A rationale for using steroids in the treatment of severe cases of H5N1 avian influenza

5-Methoxyflavone-induced AMPKα activation inhibits NF-κB and P38 MAPK signaling to attenuate influenza A virus-mediated inflammation and lung injury in vitro and in vivo

Influenza-related acute lung injury (ALI) is a life-threatening condition that results mostly from uncontrolled replication of influenza virus (IV) and severe proinflammatory responses. The methoxy flavonoid compound 5-methoxyflavone (5-MF) is believed to have superior biological activity in the treatment of cancer. However, the effects and underlying mechanism of 5-MF on IV-mediated ALI are still unclear. Here, we showed that 5-MF significantly improved the survival of mice with lethal IV infection and ameliorated IV-mediated lung edema, lung histological changes, and inflammatory cell lung recruitment. We found that 5-MF has antiviral activity against influenza A virus (IAV), which was probably associated with increased expression of radical S-adenosyl methionine domain containing 2 (RSAD2) and suppression of endosomal acidification. Moreover, IV-infected A549 cells with 5-MF treatment markedly reduced proinflammatory mediator expression (IL-6, CXCL8, TNF-α, CXCL10, CCL2, CCL3, CCL4, GM-CSF, COX-2, and PGE₂) and prevented P-IKBα, P-P65, and P-P38 activation. Interestingly, we demonstrated that 5-MF treatment could trigger activation of AMP-activated protein kinase (AMPK)α in IV-infected A549 cells, as evidenced by activation of the AMPKα downstream molecule P53. Importantly, the addition of AMPKα blocker compound C dramatically abolished 5-MF-mediated increased levels of RSAD2, the inhibitory effects on H1N1 virus-elicited endosomal acidification, and the suppression expression of proinflammatory mediators (IL-6, TNF-α, CXCL10, COX-2 and PGE₂), as well as the inactivation of P-IKBα, P-P65, and P-P38 MAPK signaling pathways. Furthermore, inhibition of AMPKα abrogated the protective effects of 5-MF on H1N1 virus-mediated lung injury and excessive inflammation in vivo. Taken together, these results indicate that 5-MF alleviated IV-mediated ALI and suppressed excessive inflammatory responses through activation of AMPKα signaling.

Analysis of Adrenocorticotropic Hormone and Cortisol Levels in Acute Respiratory Distress Syndrome COVID-19 Patients

Objective

SARS-CoV-2 infection may cause multiple organ failure. However, scarce information can be found on the impact on the endocrine system. This study was conducted to determine plasma Adrenocorticotropic hormone (ACTH) and plasma cortisol levels in a cohort of COVID-19 patients with Acute Respiratory Distress Syndrome (ARDS).

Methods

A prospective cohort study was conducted on COVID-19 patients who manifested ARDS and were admitted to the ICU of Dr. Soetomo Tertiary Hospital, Surabaya, Indonesia. Morning plasma ACTH and plasma total cortisol were measured on 45 recruited patients. The outcome of the patient was justified based on the survivance on days 7th and 30th during the follow-up with groupings of surviving for survived patients and nonsurvive for deceased patients.

Results

The ACTH and cortisol median were 1.06 (0.5–64.57) pg/mL and 17.61 (0.78–75) μg/dL, respectively. Both parameters were assembled to allow the allocation of the 45 subjects into the survive and nonsurvive groups. There was a moderate correlation between ACTH and cortisol levels in all groups (r = 0.46, p < 0.002) and particularly ACTH and cortisol levels in COVID-19 patients who survived on the 7th-day and 30th-day follow-up (r = 0.518 and r = 0.568, respectively, with p < 0.05). It is important to note that there was no correlation for an individual parameter, either ACTH only or cortisol only, compared to the outcome among patients with various comorbid.

Conclusion

ACTH or cortisol alone has no correlation to the outcome of these patients. Therefore, further study of the potential use of corticosteroid treatments guided by ACTH and cortisol levels in reducing the risk of ARDS warrants further investigation.

Compartmental Model Suggests Importance of Innate Immune Response to COVID-19 Infection in Rhesus Macaques

The pandemic outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has quickly spread worldwide, creating a serious health crisis. The virus is primarily associated with flu-like symptoms but can also lead to severe pathologies and death. We here present an ordinary differential equation model of the intrahost immune response to SARS-CoV-2 infection, fitted to experimental data gleaned from rhesus macaques. The model is calibrated to data from a nonlethal infection, but the model can replicate behavior from various lethal scenarios as well. We evaluate the sensitivity of the model to biologically relevant parameters governing the strength and efficacy of the immune response. We also simulate the effect of both anti-inflammatory and antiviral drugs on the host immune response and demonstrate the ability of the model to lessen the severity of a formerly lethal infection with the addition of the appropriately calibrated drug. Our model emphasizes the importance of tight control of the innate immune response for host survival and viral clearance.

Targeting tumour necrosis factor to ameliorate viral pneumonia

Pneumonia is a serious complication associated with inflammation of the lungs due to infection with viral pathogens. Seasonal and pandemic influenza viruses, variola virus (agent of smallpox) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; agent of COVID-19) are some leading examples. Viral pneumonia is triggered by excessive inflammation associated with dysregulated cytokine production, termed 'cytokine storm'. Several cytokines have been implicated but tumour necrosis factor (TNF) plays a critical role in driving lung inflammation, severe lung pathology and death. Despite this, the exact role TNF plays in the aetiology and pathogenesis of virus infection-induced respiratory complications is not well understood. In this review, we discuss the pathological and immunomodulatory roles of TNF in contributing to immunopathology and resolution of lung inflammation, respectively, in mouse models of influenza- and smallpox (mousepox)-induced pneumonia. We review studies that have investigated dampening of inflammation on the outcome of severe influenza and orthopoxvirus infections. Most studies on the influenza model have evaluated the efficacy of treatment with anti-inflammatory drugs, including anti-TNF agents, in animal models on the day of viral infection. We question the merits of those studies as they are not transferable to the clinic given that individuals generally present at a hospital only after the onset of disease symptoms and not on the day of infection. We propose that research should be directed at determining whether dampening lung inflammation after the onset of disease symptoms will reduce morbidity and mortality. Such a treatment strategy will be more relevant clinically.

Lymphopenia in COVID-19: Therapeutic opportunities

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is uncontrollably spread all over the world. The host immune responses strongly try to confront it with all the potential cells and cytokines. With chronically condition of SARS-CoV-2, natural killer cells and T cells become exhausted and decreasing their count leads to lymphopenia. Inability to eradicate the infected organ makes hyperinitiation of the immune system, which releases the excessive inflammatory cytokines to compensate the exhausted one as well as the low lymphocytes counts; it consequently leads to the cytokine storm syndrome. These mechanisms and the potential therapeutic targeting are discussed in this paper.

Glucocorticoid treatment of suspected organizing pneumonia after H7N9 infection: A case report

RATIONALE

H7N9 infection causes acute respiratory distress syndrome with high mortality. The use of glucocorticoids in the acute phase lessened inflammatory responses. Some case reports suggested that secondary organizing pneumonia (SOP) could occur at the recovery stage of the influenza virus infection, and the treatment with glucocorticoid was effective. However, the reports of organizing pneumonia after H7N9 infection are lacking. This study reported a patient with H7N9 virus infection who presented a suspected SOP during the recovery stage.

