Pneumonia remains a global health threat, in part due to expanding categories of susceptible individuals and increasing prevalence of antibiotic resistant pathogens. However, therapeutic stimulation ...of the lungs' mucosal defenses by inhaled exposure to a synergistic combination of Toll-like receptor (TLR) agonists known as Pam2-ODN promotes mouse survival of pneumonia caused by a wide array of pathogens. This inducible resistance to pneumonia relies on intact lung epithelial TLR signaling, and inducible protection against viral pathogens has recently been shown to require increased production of epithelial reactive oxygen species (ROS) from multiple epithelial ROS generators. To determine whether similar mechanisms contribute to inducible antibacterial responses, the current work investigates the role of ROS in therapeutically-stimulated protection against Pseudomonas aerugnosa challenges. Inhaled Pam2-ODN treatment one day before infection prevented hemorrhagic lung cytotoxicity and mouse death in a manner that correlated with reduction in bacterial burden. The bacterial killing effect of Pam2-ODN was recapitulated in isolated mouse and human lung epithelial cells, and the protection correlated with inducible epithelial generation of ROS. Scavenging or targeted blockade of ROS production from either dual oxidase or mitochondrial sources resulted in near complete loss of Pam2-ODN-induced bacterial killing, whereas deficiency of induced antimicrobial peptides had little effect. These findings support a central role for multisource epithelial ROS in inducible resistance against a bacterial pathogen and provide mechanistic insights into means to protect vulnerable patients against lethal infections.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Influenza pneumonia remains a common and debilitating viral infection despite vaccination programs and antiviral agents developed for prophylaxis and treatment. The neuraminidase inhibitor ...oseltamivir is frequently prescribed for established influenza A virus infections, but the emergence of neuraminidase inhibitor resistant viruses, a brief therapeutic window and competing diagnoses complicate its use. PUL-042 is a clinical stage, aerosol drug comprised of synthetic ligands for Toll-like receptor (TLR) 2/6 and TLR 9. This host-targeted, innate immune stimulant broadly protects against bacterial, fungal and viral pneumonias, including those caused by influenza, when given prophylactically to animals. This study evaluated the therapeutic antiviral effects of PUL-042 against established influenza A pneumonia, when given alone or in combination with oseltamivir. Mice were treated with PUL-042 aerosol, oseltamivir or both at varying time points before or after challenge with influenza pneumonia. Treating established, otherwise lethal influenza A pneumonia (>1 LD100) with multiple inhaled doses of PUL-042 aerosol plus oral oseltamivir resulted in greater mouse survival than treatment with either drug alone. Single agent PUL-042 also protected mice against established infections following challenges with lower viral inocula (approximately 1 LD20). Aerosolized oseltamivir further enhanced survival when co-delivered with PUL-042 aerosol. The prophylactic and therapeutic benefits of PUL-042 were similar against multiple strains of influenza virus. In vitro influenza challenge of human HBEC3kt lung epithelial cells revealed PUL-042-induced protection against infection that was comparable to that observed in vivo. These studies offer new insights into means to protect susceptible populations against influenza A pneumonia.
Background and Purpose
Respiratory viral infections play central roles in the initiation, exacerbation and progression of asthma in humans. An acute paramyxoviral infection in mice can cause a ...chronic lung disease that resembles human asthma. We sought to determine whether reduction of Sendai virus lung burden in mice by stimulating innate immunity with aerosolized Toll‐like receptor (TLR) agonists could attenuate the severity of chronic asthma‐like lung disease.
Experimental Approach
Mice were treated by aerosol with 1‐μM oligodeoxynucleotide (ODN) M362, an agonist of the TLR9 homodimer, and 4‐μM Pam2CSK4 (Pam2), an agonist of the TLR2/6 heterodimer, within a few days before or after Sendai virus challenge.
Key Results
Treatment with ODN/Pam2 caused ~75% reduction in lung Sendai virus burden 5 days after challenge. The reduction in acute lung virus burden was associated with marked reductions 49 days after viral challenge in eosinophilic and lymphocytic lung inflammation, airway mucous metaplasia, lumenal mucus occlusion and hyperresponsiveness to methacholine. Mechanistically, ODN/Pam2 treatment attenuated the chronic asthma phenotype by suppressing IL‐33 production by type 2 pneumocytes, both by reducing the severity of acute infection and by down‐regulating Type 2 (allergic) inflammation.
