Immune derangement occurs in patients with H7N9 avian influenza

Should We Interfere with the Interleukin-6 Receptor During COVID-19: What Do We Know So Far?

Severe manifestations of COVID-19 consist of acute respiratory distress syndrome due to an initially local reaction leading to a systemic inflammatory response that results in hypoxia. Many therapeutic approaches have been attempted to reduce the clinical consequences of an excessive immune response to viral infection. To date, systemic corticosteroid therapy is still the most effective intervention. More recently, new hope has emerged with the use of interleukin (IL)-6 receptor inhibitors (tocilizumab and sarilumab). However, the great heterogeneity of the methodology and results of published studies obfuscate the true value of this treatment, leading to a confusing synthesis in recent meta-analyses, and the persistence of doubts in terms of patient groups and the appropriate time to treat. Moreover, their effects on the anti-infectious or pro-healing response are still poorly studied. This review aims to clarify the potential role of IL-6 receptor inhibitors in the treatment of severe forms of COVID-19.

Protective Intranasal Immunization Against Influenza Virus in Infant Mice Is Dependent on IL-6

Respiratory diseases adversely affect infants and are the focus of efforts to develop vaccinations and other modalities to prevent disease. The infant immune system differs from that of older children and adults in many ways that are as yet ill understood. We have used a C57BL/6 mouse model of infection with a laboratory- adapted strain of influenza (PR8) to delineate the importance of the cytokine IL-6 in the innate response to primary infection and in the development of protective immunity in adult mice. Herein, we used this same model in infant (14 days of age) mice to determine the effect of IL-6 deficiency. Infant wild type mice are more susceptible than older mice to infection, similar to the findings in humans. IL-6 is expressed in the lung in the early response to PR8 infection. While intramuscular immunization does not protect against lethal challenge, intranasal administration of heat inactivated virus is protective and correlates with expression of IL-6 in the lung, activation of lung CD8 cells, and development of an influenza-specific antibody response. In IL-6 deficient mice, this response is abrogated, and deficient mice are not protected against lethal challenge. These studies support the importance of the role of the tissue environment in infant immunity, and further suggest that IL-6 may be helpful in the generation of protective immune responses in infants.

Highly pathogenic H7N9 avian influenza virus infection associated with up-regulation of PD-1/PD-Ls pathway-related molecules

To investigate the main transcriptional and biological changes of human host during low and highly pathogenic avian H7N9 influenza virus infection and to analyze the possible causes of escalated virulence and the systematic progression of H7N9 virus infection, we utilized whole transcriptome sequencing (RNA-chip and RNA-seq) and other biomolecular methods to analyze and verify remarkable changes of host cells during these two subtypes of H7N9 influenza viruses infection. Whole transcriptome analysis showed the global profiles of differentially expressed genes (DEGs) and identified 458 DEGs associated with major changes in biological processes of the host cells after infection with 2017 HPAI H7N9 virus versus 2013 LPAI H7N9 virus, mainly including drastically increased defense responses to viruses (e.g. negative regulation of viral gene replication), IFNs related pathways, immune response/native immune response, and inflammatory response. Genes of programmed cell death 1 (PD-1) pathways were found changed remarkably and several highly correlated non-coding RNAs were identified. The results suggested that HPAI H7N9 virus induces stronger immune response and suppressing response than LPAI H7N9. Meanwhile, PD-1/PD-Ls signaling pathways work together in regulating host responses including antiviral defense, lethal inflammation caused by the virus and immune response, thus contribute to the high pathogenicity of 2017H7N9 virus that can be regulated by non-coding RNAs. The present study represents a comprehensive understanding and good reference of regulation of pathogenicity of H7N9 virus even other fatal viruses and correlated host immune responses.