PATIENT CONCERN

A 68-year-old woman who was diagnosed with H7N9 viral pneumonia. After standard antiviral treatment, venous-venous extracorporeal membranous oxygenation (VV-ECMO) and other supportive treatment, the antigen in the alveolar lavage fluid turned negative, and the shadow in the lung was partially absorbed. However, the imaging manifestations were deteriorated at 3 weeks after disease onset, presented as exudation and consolidation shadow distributed under the pleura and along the bronchial vascular bundles. The oxygenation could not be improved. Repeated sputum, alveolar lavage fluid, and blood pathogen examinations showed negative results. Broad-spectrum anti-infective treatment was ineffective. However, the autoantibodies (ANA, anti-SSA/Ro60, anti-SSA/Ro52) were detected.

DIAGNOSIS

SOP was considered.

INTERVENTIONS

Glucocorticoid treatment begun at week 4 from the disease onset. The regimen was methylprednisolone at an initial dose of 40 mg twice a day for 1 week, tapering within 70 days until total withdrawal.

OUTCOMES

The oxygenation was rapidly improved after initiation of methylprednisolone. The shadow in the lung gradually resolved, and the patient was discharged after improvement of the disease condition. The clinical disease course, imaging findings, and treatment effects in the previous cases of SOP after influenza virus infection were similar to those in this case, suggesting the occurrence of SOP after H7N9 virus infection.

LESSONS

Organizing pneumonia might occur during the recovery stage of influenza virus infection. When the clinical symptoms do not improve and the shadow in the lung shows no obvious absorption after elimination of the H7N9 influenza virus, or the clinical symptoms are aggravated again after improvement, the probability of transforming into the organizing pneumonia should be taken into consideration.

Predicting Host Immune Cell Dynamics and Key Disease-Associated Genes Using Tissue Transcriptional Profiles

Motivation: Immune cell dynamics is a critical factor of disease-associated pathology (immunopathology) that also impacts the levels of mRNAs in diseased tissue. Deconvolution algorithms attempt to infer cell quantities in a tissue/organ sample based on gene expression profiles and are often evaluated using artificial, non-complex samples. Their accuracy on estimating cell counts given temporal tissue gene expression data remains not well characterized and has never been characterized when using diseased lung. Further, how to remove the effects of cell migration on transcript counts to improve discovery of disease factors is an open question. Results: Four cell count inference (i.e., deconvolution) tools are evaluated using microarray data from influenza-infected lung sampled at several time points post-infection. The analysis finds that inferred cell quantities are accurate only for select cell types and there is a tendency for algorithms to have a good relative fit (R 2 ) but a poor absolute fit (normalized mean squared error; NMSE), which suggests systemic biases exist. Nonetheless, using cell fraction estimates to adjust gene expression data, we show that genes associated with influenza virus replication and increased infection pathology are more likely to be identified as significant than when applying traditional statistical tests.

Pulmonary complications of influenza infection: a targeted narrative review

Severe influenza infection represents a leading cause of global morbidity and mortality. Several clinical syndromes that involve a number of organs may be associated with Influenza infection. However, lower respiratory complications remain the most common and serious sequel of influenza infection. These include influenza pneumonia, superinfection with bacteria and fungi, exacerbation of underlying lung disease and ARDS. This review analyzes the available literature on the epidemiology and clinical considerations of these conditions. It also provides an overview of the effects of type of influenza, antiviral therapy, vaccination and other therapies on the outcome of these complications.

A Systems and Treatment Perspective of Models of Influenza Virus-Induced Host Responses

Severe influenza infections are often characterized as having unique host responses (e.g., early, severe hypercytokinemia). Neuraminidase inhibitors can be effective in controlling the severe symptoms of influenza but are often not administered until late in the infection. Several studies suggest that immune modulation may offer protection to high risk groups. Here, we review the current state of mathematical models of influenza-induced host responses. Selecting three models with conserved immune response components, we determine if the immune system components which most affect virus replication when perturbed are conserved across the models. We also test each model’s response to a pre-induction of interferon before the virus is administered. We find that each model emphasizes the importance of controlling the infected cell population to control viral replication. Moreover, our work shows that the structure of current models does not allow for significant responses to increased interferon concentrations. These results suggest that the current library of available published models of influenza infection does not adequately represent the complex interactions of the virus, interferon, and other aspects of the immune response. Specifically, the method used to model virus-resistant cells may need to be adapted in future work to more realistically represent the immune response to viral infection.

The role of adjuvant immunomodulatory agents for treatment of severe influenza

A severe inflammatory immune response with hypercytokinemia occurs in patients hospitalized with severe influenza, such as avian influenza A(H5N1), A(H7N9), and seasonal A(H1N1)pdm09 virus infections. The role of immunomodulatory therapy is unclear as there have been limited published data based on randomized controlled trials (RCTs). Passive immunotherapy such as convalescent plasma and hyperimmune globulin have some studies demonstrating benefit when administered as an adjunctive therapy for severe influenza. Triple combination of oseltamivir, clarithromycin, and naproxen for severe influenza has one study supporting its use, and confirmatory studies would be of great interest. Likewise, confirmatory studies of sirolimus without concomitant corticosteroid therapy should be explored as a research priority. Other agents with potential immunomodulating effects, including non-immune intravenous immunoglobulin, N-acetylcysteine, acute use of statins, macrolides, pamidronate, nitazoxanide, chloroquine, antiC5a antibody, interferons, human mesenchymal stromal cells, mycophenolic acid, peroxisome proliferator-activated receptors agonists, non-steroidal anti-inflammatory agents, mesalazine, herbal medicine, and the role of plasmapheresis and hemoperfusion as rescue therapy have supportive preclinical or observational clinical data, and deserve more investigation preferably by RCTs. Systemic corticosteroids administered in high dose may increase the risk of mortality and morbidity in patients with severe influenza and should not be used, while the clinical utility of low dose systemic corticosteroids requires further investigation.

Predictors for fatal human infections with avian H7N9 influenza, evidence from four epidemic waves in Jiangsu Province, Eastern China, 2013-2016

Background

Four epidemic waves of human infection with H7N9 have been recorded in China up to 1 June 2016, including in Jiangsu Province. However, few studies have investigated the differences in patients' characteristics among the four epidemic waves, and the analyses of factors associated with fatal infection lacked statistical power in previous studies due to limited sample size.

Methods

All laboratory‐confirmed A(H7N9) patients in Jiangsu province were analysed. Patients' characteristics were compared across four waves and between survivors and those who died. Multivariate analyses were used to identify independent predictors of death.

Results

Significant differences were found in the lengths of several time intervals (from onset of disease to laboratory confirmation, to onset of ARDS and respiratory failure, and to death) and in the development of heart failure. The proportions of overweight patients and rural patients increased significantly across the four waves. Administration of glucocorticoids and double‐dose neuraminidase inhibitors became the norm. Predictors of death included complications such as ARDS, heart failure and septic shock, administration of glucocorticoids, and disease duration.

Conclusion

Characteristics of H7N9 patients and clinical treatment options changed over time. Particular complications and the use of particular treatment, along with disease duration, could help clinicians predict the outcome of H7N9 infections.

