IL-17 Aggravates Pseudomonas aeruginosa Airway Infection in Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Pseudomonas aeruginosa in chronic lung disease: untangling the dysregulated host immune response

Pseudomonas aeruginosa is a highly adaptable opportunistic pathogen capable of exploiting barriers and immune defects to cause chronic lung infections in conditions such as cystic fibrosis. In these contexts, host immune responses are ineffective at clearing persistent bacterial infection, instead driving a cycle of inflammatory lung damage. This review outlines key components of the host immune response to chronic P. aeruginosa infection within the lung, beginning with initial pathogen recognition, followed by a robust yet maladaptive innate immune response, and an ineffective adaptive immune response that propagates lung damage while permitting bacterial persistence. Untangling the interplay between host immunity and chronic P. aeruginosa infection will allow for the development and refinement of strategies to modulate immune-associated lung damage and potentiate the immune system to combat chronic infection more effectively.

Synergistic effects of COVID-19 and Pseudomonas aeruginosa in chronic obstructive pulmonary disease: a polymicrobial perspective

This article discusses the connection between the novel coronavirus disease 2019 (COVID-19) caused by the coronavirus-2 (SARS-CoV-2) and chronic obstructive pulmonary disease (COPD). COPD is a multifaceted respiratory illness that is typically observed in individuals with chronic exposure to chemical irritants or severe lung damage caused by various pathogens, including SARS-CoV-2 and Pseudomonas aeruginosa. The pathogenesis of COPD is complex, involving a variety of genotypes and phenotypic characteristics that result in severe co-infections and a poor prognosis if not properly managed. We focus on the role of SARS-CoV-2 infection in severe COPD exacerbations in connection to P.  aeruginosa infection, covering pathogenesis, diagnosis, and therapy. This review also includes a thorough structural overview of COPD and recent developments in understanding its complicated and chronic nature. While COVID-19 is clearly linked to emphysema and chronic bronchitis at different stages of the disease, our understanding of the precise interaction between microbial infections during COPD, particularly with SARS-CoV-2 in the lungs, remains inadequate. Therefore, it is crucial to understand the host-pathogen relationship from the clinician's perspective in order to effectively manage COPD. This article aims to provide a comprehensive overview of the subject matter to assist clinicians in their efforts to improve the treatment and management of COPD, especially in light of the COVID-19 pandemic.

IL-17A facilitates type 2 inflammation in a modified eosinophilic chronic rhinosinusitis mouse model

BACKGROUND

Eosinophilic chronic rhinosinusitis (ECRS) is predominantly characterized by nasal type 2 inflammation. The pathogenesis of this condition is complex. High levels of IL-17A are associated with eosinophil infiltration in some inflammatory diseases and contribute to the severity and insensitivity of corticosteroid therapy for chronic rhinosinusitis.

METHODS

In the first experiment, we constructed a modified ECRS mouse model using four groups of mice: phosphate-buffered saline (PBS)-sensitized and nasal instillation (control); PBS-sensitized and Staphylococcus aureus enterotoxin B (SEB) nasal instillation after nasal tamponade (SEB group); ovalbumin (OVA)-sensitized and nasal instillation (OVA group); and OVA-sensitized combined with OVA and SEB nasal instillation after nasal tamponade (OVA + SEB group). In the second experiment, we examined the role of IL-17A by dividing the mice into four groups: control group; ECRS group; ECRS + anti-IL-17A group; and ECRS + IL-17A group. The latter two groups received intraperitoneal injections of anti-IL-17A antibody or IL-17A, respectively.

RESULTS

We constructed a modified ECRS mouse model (OVA + SEB group), where the IL-17A levels were upregulated in the nasal sinus of ECRS mice and the IL-17A levels were significantly correlated with eosinophil infiltration. We further demonstrated that IL-17A induced type 2 inflammation and eosinophil infiltration in the ECRS group of mice. In contrast, IL-17A neutralization attenuated type 2 inflammatory cytokine secretion and eosinophil infiltration.

CONCLUSION

OVA sensitization and unilateral nasal tamponade, combined with SEB and OVA alternate nasal instillation (OVA + SEB group), could be used to construct a more typical ECRS mouse model in which IL-17A enhanced the expression of type 2 cytokines and eosinophil infiltration.

Expression and Clinical Significance of Peripheral Blood IL-17A, IL-22, Tim-3, and gal-9 in Children with Infectious Mononucleosis

