Hypercytokinemia and hyperactivation of phospho-p38 mitogen-activated protein kinase in severe human influenza A virus infection.
BACKGROUND
We postulate that hypercytokinemia plays a role in immunopathogenesis of severe human influenza.


METHODS
We prospectively studied 39 consecutive patients who were hospitalized with severe influenza A virus infection. On laboratory confirmation of the diagnosis, paired acute-phase (obtained at hospital admission) and convalescent-phase (obtained >10 days after hospital admission) plasma samples were collected for assay of 11 cytokines and chemokines (interleukin [IL] 1 beta; IL-6; IL-10; IL-12p70; tumor necrosis factor alpha; IL-8; monokine induced by interferon [IFN]-gamma; IFN-inducible protein 10; monocyte chemoattractant protein 1; regulated upon activation, normal T cell-expressed and secreted; and IFN-gamma) using cytometric bead-array analysis and enzyme-linked immunosorbent assay. Simultaneously, virus concentration in the acute-phase nasopharyngeal aspirate was determined using real-time quantitative reverse-transcriptase polymerase chain reaction. Intracellular signaling molecules regulating lymphocyte activation, phospho-p38 mitogen-activated protein kinase and phospho-extracellular signal-regulated protein kinase in CD4+ and CD8+ T lymphocytes were studied in the acute-phase samples using flow cytometric analysis and were compared with results for samples from healthy control subjects.


RESULTS
Statistically significant increases in plasma IL-6 (3.7-fold increase), IL-8 (2.6-fold increase), IFN-induced protein 10 (4.9-fold increase), and monokine induced by IFN-gamma (2.3-fold increase) concentrations were detected during acute illness (P < .01 for all, by Wilcoxon signed-rank test); the highest concentrations were observed on symptom days 3 and 4. Corresponding plasma cytokine and chemokine concentrations and nasopharyngeal viral loads showed statistically significant correlations (rho = 0.41, 0.49, 0.54, and 0.46, respectively; P < or = .01). Phospho-p38 mitogen-activated protein kinase expression in CD4+ lymphocytes was increased, correlating with cytokine concentrations (e.g., for IFN-induced protein 10, rho = 0.78; P < .01); phospho-extracellular signal-regulated protein kinase was suppressed. Advanced age and comorbidity were associated with aberrant IL-6, IL-8, and monokine induced by IFN-gamma responses (P < .05, by Mann-Whitney U test). An elevated IL-6 concentration was independently associated with prolonged hospitalization (hospitalization for >5 days; P = .02), adjusted for age, comorbidity, and virus load.


CONCLUSIONS
Hypercytokinemia (of proinflammatory and T helper 1 cytokines) is detected in severe influenza, correlating with clinical illness and virus concentration. Hyperactivation of phospho-p38 mitogen-activated protein kinase (in T helper cells) is possibly involved. Early viral suppression may attenuate these potentially deleterious cytokine responses.
Lee
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Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China. leelsn@cuhk.edu.hk
Wong
C K
CK
Chan
P K S
PK
Lun
S W M
SW
Lui
G
G
Wong
B
B
Hui
D S C
DS
Lam
C W K
CW
Cockram
C S
CS
Choi
K W
KW
Yeung
A C M
AC
Tang
J W
JW
Sung
J J Y
JJ
D000293:Adolescent; D000328:Adult; D054370:Chemokine CXCL9 / Q000097:blood; D016207:Cytokines / Q000097:blood*; D004789:Enzyme Activation; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D009980:Influenza A virus / Q000235:genetics*; D007251:Influenza, Human / Q000097:blood* / Q000201:enzymology* / Q000473:pathology; D007371:Interferon-gamma / Q000097:blood; D016753:Interleukin-10 / Q000097:blood; D018664:Interleukin-12 / Q000097:blood; D053583:Interleukin-1beta / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D016209:Interleukin-8 / Q000097:blood; D008297:Male; D008875:Middle Aged; D010766:Phosphorylation; D011446:Prospective Studies; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
C080810:CXCL9 protein, human; D054370:Chemokine CXCL9; D016207:Cytokines; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D012367:RNA, Viral; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D018664:Interleukin-12; D007371:Interferon-gamma; D048051:p38 Mitogen-Activated Protein Kinases