exposure treatment with tacrolimus protected mice from lethal SAg-induced TSS. A closer examination revealed that tacrolimus failed to suppress SAg-induced T cell proliferation and systemic pathology, including gut dysfunction. Tacrolimus also failed to protect from lethal pneumonia induced by a SAg-producing S. aureus strain. Thus, our study showed that even though T cell activation by SAg plays a major role in the immunopathogenesis of TSS and pneumonia, tacrolimus alone has no beneficial effect.

Topics: Animals; Cytokines; Enterotoxins; HLA-DR3 Antigen; Humans; Immunosuppressive Agents; Lymphocyte Activation; Mice; Mice, Transgenic; Pneumonia, Staphylococcal; Staphylococcus aureus; Superantigens; Systemic Inflammatory Response Syndrome; T-Lymphocytes; Tacrolimus; Treatment Outcome