Statins as a novel therapeutic strategy in acute lung injury

Potential biomarkers for inflammatory response in acute lung injury

Acute lung injury (ALI) is a severe respiratory disorder occurring in critical care medicine, with high rates of mortality and morbidity. This study aims to screen the potential biomarkers for ALI. Microarray data of lung tissues from lung-specific geranylgeranyl pyrophosphate synthase large subunit 1 knockout and wild-type mice treated with lipopolysaccharide were downloaded. Differentially expressed genes (DEGs) between ALI and wild-type mice were screened. Functional analysis and the protein-protein interaction (PPI) modules were analyzed. Finally, a miRNA-transcription factor (TF)-target regulation network was constructed. Totally, 421 DEGs between ALI and wild-type mice were identified. The upregulated DEGs were mainly enriched in the peroxisome proliferator-activated receptor signaling pathway, and fatty acid metabolic process, while downregulated DEGs were related to cytokine-cytokine receptor interaction and regulation of cytokine production. Cxcl5, Cxcl9, Ccr5, and Cxcr4 were key nodes in the PPI network. In addition, three miRNAs (miR505, miR23A, and miR23B) and three TFs (PU1, CEBPA, and CEBPB) were key molecules in the miRNA-TF-target network. Nine genes including ADRA2A, P2RY12, ADORA1, CXCR1, and CXCR4 were predicted as potential druggable genes. As a conclusion, ADRA2A, P2RY12, ADORA1, CXCL5, CXCL9, CXCR1, and CXCR4 might be novel markers and potential druggable genes in ALI by regulating inflammatory response.

Amelioration of Endotoxin-Induced Acute Lung Injury and Alveolar Epithelial Cells Apoptosis by Simvastatin Is Associated with Up-Regulation of Survivin/NF-kB/p65 Pathway

Disruption of the alveolar−endothelial barrier caused by inflammation leads to the progression of septic acute lung injury (ALI). In the present study, we investigated the beneficial effects of simvastatin on the endotoxin lipopolysaccharide (LPS)-induced ALI and its related mechanisms. A model of ALI was induced within experimental sepsis developed by intraperitoneal injection of a single non-lethal LPS dose after short-term simvastatin pretreatment (10−40 mg/kg orally). The severity of the lung tissue inflammatory injury was expressed as pulmonary damage scores (PDS). Alveolar epithelial cell apoptosis was confirmed by TUNEL assay (DNA fragmentation) and expressed as an apoptotic index (AI), and immunohistochemically for cleaved caspase-3, cytochrome C, and anti-apoptotic Bcl-xL, an inhibitor of apoptosis, survivin, and transcriptional factor, NF-kB/p65. Severe inflammatory injury of pulmonary parenchyma (PDS 3.33 ± 0.48) was developed after the LPS challenge, whereas simvastatin significantly and dose-dependently protected lung histology after LPS (p < 0.01). Simvastatin in a dose of 40 mg/kg showed the most significant effects in amelioration alveolar epithelial cells apoptosis, demonstrating this as a marked decrease of AI (p < 0.01 vs. LPS), cytochrome C, and cleaved caspase-3 expression. Furthermore, simvastatin significantly enhanced the expression of Bcl-xL and survivin. Finally, the expression of survivin and its regulator NF-kB/p65 in the alveolar epithelium was in strong positive correlation across the groups. Simvastatin could play a protective role against LPS-induced ALI and apoptosis of the alveolar−endothelial barrier. Taken together, these effects were seemingly mediated by inhibition of caspase 3 and cytochrome C, a finding that might be associated with the up-regulation of cell-survival survivin/NF-kB/p65 pathway and Bcl-xL.

The effect of statins on the prevalence and mortality of influenza virus infection: a systematic review and meta-analysis

INTRODUCTION

Influenza virus infection is associated with high morbidity and mortality, and so additional therapeutic strategies to reduce the burden for healthcare systems are needed. Statins, by virtue of their anti-inflammatory and immunomodulatory effects, have been hypothesized as capable of influencing the host's response against the influenza virus. The aim of this meta-analysis was to assess the effect of ongoing statin treatment on susceptibility to influenza virus infection and on influenza-associated mortality.

