IL-17 stimulates neutrophils to release S100A8/A9 to promote lung epithelial cell apoptosis in Mycoplasma pneumoniae-induced pneumonia in children

The role of calprotectin in vascular calcification

PURPOSE OF REVIEW

Vascular calcification significantly contributes to cardiovascular morbidity and mortality, particularly in high-risk populations like chronic kidney disease (CKD) patients. Calprotectin, a heterodimeric protein with pro-inflammatory and pro-calcific properties, has emerged as a key molecule in vascular pathology. This review highlights the mechanisms linking calprotectin to vascular calcification, its clinical relevance, and its potential as a therapeutic target.

RECENT FINDINGS

Vascular calcification is an active, cell-mediated process involving vascular smooth muscle cell (VSMC) dysfunction, inflammation, matrix remodeling, and cellular senescence. Calprotectin is strongly associated with cardiovascular disease and vascular calcification, particularly in CKD. Mechanistic studies reveal that calprotectin promotes calcification through the activation of RAGE and TLR4 signaling pathways, driving inflammatory cascades. Preclinical studies demonstrate that pharmacological inhibition of calprotectin attenuates vascular calcification in animal models, supporting its potential as a therapeutic target.

SUMMARY

Calprotectin is emerging as a promising biomarker and therapeutic target in vascular calcification, particularly in CKD and aging-related vascular diseases. However, further studies are required to clarify its mechanisms and assess the long-term efficacy and safety of calprotectin-targeted therapies. A deeper understanding of calprotectin's multifaceted role could pave the way for innovative therapeutic strategies targeting both inflammation and mineralization in calcification-related vascular diseases.

Development and validation of an early diagnosis model for severe mycoplasma pneumonia in children based on interpretable machine learning

BACKGROUND

Pneumonia is a major threat to the health of children, especially those under the age of five. Mycoplasma  pneumoniae infection is a core cause of pediatric pneumonia, and the incidence of severe mycoplasma pneumoniae pneumonia (SMPP) has increased in recent years. Therefore, there is an urgent need to establish an early warning model for SMPP to improve the prognosis of pediatric pneumonia.

METHODS

The study comprised 597 SMPP patients aged between 1 month and 18 years. Clinical data were selected through Lasso regression analysis, followed by the application of eight machine learning algorithms to develop early warning model. The accuracy of the model was assessed using validation and prospective cohort. To facilitate clinical assessment, the study simplified the indicators and constructed visualized simplified model. The clinical applicability of the model was evaluated by DCA and CIC curve.

RESULTS

After variable selection, eight machine learning models were developed using age, sex and 21 serum indicators identified as predictive factors for SMPP. A Light Gradient Boosting Machine (LightGBM) model demonstrated strong performance, achieving AUC of 0.92 for prospective validation. The SHAP analysis was utilized to screen advantageous variables, which contains of serum S100A8/A9, tracheal computed tomography (CT), retinol-binding protein(RBP), platelet larger cell ratio(P-LCR) and CD4+CD25+Treg cell counts, for constructing a simplified model (SCRPT) to improve clinical applicability. The SCRPT diagnostic model exhibited favorable diagnostic efficacy (AUC > 0.8). Additionally, the study found that S100A8/A9 outperformed clinical inflammatory markers can also differentiate the severity of MPP.

CONCLUSIONS

The SCRPT model consisting of five dominant variables (S100A8/A9, CT, RBP, PLCR and Treg cell) screened based on eight machine learning is expected to be a tool for early diagnosis of SMPP. S100A8/A9 can also be used as a biomarker for validity differentiation of SMPP when medical conditions are limited.

Sodium propionate protects against bronchopulmonary dysplasia by inhibiting IL-17-mediated apoptosis of alveolar epithelial cells

Sodium propionate (SP) has been shown to enhance alveolar growth retardation in Bronchopulmonary Dysplasia (BPD), but the mechanism remains unclear. The aim of this study is to explore the potential mechanism of SP in the treatment of BPD by utilizing animal and cell models along with bioinformation analysis. Neonatal mice were exposed to either air (21% O2) or hyperoxia (85% O2) from the first day after birth to establish the BPD model. The neonatal mice were intraperitoneally injected with normal saline (control group) or SP (500 mg/kg, SP group) from day 8 to day 14. SP significantly reduced the inflammatory condition of alveolar septal thickening, and decreased the alveolar fusion and mitigated weight loss in BPD mice. ELISA results demonstrated that SP significantly inhibited the secretion of IL-17, IL-6 and TNFα. Transcriptome analysis confirmed that IL-17 signaling pathway is closely related to the therapeutic effects of SP on BPD. In addition, MX2, MMP10, IL-11, ZMAT4 and SEC1 genes were identified as key and potential targets involved in the mechanism of SP treating BPD. Meanwhile, in mouse alveolar epithelial cells, apoptosis was induced by hyperoxia, but it was reduced following SP intervention. The expression of IL-17 pathway related genes: IL-17A, IL-6, TNFα and cox2 was decreased in hyperoxia treated cells after SP intervention. In conclusion, through transcriptome analysis, animal and cell experiments, we explored the role of sodium propionate in attenuating apoptosis in a BPD model through IL-17 pathway.