Current and future developments in the treatment of virus-induced hypercytokinemia

Emerging pathogenic viruses such as Ebola and Middle Eastern Respiratory Syndrome coronavirus (MERS-CoV) can cause acute infections through the evasion of the host's antiviral immune responses and by inducing the upregulation of inflammatory cytokines. This immune dysregulation, termed a cytokine storm or hypercytokinemia, is potentially fatal and is a significant underlying factor in increased mortality of infected patients. The prevalence of global outbreaks in recent years has offered opportunities to study the progression of various viral infections and have provided an improved understanding of hypercytokinemia associated with these diseases. However, despite this increased knowledge and the study of the infections caused by a range of emerging viruses, the therapeutic options still remain limited. This review aims to explore alternative experimental strategies for treating hypercytokinemia induced by the Ebola, avian influenza and Dengue viruses; outlining their modes of action, summarizing their preclinical assessments and potential clinical applications.

The therapeutic effects of sodium cromoglycate against influenza A virus H5N1 in mice

Objectives

To identify the protective role of sodium cromoglycate in mice during influenza virus infection.

Design

H5N1 virus‐infected mice were treated with the mast cell stabilizer sodium cromoglycate (SCG) to investigate its therapeutic effect.

Sample

The nose, trachea and lungs from mice were collected.

Main outcome measures

Virus replication and host responses were determined by plaque assay, quantitative PCR, immunohistochemistry, and histology.

Results

SCG‐treated mice survived better than did PBS‐treated mice after H5N1 virus infection. Mild pathological changes with fewer inflammatory cell infiltration and fewer virus antigens were observed in the nose, trachea, and lungs of SCG‐treated mice on days 3 and 5 post‐infection. However, no significant changes in viral load in the lungs were detected between SCG‐ and PBS‐treated mice. Furthermore, significantly decreased expression of interleukin‐6, tumor necrosis factor‐a, Toll‐like receptor 3, and TIR‐domain‐containing adapter‐inducing interferon‐b was detected in the lungs of SCG‐treated mice, and no higher expression of interferon‐c was detected.

Conclusion

These results suggest that SCG has therapeutic roles in H5N1 virus‐infected mice by alleviating the inflammatory response rather than inhibition of viral replication in the lungs.

Corticosteroid use as adjunct therapy for respiratory syncytial virus infection in adult allogeneic stem cell transplant recipients

BACKGROUND

Respiratory syncytial virus (RSV) infection causes significant morbidity and mortality in allogeneic stem cell transplant (allo-SCT) recipients. Although ribavirin and immunoglobulins are common components of therapy, the role of adjunct corticosteroids is not established.

OBJECTIVES

We sought to evaluate corticosteroid utilization in the setting of post-allo-SCT RSV infection in our center and assess post-transplant outcomes including pulmonary function decline.

METHODS

Patients with a history of RSV infection from 2008 to 2014 seen at our institution were identified. Treatment and outcome data were retrospectively collected. Forced expiratory volume at 1 s (FEV1) and carbon monoxide diffusion capacity (DLCO) were collected pre- and post-RSV infection.

RESULTS

During the observation period, RSV was isolated in 53 of 552 patients undergoing allo-SCT (10%) and 45 had evaluable therapy data. RSV-related mortality in this cohort was 4/45 (9%). Twenty-one (47%) were on corticosteroids prior to RSV diagnosis, of whom 11 (24%) had a dose increase post symptom onset. Eight (18%) patients were started on corticosteroids at the time of RSV infection. Corticosteroid therapy at symptom onset was associated with a higher rate of upper respiratory infection (URTI) to lower respiratory infection (LRTI) progression risk ratio (RR) 2.49 (1.21-5.13; P = 0.016), hospital admission RR 2.05 (1.24-3.37; P = 0.005), or intensive care unit admission RR 2.91 (1.89-5.01; P = 0.002). No significant difference was seen with FEV1 and DLCO decline (P = 0.3 and 0.24, respectively) or mortality (P = 0.26).

CONCLUSION

Adjunct corticosteroid use in the setting of RSV infection did not improve RSV-related outcomes including long-term pulmonary function. Our results do not support the routine use of corticosteroids; however, this finding does need to be verified in a larger cohort of patients.

Experimental antiviral drugs against pandemic influenza

ABSTRACT 

The aim of this review is to selectively identify some representative experimental antiviral drugs which are promising in preclinical and clinical studies, but yet to be fully licensed, and discuss how they have a potential role in complementing our existing arsenal of antiviral drugs to combat pandemic influenza. This review will focus on discussing their mechanisms of actions, current state of development, safety, efficacy from preclinical and/or clinical studies. These experimental drugs can be classified into virus or host specific, depending on the individual drug's targeting action. This article will highlight novel anti-inflammatory drugs which can be used to mitigate cytokine storm caused by pandemic influenza viruses as a treatment option or strategy.

Treatment with the reactive oxygen species scavenger EUK-207 reduces lung damage and increases survival during 1918 influenza virus infection in mice

The 1918 influenza pandemic caused over 40 million deaths worldwide, with 675,000 deaths in the United States alone. Studies in several experimental animal models showed that 1918 influenza virus infection resulted in severe lung pathology associated with dysregulated immune and cell death responses. To determine if reactive oxygen species produced by host inflammatory responses play a central role in promoting severity of lung pathology, we treated 1918 influenza virus-infected mice with the catalytic catalase/superoxide dismutase mimetic, salen-manganese complex EUK-207 beginning 3 days postinfection. Postexposure treatment of mice infected with a lethal dose of the 1918 influenza virus with EUK-207 resulted in significantly increased survival and reduced lung pathology without a reduction in viral titers. In vitro studies also showed that EUK-207 treatment did not affect 1918 influenza viral replication. Immunohistochemical analysis showed a reduction in the detection of the apoptosis marker cleaved caspase-3 and the oxidative stress marker 8-oxo-2'-deoxyguanosine in lungs of EUK-207-treated animals compared to vehicle controls. High-throughput sequencing and RNA expression microarray analysis revealed that treatment resulted in decreased expression of inflammatory response genes and increased lung metabolic and repair responses. These results directly demonstrate that 1918 influenza virus infection leads to an immunopathogenic immune response with excessive inflammatory and cell death responses that can be limited by treatment with the catalytic antioxidant EUK-207.

Inhibition of the inflammatory cytokine tumor necrosis factor-alpha with etanercept provides protection against lethal H1N1 influenza infection in mice

INTRODUCTION

Factors implicated in influenza-mediated morbidity and mortality include robust cytokine production (cytokine storm), excessive inflammatory infiltrates, and virus-induced tissue destruction. Tumor necrosis factor-alpha (TNF-α) is an important pro-inflammatory cytokine present during influenza infection, but it is unclear whether direct inhibition of TNF-α can elicit protection against influenza infection.

METHODS

In this study, the commercially available TNF-α inhibitor etanercept was used to inhibit TNF-α induced by lethal A/FM/1/47 (H1N1) influenza virus infection of mice. The effects of TNF-α inhibition on mouse survival, pathologic changes, immune cell infiltration, inflammatory cytokine secretion, Toll-like receptor expression, and activation of the NF-κB (nuclear factor kappa B) signaling pathway were evaluated.