MATERIAL AND METHODS

Studies investigating the impact of statin treatment on influenza prevalence and mortality were searched for in the PubMed-Medline, Scopus, ISI Web of Knowledge, Embase, Proquest, OVID, EBSCO, and CINAHL databases (up to 8 November 2021). Fixed- and random-effects models and the generic inverse variance method were used for quantitative data synthesis.

RESULTS

In the meta-analysis of 14 arms of 2 eligible studies, including 14,997 flu-vaccinated and unvaccinated patients, treatment with statins was associated with a reduction of influenza virus prevalence (odds ratio (OR) = 0.85, 95% confidence interval (CI): 0.73-0.99; p = 0.040). No significant effect of statins on the susceptibility to influenza infection was observed in the distinct communities of either vaccinated or unvaccinated subjects. Among 9 arms of 6 eligible studies, including 87,204 patients, the use of statins among patients with influenza was associated with a reduced mortality (OR = 0.68, 95% CI: 0.56, 0.82; p < 0.001). This result was confirmed for both 30-day mortality since influenza infection diagnosis (OR = 0.61, 95% CI: 0.47, 0.80; p <0.001) and for up to 90-day mortality (OR = 0.74, 95% CI: 0.55, 1.00; p = 0.042).

CONCLUSIONS

Reduced influenza prevalence and increased survival from influenza infection was observed in patients on ongoing statin treatment. Further research is needed to define the possible role of statins as adjunctive therapy in patients with influenza infection.

Salidroside Protects Against Influenza A Virus-Induced Acute Lung Injury in Mice

Influenza A virus infections can cause acute lung injury (ALI) in humans; thus, the identification of potent antiviral agents is urgently required. Herein, the effects of salidroside on influenza A virus-induced ALI were investigated in a murine model. BALB/c mice were intranasally inoculated with H1N1 virus and treated with salidroside. The results of this study show that salidroside treatment (30 and 60 mg/kg) significantly attenuated the H1N1 virus-induced histological alterations in the lung and inhibited inflammatory cytokine production. Salidroside also decreased the wet/dry ratio, viral titers, and Toll-like receptor 4 expression in the lungs. Therefore, salidroside may represent a potential therapeutic reagent for the treatment of influenza A virus-induced ALI.

Unveiling COVID-19-associated organ-specific cell types and cell-specific pathway cascade

The novel coronavirus or COVID-19 has first been found in Wuhan, China, and became pandemic. Angiotensin-converting enzyme 2 (ACE2) plays a key role in the host cells as a receptor of Spike-I Glycoprotein of COVID-19 which causes final infection. ACE2 is highly expressed in the bladder, ileum, kidney and liver, comparing with ACE2 expression in the lung-specific pulmonary alveolar type II cells. In this study, the single-cell RNAseq data of the five tissues from different humans are curated and cell types with high expressions of ACE2 are identified. Subsequently, the protein-protein interaction networks have been established. From the network, potential biomarkers which can form functional hubs, are selected based on k-means network clustering. It is observed that angiotensin PPAR family proteins show important roles in the functional hubs. To understand the functions of the potential markers, corresponding pathways have been researched thoroughly through the pathway semantic networks. Subsequently, the pathways have been ranked according to their influence and dependency in the network using PageRank algorithm. The outcomes show some important facts in terms of infection. Firstly, renin-angiotensin system and PPAR signaling pathway can play a vital role for enhancing the infection after its intrusion through ACE2. Next, pathway networks consist of few basic metabolic and influential pathways, e.g. insulin resistance. This information corroborate the fact that diabetic patients are more vulnerable to COVID-19 infection. Interestingly, the key regulators of the aforementioned pathways are angiontensin and PPAR family proteins. Hence, angiotensin and PPAR family proteins can be considered as possible therapeutic targets. Contact: sagnik.sen2008@gmail.com, umaulik@cse.jdvu.ac.in Supplementary information: Supplementary data are available online.