Whole transcriptome analysis of Mycoplasma bovis-host interactions under in vitro and in vivo conditions

Mycoplasma bovis mastitis is becoming increasingly problematic for dairy cattle farming. M. bovis is inherently resistant to beta-lactam antimicrobials and no effective vaccine is available. The major constraints to developing effective control tools are limited knowledge of M. bovis virulence factors and the underlying pathogenic mechanisms. The objective of this study was to determine virulence-associated genes of M. bovis and host immune response genes expressed during the early stages of host-pathogen interactions. We conducted in vitro infection of mammary epithelial cell (MAC-T) lines and in vivo intramammary infection of dairy cows with M. bovis strain PG45 and evaluated whole transcriptome differential gene expression. A total of 614 and 7161 genes of M. bovis and bovine host cells were differentially expressed, respectively. Insertion sequence (IS) genes that are involved in transposase activity such as ISMbov1, ISMbov2, ISMbov3, and ISMbov9 were significantly upregulated, whereas protein translation-associated genes were significantly downregulated. In MAC-T cells, genes involved in apoptosis pathways and proinflammatory cytokines were significantly upregulated, whereas genes involved in cell cycle, ribosome biogenesis, and steroid biosynthesis were significantly downregulated. Genes encoding formation of neutrophil extracellular traps and proinflammatory cytokines, were significantly upregulated in the mammary gland of M. bovis challenged cows, whereas genes involved in steroid biosynthesis and metabolism were significantly downregulated. Altogether, while our findings shed light on the simultaneous transcriptional changes in M. bovis and the host during infection, further studies are required to understand a complete picture of these interactions that lead to mastitis.

Dual RNA-seq reveals the complement protein C3-mediated host-pathogen interaction in the brain abscess caused by Staphylococcus aureus

This study aimed to elucidate the complement protein C3-mediated host-pathogen interaction in the brain abscess caused by Staphylococcus aureus infection. Dual RNA-seq was employed to analyze the transcriptomic differences between C3 deficiency and wild-type mice of S. aureus-induced brain abscess model, and then we investigated the potential regulatory pathways of S. aureus-host interaction mediated by C3 and S. aureus genes associated with the pathogenesis of brain abscess. Finally, C3 deficient-mice and hla mutants of S. aureus were used to verify the specific pathogen-host interaction. In the S. aureus-induced brain abscess mouse model, the transcriptomic analysis revealed significant changes in bacterial virulence factors, such as hemolysin. Based on these data, we predicted a regulatory network formed by genes like hrcA and dnaK, which represent a possible regulation mechanism of S. aureus responding to the host. Furthermore, we identified that hla was the C3 response gene in S. aureus. From the host perspective, we observed that the absence of C3 significantly impacted the host's inflammatory response, primarily by altering the gene expression of several key immune and inflammatory pathways. These findings suggest that C3 deficiency may impair the host's ability to recognize and respond to external pathogens. To the best of our knowledge, this study proposed that S. aureus may affect host immune response through C3, and C3 plays a critical role in regulating inflammation and immune signaling pathways in the brain abscess caused by S. aureus infection.IMPORTANCEIn this work, we employed immunofluorescence and Western blot analysis to reveal a significant upregulation of microglia-derived C3 in the brain abscess mice model caused by S. aureus infection. By integrating the individual RNA sequencing data of S. aureus and the dual RNA-seq data of S. aureus infection brain abscess mice model, the potential regulatory pathways between S. aureus and host were identified, and host C3 not only affects the immune response but also mediates the regulation network of S. aureus. This study provided the potential novel targets for therapeutic strategies in mitigating the effects of S. aureus infections and improving treatment outcomes.

S100A9 induces tissue remodeling of human nasal epithelium in chronic rhinosinusitis with nasal polyp

BACKGROUND

Chronic inflammation triggers tissue remodeling in human nasal epithelial (HNE) cells. S100A9, a protein secreted by inflammatory cells, exhibits potent proinflammatory activity. However, its effect on HNE cell remodeling, such as squamous metaplasia, remains unclear. Therefore, this study aimed to determine the effects and underlying pathways of S100A9 on HNE cell remodeling and investigate its clinical implications in chronic rhinosinusitis (CRS).

