Attenuating immune pathology using a microbial-based intervention in a mouse model of cigarette smoke-induced lung inflammation.

BACKGROUND: Cigarette smoke exposure is the major risk factor for developing COPD. Presently, available COPD treatments focus on suppressing inflammation and providing bronchodilation. However, these options have varying efficacy in controlling symptoms and do not reverse or limit the progression of COPD. Treatments strategies using bacterial-derived products have shown promise in diseases characterized by inflammation and immune dysfunction. This study investigated for the first time whether a novel immunotherapy produced from inactivated Klebsiella (hereafter referred to as KB) containing all the major Klebsiella macromolecules, could attenuate cigarette smoke exposure-induced immune responses. We hypothesized that KB, by re-directing damaging immune responses, would attenuate cigarette smoke-induced lung inflammation and bronchoalveolar (BAL) cytokine and chemokine production. METHODS: KB was administered via a subcutaneous injection prophylactically before initiating a 3-week acute nose-only cigarette smoke exposure protocol. Control mice received placebo injection and room air. Total BAL and differential cell numbers were enumerated. BAL and serum were analysed for 31 cytokines, chemokines, and growth factors. Lung tissue and blood were analysed for Ly6CHI monocytes/macrophages and neutrophils. Body weight and clinical scores were recorded throughout the experiment. RESULTS: We demonstrate that KB treatment attenuated cigarette smoke-induced lung inflammation as shown by reductions in levels of BAL IFNγ, CXCL9, CXCL10, CCL5, IL-6, G-CSF, and IL-17. KB additionally attenuated the quantity of BAL lymphocytes and macrophages. In parallel to the attenuation of lung inflammation, KB induced a systemic immune activation with increases in Ly6CHI monocytes/macrophages and neutrophils. CONCLUSIONS: This is the first demonstration that subcutaneous administration of a microbial-based immunotherapy can attenuate cigarette smoke-induced lung inflammation, and modulate BAL lymphocyte and macrophage levels, while inducing a systemic immune activation and mobilization. These data provide a foundation for future studies exploring how KB may be used to either reverse or prevent progression of established emphysema and small airways disease associated with chronic cigarette smoke exposure. The data suggest the intriguing possibility that KB, which stimulates rather than suppresses systemic immune responses, might be a novel means by which the course of COPD pathogenesis may be altered.

A novel microbe-based treatment that attenuates the inflammatory profile in a mouse model of allergic airway disease.

There is an unmet need for effective new and innovative treatments for asthma. It is becoming increasingly evident that bacterial stimulation can have beneficial effects at attenuating allergic airway disease through immune modulation. Our aim was to test the ability of a novel inactivated microbe-derived therapeutic based on Klebsiella (KB) in a model of allergic airway disease in mice. BALB/c mice were exposed intranasally to house dust mite (HDM) for two weeks. Mice were treated prophylactically via subcutaneous route with either KB or placebo for one week prior to HDM exposure and throughout the two week exposure period. 24 hours after the last exposure, lungs were analysed for inflammatory cell infiltrate, gene expression, cytokine levels, goblet cell metaplasia, and serum was analysed for allergen-specific serum IgE levels. HDM exposed mice developed goblet cell hyperplasia, elevated allergen-specific serum IgE, airway eosinophilia, and a concomitant increase in TH2 cytokines including IL-4, IL-13 and IL-5. Treatment with KB attenuated HDM-mediated airway eosinophilia, total bronchoalveolar lavage (BAL) cell numbers, BAL TH2 cytokine production, and goblet cell metaplasia. Our prophylactic intervention study illustrates the potential of subcutaneous treatment with bacterial derived biologics as a promising approach for allergic airway disease treatment.

The interplay between cell death signaling pathways in the heart.

To date, one of the most intriguing and compelling concepts to impact contemporary cell biology is the notion that cell fate is "programmed" or genetically controlled. Indeed, the regulation of cell fate is crucial for embryonic development, and tissue homeostasis. Given the importance of removing damaged or irreversibly injured cells from the body, it is not surprising that defects in the regulatory mechanisms that govern cell death and/or survival more generally have been implicated in a number of human pathologies including cancer, neurodegenerative diseases, and cardiac failure. Several processes involved in the regulation of cell fate through apoptosis, necrosis, and autophagy are commonly linked through the actions of certain Bcl-2 proteins that act on the mitochondrion. For example, the Bcl-2 protein Beclin-1 is actively involved in the clearance of damaged mitochondria via mitophagy, while other Bcl-2 proteins such as Bax/Bak can initiate apoptosis or necrotic signaling pathways. The overlapping and redundant nature of these proteins highlights their evolutionary importance for regulating cardiac cell survival and death during normal and disease states. Here, we explore the interrelationship between these signaling pathways and the cellular effectors that influence cardiac cell fate.