RESULTS

The intranasal delivery of etanercept provided significant protection against mortality (30% of mice survived up to 14 days after infection) in mice treated with etanercept. In contrast, no survivors were found beyond 6 days in mice treated with saline after lethal challenge with H1N1 influenza virus. It was observed that etanercept significantly reduced inflammatory cell infiltration (for example, macrophages and neutrophils), inflammatory cytokine secretion (for example, interleukin-6, TNF-α, and interferon gamma), and expression of Toll-like receptors (TLR-3, TLR-4, and TLR-7). Etanercept also downregulated and inhibited the cascade proteins of the NF-κB signaling pathway (for example, MyD88, TRIF, NF-κB, and p65), as well as enhanced host control of virus replication.

CONCLUSIONS

These findings indicate that etanercept, by blocking TNF-α, can significantly downregulate excessive inflammatory immune responses and provide protection against lethal influenza infection, making its use a novel strategy for controlling severe influenza-induced viral pneumonia.

Glucocorticosteroid in treatment of severe pneumonia

Airway diseases such as pneumonia constitute a major health burden on a global scale; untreated pneumonia may develop to severe pneumonia and consequently lead to to fatal episodes of mortality and morbidity. The balance between inflammatory mediators is key for the outcome of the pulmonary infection; elimination of invading pathogen was marked by the release of cytokines and other inflammatory mediators from alveolar macrophages and glucocorticoid steroids (GCs) acting on the inflammatory component. Treatments of severe pneumonia with GCs have been developing for years with inconclusive results. In many cases GCs have been administered empirically without clinical evidence. Recent studies assess beneficial impact on treatment of severe pneumonia by suggesting specific dosage, period of administration, and tapered dosage.

Immunomodulatory Activity and Protective Effects of Polysaccharide from Eupatorium adenophorum Leaf Extract on Highly Pathogenic H5N1 Influenza Infection

The development of novel broad-spectrum, antiviral agents against H5N1 infection is urgently needed. In this study, we evaluated the immunomodulatory activities and protective effect of Eupatorium adenophorum polysaccharide (EAP) against the highly pathogenic H5N1 subtype influenza virus. EAP treatment significantly increased the production of IL-6, TNF-α, and IFN-γ both in vivo and in vitro as measured by qPCR and ELISA. In a mouse infection model, intranasal administration of EAP at a dose of 25 mg/kg body weight prior to H5N1 viral challenge efficiently inhibited viral replication, decreased lung lesions, and increased survival rate. We further evaluated the innate immune recognition of EAP, as this process is regulated primarily Dectin-1 and mannose receptor (MR). These results indicate that EAP may have immunomodulatory properties and a potential prophylactic effect against H5N1 influenza infection. Our investigation suggests an alternative strategy for the development of novel antiinfluenza agents and benefits of E. adenophorum products.

Clinical features and factors associated with outcomes of patients infected with a Novel Influenza A (H7N9) virus: a preliminary study

OBJECTIVE

The present study aimed to analyze clinical features and factors associated with treatment outcomes of H7N9 influenza A virus infection.

METHODS

The clinical progress in 18 H7N9-infected patients was monitored and recorded. The clinical features of H7N9 infection were noted and factors associated with treatment outcomes were analyzed by univariate analyses.

RESULTS

The average ages of patients in recovered and critical conditions were 67.0±10.83 years and 72.75±12.0 years, respectively. Renal insufficiency developed more frequently in critically ill patients (P = 0.023). The duration of traditional Chinese medicine (TCM) therapy was longer in recovered patients than in critically ill patients (P = 0.01). Laboratory tests showed that levels of C-reactive protein, serum creatinine, and myoglobin were significantly higher in critically ill patients than in recovered patients (P = 0.011, 0.04, and 0.016, respectively). Meanwhile, levels of all T cell subsets examined including total CD3(+), CD4(+), CD8(+), and CD45(+) T cells were lower in critically ill patients than in recovered patients (P = 0.033, 0.059, 0.015, and 0.039, respectively). Logistic regression analysis demonstrated that C-reactive protein level, myoglobin level and TCM therapy duration were likely associated with treatment outcomes of H7N9 infection (P = 0.032, 0.041 and 0.017, respectively).

CONCLUSION

Elderly people may have increased risk for H7N9 virus infection. T cell-mediated responses play an important role in defense against the H7N9 virus. C-reactive protein level, myoglobin level and TCM duration may be associated with treatment outcomes of H7N9 infection.

Reduction of influenza virus-induced lung inflammation and mortality in animals treated with a phosophodisestrase-4 inhibitor and a selective serotonin reuptake inhibitor

Inflammatory responses contribute to the morbidity and mortality of severe influenza. Current antiviral therapy offers limited success in treating severe influenza infection with both H1N1 and H5N1 viruses. We evaluated the effect of a neuraminidase inhibitor in combination with immunomodulatory drugs in vitro and in a mouse model of influenza A H1N1 infection by determining survival rate, lung inflammation markers and histopathology. Sertraline and rolipram significantly improved survival in mice infected with a lethal dose of influenza A H1N1 virus. Prophylactic treatment resulted in survival rates of 40% (rolipram), 30% (oseltamivir), 0% (sertraline), 100% (rolipram/oseltamivir) and 70% (sertraline/oseltamivir). Treatment in a therapeutic setting (24 h post-infection) resulted in 80% (rolipram/oseltamivir) and 40% (sertraline/oseltamivir) survival. Sertraline and rolipram had no effect on virus replication in vitro and in vivo, but significantly reduced lung inflammation. A significant reduction in cellular infiltration (10-fold) along with inflammatory cytokines monocyte chemotactic protein-1 (10-fold), interleukin-6 (5-fold) and regulated on activation normal T cell expressed and secreted (5-fold) was observed in the animals treated with the combination compared to oseltamivir alone. Lung histopathology of mice treated with combinations revealed significantly reduced consolidation, infiltration and alveolitis compared to oseltamivir alone. Rolipram and sertraline reduced H1N1 virus-induced lung inflammation and mortality. These data support further development of immunomodulatory agents for severe influenza.

A case of novel swine influenza A (H1N1) pneumonia complicated with virus-associated hemophagocytic syndrome

Influenza related to complications such as pneumonia and encephalitis have sporadically been reported. However, influenza A (H1N1)-virus-associated hemophagocytic syndrome (VAHS) has rarely been reported. A 39-year old woman complained of high fever and was referred to us. Chest infiltrations in both lungs and a positive polymerase chain reaction (PCR) for novel swine-origin influenza A (H1N1) in bronchial alveolar lavage fluid (BALF) specimen was confirmed and she was diagnosed with influenza A (H1N1) pneumonia. Pancytopenia was found, and hemophagocytic syndrome (HPS) was diagnosed by bone marrow aspiration. Following intravenous administration of antiflu drug and combination therapy of steroid pulse and erythromycin IV, the patient’s respiratory dysfunction and lab data gradually improved and she was discharged on day 21. Whereas secondary HPS related to viral infections such as Epstein–Barr virus, cytomegalovirus, and human herpesvirus type 6 are commonly seen, H1N1 pneumonia complicated with secondary VAHS is rare.

Combination therapy with immune-modulators and moxifloxacin on fulminant macrolide-resistant Mycoplasma pneumoniae infection: A case report

This report entails a case of refractory pneumonia with a wild variety of extra-pulmonary manifestations due to macrolide-resistant Mycoplasma pneumoniae infection in a 7-year-old boy. The diagnosis was based on isolating M. pneumoniae through cultivation from the patient's bronchial aspirations at admission and the following susceptibility testing. Initial treatments consisting of a combination of azithromycin and standard-dosed methylprednisone (2 mg/kg) were completely nonresponsive and the patient's condition deteriorated rapidly. However, methylprednisone pulse therapy (20 mg/kg for 3 days, tapering within 1 month) and intravenous immunoglobulin (1 g/kg/day, two doses), in addition to moxifloxacin (10 mg/kg for 7 days) were remarkably effective and led to a favorable outcome without any observed side effects during inpatient hospitalization and outpatient follow-up.