METHODS

Cultured HNE cells were treated with S100A9. Bulk RNA sequencing was performed to analyze gene ontology (GO). Ingenuity pathway analysis (IPA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were also analyzed. Additionally, immunohistochemistry and multiplex immunofluorescence were performed on tissue samples obtained from 60 patients, whose clinical informations were also reviewed.

RESULTS

GO enrichment analysis indicated that S100A9 induced tissue remodeling in HNE cells toward squamous metaplasia. IPA and KEGG commonly showed that S100A9 affected HNE cells associated with the IL-17 signaling pathway, including target molecules such as matrix metalloproteinase 1 (MMP1) and small proline-rich protein 2A (SPRR2A). Squamous metaplasia with a marked expression of S100A9 was observed in 50% of CRS with nasal polyps (CRSwNPs). In addition, in multiplex immunofluorescence, the S100A9 in sub-epithelium was co-expressed with myeloperoxidase, a neutrophil marker, and MMP1 and SPRR2A were strongly expressed in epithelial remodeling. Clinically, the expression of S100A9 correlated with sino-nasal outcome test-22 (r = 0.294, p = 0.022) and Lund-Mackay scores (r = 0.348, p = 0.006).

CONCLUSION

S100A9 induces tissue remodeling in HNE cells. Its increased expression in CRSwNP, particularly squamous epithelium, correlates with disease severity. This suggests the clinical potential of S100A9 as a biomarker for CRS severity.

Enhanced insights into the neutrophil-driven immune mechanisms during Mycoplasma pneumoniae infection

Mycoplasma pneumoniae (MP) infections represent a significant component of community-acquired pneumonia, especially in children, invoking a complex neutrophil-mediated immune response, crucial for host defense. This review consolidates current knowledge on the role of neutrophils in MP infection, focusing on their recruitment, migration and activation, as well as the molecular mechanisms underpinning these processes. Significant findings indicate that specific bacterial components, notably CARDS toxin and lipoproteins, intensify neutrophil recruitment via signaling pathways, including the IL-23/IL-17 axis and G-CSF. Furthermore, neutrophils engage in a series of responses, including phagocytosis, degranulation and NETosis, to combat infection effectively. However, dysregulated neutrophil activity can lead to exacerbated lung injury, highlighting the delicate balance required in neutrophil responses. Age and immunodeficiency also emerge as critical factors influencing the severity of MP infections. This review emphasizes the dual role of neutrophils in both defending against and exacerbating MP infections, suggesting that targeted therapeutic strategies could mitigate the adverse effects while enhancing beneficial neutrophil functions.

Blocking IL-17a Signaling Decreases Lung Inflammation and Improves Alveolarization in Experimental Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease of preterm infants that is associated with life-long morbidities. Inflammatory insults contribute to BPD pathogenesis. Although the proinflammatory cytokine, IL-17a, plays a role in various neonatal inflammatory disorders, its role in BPD pathogenesis is unclear. To test the hypothesis that blocking IL-17a signaling decreases lipopolysaccharide (LPS)-mediated experimental BPD in neonatal mice, wild-type mice were injected intraperitoneally with phosphate-buffered saline or LPS during the saccular lung developmental phase. Pulmonary IL-17a expression was determined by enzyme-linked immunosorbent assay and by flow cytometry. LPS-injected mice had higher pulmonary IL-17a protein levels and IL-17a+ and IL-22+ cells. γδ T cells, followed by non-T lymphoid cells, were the primary producers of IL-17a. Wild-type mice were then injected intraperitoneally with isotype antibody (Ab) or IL-17a Ab, while they were treated with phosphate-buffered saline or LPS, followed by quantification of lung inflammatory markers, alveolarization, vascularization, cell proliferation, and apoptosis. LPS-mediated alveolar simplification, apoptosis, and cell proliferation inhibition were significantly greater in mice treated with isotype Ab than in those treated with IL-17a Ab. Furthermore, STAT1 activation and IL-6 levels were significantly greater in LPS-exposed mice treated with isotype Ab than in those treated with IL-17a Ab. The study results indicate that blocking IL-17a signaling decreases LPS-mediated experimental BPD.

Calprotectin is regulated by IL-17A and induces steroid hyporesponsiveness in asthma

BACKGROUND

Calprotectin, a calcium-binding protein, plays a crucial role in inflammation and has been associated with various inflammatory diseases, including asthma. However, its regulation and impact on steroid hyporesponsiveness, especially in severe asthma, remain poorly understood.