To investigate the expression and clinical significance of peripheral blood interleukin (IL)-17A, IL-22, T cell immunoglobulin molecule-3 (Tim-3), and galectin-9 (gal-9) in children with infectious mononucleosis (IM) caused by the Epstein-Barr virus (EBV). Peripheral blood of 54 children with IM (case group) was collected and divided into a liver damage group and a non-liver damage group. During the same period, 20 healthy children were in the control group. IL-17A and IL-22 were measured by enzyme-linked immunosorbent assay. Real-time quantitative polymerase chain reaction was used to measure the mRNA expression of Tim-3 and gal-9. Their correlation with clinical indicators was then analyzed. The IL-17A expression level was higher in the case group than in the control group, while Tim-3, gal-9, and IL-22 were lower than those in the control group. Tim-3 was positively correlated with gal-9, but negatively correlated with IL-17A. Tim-3 and gal-9 were positively correlated with CD4+/CD8+ cells. Conversely, they were negatively correlated with CD3+, CD3+CD8+, white blood cell, lymphocyte (L), alanine transaminase (ALT), aspartate transaminase (AST), glutamyl transpeptidase (GGT), and lactate dehydrogenase (LDH). In the case group, IL-17A was positively correlated with L, GGT, and LDH, but negatively correlated with the natural killer (NK) cell count. IL-17A and IL-22 were positively correlated with CD3+, CD3+CD8+, ALT, and AST, but they were negatively correlated with the ratio of CD4+/CD8+. In the liver damage group, IL-17A, IL-22, CD3+, CD3+CD8+, immunoglobulin A (IgA), IgG, IgM, L, ALT, AST, GGT, LDH, and α-hydroxybutyrate levels were higher than those in the non-liver damage group. However, Tim-3, gal-9, the ratio of CD4+/CD8+, and NK were lower than those in the non-liver damage group. IL-17A, IL-22, Tim-3, and gal-9 are involved in the immune pathogenesis of IM caused by EBV infection in children, which may be related to immune liver injury.

Biologic therapies for chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a disorder characterized by a complicated chronic inflammatory response that is resistant to corticosteroid therapy. As a result, there is a critical need for effective anti-inflammatory medications to treat people with COPD. Using monoclonal antibodies (mAbs) to inhibit cytokines and chemokines or their receptors could be a potential approach to treating the inflammatory component of COPD.

AREAS COVERED

The therapeutic potential that some of these mAbs might have in COPD is reviewed.

EXPERT OPINION

No mAb directed against cytokines or chemokines has shown any therapeutic impact in COPD patients, apart from mAbs targeting the IL-5 pathway that appear to have statistically significant, albeit weak, effect in patients with eosinophilic COPD. This may reflect the complexity of COPD, in which no single cytokine or chemokine has a dominant role. Because the umbrella term COPD encompasses several endotypes with diverse underlying processes, mAbs targeting specific cytokines or chemokines should most likely be evaluated in limited and focused populations.

The Lung Microbiome: A New Frontier for Lung and Brain Disease

Due to the limitations of culture techniques, the lung in a healthy state is traditionally considered to be a sterile organ. With the development of non-culture-dependent techniques, the presence of low-biomass microbiomes in the lungs has been identified. The species of the lung microbiome are similar to those of the oral microbiome, suggesting that the microbiome is derived passively within the lungs from the oral cavity via micro-aspiration. Elimination, immigration, and relative growth within its communities all contribute to the composition of the lung microbiome. The lung microbiome is reportedly altered in many lung diseases that have not traditionally been considered infectious or microbial, and potential pathways of microbe-host crosstalk are emerging. Recent studies have shown that the lung microbiome also plays an important role in brain autoimmunity. There is a close relationship between the lungs and the brain, which can be called the lung-brain axis. However, the problem now is that it is not well understood how the lung microbiota plays a role in the disease-specifically, whether there is a causal connection between disease and the lung microbiome. The lung microbiome includes bacteria, archaea, fungi, protozoa, and viruses. However, fungi and viruses have not been fully studied compared to bacteria in the lungs. In this review, we mainly discuss the role of the lung microbiome in chronic lung diseases and, in particular, we summarize the recent progress of the lung microbiome in multiple sclerosis, as well as the lung-brain axis.

IL-17A Promotes Epithelial ADAM9 Expression in Cigarette Smoke-Related COPD

Background

It has been reported that a disintegrin and metalloproteinase 9 (ADAM9) is involved in the pathogenesis of cigarette smoke (CS)-associated chronic obstructive pulmonary disease (COPD). But how CS exposure leads to upregulation of ADAM9 remains unknown.

Methods

Patients who underwent lobectomy for a solitary pulmonary nodule were enrolled and divided into three groups: non-smokers with normal lung function, smokers without COPD and smoker patients with COPD. Immunoreactivity of interleukin (IL)-17A and ADAM9 in small airways and alveolar walls was measured by immunohistochemistry. Wild-type and Il17a^−/− C57BL/6 mice were exposed to CS for six months, and ADAM9 expression in the airway epithelia was measured by immunoreactivity. In addition, the protein and mRNA expression levels of IL-17A and ADAM9 were assessed in CS extract (CSE) and/or IL-17A-treated human bronchial epithelial (HBE) cells.

Results

The immunoreactivity of ADAM9 was increased in the airway epithelia and alveolar walls of patients with COPD compared to that of the controls. The expression of IL-17A was also upregulated in airway epithelial cells of patients with COPD and correlated positively with the level of ADAM9. The results from the animal model showed that Il17a^−/− mice were protected from emphysema induced by CS exposure, together with a reduced level of ADAM9 expression in the airway epithelia, suggesting a possible link between ADAM9 and IL-17A. Consistently, our in vitro cell model showed that CSE stimulated the expression of ADAM9 and IL-17A in HBE cells in a dose- and time-dependent manner. Recombinant IL-17A induced ADAM9 upregulation in HBE cells and had a synergistic effect with CSE, whereas blocking IL-17A inhibited CSE-induced ADAM9 expression. Further analysis revealed that IL-17A induced c-Jun N-terminal kinase (JNK) phosphorylation, thereby increasing ADAM9 expression.

Conclusion

Our results revealed a novel role of IL-17A in CS-related COPD, where IL-17A contributes to ADAM9 expression by activating JNK signaling.