key: cord-0915267-r4x156vk
authors: Antalis, Emmanouil; Spathis, Aris; Kottaridi, Christine; Kossyvakis, Athanasios; Pastellas, Kalliopi; Tsakalos, Konstantinos; Mentis, Andreas; Kroupis, Christos; Tsiodras, Sotirios
title: Th17 serum cytokines in relation to laboratory‐confirmed respiratory viral infection: A pilot study
date: 2019-02-04
journal: J Med Virol
DOI: 10.1002/jmv.25406
sha: 1b5954d845694ddd2695243d5732946aec56fbc2
doc_id: 915267
cord_uid: r4x156vk

BACKGROUND: Th17 cytokines are associated with modulation of inflammation and may be beneficial in clearing influenza infection in experimental models. The Th17 cytokine profile was evaluated in a pilot study of respiratory virus infections. METHODS: Consecutive patients with symptoms of respiratory tract infection visiting the emergency department of a tertiary care hospital during the winter influenza season of 2014 to 2015 were evaluated. CLART PneumoVir kit, (GENOMICA, Madrid, Spain) was used for viral detection of all known respiratory viruses. Th17 cytokine profile was evaluated with the MILLIPLEX MAP Human TH17 Magnetic Bead Panel (Millipore Corp., Billerica, MA). Correlation of the TH17 profile with viral detection was performed with univariate and multivariate analysis. RESULTS: Seventy‐six patients were evaluated (median age 56 years, 51.3% female); a respiratory virus was identified in 60 (78.9%) patients; 45% had confirmed influenza. Influenza A (H3N2) correlated with higher levels of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), interleukin 1β (IL‐1β), IL‐17A, IL‐17E, IL‐17F, IL‐21, IL‐22, and IL‐23 (P < 0.05 by analysis of variance [ANOVA]) compared with respiratory syncytial virus (RSV). Parainfluenza virus (PIV) similarly had higher levels of GM‐CSF, IL‐1b, IL‐17A, IL‐22 compared with those detected in RSV, influenza B and any other virus infection ( P < 0.05; ANOVA). Increasing age (β‐coefficient = 1.11, 95% CI, 1.04‐1.2, P < 0.01) as well as IL‐17A levels (β‐coefficient = 1.03, 95% CI, 1.001‐1.05, P = 0.04) predicted hospital admission. CONCLUSION: Main Th17 cell effector cytokines were upregulated in laboratory‐confirmed A(H3N2) influenza and PIV. Excessive amounts of Th17 cytokines may be implicated in the pathogenesis and immune control of acute influenza and PIV infection in humans and may predict the severity of disease.

A significant interplay between innate and adaptive immunity controls the response to respiratory viral infections. 1 Influenza upon infecting a human cell is recognized by pattern recognition receptors; this leads to the mobilization of the innate immune system and the secretion of chemokines and cytokine. [1] [2] [3] Through a sequence of events neighboring innate immune cells activate transforming growth factor-β from its latent form and result in further secretion of chemokines and interleukins from parenchymal and inflammatory cells. 2 In the initial phase of the immune response, a crucial role is contributed by proinflammatory cytokines, members of the inter- have been proposed to be associated with modulation of inflammation and may be beneficial in clearance of influenza infection. 4 However, others have suggested a potential role in increasing disease related severity in animal models. 5 Limited data have suggested an association of an exaggerated systemic Th1 and Th17 response in severe disease with respiratory involvement in patients suffering from pandemic influenza caused by the AH1N1pdm09 strain. 6 In the current study, we evaluated the Th17 cytokine profile in a pilot study of respiratory virus infection where molecular testing was used for virus identification. 

Seventy-six patients were evaluated with a median age 56 years, (interquartile range [IQR] 39-78 years); 48.7% were female. A respiratory virus was identified in 60 (78.9%) patients (Table 1) Laboratory and cytokine data per specific virus infection for patients in the study are depicted in Table 2 . Data are additionally shown for six healthy volunteers that had significantly lower cytokine values from all the rest of the group (P < 0.01 for all comparisons; Table 2 ). Elevated C-reactive protein levels values were noted for most of the patients seen (Table 2 ; normal values less than 6 mg/L).

The highest C-reactive protein levels values were seen with PIV detection that reached statistical significance when compared with the levels seen with all other viruses including all types of influenza, We did not identify a significant association of the IL-17 cascade with specific clinical parameters like the presence of fever, the height of fever (eg, >38.3°C), wheezing, myalgias, and the presence of a dry or a productive cough. Presence of nasal symptoms showed a statistically significant negative correlation with all studied cytokines except for IL-6 (P < 0.05 for all comparison-independent samples t test). A logistic regression model adjusting for age, the presence of any comorbidity, and an interaction term for WBCs, CRP levels, and IL-17A levels found that age (β-coefficient = 1.11, 95% CI, 1.04-1.2, P < 0.01) as well as IL-17A levels (β-coefficient = 1.03, 95% CI, 1.001- It is unclear how IL-17 is involved in the immune response to influenza or PIV infections. A crucial role for IL-17-mediated inflammation has been found for microbial clearance 8 ; on the other hand, uncontrolled signaling has been associated with autoimmune disease and even cancer progression. 8 Specific family members have discrete roles in human immunity eg, IL-17F is mainly involved in mucosal host defense mechanisms, whereas IL-17E (IL-25) is an amplifier of Th2 immune responses. [9] [10] [11] Over the last few years very few studies have examined the role of the Th17 pathway in human influenza infections, 12 and none to our knowledge in humans with the respiratory infection, and in comparison with other viruses affecting the respiratory tract. Recent literature suggests that Th17 adaptive immunity may be involved in the clearance of influenza viruses from the respiratory tract.

