Chlamydophila pneumoniae re-infection triggers the production of IL-17A and IL-17E, important regulators of airway inflammation

Improvement of Bronchial Immune Hypersensitivity Reaction Using Extracts from Chrysanthemum morifolium Ramatuelle and Scutellaria baicalensis Georgi

Chrysanthemum morifolium Ramatuelle and Scutellaria baicalensis Georgi (skullcap) have been used as safe raw materials for drinking or as traditional medicines in Korea. In this study, we investigated the potential therapeutic effects of ovalbumin-induced asthma in a mouse model. After establishing the model, mice were treated with a mixture of chrysanthemum and skullcap extracts at different mixing ratios (6 : 4, 7 : 3, and 8 : 2). Immune cell counts and the production of various inflammatory cytokines were measured using biochemical tests. Among the mixtures tested, the 7 : 3 ratio (CS73) showed the most pronounced effects. CS73 significantly reduced the levels of the inflammatory cytokines interleukin- (IL-) 1β, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17A, IL-17F, and IL-17E in the serum and bronchoalveolar lavage fluid of asthmatic mice. In addition, CS73 treatment significantly increased the production of IL-2 and interferon-γ and decreased the production of immunoglobulin E, histamine, and thymic stromal lymphopoietin in asthmatic mice compared to the control group. Our results suggest that the combination of chrysanthemum and skullcap extracts, especially at a 7 : 3 ratio, can be used to improve bronchial health and contribute to improved public health.

Ambroxol Treatment Suppresses the Proliferation of Chlamydia pneumoniae in Murine Lungs

Ambroxol (Ax) is used as a mucolytics in the treatment of respiratory tract infections. Ax, at a general dose for humans, does not alter Chlamydia pneumoniae growth in mice. Therefore, we aimed to investigate the potential anti-chlamydial effect of Ax at a concentration four timed higher than that used in human medicine. Mice were infected with C. pneumoniae and 5-mg/kg Ax was administered orally. The number of recoverable C. pneumoniae inclusion-forming units (IFUs) in Ax-treated mice was significantly lower than that in untreated mice. mRNA expression levels of several cytokines, including interleukin 12 (IL-12), IL-23, IL-17F, interferon gamma (IFN-γ), and surfactant protein (SP)-A, increased in infected mice treated with Ax. The IFN-γ protein expression levels were also significantly higher in infected and Ax-treated mice. Furthermore, the in vitro results suggested that the ERK 1/2 activity was decreased, which is essential for the C. pneumoniae replication. SP-A and SP-D treatments significantly decreased the number of viable C. pneumoniae IFUs and significantly increased the attachment of C. pneumoniae to macrophage cells. Based on our results, a dose of 5 mg/kg of Ax exhibited an anti-chlamydial effect in mice, probably an immunomodulating effect, and may be used as supporting drug in respiratory infections caused by C. pneumoniae.

Beneficial Immunomodulatory Effects of Fluticasone Propionate in Chlamydia pneumoniae-Infected Mice

The associations between inhaled corticosteroid (ICS) use and pulmonary infections remains controversial. Chlamydia pneumoniae (C. pneumoniae) accounts for asthma exacerbations; however, there are no data regarding ICS effects on C. pneumoniae infections. Thus, we investigated whether fluticasone propionate (FP) or budesonide (BUD) could affect C. pneumoniae infection in vitro and in vivo, focusing on the possible mechanisms that lead to potential anti-chlamydial outcomes. We performed direct qPCR to detect C. pneumoniae growth in infected, FP-treated, and BUD-treated A549 cells. Furthermore, FP or BUD was administered by inhalation to C. pneumoniae-infected mice. The recoverable C. pneumoniae was determined by indirect immunofluorescence. Expression levels of interferon (IFN)-γ and IFN-γ inducible chemokines were assessed by qPCR. We measured the protein concentrations of IFN-γ and of other cytokines that potentially participate in the anti-chlamydial response by ELISA. We found that FP treatment suppressed Chlamydia growth in A549 cells and in mice. Higher levels of IFN-γ gene expression were observed in FP-treated mice compared to the untreated and BUD-treated mice (p < 0.0001). IFN-γ and anti-chlamydial protein MIG/CXCL9 values were significantly higher after FP inhalation. Collectively, FP, but not BUD, suppressed C. pneumoniae growth in vitro and in vivo, which was likely due to the enhanced IFN-γ related responses.

Th17/IL-17 Axis Regulated by Airway Microbes Get Involved in the Development of Asthma

PURPOSE OF REVIEW

Bronchial asthma is a common respiratory disease induced by immune imbalance, characterized by chronic non-specific airway inflammation and airway hyperresponsiveness (AHR). Many factors induce asthma, among which respiratory infection is the important cause. In this review, we discuss how respiratory microbes participate in the occurrence and progression of asthma via Th17/IL-17 axis.

RECENT FINDINGS

Pathogenesis of asthma has been considered as closely related to the imbalance in number and function of Th1/Th2 in the CD4⁺ T lymphocyte subsets. Recent studies have shown that Th17 cell and its secretory IL-17 also play an important role in AHR. Respiratory virus, bacteria, fungi, and other respiratory microbial infections can directly or indirectly induce the differentiation of Th17 cell and the production of related cytokines to induce AHR. Respiratory microbial infection can affect the TH17/IL-17A axis through a variety of mechanisms, thereby promoting the occurrence and development of asthma, and these specific mechanisms may provide new effective therapeutic ideas for asthma.

