sirolimus and Orthomyxoviridae-Infections

Influenza virus infection often causes severe disease and acute respiratory distress syndrome. It is a common belief that overwhelming immune response contributes to the severe illness. Physicians and researchers have put forth immune modulation as salvage therapy for better recovery. However, empiric corticosteroid failed in both humans and animal models. Reported success with Rapamycin in humans prompted a comprehensive animal study and mechanistic dissection. Here we report the effect of Rapamycin alone or in combination with Oseltamivir for severe influenza in BALB/c mice. We found that Rapamycin had no antiviral effect against H1N1, H3N2 and novel-H1N1 influenza viruses in vitro. Rapamycin alone aggravated the severe disease of PR8 H1N1 influenza virus infection in mice. Timely Oseltamivir anti-viral therapy abolished the disease. Delayed Oseltamivir treatment could not prevent severe illness and Rapamycin adjuvant was associated with exacerbated disease. Rapamycin adjuvant suppressed influenza hemagglutinin antigen-specific T cell immunity and impaired virus clearance from the lungs. It also resulted in intensified lung pathology with increased intra-alveolar edema and hyaline deposition. Rapamycin may work as the salvage therapy for severe influenza but it is very difficult to define the appropriate window for such treatment to take effect.

Topics: Animals; Antiviral Agents; Disease Models, Animal; Disease Progression; Immunity, Cellular; Influenza A virus; Lung; Mice; Mice, Transgenic; Orthomyxoviridae Infections; Oseltamivir; Severity of Illness Index; Sirolimus; T-Lymphocytes

Impairment of immune defenses can contribute to severe influenza infections. Rapamycin is an immunosuppressive drug often used to prevent transplant rejection and is currently undergoing clinical trials for treating cancers and autoimmune diseases. We investigated whether rapamycin has deleterious effects during lethal influenza viral infections. We treated mice with two concentrations of rapamycin and infected them with A/Puerto Rico/8/1934 (A/PR8), followed by a heterosubtypic A/Hong Kong/1/68 (A/HK68) challenge. Our data show similar morbidity, mortality, and lung viral titer with both rapamycin treatment doses compared to untreated controls, with a delay in morbidity onset in rapamycin high dose recipients during primary infection. Rapamycin treatment at high dose also led to increase in percent cytokine producing T cells in the spleen. However, all infected animals had similar serum antibody responses against A/PR8. Post-A/HK68 challenge, rapamycin had no impeding effect on morbidity or mortality and had similar serum antibody levels against A/PR8 and A/HK68. We conclude that rapamycin treatment does not adversely affect morbidity, mortality, or antibody production during lethal influenza infections.

Topics: Animals; Antibody Formation; Cytokines; Disease Models, Animal; Immunosuppressive Agents; Influenza A virus; Lung; Mice; Orthomyxoviridae Infections; Sirolimus; Spleen; Survival Analysis; T-Lymphocytes; Viral Load

Recall responses by memory CD8 T cells are impaired in the absence of CD4 T cells. Although several mechanisms have been proposed, the molecular basis is still largely unknown. Using a local influenza virus infection in the respiratory tract and the lung of CD4(-/-) mice, we show that memory CD8 T cell impairment is limited to the lungs and the lung-draining lymph nodes, where viral Ags are unusually persistent and abundant in these mice. Persistent Ag exposure results in prolonged activation of the AKT-mTORC1 pathway in Ag-specific CD8 T cells, favoring their development into effector memory T cells at the expense of central memory T cells, and inhibition of mTORC1 by rapamycin largely corrects the impairment by promoting central memory T cell development. The findings suggest that the prolonged AKT-mTORC1 activation driven by persistent Ag is a critical mechanism underlying the impaired memory CD8 T cell development and responses in the absence of CD4 T cells.

Topics: Animals; Antigens; CD4 Antigens; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Immunologic Memory; Immunophenotyping; Lymphocyte Activation; Mechanistic Target of Rapamycin Complex 1; Mice; Mice, Knockout; Mice, Transgenic; Multiprotein Complexes; Orthomyxoviridae; Orthomyxoviridae Infections; Phenotype; Proto-Oncogene Proteins c-akt; Sirolimus; TOR Serine-Threonine Kinases

Interleukin 15 (IL-15) controls both the homeostasis and the peripheral activation of natural killer (NK) cells. The molecular basis for this duality of action remains unknown. Here we found that the metabolic checkpoint kinase mTOR was activated and boosted bioenergetic metabolism after exposure of NK cells to high concentrations of IL-15, whereas low doses of IL-15 triggered only phosphorylation of the transcription factor STAT5. mTOR stimulated the growth and nutrient uptake of NK cells and positively fed back on the receptor for IL-15. This process was essential for sustaining NK cell proliferation during development and the acquisition of cytolytic potential during inflammation or viral infection. The mTORC1 inhibitor rapamycin inhibited NK cell cytotoxicity both in mice and humans; this probably contributes to the immunosuppressive activity of this drug in different clinical settings.

Topics: Animals; Cell Proliferation; Cells, Cultured; Herpesviridae Infections; Humans; Immunosuppressive Agents; Inflammation; Influenza A Virus, H1N1 Subtype; Interleukin-15; Killer Cells, Natural; Lymphocyte Activation; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Mice; Mice, Inbred C57BL; Mice, Knockout; Multiprotein Complexes; Muromegalovirus; Orthomyxoviridae Infections; Poly I-C; Signal Transduction; Sirolimus; STAT5 Transcription Factor; TOR Serine-Threonine Kinases

Highly pathogenic avian influenza viruses pose a continuing global threat. Current vaccines will not protect against newly evolved pandemic viruses. The creation of 'universal' vaccines has been unsuccessful because the immunological mechanisms that promote heterosubtypic immunity are incompletely defined. We found here that rapamycin, an immunosuppressive drug that inhibits the kinase mTOR, promoted cross-strain protection against lethal infection with influenza virus of various subtypes when administered during immunization with influenza virus subtype H3N2. Rapamycin reduced the formation of germinal centers and inhibited class switching in B cells, which yielded a unique repertoire of antibodies that mediated heterosubtypic protection. Our data established a requirement for the mTORC1 complex in B cell class switching and demonstrated that rapamycin skewed the antibody response away from high-affinity variant epitopes and targeted more conserved elements of hemagglutinin. Our findings have implications for the design of a vaccine against influenza virus.

Topics: Adaptive Immunity; Animals; Antibodies, Viral; Antibody Formation; B-Lymphocytes; Cell Line; Female; Flow Cytometry; Host-Pathogen Interactions; Immunoglobulin Class Switching; Immunoglobulin M; Immunosuppressive Agents; Influenza A Virus, H3N2 Subtype; Influenza A Virus, H5N1 Subtype; Mechanistic Target of Rapamycin Complex 1; Mice; Mice, Inbred C57BL; Mice, Knockout; Multiprotein Complexes; Orthomyxoviridae; Orthomyxoviridae Infections; Sirolimus; Survival Analysis; T-Lymphocytes; TOR Serine-Threonine Kinases