Chinese Herbs and Repurposing Old Drugs as Therapeutic Agents in the Regulation of Oxidative Stress and Inflammation in Pulmonary Diseases

Several pro-inflammatory factors and proteins have been characterized that are involved in the pathogenesis of inflammatory diseases, including acute respiratory distress syndrome, chronic obstructive pulmonary disease, and asthma, induced by oxidative stress, cytokines, bacterial toxins, and viruses. Reactive oxygen species (ROS) act as secondary messengers and are products of normal cellular metabolism. Under physiological conditions, ROS protect cells against oxidative stress through the maintenance of cellular redox homeostasis, which is important for proliferation, viability, cell activation, and organ function. However, overproduction of ROS is most frequently due to excessive stimulation of either the mitochondrial electron transport chain and xanthine oxidase or reduced nicotinamide adenine dinucleotide phosphate (NADPH) by pro-inflammatory cytokines, such as interleukin-1β and tumor necrosis factor α. NADPH oxidase activation and ROS overproduction could further induce numerous inflammatory target proteins that are potentially mediated via Nox/ROS-related transcription factors triggered by various intracellular signaling pathways. Thus, oxidative stress is considered important in pulmonary inflammatory processes. Previous studies have demonstrated that redox signals can induce pulmonary inflammatory diseases. Thus, therapeutic strategies directly targeting oxidative stress may be effective for pulmonary inflammatory diseases. Therefore, drugs with anti-inflammatory and anti-oxidative properties may be beneficial to these diseases. Recent studies have suggested that traditional Chinese medicines, statins, and peroxisome proliferation-activated receptor agonists could modulate inflammation-related signaling processes and may be beneficial for pulmonary inflammatory diseases. In particular, several herbal medicines have attracted attention for the management of pulmonary inflammatory diseases. Therefore, we reviewed the pharmacological effects of these drugs to dissect how they induce host defense mechanisms against oxidative injury to combat pulmonary inflammation. Moreover, the cytotoxicity of oxidative stress and apoptotic cell death can be protected via the induction of HO-1 by these drugs. The main objective of this review is to focus on Chinese herbs and old drugs to develop anti-inflammatory drugs able to induce HO-1 expression for the management of pulmonary inflammatory diseases.

Pretreatment with atorvastatin ameliorates cobra venom factor-induced acute lung inflammation in mice

Background

The complement system plays a critical role as the pathogenic factor in the models of acute lung injury due to various causes. Cobra venom factor (CVF) is a commonly used complement research tool. The CVF can cause acute inflammation in the lung by producing complement activation components. Atorvastatin (ATR) is a 3-hydroxy-3-methylglutaryl coenzyme A inhibitor approved for control of plasma cholesterol levels. This inhibitor can reduce the acute pulmonary inflammatory response. However, the ability of ATR in treating acute lung inflammation caused by complement activation is still unknown. Therefore, we investigated the effect of ATR on lung inflammation in mice induced by activation of the complement alternative pathway in this study.

Methods

ATR (10 mg/kg/day via oral gavage) was administered for 7 days before tail vein injection of CVF (25 μg/kg). On the seventh day, all mice were sacrificed 1 h after injection. The lung lobe, bronchoalveolar lavage fluid (BALF), and blood samples were collected. The myeloperoxidase (MPO) activity of the lung homogenate, the leukocyte cell count, and the protein content of BALF were measured. The levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), P-selectin, and Intercellular cell adhesion molecule-1 (ICAM-1) in BALF and serum were determined by enzyme-linked immunosorbent assay. The pathological change of the lung tissue was observed by hematoxylin and eosin staining. The deposition of C5b-9 in the lung tissue was detected by immunohistochemistry. The phosphorylation of NF-κB p65 in the lung tissues was examined by immunohistochemistry and western blotting.