Cytokines and neutrophils responses in influenza pneumonia

This case report shows a striking correlation of remarkable brief high levels of pro- and anti-inflammatory cytokines coupled with increased neutrophil activation, followed by a sharp decrease in cytokine levels and increased neutrophil apoptosis associated with the favorable clinical outcomes of a patient with severe influenza infection. The host response examined in our case is not complete, given it did not assess the full spectrum of host response. The brief neutrophil and cytokine response seen in our case in the absence of antiviral therapy and in the presence of methotrexate immunosuppressive therapy rise the question as to whether the latter optimally modulated the macrophage function, resulting in a favorable outcome of severe influenza viral infection.

Innate immunity to H5N1 influenza viruses in humans

Avian influenza virus infections in the human population are rare due to their inefficient direct human-to-human transmission. However, when humans are infected, a strong inflammatory response is usually induced, characterized by elevated levels of cytokines and chemokines in serum, believed to be important in the severe pathogenesis that develops in a high proportion of these patients. Extensive research has been performed to understand the molecular viral mechanisms involved in the H5N1 pathogenesis in humans, providing interesting insights about the virus-host interaction and the regulation of the innate immune response by these highly pathogenic viruses. In this review we summarize and discuss the most important findings in this field, focusing mainly on H5N1 virulence factors and their impact on the modulation of the innate immunity in humans.

Inducible nitric oxide contributes to viral pathogenesis following highly pathogenic influenza virus infection in mice

Highly pathogenic influenza A viruses, including avian H5N1 viruses and the 1918 pandemic virus, cause severe respiratory disease in humans and animals. Virus infection is followed by intense pulmonary congestion due to an extensive influx of macrophages and neutrophils, which can release large quantities of reactive oxygen species potentially contributing to the pathogenesis of lung disease. Here, the role of nitric oxide (NO), a potent signaling molecule in inflammation, was evaluated following highly pathogenic influenza virus challenge in mice. We observed higher levels of NO in mice infected with H5N1 and 1918 viruses as compared to a seasonal H1N1 virus. Mice deficient in inducible NO synthase (NOS2(-/-)) exhibited reduced morbidity, reduced mortality, and diminished cytokine production in lung tissue following H5N1 and 1918-virus challenge, compared with wild-type control mice. Furthermore, systemic treatment of mice with the NOS inhibitor NG-monomethyl-l-arginine delayed weight loss and death among 1918 virus infected mice compared to untreated control animals. This study demonstrates that NO contributes to the pathogenic outcome of H5N1 and 1918 viral infections in the mouse model.

Enhanced anti-influenza agents conjugated with anti-inflammatory activity

Influenza therapy with a single targeted compound is often limited in efficacy due to the rapidly developed drug resistance. Moreover, the uncontrolled virus-induced cytokines could cause the high mortality of human infected by H5N1 avian influenza virus. In this study, we explored the novel dual-targeted bifunctional anti-influenza drugs formed by conjugation with anti-inflammatory agents. In particular, the caffeic acid (CA)-bearing zanamivir (ZA) conjugates ZA-7-CA (1) and ZA-7-CA-amide (7) showed simultaneous inhibition of influenza virus neuraminidase and suppression of pro-inflammatory cytokines. These ZA conjugates provided remarkable protection of cells and mice against influenza infections. Intranasal administration of low dosage (<1.2 μmol/kg/day) of ZA conjugates exhibited much greater effect than the combination therapy with ZA and the anti-inflammatory agents in protection of the lethally infected mice by H1N1 or H5N1 influenza viruses.

Hemophagocytic lymphohistiocytosis of indeterminate cause: a fatal adult case

Hemophagocytic lymphohistiocytosis (HLH) is an uncommon life-threatening disorder characterized by wide spread non-neoplastic proliferation and inappropriate activation of mature macrophages resulting in hypercytokinemia. This uncontrollable and ineffective systemic immune response causes fever, hepatosplenomegaly, cytopenias and subsequently multiorgan failure. The authors report a case of a 41-year-old male patient with a 30-day history of weight loss, fever, icterus, hepatomegaly, and cytopenias. The diagnostic workup disclosed hypertriglyceridemia, hypofibrinogenemia, and elevated ferritin. Bone marrow examination and clinical course raised the suspicion of HLH and treatment was started with high-dose corticosteroids and immune globulin. The patient underwent multi-organ failure and expired after 58 days of hospitalization. The autopsy finding included massive bone marrow infiltration by non-neoplastic histiocytes, many of them showing hemophagocytosis, which immunohistochemical study revealed diffuse CD68-positive histiocytes, which were negative for S100 protein. Hemophagocytosis was also observed in the lungs, lymph nodes and liver. The immediate cause of death was attributed to a massive intestinal bleeding due to extensive ischemic necrosis at the duodenum/jejunal transition area.

Quelling the storm: utilization of sphingosine-1-phosphate receptor signaling to ameliorate influenza virus-induced cytokine storm

Initial and early tissue injury associated with severe influenza virus infection is the result of both virus-mediated lysis of infected pulmonary cells coupled with an exuberant immune response generated against the virus. The excessive host immune response associated with influenza virus infection has been termed "cytokine storm." Therapies that target virus replication are available; however, the selective pressure by such antiviral drugs on the virus often results in mutation and the escape of virus progeny now resistant to the antiviral regimen, thereby rendering such treatments ineffective. This event highlights the necessity for developing novel methods to combat morbidity and mortality caused by influenza virus infection. One potential method is restricting the host's immune response. However, prior treatment regimens employing drugs like corticosteroids that globally suppress the host's immune response were found unsatisfactory in large part because they disrupted the host's ability to control virus replication. Here, we discuss a novel therapy that utilizes sphingosine-1-phosphate (S1P) receptor signaling that has the ability to significantly limit immunopathologic injury caused by the host's innate and adaptive immune response, thereby significantly aborting morbidity and mortality associated with influenza virus infection. Moreover, S1P analog therapy allows for sufficient anti-influenza T cell and antibody formation to control infection. We review the anti-inflammatory effects of S1P signaling pathways and how modulation of these pathways during influenza virus infection restricts immunopathology. Finally, we discuss that combinatorial administration of S1P simultaneously with a current antiviral enhances the treatment efficacy for virulent influenza virus infections above that of either drug treatment alone. Interestingly, the scope of S1P receptor therapy reported here is likely to extend beyond influenza virus infection and could prove useful for the treatment of multiple maladies like other viral infections and autoimmune diseases where the host's inflammatory response is a major component in the disease process.