T-Cell-Intrinsic Receptor Interacting Protein 2 Regulates Pathogenic T Helper 17 Cell Differentiation

Receptor interacting protein 2 (RIP2) plays a role in sensing intracellular pathogens, but its function in T cells is unclear. We show that RIP2 deficiency in CD4+ T cells resulted in chronic and severe interleukin-17A-mediated inflammation during Chlamydia pneumoniae lung infection, increased T helper 17 (Th17) cell formation in lungs of infected mice, accelerated atherosclerosis, and more severe experimental autoimmune encephalomyelitis. While RIP2 deficiency resulted in reduced conventional Th17 cell differentiation, it led to significantly enhanced differentiation of pathogenic (p)Th17 cells, which was dependent on RORα transcription factor and interleukin-1 but independent of nucleotide oligomerization domain (NOD) 1 and 2. Overexpression of RIP2 resulted in suppression of pTh17 cell differentiation, an effect mediated by its CARD domain, and phenocopied by a cell-permeable RIP2 CARD peptide. Our data suggest that RIP2 has a T cell-intrinsic role in determining the balance between homeostatic and pathogenic Th17 cell responses.

Chlamydia pneumoniae Infection Exacerbates Atherosclerosis in ApoB100only/LDLR-/- Mouse Strain

Aims

Hyperlipidaemia model animals have been used to elucidate the role of Chlamydia pneumoniae (Cpn) infection in atherosclerosis. The aims of this study were to investigate the proatherogenic effect of multiple Cpn infections in ApoB100only/LDLR^−/− mice which based on lipid profile can be regarded as the most suitable mouse model of human hypercholesterolemia and to compare the lesion development to that in a major atherosclerosis model ApoE^−/− mice.

Methods and Results

Aorta samples of ApoB100only/LDLR^−/− mice infected three times with Cpn were subjected to morphometric analyses. Morphometric evaluation disclosed that Cpn infections exacerbated atherosclerosis development in the aortic root and descending aorta of the mice fed with normal diet. Viable Cpn was detected in the ascending aorta by RT-PCR. Chlamydial 16SrRNA expression showed the presence of viable Cpn in the aorta of infected animals. A similar rate of acceleration of atherosclerosis was observed when the infection protocol was applied in ApoB100only/LDLR^−/− and in ApoE^−/− mice.

Conclusion

Similar to ApoE^−/− mice, ApoB100only/LDLR^−/− mice with more human-relevant serum lipoprotein composition develop increased atherosclerosis after Cpn infections; thus this mouse strain can be used as a model of infection-related atherosclerosis enhancement and can provide further evidence for the proatherogenic influence of Cpn in mice.

IL-17A promotes microglial activation and neuroinflammation in mouse models of intracerebral haemorrhage

Microglial activation is an important contributor to neuroinflammation in intracerebral haemorrhage (ICH). IL-17A has been demonstrated to be involved in neuroinflammatory diseases such as multiple sclerosis. However, the exact mechanism of IL-17A mediated microglial activation in ICH has not been well identified. The purpose of this experiment is to investigate the role of IL-17A in ICH induced microglial activation and neuroinflammation. ICH mice were made by injection of autologous blood model. IL-17A expression and inflammatory factors in perihematomal region, and neurological function of mice were examined after ICH. In addition, IL-17A-neutralizing antibody was utilized to potentially prevent microglial activation and neuroinflammation in ICH mice. The expression of IL-17A, inflammatory factors and microglial activation in perihematomal region were significantly increased, and neurological function of mice was impaired after ICH. In addition, IL-17A Ab prevented ICH-induced cytokine expression, including TNF-α, IL-1β and IL-6, and downstream signaling molecules, including MyD88, TRIF, IκBα, and NF-κBp65 expression, and attenuated microglial activation. IL-17A Ab significantly reduced brain water content and improved neurological function of ICH mice. In conclusion, our results demonstrated that IL-17A was involved in ICH-induced microglial activation and neuroinflammation. IL-17A Ab might also provide a promising therapeutic strategy in ICH.

Phosphorylated STAT3 and PD-1 regulate IL-17 production and IL-23 receptor expression in Mycobacterium tuberculosis infection

We studied the factors that regulate IL-23 receptor expression and IL-17 production in human tuberculosis infection. Mycobacterium tuberculosis (M. tb)-stimulated CD4(+) T cells from tuberculosis patients secreted less IL-17 than did CD4(+) T cells from healthy tuberculin reactors (PPD(+) ). M. tb-cultured monocytes from tuberculosis patients and PPD(+) donors expressed equal amounts of IL-23p19 mRNA and protein, suggesting that reduced IL-23 production is not responsible for decreased IL-17 production by tuberculosis patients. Freshly isolated and M. tb-stimulated CD4(+) T cells from tuberculosis patients had reduced IL-23 receptor and phosphorylated STAT3 (pSTAT3) expression, compared with cells from PPD(+) donors. STAT3 siRNA reduced IL-23 receptor expression and IL-17 production by CD4(+) T cells from PPD(+) donors. Tuberculosis patients had increased numbers of PD-1(+) T cells compared with healthy PPD(+) individuals. Anti-PD-1 antibody enhanced pSTAT3 and IL-23R expression and IL-17 production by M. tb-cultured CD4(+) T cells of tuberculosis patients. Anti-tuberculosis therapy decreased PD-1 expression, increased IL-17 and IFN-γ production and pSTAT3 and IL-23R expression. These findings demonstrate that increased PD-1 expression and decreased pSTAT3 expression reduce IL-23 receptor expression and IL-17 production by CD4(+) T cells of tuberculosis patients.