Pneumonia Severity and Phase Linked to Virus-Specific T Cell Responses with Distinct Immune Checkpoints during pH1N1 Infection.

The detailed features and the longitudinal variation of influenza-specific T cell responses within naturally infected patients and the relationship with disease severity remain uncertain. In this study, we characterized the longitudinal influenza-specific CD4+ and CD8+ T cell responses, T cell activation, and migration-related cytokine/chemokine secretion in pH1N1-infected patients with or without viral pneumonia with human PBMCs. Both the influenza-specific CD4+ and CD8+ T cells presented higher responses in patients with severe infection than in mild ones, but with distinct longitudinal variations, phenotypes of memory markers, and immune checkpoints. At 7 ± 3 d after onset of illness, effector CD8+ T cells (CD45RA+CCR7-) with high expression of inhibitory immune receptor CD200R dominated the specific T cell responses. However, at 21 ± 3 d after onset of illness, effector memory CD4+ T cells (CD45RA-CCR7-) with high expression of PD1, CTLA4, and LAG3 were higher among the patients with severe disease. The specific T cell magnitude, T cell activation, and migration-related cytokines/chemokines possessed a strong connection with disease severity. Our findings illuminate the distinct characteristics of immune system activation during dynamic disease phases and its correlation with lung injury of pH1N1 patients.

Disease burden and prognostic factors for clinical failure in elderly community acquired pneumonia patients.

BACKGROUND: The study was to evaluate initial antimicrobial regimen and clinical outcomes and to explore risk factors for clinical failure (CF) in elderly patients with community-acquired pneumonia (CAP). METHODS: 3011 hospitalized elderly patients were enrolled from 13 national teaching hospitals between January 1, 2014 and December 31, 2014 initiated by the CAP-China network. Risk factors for CF were screened by multivariable logistic regression analysis. RESULTS: The incidence of CF in elderly CAP patients was 13.1%. CF patients were older, longer hospital stays and higher treatment costs than clinical success (CS) patients. The CF patients were more prone to present hyperglycemia, hyponatremia, hypoproteinemia, pleural effusion, respiratory failure and cardiovascular events. Inappropriate initial antimicrobial regimens in CF group were significantly higher than CS group. Undertreatment, CURB-65, PH < 7.3, PaO2/FiO2 < 200 mmHg, sodium < 130 mmol/L, healthcare-associated pneumonia, white blood cells > 10,000/mm3, pleural effusion and congestive heart failure were independent risk factors for CF in multivariable logistic regression analysis. Male and bronchiectasis were protective factors. CONCLUSIONS: Discordant therapy was a cause of CF. Early accurate detection and management of prevention to potential causes is likely to improve clinical outcomes in elderly patients CAP. TRIAL REGISTRATION: A Retrospective Study on Hospitalized Patients With Community-acquired Pneumonia in China (CAP-China) (RSCAP-China), NCT02489578. Registered 16 March 2015, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0005E5S&selectaction=Edit&uid=U0000GWC&ts=2&cx=1bnotb.

Effects of age, comorbidity and adherence to current antimicrobial guidelines on mortality in hospitalized elderly patients with community-acquired pneumonia.

BACKGROUND: Limited information exists on the clinical characteristics predictive of mortality in patients aged ≥65 years in many countries. The impact of adherence to current antimicrobial guidelines on the mortality of hospitalized elderly patients with community-acquired pneumonia (CAP) has never been assessed. METHODS: A total of 3131 patients aged ≥65 years were enrolled from a multi-center, retrospective, observational study initiated by the CAP-China network. Risk factors for death were screened with multivariable logistic regression analysis, with emphasis on the evaluation of age, comorbidities and antimicrobial treatment regimen with regard to the current Chinese CAP guidelines. RESULTS: The mean age of the study population was 77.4 ± 7.4 years. Overall in-hospital and 60-day mortality were 5.7% and 7.6%, respectively; these rates were three-fold higher in those aged ≥85 years than in the 65-74 group (11.9% versus 3.2% for in-hospital mortality and 14.1% versus 4.7% for 60-day mortality, respectively). The mortality was significantly higher among patients with comorbidities compared with those who were otherwise healthy. According to the 2016 Chinese CAP guidelines, 62.1% of patients (1907/3073) received non-adherent treatment. For general-ward patients without risk factors for Pseudomonas aeruginosa (PA) infection (n = 2258), 52.3% (1094/2090) were over-treated, characterized by monotherapy with an anti-pseudomonal ß-lactam or combination with fluoroquinolone + ß-lactam; while 71.4% of intensive care unit (ICU) patients (120/168) were undertreated, without coverage of atypical bacteria. Among patients with risk factors for PA infection (n = 815), 22.9% (165/722) of those in the general ward and 74.2% of those in the ICU (69/93) were undertreated, using regimens without anti-pseudomonal activity. The independent predictors of 60-day mortality were age, long-term bedridden status, congestive heart failure, CURB-65, glucose, heart rate, arterial oxygen saturation (SaO2) and albumin levels. CONCLUSIONS: Overtreatment in general-ward patients and undertreatment in ICU patients were critical problems. Compliance with Chinese guidelines will require fundamental changes in standard-of-care treatment patterns. The data included herein may facilitate early identification of patients at increased risk of mortality. TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov ( NCT02489578 ).