Mast cell-induced lung injury in mice infected with H5N1 influenza virus

Although an important role for mast cells in several viral infections has been demonstrated, its role in the invasion of highly pathogenic H5N1 influenza virus is unknown. In the present study, we demonstrate that mast cells were activated significantly by H5N1 virus (A/chicken/Henan/1/2004) infection both in vivo and in vitro. Mast cells could possibly intensify the lung injury that results from H5N1 infection by releasing proinflammatory mediators, including histamine, tryptase, and gamma interferon (IFN-γ). Lung lesions and apoptosis induced by H5N1 infection were reduced dramatically by treatment with ketotifen, which is a mast cell degranulation inhibitor. A combination of ketotifen and the neuraminidase inhibitor oseltamivir protected 100% of the mice from death postinfection. In conclusion, our data suggest that mast cells play a crucial role in the early stages of H5N1 influenza virus infection and provide a new approach to combat highly pathogenic influenza virus infection.

[Lung diffusion capacity and quality of life 6 months after discharge from the ICU among survivors of acute respiratory distress syndrome due to influenza A H1N1]

OBJECTIVE

An evaluation is made of lung function and quality of life 6 months after discharge from the Intensive Care Unit (ICU) among survivors of acute respiratory distress syndrome (ARDS) due to pandemic 2009 influenza A H1N1, based on studies of lung function and the EQ-5D health questionnaire.

DESIGN

Case series.

SETTING

The ICU of Dr. Leónidas Lucero Acute Cases Municipal Hospital, Bahía Blanca, Argentina.

PATIENTS

PATIENTS discharged from the ICU who had been admitted with ARDS in 2009 due to influenza A H1N1.

RESULTS

Eleven patients were studied. Seven were positive for influenza H1N1 and four were negative. The mean age was 37±9.5 years, and 73% were males. Quality of life, as measured by the EQ-5D, showed changes in the 5 components in all patients, particularly in the pain/discomfort dimension 1.55±0.52; health status (EQ%health) was 70%±24. The indices adjusted for Argentina were Time Trade Off (TTO) 0.903±0.085 and Visual Analog Scale (VAS) 0.827±0.153. In all patients, spirometry and the study of pulmonary diffusion (DLCO) showed values of >80%. There was no correlation between lung diffusion and quality of life (%DLCO and EQ%health). A correlation was observed between quality of life and TTO (EQ%health and TTO), and between quality of life and the VAS score (EQ%health and VAS).

CONCLUSION

Although the sample is small, our results suggest that patients with ARDS due to influenza A H1N1 evaluated 6 months after discharge from the ICU show no deterioration of lung function, and the impact on quality of life is moderate-in contrast to the situation found in patients with ARDS of other etiologies.

Inhibition of highly pathogenic avian H5N1 influenza virus propagation by RNA oligonucleotides targeting the PB2 gene in combination with celecoxib

BACKGROUND

Highly pathogenic avian influenza virus H5N1 can cause acute respiratory infections with an uncontrolled virus-induced cytokine storm in both poultry and humans. In view of the high mortality of H5N1 influenza virus infection, the development of novel broad-spectrum prophylactic and therapeutic agents against infection is urgently needed. In the present study, we attempted to explore whether the combinational use of a viral gene-targeted agent and immunomodulator is feasible as a new strategy against the H5N1 infection.

METHODS

Four antisense RNA oligonucleotides targeting the polymerase basic protein 2 (PB2) gene of H5N1-HPIV were designed and screened for their ability to inhibit H5N1 influenza viral propagation.

RESULTS

In Madin-Darby canine kidney cells, the RNA oligonucleotides efficiently inhibited viral replication, as measured by hemagglutinin production, plaque formation and viral RNA expression assays. In a mouse infection model, a combinational treatment in mice with the PB2 oligonucleotides and celecoxib significantly reduced the viral load, regulated cytokine profiles, and improved lung lesions and animal survival compared to the single use of either PB2 oligonucleotides or the immunomodulatory agent, celecoxib.

CONCLUSIONS

The results obtained in the present study suggest the potential use of PB2-targeted oligonucleotides in conjunction with immunomodulators for the control of H5N1 influenza infection.

Suppression of cytokine storm with a sphingosine analog provides protection against pathogenic influenza virus

Human pandemic H1N1 2009 influenza virus rapidly infected millions worldwide and was associated with significant mortality. Antiviral drugs that inhibit influenza virus replication are the primary therapy used to diminish disease; however, there are two significant limitations to their effective use: (i) antiviral drugs exert selective pressure on the virus, resulting in the generation of more fit viral progeny that are resistant to treatment; and (ii) antiviral drugs do not directly inhibit immune-mediated pulmonary injury that is a significant component of disease. Here we show that dampening the host's immune response against influenza virus using an immunomodulatory drug, AAL-R, provides significant protection from mortality (82%) over that of the neuraminidase inhibitor oseltamivir alone (50%). AAL-R combined with oseltamivir provided maximum protection against a lethal challenge of influenza virus (96%). Mechanistically, AAL-R inhibits cellular and cytokine/chemokine responses to limit immunopathologic damage, while maintaining host control of virus replication. With cytokine storm playing a role in the pathogenesis of a wide assortment of viral, bacterial, and immunologic diseases, a therapeutic approach using sphingosine analogs is of particular interest.

Chronic heat stress weakened the innate immunity and increased the virulence of highly pathogenic avian influenza virus H5N1 in mice

Chronic heat stress (CHS) can negatively affect immune response in animals. In this study we assessed the effects of CHS on host innate immunity and avian influenza virus H5N1 infection in mice. Mice were divided into two groups: CHS and thermally neutral (TN). The CHS treatment group exhibited reduced local immunity in the respiratory tract, including the number of pulmonary alveolar macrophages and lesions in the nasal mucosa, trachea, and lungs. Meanwhile, CHS retarded dendritic cells (DCs) maturation and reduced the mRNA levels of IL-6 and IFN-β significantly (P < .05). After the CHS treatment, mice were infected with H5N1 virus. The mortality rate and viral load in the lungs of CHS group were higher than those of TN group. The results suggest that the CHS treatment could suppress local immunity in the respiratory tract and innate host immunity in mice significantly and moderately increased the virulence in H5N1-infected mice.

Pandemic 2009 H1N1 virus infection associated with purpuric skin lesions: a case report

Introduction

The influenza virus infection may be severe in non-immune people. Common complications of influenza virus include upper and lower respiratory tract infections, otitis media, myocarditis, acute respiratory distress syndrome and multi-organ failure. There have been cases of vasculitis following influenza vaccination, and rash and acute purpura may occur in certain viral infections. To the best of our knowledge, there are no reports concerning cases of systemic vasculitis associated with pandemic 2009 (H₁N₁) infection.

Case presentation

A 23-year-old Caucasian woman was hospitalized at the "L. Spallanzani" National Institute for Infectious Diseases in Rome, Italy. Clinical and radiological features including laboratory findings of this case are illustrated. Notably, the patient had fever, severe abdominal pain, hematuria, arthritis, and purpuric manifestations associated with a normal platelet count. Nasopharyngeal and rectal swabs revealed pandemic 2009 (H₁N₁) virus by reverse-transcriptase-polymerase-chain-reaction assay. Routine laboratory analyses showed elevated inflammatory parameters. The autoimmune panel tests were normal. Steroid therapy associated with oseltamivir achieved an evident and rapid improvement. On day seven the patient chose to leave the hospital against medical advice.