A Risk Classification Model to Predict Mortality Among Laboratory-Confirmed Avian Influenza A H7N9 Patients: A Population-Based Observational Cohort Study

BACKGROUND

Avian influenza A H7N9 (A/H7N9) is characterized by rapid progressive pneumonia and respiratory failure. Mortality among laboratory-confirmed cases is above 30%; however, the clinical course of disease is variable and patients at high risk for death are not well characterized.

METHODS

We obtained demographic, clinical, and laboratory information on all A/H7N9 patients in Zhejiang province from China Centers for Disease Control and Prevention electronic databases. Risk factors for death were identified using logistic regression and a risk score was created using regression coefficients from multivariable models. We externally validated this score in an independent cohort from Jiangsu province.

RESULTS

Among 305 A/H7N9 patients, 115 (37.7%) died. Four independent predictors of death were identified: older age, diabetes, bilateral lung infection, and neutrophil percentage. We constructed a score with 0-13 points. Mortality rates in low- (0-3), medium- (4-6), and high-risk (7-13) groups were 4.6%, 32.1%, and 62.7% (Ptrend < .0001). In a validation cohort of 111 A/H7N9 patients, 61 (55%) died. Mortality rates in low-, medium-, and high-risk groups were 35.5%, 55.8, and 67.4% (Ptrend = .0063).

CONCLUSIONS

We developed and validated a simple-to-use, predictive risk score for clinical use, identifying patients at high mortality risk.

Concomitant severe influenza and cryptococcal infections: A case report and literature review

Concomitant influenza and cryptococcal infections are rare. Herein, we describe an unusual case of an avian influenza A (H7N9) infection with several severe mixed bacterial infections and systemic super-infection with Cryptococcus neoformans presenting as ventilator-associated pneumonia (VAP) and bloodstream infection in a previously immunocompetent man during hospitalization.A 58-year-old man was admitted to our hospital complaining of hyperpyrexia, dyspnoea, cough, and phlegm with blood. A chest computed tomography scan revealed multiple ground-glass opacities and consolidation in both lungs with right pleural effusion. An initial sputum test was positive for influenza A (H7N9) virus. After antiviral treatment and other supportive measures, the patient's condition improved. However, the patient's condition deteriorated again approximately 2 weeks after admission, and bronchoalveolar lavage fluid (BALF) and blood cultures were positive for C. neoformans. Therapy with intravenous liposomal amphotericin B and fluconazole was started. After a 2-week antifungal treatment, BALF and blood cultures were negative for C. neoformans. However, the patient had persistent lung infiltrates with severe pulmonary fibrosis with a prolonged course of disease. On hospital day 40, BALF and blood cultures were both positive for multidrug-resistant Stenotrophomonas maltophilia. Finally, the patient developed septic shock, disseminated intravascular coagulation and multi-organ failure and succumbed to treatment failure.Cryptococcal infection can occur in patients with severe influenza during hospitalization with a more severe condition, and the clinician should be aware of this infection.

Management of Sepsis-Induced Immunosuppression

It is now well established that profound immunosuppression develops within a few days after sepsis onset in patients. This should be considered additional organ failure because it is associated with increased rate of nosocomial infections, mortality, and long-term complications, thus constituting the rationale for immunomodulation in patients. Nevertheless, the demonstration of the efficacy of such therapeutic strategy in improving deleterious outcomes in sepsis remains to be made. Results from clinical trials based on interleukin 7 and granulocyte macrophage colony-stimulating factor immunoadjuvant therapies in septic shock patients are expected for 2018.

Fc functional antibodies in humans with severe H7N9 and seasonal influenza

BACKGROUND

Both seasonal and novel avian influenza viruses can result in severe infections requiring hospitalization. Anti-influenza antibodies (Abs) with Fc-mediated effector functions, such as Ab-dependent cellular cytotoxicity (ADCC), are of growing interest in control of influenza but have not previously been studied during severe human infections. As such, the objective of this study was to examine Fc-mediated Ab functions in humans hospitalized with influenza infection.