Bidirectional regulation of nuclear factor-κB and mammalian target of rapamycin signaling functionally links Bnip3 gene repression and cell survival of ventricular myocytes.

BACKGROUND: Tumor necrosis factor-α and other proinflammatory cytokines activate the canonical nuclear factor (NF)-κB pathway through the kinase IKKß. Previously, we established that IKKß is also critical for Akt-mediated NF-κB activation in ventricular myocytes. Akt activates the kinase mammalian target of rapamycin (mTOR), which mediates important processes such as cardiac hypertrophy. However, whether mTOR regulates cardiac myocyte cell survival is unknown. METHODS AND RESULTS: Herein, we demonstrate bidirectional regulation between NF-κB signaling and mTOR, the balance which determines ventricular myocyte survival. Overexpression of IKKß resulted in mTOR activation and conversely overexpression of mTOR lead to NF-κB activation. Loss of function approaches demonstrated that endogenous levels of IKKß and mTOR also signal through this pathway. NF-κB activation by mTOR was mediated by phosphorylation of the NF-κB p65 subunit increasing p65 nuclear translocation and activation of gene transcription. This circuit was also important for NF-κB activation by the canonical tumor necrosis factor-α pathway. Our previous work has shown that NF-κB signaling suppresses transcription of the death gene Bnip3 resulting in ventricular myocyte survival. Inhibition of mTOR with rapamycin decreased NF-κB activation resulting in increased Bnip3 expression and cell death. Conversely, mTOR overexpression suppressed Bnip3 levels and cell death of ventricular myocytes in response to hypoxia. CONCLUSIONS: To our knowledge, these data provide the first evidence for a bidirectional link between NF-κB signaling and mTOR that is critical in the regulation of Bnip3 expression and cardiac myocyte death. Hence, modulation of this axis may be cardioprotective during ischemia.

Autophagy in the heart: too much of a good thing?

Autophagy constitutes a catabolic process involving lysosomal degradation of damaged and redundant cytosolic components into biomolecules, via an elaborate lysosomal pathway. Autophagy is a highly regulated and evolutionary conserved process crucial for normal tissue homeostasis and cell life. Certain members of the Bcl-2 gene family, including the BH3 only protein Bnip3 regulate autophagy during cardiac stress during ischemic or hypoxic injury as means of discarding damaged mitochondria and organelles to avert cell death. Defects in the regulation of autophagy have been associated with a number of human pathologies including cancer, neurodegenerative diseases, and heart failure. Here, we discuss the molecular regulation of autophagy in the heart and cellular demise from "too much a good thing."

Resveratrol induces mitochondrial biogenesis and ameliorates Ang II-induced cardiac remodeling in transgenic rats harboring human renin and angiotensinogen genes.

There is compelling evidence to indicate an important role for increased local renin-angiotensin system activity in the pathogenesis of cardiac hypertrophy and heart failure. Resveratrol is a natural polyphenol that activates SIRT1, a novel cardioprotective and longevity factor having NAD(+)-dependent histone deacetylase activity. We tested the hypothesis whether resveratrol could prevent from angiotensin II (Ang II)-induced cardiovascular damage. Four-week-old double transgenic rats harboring human renin and human angiotensinogen genes (dTGR) were treated for 4 weeks either with SIRT1 activator resveratrol or SIRT1 inhibitor nicotinamide. Untreated dTGR and their normotensive Sprague-Dawley control rats (SD) received vehicle. Untreated dTGR developed severe hypertension as well as cardiac hypertrophy, and showed pronounced cardiovascular mortality compared with normotensive SD rats. Resveratrol slightly but significantly decreased blood pressure, ameliorated cardiac hypertrophy and prevented completely Ang II-induced mortality, whereas nicotinamide increased blood pressure without significantly influencing cardiac hypertrophy or survival. Resveratrol decreased cardiac ANP mRNA expression and induced cardiac mRNA expressions of mitochondrial biogenesis markers peroxisome proliferator-activated receptor-gamma coactivator (PGC-1alpha), mitochondrial transcription factor (Tfam), nuclear respiratory factor 1 (NRF-1) and cytochrome c oxidase subunit 4 (cox4). Resveratrol dose-dependently increased SIRT1 activity in vitro. Our findings suggest that the beneficial effects of SIRT1 activator resveratrol on Ang II-induced cardiac remodeling are mediated by blood pressure-dependent pathways and are linked to increased mitochondrial biogenesis.