Disease characteristics and management of hospitalised adolescents and adults with community-acquired pneumonia in China: a retrospective multicentre survey.

OBJECTIVES: To describe the clinical characteristics and management of patients hospitalised with community-acquired pneumonia (CAP) in China. DESIGN: This was a multicentre, retrospective, observational study. SETTING: 13 teaching hospitals in northern, central and southern China from 1 January 2014 to 31 December 2014 PARTICIPANTS: Information on hospitalised patients aged ≥14 years with radiographically confirmed pneumonia with illness onset in the community was collected using standard case report forms. PRIMARY AND SECONDARY OUTCOME MEASURES: Resource use for CAP management. RESULTS: Of 14 793 patients screened, 5828 with radiographically confirmed CAP were included in the final analysis. Low mortality risk patients with a CURB-65 score 0-1 and Pneumonia Severity Index risk class I-II accounted for 81.2% (4434/5594) and 56.4% (2034/3609) patients, respectively. 21.7% (1111/5130) patients had already achieved clinical stability on admission. A definite or probable pathogen was identified only in 12.7% (738/5828) patients. 40.9% (1575/3852) patients without pseudomonal infection risk factors received antimicrobial overtreatment regimens. The median duration between clinical stability to discharge was 5.0 days with 30-day mortality of 4.2%. CONCLUSIONS: These data demonstrated the overuse of health resources in CAP management, indicating that there is potential for improvement and substantial savings to healthcare systems in China. TRIAL REGISTRATION NUMBER: NCT02489578; Results.

Risk factors for nosocomial infection among hospitalised severe influenza A(H1N1)pdm09 patients.

BACKGROUND AND OBJECTIVE: Nosocomial infections following influenza are important causes of death, requiring early implementation of preventive measures, but predictors for nosocomial infection in the early stage remained undetermined. We aimed to determine risk factors that can help clinicians identify patients with high risk of nosocomial infection following influenza on admission. METHOD: Using a database prospectively collected through a Chinese national network for hospitalised severe influenza A(H1N1)pdm09 patients, we compared the characteristics on admission between patients with and without nosocomial infection. RESULT: A total of 2146 patients were enrolled in the final analysis with a median age of 36.0 years, male patients comprising 50.2% of the sample and 232 (10.8%) patients complicated with nosocomial infection. Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia and Staphylococcus aureus were the leading pathogens, and invasive fungal infection was found in 30 cases (12.9%). The in-hospital mortality was much higher in patients with nosocomial infection than those without (45.7% vs 11.8%, P < 0.001). Need for mechanical ventilation (OR: 3.336; 95% CI 2.362-4.712), sepsis (OR: 2.125; 95% CI 1.236-3.651), ICU admission on first day (OR: 2.074; 95% CI 1.425-3.019), lymphocytopenia (OR: 1.906; 95% CI 1.361-2.671), age > 65 years (OR: 1.83; 95% CI 1.04-3.21) and anaemia (OR: 1.39; 95% CI 1.39-2.79) were independently associated with nosocomial infection. CONCLUSION: Need for mechanical ventilation, sepsis, ICU admission on first day, lymphocytopenia, older age and anaemia were independent risk factors that can help clinicians identify severe influenza A(H1N1)pdm09 patients at high risk of nosocomial infection.