METHODS

This study investigated the regulation of calprotectin proteins (S100A8 and S100A9) by IL-17 and its role in steroid hyporesponsiveness using in vitro and in vivo models. Calprotectin expression was assessed in primary bronchial fibroblasts from healthy controls and severe asthmatic patients, as well as in mouse models of steroid hyporesponsive lung inflammation induced by house dust mite (HDM) allergen and cyclic-di-GMP (cdiGMP) adjuvant. The effects of IL-17A stimulation on calprotectin expression and steroid response markers in bronchial epithelial and fibroblast cells were examined. Additionally, the therapeutic potential of paquinimod, a calprotectin inhibitor, in mitigating airway inflammation and restoring steroid response signatures in the mouse model was evaluated.

RESULTS

The results demonstrated upregulation of calprotectin expression in asthmatic bronchial fibroblasts compared to healthy controls, as well as in refractory asthma samples compared to non-refractory asthma. IL-17 stimulation induced calprotectin expression and dysregulated glucocorticoid response signatures in lung epithelial and fibroblast cells. Treatment with paquinimod reversed IL-17-induced dysregulation of steroid signatures, indicating the involvement of calprotectin in this process. In the HDM/cdiGMP mouse model, paquinimod significantly attenuated airway inflammation and hyperresponsiveness, and restored steroid response signatures, whereas dexamethasone showed limited efficacy. Mechanistically, paquinimod inhibited MAPK/ERK and NF-κB pathways downstream of calprotectin, leading to reduced lung inflammation.

CONCLUSION

These findings highlight calprotectin as a potential therapeutic target regulated by IL-17 in steroid hyporesponsive asthma. Targeting calprotectin may offer a promising approach to alleviate airway inflammation and restore steroid responsiveness in severe asthma. Further investigations are warranted to explore its therapeutic potential in clinical settings and elucidate its broader implications in steroid mechanisms of action.

Single-cell transcriptome atlas revealed bronchoalveolar immune features related to disease severity in pediatric Mycoplasma pneumoniae pneumonia

The mechanisms underlying protective immunity in mild Mycoplasma pneumoniae pneumonia (MPP) and the pathogenesis of severe MPP, characterized by dysregulated immune responses, remain unclear. Here, we performed single-cell RNA sequencing (scRNA-seq) to profile bronchoalveolar lavage fluid (BALF) samples from 13 healthy donors and 24 hospitalized pediatric patients with MPP, covering both mild and severe cases. Severe MPP patients exhibited high levels of exhausted T cells and M1-like macrophages, with the exhaustion of T cells attributed to persistent type I interferon signaling and inadequate assistance from CD4+ T cells. Significant cell-cell interactions between exhausted T cells and programmed death-ligand 1+ (PD-L1+) macrophages were detected in severe patients, potentially mediated through inhibitor molecules (e.g., PD1) and their receptors (e.g., PD-L1), as well as human leukocyte antigen class I molecules and their receptors (e.g., KLRC1/D2), resulting in the dysfunction of anti-MP immune responses. Mild MPP patients were featured by an increased abundance of neutrophils, coupled with enhanced activation, contributing to protective immunity. Together, our study provides a detailed characterization of the BALF immune landscape in MPP patients, revealing distinct immune characteristics between mild and severe cases, which offers a valuable resource for understanding MPP immunopathogenesis and formulating effective therapeutic strategies.

Fragile Guts Make Fragile Brains: Intestinal Epithelial Nrf2 Deficiency Exacerbates Neurotoxicity Induced by Polystyrene Nanoplastics

Oral ingestion is the primary route for human exposure to nanoplastics, making the gastrointestinal tract one of the first and most impacted organs. Given the presence of the gut-brain axis, a crucial concern arises regarding the potential impact of intestinal damage on the neurotoxic effects of nanoplastics (NPs). The intricate mechanisms underlying NP-induced neurotoxicity through the microbiome-gut-brain axis necessitate further investigation. To address this, we used mice specifically engineered with nuclear factor erythroid-derived 2-related factor 2 (Nrf2) deficiency in their intestines, a strain whose intestines are particularly susceptible to polystyrene NPs (PS-NPs). We conducted a 28-day repeated-dose oral toxicity study with 2.5 and 250 mg/kg of 50 nm PS-NPs in these mice. Our study delineated how PS-NP exposure caused gut microbiota dysbiosis, characterized by Mycoplasma and Coriobacteriaceae proliferation, resulting in increased levels of interleukin 17C (IL-17C) production in the intestines. The surplus IL-17C permeated the brain via the bloodstream, triggering inflammation and brain damage. Our investigation elucidated a direct correlation between intestinal health and neurological outcomes in the context of PS-NP exposure. Susceptible mice with fragile guts exhibited heightened neurotoxicity induced by PS-NPs. This phenomenon was attributed to the elevated abundance of microbiota associated with IL-17C production in the intestines of these mice, such as Mesorhizobium and Lwoffii, provoked by PS-NPs. Neurotoxicity was alleviated by in vivo treatment with anti-IL-17C-neutralizing antibodies or antibiotics. These findings advanced our comprehension of the regulatory mechanisms governing the gut-brain axis in PS-NP-induced neurotoxicity and underscored the critical importance of maintaining intestinal health to mitigate the neurotoxic effects of PS-NPs.

