Manipulation of immunity to and pathology of respiratory infections

Effect of Reactive Oxygen Species on the Endoplasmic Reticulum and Mitochondria during Intracellular Pathogen Infection of Mammalian Cells

Oxidative stress, particularly reactive oxygen species (ROS), are important for innate immunity against pathogens. ROS directly attack pathogens, regulate and amplify immune signals, induce autophagy and activate inflammation. In addition, production of ROS by pathogens affects the endoplasmic reticulum (ER) and mitochondria, leading to cell death. However, it is unclear how ROS regulate host defense mechanisms. This review outlines the role of ROS during intracellular pathogen infection, mechanisms of ROS production and regulation of host defense mechanisms by ROS. Finally, the interaction between microbial pathogen-induced ROS and the ER and mitochondria is described.

The safety profile of Polyoxidonium in daily practice: results from postauthorization safety study in Slovakia

AIM

This study assessed the safety of Polyoxidonium^® 6 mg lyophilisate for solution for injection in routine practice with a special focus on signs or symptoms of potential adverse renal effects.

MATERIALS & METHODS

A local, multicenter, prospective, open-label, noninterventional, uncontrolled postauthorization safety study was conducted in 15 healthcare centers in Slovakia. Adult patients who received commercially available Polyoxidonium 6 mg lyophilisate for solution for injection as a part of their routine care were observed for one cycle of treatment, consisting of five or ten injections. For safety assessment, adverse events were monitored with a special focus on signs or symptoms of potential adverse renal effects. At the end of the study, investigators and subjects rated the overall tolerance of Polyoxidonium treatment as well as improvement. Data collection was based on the review of medical records and routine examination of subjects.

RESULTS

In total, 502 subjects were enrolled and 498 (99.2%) subjects completed the study. 19 (3.8%) subjects experienced a total of 34 adverse events. Only one (0.1%) subject experienced eight adverse drug reactions (ADRs): restlessness, fatigue, feeling hot (n = 2), pyrexia (n = 3) and asthenia. There were no renal ADRs or serious ADRs. At the end of the study, both investigators and subjects very positively rated global tolerability and global improvement.

CONCLUSION

Polyoxidonium was well tolerated in the heterogenous population of patients, mostly with chronic recurrent bacterial or viral infections. No renal ADRs were reported in this postauthorization safety study, which was designed with a special focus on identifying potential adverse renal effects.

NADPH oxidases: an overview from structure to innate immunity-associated pathologies

Oxygen-derived free radicals, collectively termed reactive oxygen species (ROS), play important roles in immunity, cell growth, and cell signaling. In excess, however, ROS are lethal to cells, and the overproduction of these molecules leads to a myriad of devastating diseases. The key producers of ROS in many cells are the NOX family of NADPH oxidases, of which there are seven members, with various tissue distributions and activation mechanisms. NADPH oxidase is a multisubunit enzyme comprising membrane and cytosolic components, which actively communicate during the host responses to a wide variety of stimuli, including viral and bacterial infections. This enzymatic complex has been implicated in many functions ranging from host defense to cellular signaling and the regulation of gene expression. NOX deficiency might lead to immunosuppression, while the intracellular accumulation of ROS results in the inhibition of viral propagation and apoptosis. However, excess ROS production causes cellular stress, leading to various lethal diseases, including autoimmune diseases and cancer. During the later stages of injury, NOX promotes tissue repair through the induction of angiogenesis and cell proliferation. Therefore, a complete understanding of the function of NOX is important to direct the role of this enzyme towards host defense and tissue repair or increase resistance to stress in a timely and disease-specific manner.

The 1918 influenza pandemic: lessons for 2009 and the future

The 1918 to 1919 H1N1 influenza pandemic is among the most deadly events in recorded human history, having killed an estimated 50 to 100 million persons. Recent H5N1 avian influenza epizootics associated with sporadic human fatalities have heightened concern that a new influenza pandemic, one at least as lethal as that of 1918, could be developing. In early 2009, a novel pandemic H1N1 influenza virus appeared, but it has not exhibited unusually high pathogenicity. Nevertheless, because this virus spreads globally, some scientists predict that mutations will increase its lethality. Therefore, to accurately predict, plan, and respond to current and future influenza pandemics, we must first better-understand the events and experiences of 1918. Although the entire genome of the 1918 influenza virus has been sequenced, many questions about the pandemic it caused remain unanswered. In this review, we discuss the origin of the 1918 pandemic influenza virus, the pandemic's unusual epidemiologic features and the causes and demographic patterns of fatality, and how this information should impact our response to the current 2009 H1N1 pandemic and future pandemics. After 92 yrs of research, fundamental questions about influenza pandemics remain unanswered. Thus, we must remain vigilant and use the knowledge we have gained from 1918 and other influenza pandemics to direct targeted research and pandemic influenza preparedness planning, emphasizing prevention, containment, and treatment.

Sudden death in toddlers caused by influenza B infection: a report of two cases and a review of the literature

Sudden fatal cases of influenza B infection in a 4-year-old girl and a 2-year-old boy are presented. Both children complained of abdominal pain without respiratory, neurologic or cardiac symptoms; additionally the girl had vomiting within 2 days of death. Autopsy revealed histological changes in the respiratory system consistent with a viral infection. Influenza B infection was identified by immunohistochemistry in the girl and real-time polymerase chain reaction in the boy. Additional testing including cultures, toxicology, and screening for metabolic disorders were negative. These cases illustrate the usefulness of viral testing, especially for influenza, in the medical legal autopsy of children even when the classic respiratory symptoms of flu are lacking.

An absence of reactive oxygen species improves the resolution of lung influenza infection

Three influenza virus pandemics occurred in the last century, in 1918 killing 40-50 million people. In the absence of strain-specific vaccines, with potential resistance to antivirals and the threat of an imminent pandemic, strategies that alleviate symptoms are a priority. Reactive oxygen species are potent antimicrobial agents but cause immunopathology when produced in excess. Mice lacking a functional phagocyte NADPH oxidase (Cybb tm1 mice) or treated with the metalloporphyrin antioxidant manganese (III) tetrakis (N-ethyl pyridinium-2-yl) porpyhrin (MnTE-2-PyP) show heightened inflammatory infiltrates in their airways in response to pulmonary influenza infection, with augmented macrophage populations and a Th1-skewed T cell infiltrate. Underlying this exuberant macrophage response was a significant reduction in apoptosis and down-regulation of the myeloid inhibitory molecule CD200. Both, Cybb tm1 and MnTE-2-PyP-treated mice exhibited a reduced influenza titer in the lung parenchyma. Inflammatory infiltrate into the lung parenchyma was markedly reduced and lung function significantly improved. Manipulation of the homeostatic control of myeloid cells by inflammatory mediators therefore represents a novel therapeutic strategy in the treatment of influenza virus infection.