Vγ4+γδT Cells Aggravate Severe H1N1 Influenza Virus Infection-Induced Acute Pulmonary Immunopathological Injury via Secreting Interleukin-17A.

The influenza A (H1N1) pdm09 virus remains a critical global health concern and causes high levels of morbidity and mortality. Severe acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are the major outcomes among severely infected patients. Our previous study found that interleukin (IL)-17A production by humans or mice infected with influenza A (H1N1) pdm09 substantially contributes to ALI and subsequent morbidity and mortality. However, the cell types responsible for IL-17A production during the early stage of severe influenza A (H1N1) pdm09 infection remained unknown. In this study, a mouse model of severe influenza A (H1N1) pdm09 infection was established. Our results show that, in the lungs of infected mice, the percentage of γδT cells, but not the percentages of CD4+Th and CD8+Tc cells, gradually increased and peaked at 3 days post-infection (dpi). Further analysis revealed that the Vγ4+γδT subset, but not the Vγ1+γδT subset, was significantly increased among the γδT cells. At 3 dpi, the virus induced significant increases in IL-17A in the bronchoalveolar lavage fluid (BALF) and serum. IL-17A was predominantly secreted by γδT cells (especially the Vγ4+γδT subset), but not CD4+Th and CD8+Tc cells at the early stage of infection, and IL-1ß and/or IL-23 were sufficient to induce IL-17A production by γδT cells. In addition to secreting IL-17A, γδT cells secreted interferon (IFN)-γ and expressed both an activation-associated molecule, natural killer group 2, member D (NKG2D), and an apoptosis-associated molecule, FasL. Depletion of γδT cells or the Vγ4+γδT subset significantly rescued the virus-induced weight loss and improved the survival rate by decreasing IL-17A secretion and reducing immunopathological injury. This study demonstrated that, by secreting IL-17A, lung Vγ4+γδT cells, at least, in part mediated influenza A (H1N1) pdm09-induced immunopathological injury. This mechanism might serve as a promising new target for the prevention and treatment of ALI induced by influenza A (H1N1) pdm09.

Effect of low-to-moderate-dose corticosteroids on mortality of hospitalized adolescents and adults with influenza A(H1N1)pdm09 viral pneumonia.

BACKGROUND: The effect of corticosteroids on influenza A(H1N1)pdm09 viral pneumonia patients remains controversial, and the impact of dosage has never been studied. METHODS: Using data of hospitalized adolescent and adult patients with influenza A(H1N1)pdm09 viral pneumonia, prospectively collected from 407 hospitals in mainland China, the effects of low-to-moderate-dose (25-150 mg d-1 ) and high-dose (>150 mg d-1 ) corticosteroids on 30-day mortality, 60-day mortality, and nosocomial infection were assessed with multivariate Cox regression and propensity score-matched case-control analysis. RESULTS: In total, 2141 patients (median age: 34 years; morality rate: 15.9%) were included. Among them, 1160 (54.2%) had PaO2 /FiO2 <300 mm Hg on admission, and 1055 (49.3%) received corticosteroids therapy. Corticosteroids, without consideration of dose, did not influence either 30-day or 60-day mortality. Further analysis revealed that, as compared with the no-corticosteroid group, low-to-moderate-dose corticosteroids were related to reduced 30-day mortality (adjusted hazard ratio [aHR] 0.64 [95% CI 0.43-0.96, P=.033]). In the subgroup analysis among patients with PaO2 /FiO2 <300 mm Hg, low-to-moderate-dose corticosteroid treatment significantly reduced both 30-day mortality (aHR 0.49 [95% CI 0.32-0.77]) and 60-day mortality (aHR 0.51 [95% CI 0.33-0.78]), while high-dose corticosteroid therapy yielded no difference. For patients with PaO2 /FiO2 ≥300 mm Hg, corticosteroids (irrespective of dose) showed no benefit and even increased 60-day mortality (aHR 3.02 [95% CI 1.06-8.58]). Results were similar in the propensity model analysis. CONCLUSIONS: Low-to-moderate-dose corticosteroids might reduce mortality of influenza A(H1N1)pdm09 viral pneumonia patients with PaO2 /FiO2 <300 mm Hg. Mild patients with PaO2 /FiO2 ≥300 mm Hg could not benefit from corticosteroid therapy.