Results

The lung inflammation levels were determined by measuring the leukocyte cell numbers and protein content of BALF, the lung MPO activity, and expression and staining of the inflammatory mediators (IL-6 and TNF-α), and adhesion molecules (P-selectin and ICAM-1) for lung lesion. A significant reduction in the lung inflammation levels was observed after 7 days in ATR pre-treated mice with a CVF-induced lung disease. Deposition of C5b-9 was significantly alleviated by ATR pretreatment. Early intervention with ATR significantly reduced the development of acute lung inflammation on the basis of phosphorylation of NF-κB p65 in the lung.

Conclusion

These findings suggest the identification of ATR treatment for the lung inflammation induced by activating the complement system on the basis of its anti-inflammatory response. Together with the model replicating the complement activating characteristics of acute lung injury, the results may be translatable to the overactivated complement relevant diseases.

Gene Expression Analysis to Assess the Relevance of Rodent Models to Human Lung Injury

The relevance of animal models to human diseases is an area of intense scientific debate. The degree to which mouse models of lung injury recapitulate human lung injury has never been assessed. Integrating data from both human and animal expression studies allows for increased statistical power and identification of conserved differential gene expression across organisms and conditions. We sought comprehensive integration of gene expression data in experimental acute lung injury (ALI) in rodents compared with humans. We performed two separate gene expression multicohort analyses to determine differential gene expression in experimental animal and human lung injury. We used correlational and pathway analyses combined with external in vitro gene expression data to identify both potential drivers of underlying inflammation and therapeutic drug candidates. We identified 21 animal lung tissue datasets and three human lung injury bronchoalveolar lavage datasets. We show that the metasignatures of animal and human experimental ALI are significantly correlated despite these widely varying experimental conditions. The gene expression changes among mice and rats across diverse injury models (ozone, ventilator-induced lung injury, LPS) are significantly correlated with human models of lung injury (Pearson r = 0.33-0.45, P < 1E^-16). Neutrophil signatures are enriched in both animal and human lung injury. Predicted therapeutic targets, peptide ligand signatures, and pathway analyses are also all highly overlapping. Gene expression changes are similar in animal and human experimental ALI, and provide several physiologic and therapeutic insights to the disease.

Treating the host response to emerging virus diseases: lessons learned from sepsis, pneumonia, influenza and Ebola

There is an ongoing threat of epidemic or pandemic diseases that could be caused by influenza, Ebola or other emerging viruses. It will be difficult and costly to develop new drugs that target each of these viruses. Statins and angiotensin receptor blockers (ARBs) have been effective in treating patients with sepsis, pneumonia and influenza, and a statin/ARB combination appeared to dramatically reduce mortality during the recent Ebola outbreak. These drugs target (among other things) the endothelial dysfunction found in all of these diseases. Most scientists work on new drugs that target viruses, and few accept the idea of treating the host response with generic drugs. A great deal of research will be needed to show conclusively that these drugs work, and this will require the support of public agencies and foundations. Investigators in developing countries should take an active role in this research. If the next Public Health Emergency of International Concern is caused by an emerging virus, a "top down" approach to developing specific new drug treatments is unlikely to be effective. However, a "bottom up" approach to treatment that targets the host response to these viruses by using widely available and inexpensive generic drugs could reduce mortality in any country with a basic health care system. In doing so, it would make an immeasurable contribution to global equity and global security.

Impact of statins on ALI/ARDS: A meta-analysis

BACKGROUND

Statins may be beneficial in treating acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), but their application remains controversial.

OBJECTIVES

This meta-analysis of published studies investigated their potential benefit in ALI/ARDS treatment.

METHODS

PubMed, EMBASE, Google Scholar and Cochrane databases were searched and all randomized controlled trials (RCT) and cohort studies with head-to-head comparison between statin and standard care were included.

