Plasma cytokine levels and cytokine gene polymorphisms in Mexican patients during the influenza pandemic A(H1N1)pdm09.

BACKGROUND: In Mexico, the initial severe cases of the 2009 influenza pandemic virus A (H1N1) [A(H1N1)pdm09] were detected in early March. The immune mechanisms associated with the severe pneumonia caused by infection with this new virus have not been completely elucidated. Polymorphisms in interleukin genes have previously been associated with susceptibility to infectious diseases due to their influence on cytokine production. OBJECTIVES: The present case-control study was performed to compare several immunologic and genetic parameters of patients and controls during the initial phase of the pandemic. STUDY DESIGN: Sixty-five patients who were hospitalized due to infection with the influenza A(H1N1)pdm09 virus and 46 healthy controls were studied. A hemagglutination inhibition assay (HIA) was performed to measure anti-influenza antibody titers in these subjects. Protein levels of the cytokines interleukin (IL)-4, IL-6, IL-8, IL-10, tumor necrosis factor-α (TNFα), interferon gamma (IFNγ), transforming growth factor beta (TGFß)1 and TGFß2 were quantified in plasma. Single nucleotide polymorphisms in IL6, IL10 and TNFα were also assessed. RESULTS: Influenza patients had lower antibody titers and produced significantly higher levels of IL-6, IL-10 and TNFα than healthy controls. The frequencies of the TNFα -308G, IL-10 -592C and IL-10 -1082A alleles and the IL10 -1082(A/A) genotype were associated with susceptibility to severe disease, while the haplotypes TNFα AG and IL-10 GTA and GCA were associated with protection from severe disease [P=0.016, OR (CI)=0.11 (0.01-0.96); P=0.0187, OR (CI)=0.34 (0.13-0.85); P=0.013, OR (CI)=0.39 (0.18-0.83)]. CONCLUSIONS: This study demonstrates that the influenza A(H1N1)pdm09 patients and healthy controls have different profiles of immune parameters and that there is an association between IL-10 and TNFα polymorphisms and the outcome of this disease.

Difference between early clinical features of swine origin A H1N1 influenza confirmed and not confirmed infection in Mexico.

INTRODUCTION: The Swine Origin A H1N1 Influenza Virus (SOIV) pandemic emerged in April 2009 affecting people and health-care systems worldwide. This study examined the differences among the early clinical features presented in confirmed SOIV cases, those who tested negative for SOIV infection, fatalities, and hospitalized cases. METHODOLOGY: We reviewed 1,024 initial medical records of patients presenting with acute respiratory symptoms who attended the respiratory emergency room of a general hospital in Mexico and had a confirmatory test for influenza AH1N1 by RT-PCR from April to December 2009. RESULTS: Out of 1,024 cases, 457 (44%) were men with a mean age of 31±17 years; however, of these, SOIV confirmed cases were younger (26±8, p=0.000). SOIV infection was confirmed in 36% of the patients. Most (%?) cases presented mild infection, 20% of the patients required hospitalization, and 0.09% patients died. Asthma was more frequent in confirmed cases (p=0.028). Presence of COPD, systemic arterial hypertension, and diabetes mellitus was significant in confirmed hospitalized cases. Pulmonary rales, wheezing, and sudden symptom onset were more frequent and statistically significant in confirmed patients. Influenza-like illness was more frequent in confirmed cases (p=0.049).  CONCLUSIONS: This study presents one of the largest series of the new SOIV infection confirmed by RT-PCR reported. This infection is frequently mild and affects mainly young adults. Sudden symptoms onset, pulmonary rales, and wheezing are early features of this infection. Asthma, COPD, systemic arterial hypertension, and diabetes mellitus should be identified to identify potentially severe and fatal cases. ILI helps distinguish SOIV infection.