Conclusion and Implications
These data suggest that treatment of susceptible human hosts with aerosolized ODN and Pam2 at the time of a respiratory viral infection might attenuate the severity of the acute infection and reduce initiation, exacerbation and progression of asthma.
Viral pneumonias cause profound worldwide morbidity, necessitating novel strategies to prevent and treat these potentially lethal infections. Stimulation of intrinsic lung defenses via inhalation of ...synergistically acting Toll-like receptor (TLR) agonists protects mice broadly against pneumonia, including otherwise-lethal viral infections, providing a potential opportunity to mitigate infectious threats. As intact lung epithelial TLR signaling is required for the inducible resistance and as these cells are the principal targets of many respiratory viruses, the capacity of lung epithelial cells to be therapeutically manipulated to function as autonomous antiviral effectors was investigated. Our work revealed that mouse and human lung epithelial cells could be stimulated to generate robust antiviral responses that both reduce viral burden and enhance survival of isolated cells and intact animals. The antiviral protection required concurrent induction of epithelial reactive oxygen species (ROS) from both mitochondrial and dual oxidase sources, although neither type I interferon enrichment nor type I interferon signaling was required for the inducible protection. Taken together, these findings establish the sufficiency of lung epithelial cells to generate therapeutically inducible antiviral responses, reveal novel antiviral roles for ROS, provide mechanistic insights into inducible resistance, and may provide an opportunity to protect patients from viral pneumonia during periods of peak vulnerability.
Viruses are the most commonly identified causes of pneumonia and inflict unacceptable morbidity, despite currently available therapies. While lung epithelial cells are principal targets of respiratory viruses, they have also been recently shown to contribute importantly to therapeutically inducible antimicrobial responses. This work finds that lung cells can be stimulated to protect themselves against viral challenges, even in the absence of leukocytes, both reducing viral burden and improving survival. Further, it was found that the protection occurs via unexpected induction of reactive oxygen species (ROS) from spatially segregated sources without reliance on type I interferon signaling. Coordinated multisource ROS generation has not previously been described against viruses, nor has ROS generation been reported for epithelial cells against any pathogen. Thus, these findings extend the potential clinical applications for the strategy of inducible resistance to protect vulnerable people against viral infections and also provide new insights into the capacity of lung cells to protect against infections via novel ROS-dependent mechanisms.
Cardiovascular disease (CVD) is the leading cause of death in the United States and globally and is largely attributable to atherosclerosis. Evidence indicates that multiple dietary components ...contribute to the complex etiology of CVD and associated events and mortality. Public health authorities and scientific organizations have recommended reduced saturated fatty acid (SFA) intake for decades to promote cardiovascular health which is linked to favorable impacts on established and emerging atherosclerotic CVD (CVD) risk factors. Recently, a debate has emerged about whether SFA intake should be reduced for CVD prevention which has contributed to confusion among healthcare professionals, including registered dietitian nutritionists (RDNs), and the general public, and necessitates the critical evaluation of the evidence. The objective of this evidence-based nutrition practice guideline is to provide healthcare and public health professionals, particularly RDNs, with evidence-based recommendations on how to address SFA intake in adults within an individualized healthy dietary pattern. Moderate evidence supports the reduction of SFA intake for CVD event reduction, low to moderate certainty evidence supports prioritization of replacement of SFAs with polyunsaturated fatty acids, and low certainty evidence supports focusing on reducing the total amount of SFA rather than specific food sources of SFA. Guideline implementation should include consideration of individual preferences; principles of inclusion, diversity, equity, and access; and potential nutritional deficiencies that may occur with reduced SFA intake. Future research is needed to address gaps that were identified and provide high-quality evidence to support stronger future recommendations based on the relationship between SFA and CVD.