METHODS

Serum Ab response was studied in subjects hospitalized with either pandemic H7N9 avian influenza virus in China (n = 18) or circulating seasonal influenza viruses in Melbourne, Australia (n = 16). Recombinant soluble Fc receptor dimer ELISAs, natural killer (NK) cell activation assays, and Ab-dependent killing assays with influenza-infected target cells were used to assess the Fc functionality of anti-influenza hemagglutinin (HA) Abs during severe human influenza infection.

RESULTS

We found that the peak generation of Fc functional HA Abs preceded that of neutralizing Abs for both severe H7N9 and seasonal influenza infections. Subjects who succumbed to complications of H7N9 infection demonstrated reduced HA-specific Fc receptor-binding Abs (in magnitude and breadth) immediately prior to death compared with those who survived. Subjects who recovered from H7N9 and severe seasonal influenza infections demonstrated increased Fc receptor-binding Abs not only against the homologous infecting strain but against HAs from different influenza A subtypes.

CONCLUSION

Collectively, survivors of severe influenza infection rapidly generate a functional Ab response capable of mediating ADCC against divergent influenza viruses. Broadly binding HA Abs with Fc-mediated functions may be a useful component of protective immunity to severe influenza infection.

FUNDING

The National Health and Medical Research Council ([NHMRC] grants 1023294, 1041832, and 1071916), the Australian Department of Health, and the joint University of Melbourne/Fudan University International Research and Research Training Fund provided funding for this study.

A new reassortment of influenza A (H7N9) virus causing human infection in Beijing, 2014

A 73-year-old man was confirmed to have an influenza A (H7N9) virus infection, and the causative agent A/Beijing/02/2014(H7N9) virus was isolated. Genetic and phylogenetic analyses revealed that the virus belonged to a novel genotype, which probably emerged and further reassorted with other H9 or H7 viruses in poultry before transmitting to humans. This virus caused a severe infection with high levels of cytokines and neutralizing antibodies. Eventually, the patient was cured after serially combined treatments. Taken together, our findings indicated that this novel genotype of the human H7N9 virus did not evolve directly from the first Beijing isolate A/Beijing/01/2013(H7N9), suggesting that the H7N9 virus has not obtained the ability for human-to-human transmissibility and the virus only evolves in poultry and then infects human by direct contact. Hence, the major measures to prevent human H7N9 virus infection are still to control and standardize the live poultry trade. Early antiviral treatment with combination therapies, including mechanical ventilation, nutrition support and symptomatic treatment, are effective for H7N9 infection.

Severe Infection With Avian Influenza A Virus is Associated With Delayed Immune Recovery in Survivors

Human infection with avian influenza A virus (H7N9) is a concern because of the mortality rate. Previously, we characterized immunological responses during active infection with it and reported evidence of impaired antigen-presenting capability, particularly in severely affected individuals. Here we describe an investigation of immunological responses during a 1-year follow-up of survivors of H7N9 infection. Survivors of H7N9 infection were classified as having had mild (n = 42) or severe infection (n = 26). Their immune status, including human leukocyte antigen-DR expression on monocytes, and their ability to mount cytokine responses were assessed at 1, 3, and 12 months postinfection.The total lymphocyte count and the percentages of different types of lymphocytes had normalized by 1 month postinfection. However, there was evidence of ongoing impairment of immune responses in those who had had severe infection. This included reduced human leukocyte antigen-DR expression on CD14 monocytes, reduced interferon-γ production by T cells, and higher plasma levels of the matrix metalloproteinases 2, 3, and 9. By 3 months postinfection, these had all normalized.After severe H7N9 infection, recovery of the antigen-presenting capability of monocytes and T-cell responses are delayed. This may lead to an increased vulnerability to secondary bacterial infections.