RESULTS

Three RCTs and six cohort studies were included. Overall, statins treatment had no significant effect on mortality compared with placebo (RCTs: OR = 0.99, 95% CI = 0.72, 1.37; cohorts: OR = 0.99, 95% CI = 0.71, 1.37). In addition, ventilator-free days were comparable between the two groups (RCTs: SMD = 0.08, 95% CI = -0.03, 0.19; cohorts: SMD = 0.06, 95% CI = -0.17, 0.29). The one-way sensitivity analysis confirmed the stability of results.

CONCLUSION

The results did not show that statins had effects on mortality and ventilator-free days among ALI/ARDS patients. However, this meta-analysis is limited by the number of RCTs included.

Simvastatin prevents vascular complications in the chronic reactive oxygen species murine model of systemic sclerosis

Aims Systemic sclerosis (SSc) is characterized by vasculopathy and organ fibrosis. Although microvascular alterations are very well characterized, structural and functional abnormalities of large vessels are not well defined. Therefore, we evaluated the effect of simvastatin administration on aortic and small renal arteries thickening, and on myofibroblasts differentiation in a murine model of SSc. Methods and results SSc was induced in BALB/c mice by daily subcutaneous injections of hypochlorous acid (HOCl, 100 μl) for 6 weeks. Mice (n = 23) were randomized to receive: HOCl (n = 10); HOCl plus simvastatin (40 mg/kg; n = 8); or vehicle (n = 5). Simvastatin administration started 30 min after HOCl injection, and up to week 6. Aortic and small renal arteries intima-media thickness was evaluated by histological analysis. Immunostaining for α-smooth muscle actin (SMA), vascular endothelial growth factor receptor 2 (VEGFR2), and CD31 in aortic tissues was performed to evaluate myofibroblast differentiation and endothelial markers.In HOCl-treated mice, intima-media thickening with reduced lumen diameter was observed in the aorta and in small renal arteries and simvastatin administration prevented this increase. Aortic and renal myofibroblasts count, as expressed by α-SMA + density, was lower in the group of mice treated with simvastatin compared to HOCl-treated mice. Simvastatin prevented the reduction in VEGFR2 and CD31 expression induced by HOCl. Conclusions The administration of simvastatin regulates collagen deposition in the aortic tissues and in the small renal arteries by modulating myofibroblasts differentiation and vascular markers. Further studies are needed to better address the effect of statins in the macrovascular component of SSc.

Host-directed therapies for improving poor treatment outcomes associated with the middle east respiratory syndrome coronavirus infections

Three years after its first discovery in Jeddah Saudi Arabia, the novel zoonotic pathogen of humans, the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) continues to be a major threat to global health security.(1) Sporadic community acquired cases of MERS continue to be reported from the Middle East. The recent nosocomial outbreaks in hospitals in Seoul, Korea and at the National Guard Hospital in Riyadh, Saudi Arabia indicate the epidemic potential of MERS-CoV. Currently there are no effective anti-MERS-CoV anti-viral agents or therapeutics and MERS is associated with a high mortality rate (40%) in hospitalised patients. A large proportion of MERS patients who die have a range of pulmonary pathology ranging from pneumonia to adult respiratory distress syndrome with multi-organ failure, compounded by co-morbidities, reflecting a precarious balance of interactions between the host-immune system and MERS-CoV. Whilst we wait for new MERS-CoV specific drugs, therapeutics and vaccines to be developed, there is a need to advance a range of Host-Directed Therapies. A range of HDTs are available, including commonly used drugs with good safety profiles, which could augment host innate and adaptive immune mechanisms to MERS-CoV, modulate excessive inflammation and reduce lung tissue destruction. We discuss the rationale and potential of using Host-Directed Therapies for improving the poor treatment outcomes associated with MERS. Carefully designed randomized controlled trials will be needed to determine whether HDTs could benefit patients with MERS. The recurrent outbreaks of MERS-CoV infections at hospitals in the Middle East present unique opportunities to conduct randomized clinical trials. The time has come for a more coordinated global response to MERS and a multidisciplinary global MERS-CoV response group is required to take forward priority research agendas.