Periodontitis‐mediated alveolar bone loss is caused by dysbiotic shifts in the commensal oral microbiota that upregulate proinflammatory osteoimmune responses. The study purpose was to determine ...whether antimicrobial‐induced disruption of the commensal microbiota has deleterious effects on alveolar bone. We administered an antibiotic cocktail, minocycline, or vehicle‐control to sex‐matched C57BL/6T mice from age 6‐ to 12 weeks. Antibiotic cocktail and minocycline had catabolic effects on alveolar bone in specific‐pathogen‐free (SPF) mice. We then administered minocycline or vehicle‐control to male mice reared under SPF and germ‐free conditions, and we subjected minocycline‐treated SPF mice to chlorhexidine oral antiseptic rinses. Alveolar bone loss was greater in vehicle‐treated SPF versus germ‐free mice, demonstrating that the commensal microbiota drives naturally occurring alveolar bone loss. Minocycline‐ versus vehicle‐treated germ‐free mice had similar alveolar bone loss outcomes, implying that antimicrobial‐driven alveolar bone loss is microbiota dependent. Minocycline induced phylum‐level shifts in the oral bacteriome and exacerbated naturally occurring alveolar bone loss in SPF mice. Chlorhexidine further disrupted the oral bacteriome and worsened alveolar bone loss in minocycline‐treated SPF mice, validating that antimicrobial‐induced oral dysbiosis has deleterious effects on alveolar bone. Minocycline enhanced osteoclast size and interface with alveolar bone in SPF mice. Neutrophils and plasmacytoid dendritic cells were upregulated in cervical lymph nodes of minocycline‐treated SPF mice. Paralleling the upregulated proinflammatory innate immune cells, minocycline therapy increased TH1 and TH17 cells that have known pro‐osteoclastic actions in the alveolar bone. This report reveals that antimicrobial perturbation of the commensal microbiota induces a proinflammatory oral dysbiotic state that exacerbates naturally occurring alveolar bone loss.
The alveolar bone is a unique osseous tissue due to the presence of the teeth and the proximity of commensal oral microbes. Commensal microbe effects on alveolar bone homeostasis have been attributed ...to the oral microbiota, yet the impact of commensal gut microbes is unknown. Study purpose was to elucidate whether commensal gut microbes regulate osteoimmune mechanisms and skeletal homeostasis in alveolar bone. Male C57BL/6T germfree (GF) littermate mice were maintained as GF or monoassociated with segmented filamentous bacteria (SFB), a commensal gut bacterium. SFB has been shown to elicit broad immune response effects, including the induction of TH17/IL17A immunity, which impacts the development and homeostasis of host tissues. SFB colonized the gut, but not oral cavity, and increased IL17A levels in the ileum and serum. SFB had catabolic effects on alveolar bone and non-oral skeletal sites, which was attributed to enhanced osteoclastogenesis. The alveolar bone marrow of SFB vs. GF mice had increased dendritic cells, activated helper T-cells, TH1 cells, TH17 cells, and upregulated Tnf. Primary osteoblast cultures from SFB and GF mice were stimulated with vehicle-control, IL17A, or TNF to elucidate osteoblast-derived signaling factors contributing to the pro-osteoclastic phenotype in SFB mice. Treatment of RAW264.7 osteoclastic cells with supernatants from vehicle-stimulated SFB vs. GF osteoblasts recapitulated the osteoclast phenotype found in vivo. Supernatants from TNF-stimulated osteoblasts normalized RAW264.7 osteoclast endpoints across SFB and GF cultures, which was dependent on the induction of CXCL1 and CCL2. This report reveals that commensal gut microbes have the capacity to regulate osteoimmune processes in alveolar bone. Outcomes from this investigation challenge the current paradigm that alveolar bone health and homeostasis is strictly regulated by oral microbes.
Commensal microbe effects on alveolar bone homeostasis have been attributed to the oral microbiota, yet the impact of commensal gut microbes is unknown. Studies performed with segmented filamentous bacteria (SFB) monoassociated mice revealed commensal gut microbes modulate osteoimmune responses and skeletal homeostasis in alveolar bone. This work challenges the current paradigm that alveolar bone health is strictly regulated by oral microbes.
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