Staphylococci have emerged as the most significant bacterial pathogen in the community and health care institutions, causing over two million high-risk infections per year in the United States alone. Community- acquired Methicillin-Resistant Staphylococcus aureus (CA-MRSA) is responsible for Acute Lung Injury (ALI) associated with necrotizing pneumonia often complicated by Acute Respiratory Distress Syndrome (ARDS), Toxic Shock, and Disseminated Intravascular Coagulation (DIC). Health care-associated MRSA (HA-MRSA) threatens newborns in nurseries and older patients hospitalized with medical and surgical problems. Toxic shock syndrome carries significant patient mortality in children (5%) and adults (up to 80%). This syndrome is due to production of T cell-activating exotoxins ("superantigens") by antibiotic-resistant staphylococci. Their uncontrolled proliferation and production of superantigens in the lungs often occurs in the wake of influenza virus infection doubling its annual mortality (65,000 deaths). Superantigens robustly stimulate T cells to proliferate and produce overwhelming quantities of proinflammatory cytokines/chemokines that trigger lung vascular injury, apoptosis, and hemorrhagic necrosis. Our ultimate goal is to develop new therapeutic approaches to superantigen-induced ALI. During the past funding period we developed an innovative in vivo platform termed intracellular protein/peptide therapy (IPT), to suppress the uncontrolled production of proinflammatory cytokines and chemokines in animals challenged with the superantigen staphylococcal enterotoxin B (SEB). We engineered a cell-penetrating (CP-) form of the physiologic protein Suppressor of Cytokine Signaling 3 (SOCS3) that attenuated SEB-induced acute inflammation, apoptosis, and hemorrhagic necrosis of the liver. However, endogenous SOCS3 seemed insufficient to avert "spontaneous" and fatal lung inflammation in mice born with SOCS1 deficiency, rendering SOCS1 a more attractive candidate for IPT of ALI. Based on these clinically- relevant advances, the central hypothesis of this competing renewal application is that CP-SOCS1 can attenuate ALI and protect lungs from the noxious action of proinflammatory cytokines and chemokines induced by direct airway exposure to superantigens. This central hypothesis will be tested in the following specific aims: (i) To engineer CP forms of SOCS1 that target noxious signaling evoked by T cell- derived inflammatory cytokines/chemokines in response to SEB exposure; (ii) To compare lung cytoprotective activity of CP-SOCS1 and CP-SOCS3 as a countermeasure for ALI/ARDS including antecedent influenza virus infection and (iii) To determine the inhibitory mechanism of CP-SOCS1 action in SEB-induced disease. Results from these studies will meet the urgent need for new anti-inflammatory drugs that attenuate acute lung vascular injury and DIC evoked by staphylococcal superantigens that often work in tandem with other viral and bacterial pathogens. [unreadable] [unreadable] [unreadable]