Proinflammatory effects of the hemagglutinin protein of the avian influenza A (H7N9) virus and microRNA‑mediated homeostasis response in THP‑1 cells

The pathology and immunological responses to hemagglutinin (HA) from H7N9 avian influenza viruses in humans remain unclear. The present study aimed to investigate the proinflammatory activity of the HA protein obtained from H7N9 viruses and the mechanisms underlying the homeostasis of microRNAs (miRNAs) in response to inflammatory stimuli. The expression of proinflammatory factors and miRNAs was assayed in the THP‑1 cells using reverse transcription‑quantitative polymerase chain reaction. Results showed that HA significantly increased the expression of interleukin (IL)‑1α, IL‑1β and IL‑6 in the THP‑1 cells. Furthermore, HA and lipopolysaccharide exhibited synergic effects on the expression of IL‑1α, IL‑1β and IL‑6 in the THP‑1 cells. Let‑7e can target IL‑6 and inhibit its expression. Notably, HA significantly increased let‑7e expression in THP‑1 cells and decreased the let‑7e levels in the medium. However, the knockdown of toll‑like receptor 4 (TLR4) significantly attenuated the effects of HA. These results indicate that the HA can induce inflammatory stress and may trigger an miRNA‑mediated homeostasis response to this stress. The effects of HA appeared to be mediated by the TLR4 pathway.

Limited effect of recombinant human mannose-binding lectin on the infection of novel influenza A (H7N9) virus in vitro

Mannose-binding lectin (MBL), a pattern-recognition molecule in serum, recognizes specific hexose sugars rich in mannose and N-acetylglucosamine on bacterium, yeasts, viruses as well as apoptotic cells. It has been well-identified that MBL has antiviral effects via binding to seasonal influenza H1 and H3 subtype viruses. Influenza A (H7N9) virus, a novel reassortant virus to human population, possesses the surface hemagglutinin (HA) and neuraminidase (NA) genes from duck and wild-bird influenza viruses and internal genes from poultry H9N2 viruses. As of Dec 7th, 2014, a total of 467 human infections and 183 fatal cases have been identified. Here, recombinant human (rh) MBL was tested for its binding and effects on hemagglutination inhibition (HI) and NA activity inhibition (NAI) of avian H7N9, H9N2 and human H3N2 viruses. We discovered that rhMBL exhibited a strong binding to H7N9 virus as human H3N2 did at high virus titers. However, it performed a significantly weaker HI activity effect on H7N9 comparing to those of H3N2 and H9N2, even at a much higher concentration (3.67 ± 0.33 vs. 0.026 ± 0.001 and 0.083 ± 0.02 μg/mL, respectively). Similarly, minor NAI effect of rhMBL, even at up to 10 μg/mL, was found on H7N9 virus while it displayed significant effects on both H3N2 and H9N2 at a lowest concentration of 0.0807 ± 0.009 and 0.0625 μg/mL, respectively. The HI and NAI effects of rhMBL were calcium-dependent and mediated by lectin domain. Our findings suggest that MBL, the host innate molecule, has differential interference effects with human and avian influenza virus and limited antiviral effect against H7N9 virus.

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Comparable binding of rhMBL to avian H7N9 virus as human H3N2 virus.

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Limited antiviral effect of rhMBL against avian H7N9 virus.

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Insensitivity of H7N9 virus to rhMBL may confer its infection severity.

The dysfunctional host response to influenza A H7N9: a potential treatment option?

The newly emerging human pathogen influenza A H7N9 represents a potentially major threat to human health. The virus was first shown to be pathogenic in humans in 2013, and outbreaks continue to occur in China to the present time. The current incident mortality rate is disturbingly high despite the frequent use of antiviral therapy and intensive care management. If the virus gains the capacity for efficient person-to-person transmission, a global influenza pandemic could ensue with devastating consequences. In the absence of an effective vaccine, targeted regulation of the host immune response by immune modulators might be considered. Readily available, approved drugs with immune-modulating activities might prove to be a treatment option in combination with existing antiviral agents and supportive care.