Inhibition of HMGCoA reductase by simvastatin protects mice from injurious mechanical ventilation

BACKGROUND

Mortality from severe acute respiratory distress syndrome exceeds 40% and there is no available pharmacologic treatment. Mechanical ventilation contributes to lung dysfunction and mortality by causing ventilator-induced lung injury. We explored the utility of simvastatin in a mouse model of severe ventilator-induced lung injury.

METHODS

Male C57BL6 mice (n = 7/group) were pretreated with simvastatin or saline and received protective (8 mL/kg) or injurious (25 mL/kg) ventilation for four hours. Three doses of simvastatin (20 mg/kg) or saline were injected intraperitoneally on days -2, -1 and 0 of the experiment. Lung mechanics, (respiratory system elastance, tissue damping and airway resistance), were evaluated by forced oscillation technique, while respiratory system compliance was measured with quasi-static pressure-volume curves. A pathologist blinded to treatment allocation scored hematoxylin-eosin-stained lung sections for the presence of lung injury. Pulmonary endothelial dysfunction was ascertained by bronchoalveolar lavage protein content and lung tissue expression of endothelial junctional protein Vascular Endothelial cadherin by immunoblotting. To assess the inflammatory response in the lung, we determined bronchoalveolar lavage fluid total cell content and neutrophil fraction by microscopy and staining in addition to Matrix-Metalloprotease-9 by ELISA. For the systemic response, we obtained plasma levels of Tumor Necrosis Factor-α, Interleukin-6 and Matrix-Metalloprotease-9 by ELISA. Statistical hypothesis testing was undertaken using one-way analysis of variance and Tukey's post hoc tests.

RESULTS

Ventilation with high tidal volume (HVt) resulted in significantly increased lung elastance by 3-fold and decreased lung compliance by 45% compared to low tidal volume (LVt) but simvastatin abrogated lung mechanical alterations of HVt. Histologic lung injury score increased four-fold by HVt but not in simvastatin-pretreated mice. Lavage pleocytosis and neutrophilia were induced by HVt but were significantly attenuated by simvastatin. Microvascular protein permeability increase 20-fold by injurious ventilation but only 4-fold with simvastatin. There was a 3-fold increase in plasma Tumor Necrosis Factor-α, a 7-fold increase in plasma Interleukin-6 and a 20-fold increase in lavage fluid Matrix-Metalloprotease-9 by HVt but simvastatin reduced these levels to control. Lung tissue vascular endothelial cadherin expression was significantly reduced by injurious ventilation but remained preserved by simvastatin.

CONCLUSION

High-dose simvastatin prevents experimental hyperinflation lung injury by angioprotective and anti-inflammatory effects.

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.

How will physicians respond to the next influenza pandemic?

The emergence of the H7N9 virus in China is another reminder of the threat of a global influenza pandemic. Many believe we could confront a pandemic by expanding our capacity to provide timely supplies of affordable pandemic vaccines and antiviral agents. Experience in 2009 demonstrated that this cannot and will not be done. Consequently, physicians may have little more to offer their patients than they had in the 1918 pandemic. Fortunately, several modern drugs (eg, statins, angiotensin II receptor blockers, angiotensin-converting enzyme inhibitors) can modify the host response to inflammatory illness, and laboratory and clinical studies suggest they might be used to treat pandemic patients. Unfortunately, little attention has been given to the research needed to support their use in patient care. There is no guarantee these drugs will work, but physicians will never know unless those responsible for pandemic preparedness recognize and act on the extraordinary possibility that they might save lives.