Conclusion

Complications related to influenza infection can be life threatening, particularly in immunocompromised patients. Henoch-Schönlein purpura triggered by the novel influenza virus infection could be an attractive pathogenetic hypothesis. We have discussed both the diagnosis and the challenge of therapy protocols. Steroid therapy is part of the management of severe vasculitis. Our case suggests that steroid therapy associated with antivirals can prevent the risk of further complications such as hemorrhage and multi-organ failure during severe vasculitis, without enhancing the virulence of the influenza virus. The possible role of pandemic 2009 (H₁N₁) in the pathogenesis of hemorrhagic manifestations should be further investigated.

A case of successful treatment with polymyxin B-immobilized fiber column direct hemoperfusion in acute respiratory distress syndrome after influenza A infection

We report a case of acute respiratory distress syndrome (ARDS) after influenza A infection who was successfully treated with combined treatment including direct hemoperfusion with polymyxin B-immobilized fiber (PMX-DHP) column. A 56-year-old Japanese man was admitted to our hospital in January 2010 because of progressive dyspnea, hypoxemia, fever and bilateral diffuse infiltration on chest radiograph after pandemic influenza A infection. His chest computed tomography showed diffuse and patchy bilateral ground-glass opacities, and we diagnosed ARDS after influenza A infection. The patient was successfully treated with PMX-DHP in addition to the treatment with oseltamivir, corticosteroid, sivelestat and antibiotics with mechanical ventilation, and the patient recovered with only minor pulmonary fibrotic change. Although the efficacy of PMX-DHP treatment in patients with acute lung injury (ALI)/ARDS after influenza virus infection is not well established, this treatment could be a possible therapeutic modality in treating the patients with this disease.

Genomic profiling of tumor necrosis factor alpha (TNF-alpha) receptor and interleukin-1 receptor knockout mice reveals a link between TNF-alpha signaling and increased severity of 1918 pandemic influenza virus infection

The influenza pandemic of 1918 to 1919 was one of the worst global pandemics in recent history. The highly pathogenic nature of the 1918 virus is thought to be mediated in part by a dysregulation of the host response, including an exacerbated proinflammatory cytokine response. In the present study, we compared the host transcriptional response to infection with the reconstructed 1918 virus in wild-type, tumor necrosis factor (TNF) receptor-1 knockout (TNFRKO), and interleukin-1 (IL-1) receptor-1 knockout (IL1RKO) mice as a means of further understanding the role of proinflammatory cytokine signaling during the acute response to infection. Despite reported redundancy in the functions of IL-1β and TNF-α, we observed that reducing the signaling capacity of each of these molecules by genetic disruption of their key receptor genes had very different effects on the host response to infection. In TNFRKO mice, we found delayed or decreased expression of genes associated with antiviral and innate immune signaling, complement, coagulation, and negative acute-phase response. In contrast, in IL1RKO mice numerous genes were differentially expressed at 1 day postinoculation, including an increase in the expression of genes that contribute to dendritic and natural killer cell processes and cellular movement, and gene expression profiles remained relatively constant at later time points. We also observed a compensatory increase in TNF-α expression in virus-infected IL1RKO mice. Our data suggest that signaling through the IL-1 receptor is protective, whereas signaling through the TNF-α receptor increases the severity of 1918 virus infection. These findings suggest that manipulation of these pathways may have therapeutic benefit.

Impact of corticosteroid treatment and antiviral therapy on clinical outcomes in hematopoietic cell transplant patients infected with influenza virus

The impact of cytokines induced during influenza infection has been described, but the effect of corticosteroids on clinical outcomes is unclear. Although antiviral therapy has been well studied in immunocompetent subjects, few data exist on its clinical efficacy in immunocompromised populations. Data from 143 hematopoietic cell transplant recipients with documented seasonal influenza infection were reviewed to examine the impact of different corticosteroid regimens and antiviral therapy on clinical outcomes. In multivariable analyses, there was no observed difference between patients who received no, low doses (<1 mg/kg/day), or high doses (≥ 1 mg/kg/day) of corticosteroids with regard to the development of lower respiratory tract disease (LRD), hypoxemia, need for mechanical ventilation, or death. However, treatment with high-dose steroids was associated with a trend toward prolonged viral shedding (odds ratio [OR], 3.3; 95% confidence interval [CI], 1.0-11; P = .05). In multivariable analyses, antiviral therapy initiated to treat upper respiratory tract infection (URI) was associated with fewer cases of LRD (OR, 0.04; 95% CI, 0-0.2; P < .01) and fewer hypoxemia episodes (OR, 0.3; 95% CI, 0.1-0.9; P = .03). Our results suggest that corticosteroids are not associated with adverse clinical outcomes in hematopoietic cell transplant recipients infected with influenza, although use of higher doses may delay viral clearance. Antiviral therapy initiated during the URI phase reduced the risk of LRD and hypoxemia.

Mice lacking both TNF and IL-1 receptors exhibit reduced lung inflammation and delay in onset of death following infection with a highly virulent H5N1 virus

BACKGROUND

Highly pathogenic avian influenza viruses of the H5N1 subtype continue to cross the species barrier to infect humans and cause severe disease. It has been suggested that an exaggerated immune response contributes to the pathogenesis of H5N1 virus infection in mammals. In particular, H5N1 virus infections are associated with a high expression of the proinflammatory cytokines, including interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-α).

METHODS

We investigated the compounding affects of both cytokines on the outcome of H5N1 virus disease by using triple mutant mice deficient in 3 signaling receptors, TNF-R1, TNF-R2, and IL-1-RI.

RESULTS

Triple mutant mice exhibited reduced morbidity and a significant delay in mortality following lethal challenge with a lethal H5N1 virus, whereas no such differences were observed with the less virulent A/PR/8/34 (H1N1) virus. H5N1-infected triple mutant mice displayed diminished cytokine production in lung tissue and a quantifiable decrease of macrophages and neutrophils in the lungs postinfection. Moreover, morphometric analysis of airway sections revealed less extensive inflammation in H5N1-infected triple mutant mice, compared with infected wild-type mice.

CONCLUSIONS

The combined signaling from the TNF or IL-1 receptors promotes maximal lung inflammation that may contribute to the severity of disease caused by H5N1 virus infection.

Methylprednisolone infusion for life-threatening H1N1-virus infection

BACKGROUND

During winter 2009 we treated with prolonged corticosteroid infusion eight consecutive patients affected by H1N1-virus infection and severe pneumonia. The most severe patient was a previously healthy 30-year-old man admitted to hospital because of bilateral pneumonia and severe acute respiratory failure.

METHOD

H1N1-virus infection was detected by broncho-alveolar lavage performed on day 1. After some days following admission the patient was still in a life-threatening state, not responding to oseltamivir, protective mechanical ventilation and veno-arterial extracorporeal membrane oxygenation (ECMO).

RESULTS

The addition of methylprednisolone infusion at a stress dose (1 mg/kg/24 h) as rescue therapy significantly and rapidly improved the clinical condition. Weaning from ECMO and invasive mechanical ventilation was possible within a relatively few days.

CONCLUSION

According to the literature reports more than 34% of H1N1-virus severe infections were treated with corticosteroids. This report and our experience may suggest a possible life-saving use of corticosteroids at a stress dose in severely ill patients with an H1N1-virus infection that is not responding to the most advanced treatments.