The immune system of patients suffering from influenza responds with the release of several proinflammatory cytokines. [12] [13] [14] Among this cascade of cytokines, 15 IL-6 appears to have a central role in symptom generation and local inflammatory effects. [16] [17] [18] [19] The clinical relevance of this cytokine storm is that it recruits neutrophils, monocytes, and macrophages to the sites of infection, 15 and may be associated with more severe disease and outcomes that appear to depend on the pathogenicity of the virus and the host response. The role of IL-17 in this process has not been clearly delineated yet although its importance is increasingly recognized. 4, 6, 9, [20] [21] [22] [23] Some studies have not shown a positive association with only mild increases in IL-17 levels. 19 Two studies on patients severely affected by the 2009 pandemic virus, higher IL-17A levels were noted in milder cases, a finding consistent with enhanced-viral clearance. 6, 22 In one study, there was a marked suppression of the adaptive Th1/Th17 immunity A(HN1)pdm09 influenza compared with the seasonal type A and type B influenza. 12 In another study of pediatric infections with the novel pandemic virus A(H1N1)pdm09 higher levels of interferon-α and IL-6 were seen in patients with the pandemic infection compared to controls with pneumonia attributed to other causes; moreover higher IL-6 correlated with disease severity. 24 Nevertheless, in that study, IFN-γ and IL-17 did not differ between mildly and severely affected patients. 24 An increase of IL-17 in patients suffering from diffuse alveolar damage was seen in one experimental lung immunopathology autopsy study of patients affected by the pandemic A (H1N1) virus. 25 

Regarding our RSV observations, limited literature suggests a role for IL-17 cytokines in RSV pathogenicity. [26] [27] [28] [29] [30] In one infant study, IL-17A and IL-23 levels were associated with a reduction in clinical symptoms of respiratory distress. 31 Lower levels of IL-17 cytokines in patients with RSV in our study might have contributed to an inability to properly control the host inflammatory response leading to a more serious disease pattern and sicker patients with RSV that were hospitalized longer. Sampling from other sites, for example nasal sampling or BAL (in severe cases), would assist in better understanding the difference/ synergy between local compared with systemic cytokine effects. In addition, although we carefully recorded and analyzed data on variables potentially adversely affecting an effective immune response we could not account for residual confounding in this study. We can only hypothesize about the mechanism behind the difference in the cytokine profile observed between influenza A and B in our effort. Influenza B infection remains less studied than influenza A both in humans and animals despite the fact that it is associated with a significant number of respiratory infection cases during winter. 32 Contrary to our findings, in a study of 72 patients comparing cytokine levels in type A vs type B influenza, IL-17A (the hallmark cytokine of the TH17 cell subset) along with IL-6 levels were significantly higher in type B influenza. 33 A less virulent circulating B strain could explain our findings. In an animal study that used an immunosuppressed-mouse model of influenza B infection and a cytokine panel that included IL-17, there was no evidence of an important contribution of Th17 in the pathogenicity. 34 Moreover different degrees of immunopathology was caused by two different influenza B viruses; the Victoria lineage virus was more virulent and was associated with greater morbidity and 100% lethality in these experiments. 34 Interestingly, during the period of our study the main influenza B strain across Europe and in Greece belonged to the Yamagata lineage. 35 Due to the small sample of this study, this F I G U R E 1 Continued ANTALIS ET AL.

| 969 difference will have to be verified in other studies that would specifically examine different lineages of the virus. Finally, the role of Th17 in the effects of influenza on other systems was not assessed in this effort. For example, in a mouse model of respiratory influenza a significant Th17 response in the intestine that was associated with immune intestinal injury and development of diarrhea was noted; furthermore neutralizing IL-17A reduced intestinal injury. 36 Intestinal microbiota changes and their relation to influenza or other virusmediated cytokine changes, which is an interesting field for further human research; it could not be assessed in the current effort. 36 In conclusion, we described IL-17 family cytokine level associations with respiratory viral infections confirmed by a molecular method in a pilot study. A large-scale study of patients with respiratory viral infections would further assist in concurring and understanding the observed upregulation of main Th17 cell effector cytokines in relation to specific types of respiratory viruses. This association and especially the one observed for influenza AH3N2 and PIV is novel and merits consideration even if the finding comes from a small pilot. Future verification of our study results as well as further exploitation of this cytokine pathway for diagnostic, therapeutic, and prognostic purpose that may greatly assist in the management of common but potentially serious viral respiratory infections is necessary.

http://orcid.org/0000-0002-0463-4321

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