Novel concepts of acute lung injury and alveolar-capillary barrier dysfunction

In this review we summarize recent major advances in our understanding on the molecular mechanisms, mediators, and biomarkers of acute lung injury (ALI) and alveolar-capillary barrier dysfunction, highlighting the role of immune cells, inflammatory and noninflammatory signaling events, mechanical noxae, and the affected cellular and molecular entities and functions. Furthermore, we address novel aspects of resolution and repair of ALI, as well as putative candidates for treatment of ALI, including pharmacological and cellular therapeutic means.

Statins decrease lung inflammation in mice by upregulating tetraspanin CD9 in macrophages

Tetraspanins organize protein complexes in tetraspanin-enriched membrane microdomains that are distinct from lipid rafts. Our previous studies suggested that reduction in the levels of tetraspanins CD9 and CD81 may be involved in the progression of inflammatory lung diseases, especially COPD. To search for agents that increase the levels of these tetraspanins, we screened 1,165 drugs in clinical use and found that statins upregulate CD9 and CD81 in RAW264.7 macrophages. The lipophilic statins, fluvastatin and simvastatin, reversed LPS-induced downregulation of CD9 and CD81, simultaneously preventing TNF-α and matrix metalloproteinase-9 production and spreading of RAW264.7 cells. These statins exerted anti-inflammatory effects in vitro in wild-type macrophages but not in CD9 knockout macrophages, and decreased lung inflammation in vivo in wild-type mice but not in CD9 knockout mice, suggesting that their effects are dependent on CD9. Mechanistically, the statins promoted reverse transfer of the LPS-signaling mediator CD14 from lipid rafts into CD9-enriched microdomains, thereby preventing LPS receptor formation. Finally, upregulation of CD9/CD81 by statins was related to blockade of GTPase geranylgeranylation in the mevalonate pathway. Our data underscore the importance of the negative regulator CD9 in lung inflammation, and suggest that statins exert anti-inflammatory effects by upregulating tetraspanin CD9 in macrophages.

Treating influenza with statins and other immunomodulatory agents

Statins not only reduce levels of LDL-cholesterol, they counteract the inflammatory changes associated with acute coronary syndrome and improve survival. Similarly, in patients hospitalized with laboratory-confirmed seasonal influenza, statin treatment is associated with a 41% reduction in 30-day mortality. Most patients of any age who are at increased risk of influenza mortality have chronic low-grade inflammation characteristic of metabolic syndrome. Moreover, differences in the immune responses of children and adults seem responsible for the low mortality in children and high mortality in adults seen in the 1918 influenza pandemic and in other acute infectious and non-infectious conditions. These differences probably reflect human evolutionary development. Thus the host response to influenza seems to be the major determinant of outcome. Outpatient statins are associated with reductions in hospitalizations and deaths due to sepsis and pneumonia. Inpatient statins are also associated with reductions in short-term pneumonia mortality. Other immunomodulatory agents--ACE inhibitors (ACEIs), angiotensin receptor blockers (ARBs), PPARγ and PPARα agonists (glitazones and fibrates) and AMPK agonists (metformin)--also reduce mortality in patients with pneumonia (ACEIs, ARBs) or in mouse models of influenza (PPAR and AMPK agonists). In experimental studies, treatment has not increased virus replication. Thus effective management of influenza may not always require targeting the virus with vaccines or antiviral agents. Clinical investigators, not systems biologists, have been the first to suggest that immunomodulatory agents might be used to treat influenza patients, but randomized controlled trials will be needed to provide convincing evidence that they work. To guide the choice of which agent(s) to study, we need new types of laboratory research in animal models and clinical and epidemiological research in patients with critical illness. These studies will have crucial implications for global public health. During the 2009 H1N1 influenza pandemic, timely and affordable supplies of vaccines and antiviral agents were unavailable to more than 90% of the world's people. In contrast, statins and other immunomodulatory agents are currently produced as inexpensive generics, global supplies are huge, and they would be available to treat patients in any country with a basic health care system on the first pandemic day. Treatment with statins and other immunomodulatory agents represents a new approach to reducing mortality caused by seasonal and pandemic influenza.