Pathogenesis of pandemic H1N1 2009 influenza virus infection and the implication on management

The pandemic H1N1 2009 influenza virus has caused the first influenza pandemic of the 21st century, leading to disproportionate fatalities in the low-risk population despite the generally mild nature of the illness. Advances in science and technology have allowed very detailed study on the pathogenesis of this novel virus, and many have already been published in less than a year after the start of the pandemic. Information generated from cell lines, animal models, and clinical data analysis has provided us with greater understanding of the behavior of this virus and the associated host response. The new knowledge will allow us to formulate scientifically sound and evidence-based management plans.

Nonventilatory strategies for patients with life-threatening 2009 H1N1 influenza and severe respiratory failure

Severe respiratory failure (including acute lung injury and acute respiratory distress syndrome) caused by 2009 H1N1 influenza infection has been reported worldwide. Refractory hypoxemia is a common finding in these patients and can be challenging to manage. This review focuses on nonventilatory strategies in the advanced treatment of severe respiratory failure and refractory hypoxemia such as that seen in patients with severe acute respiratory distress syndrome attributable to 2009 H1N1 influenza. Specific modalities covered include conservative fluid management, prone positioning, inhaled nitric oxide, inhaled vasodilatory prostaglandins, and extracorporeal membrane oxygenation and life support. Pharmacologic strategies (including steroids) investigated for the treatment of severe respiratory failure are also reviewed.

Therapeutic targets for influenza – perspectives in drug development

Since new and dangerous influenza virus strains, such as H5N1 “avian flu” and more recently the swine-origin H1N1 “swine flu”, are constantly evolving, the need for effective anti-influenza drugs is pressing. It is becoming clear that the emergence of drug-resistant viruses will be a major potential problem in future efforts to control influenza virus infection. Moreover, development of vaccines against new influenza strains takes several months, and their production capacity is limited. Thus, new classes of anti-influenza drugs are highly sought after. This review focuses mainly on novel strategies, including targeting viral entry into host cells, inhibition of viral transcription and genome replication, and targeting of the NS1 influenza protein. Another approach involves viral RNA silencing by siRNAs or by antisense oligonucleotides. Inhibitors of viral neuraminidase have been the most successful approach in influenza virus breakdown to date. Viral maturation can also be blocked by inhibition of hemagglutinin-processing cellular proteinases. Compounds modifying the host cell immune response have also been reported. Design of specific compounds universally active against all viral variants with a reduced potential for the emergence of drug-resistant mutants is the main challenge in anti-influenza drug development, and the goals in this field are discussed here. A review with 140 references.

Interplay between influenza A virus and the innate immune signaling

Pathogens such as influenza A viruses (IAV) have to overcome a number of barriers defined and maintained by the host, to successfully establish an infection. One of the initial barriers is collectively characterized as the innate immune system. This is a broad anti-pathogen defense program that ranges from the action of natural killer cells to the induction of an antiviral cytokine response. In this article we will focus on new developments and discoveries concerning the interaction of IAV with the cellular innate immune signaling. We discuss new mechanisms of interference of IAV with the pathogen recognition receptor RIG-I and the type I IFN antagonist NS1 in the background of already known and established concepts. Further we summarize progress related to recently identified IFN induced proteins and the role of RNA interference in the context of IAV infection.

H1N1 influenza A virus-associated acute lung injury: response to combination oseltamivir and prolonged corticosteroid treatment

Purpose

During the 2009 H1N1 influenza A virus pandemic, a minority of patients developed rapidly progressive pneumonia leading to acute lung injury (ALI)—acute respiratory distress syndrome (ARDS). A recent meta-analysis provides support for prolonged corticosteroid treatment in ALI-ARDS. We prospectively evaluated the response to oseltamivir and prolonged corticosteroid treatment in patients with ALI-ARDS and suspected H1N1 influenza.

Methods

From June 24 through 12 July 2009, 13 patients with suspected H1N1 pneumonia and ALI-ARDS were admitted to the intensive care unit (ICU) of a tertiary care hospital. H1N1 influenza was confirmed with real-time reverse transcriptase-polymerase chain reaction assay in eight patients. Oseltamivir and corticosteroid treatment were initiated concomitantly at ICU admission; those with severe ARDS received methylprednisolone (1 mg/kg/day), and others received hydrocortisone (300 mg/day) for a duration of 21 ± 6 days.

Results

Patients with and without confirmed H1N1 influenza had similar disease severity at presentation and a comparable response to treatment. By day 7 of treatment, patients experienced a significant improvement in lung injury and multiple organ dysfunction scores (P < 0.001). Twelve patients (92%) improved lung function, were extubated, and discharged alive from the ICU. Hospital length of stay and mortality were 18.7 ± 9.6 days and 15%, respectively. Survivors were discharged home without oxygen supplementation.

Conclusions

In ARDS patients, with and without confirmed H1N1 influenza, prolonged low-to-moderate dose corticosteroid treatment was well tolerated and associated with significant improvement in lung injury and multiple organ dysfunction scores and a low hospital mortality. These findings provide the rationale for developing a randomized trial.

Antiviral therapy for respiratory tract infections

Viruses are important pathogens causing respiratory tract infections both in the community and health‐care facility settings. They are extremely common causes of morbidity in the competent hosts and some are associated with significant mortality in the compromised individuals. With wider application of molecular techniques, novel viruses are being described and old viruses are found to have new significance in different epidemiological and clinical settings. Some of these emerging pathogens may have the potential to cause pandemics or global spread of a severe disease, as exemplified by severe acute respiratory syndrome and avian influenza. Antiviral therapy of viral respiratory infections is often unnecessary in the competent hosts because most of them are self‐limiting and effective agents are not always available. In the immunocompromised individuals or for infections caused by highly pathogenic viruses, such as avian influenza viruses (AIV), antiviral treatment is highly desirable, despite the fact that many of the agents may not have undergone stringent clinical trials. In immunocompetent hosts, antiviral therapy can be stopped early because adaptive immune response can usually be mounted within 5–14 days. However, the duration of antiviral therapy in immunosuppressed hosts depends on clinical and radiological resolution, the degree and duration of immunosuppression, and therefore maintenance therapy is sometimes needed after the initial response. Immunotherapy and immunoprophylaxis appear to be promising directions for future research. Appropriate and targeted immunomodulation may play an important adjunctive role in some of these infections by limiting the extent of end‐organ damage and multi‐organ failure in some fulminant infections.

Anti-influenza drugs: the development of sialidase inhibitors

Viruses, particularly those that are harmful to humans, are the 'silent terrorists' of the twenty-first century. Well over four million humans die per annum as a result of viral infections alone. The scourge of influenza virus has plagued mankind throughout the ages. The fact that new viral strains emerge on a regular basis, particularly out of Asia, establishes a continual socio-economic threat to mankind. The arrival of the highly pathogenic avian influenza H5N1 heightened the threat of a potential human pandemic to the point where many countries have put in place 'preparedness plans' to defend against such an outcome. The discovery of the first designer influenza virus sialidase inhibitor and anti-influenza drug Relenza, and subsequently Tamiflu, has now inspired a number of continuing efforts towards the discovery of next generation anti-influenza drugs. Such drugs may act as 'first-line-of-defence' against the spread of influenza infection and buy time for necessary vaccine development particularly in a human pandemic setting. Furthermore, the fact that influenza virus can develop resistance to therapeutics makes these continuing efforts extremely important. An overview of the role of the virus-associated glycoprotein sialidase (neuraminidase) and some of the most recent developments towards the discovery of anti-influenza drugs based on the inhibition of influenza virus sialidase is provided in this chapter.