Seminal plasma S100A8/A9 as a potential biomarker of genital tract inflammation

ABSTRACT

Infections and inflammatory reactions in the male genital tract are the leading causes of male infertility with a prevalence of 6%-10%, primarily affecting testicular and epididymal function and ultimately compromising sperm quality. However, most infertile patients with genital infection/inflammation are asymptomatic and easily overlooked. Traditional indicators, including white blood cells, elastase, and other components in semen, can reflect inflammation of the genital tract, but there is still a lack of a uniform standard method of detection. Therefore, it is necessary to explore reliable markers in semen that reflect the inflammatory status of the genital tract. Using the experimental autoimmune orchitis (EAO) model to simulate noninfectious chronic orchitis, we successfully collected ejaculated seminal fluid from EAO rats using optimized electrical stimulation devices. Proteomic analysis was performed using isobaric tags for relative and absolute quantification (iTRAQ). Compared to the control group, 55 upregulated and 105 downregulated proteins were identified in seminal plasma samples from the EAO group. In a preliminary screening, the inflammation-related protein S100A8/A9 was upregulated. We further verified that S100A8/A9 was increased in seminal plasma and highly expressed in testicular macrophages of the EAO model. In patients with oligoasthenospermia and genital tract infections, we also found that S100A8/A9 levels were remarkably increased in seminal plasma and testicular macrophages. S100A8/A9 in semen may be a potential biomarker for chronic genital inflammation. Our study provides a new potential biomarker for early diagnosis and further understanding of male infertility caused by genital inflammation.

Modeling "Two-Hit" Severe Pneumonia in Mice: Pathological Characteristics and Mechanistic Studies

Severe pneumonia is one of the most common critical diseases in clinical practice. Existing models for severe pneumonia have limitations, leading to limited clinical translation. In this study, a two-hit severe pneumonia mouse model was established by inducing primary pneumonia through intratracheal instillation of 800 μg lipopolysaccharide (LPS), followed by intraperitoneal injection of 10 mg/kg LPS. The effectiveness of various inflammatory indicators and the lung tissue damage during the time course of this model were confirmed and evaluated. At 3 h post two-hit, the IL-6, TNF-α levels in peripheral blood and bronchoalveolar lavage fluid (BALF), and the white blood cells, neutrophils, and lymphocytes in BALF notably exhibited the most pronounced elevation. At 12 h post two-hit, the white blood cells and neutrophils in peripheral blood significantly increased, accompanied by notable alterations in splenic immune cells and worsened pulmonary histopathological damage. Transcriptomics of lung tissue, microbiota analysis of lung and gut, as well as plasma metabolomics analyses further indicated changes in transcriptional profiles, microbial composition, and metabolites due to the two-hit modeling. These results validate that the two-hit model mimics the clinical presentation of severe pneumonia and serves as a robust experimental tool for studying the pathogenesis of severe pneumonia and developing and assessing treatment strategies.

Hot under the clot: venous thrombogenesis is an inflammatory process

ABSTRACT

Venous thrombosis (VT) is a serious medical condition in which a blood clot forms in deep veins, often causing limb swelling and pain. Current antithrombotic therapies carry significant bleeding risks resulting from targeting essential coagulation factors. Recent advances in this field have revealed that the cross talk between the innate immune system and coagulation cascade is a key driver of VT pathogenesis, offering new opportunities for potential therapeutic interventions without inducing bleeding complications. This review summarizes and discusses recent evidence from preclinical models on the role of inflammation in VT development. We highlight the major mechanisms by which endothelial cell activation, Weibel-Palade body release, hypoxia, reactive oxygen species, inflammasome, neutrophil extracellular traps, and other immune factors cooperate to initiate and propagate VT. We also review emerging clinical data describing anti-inflammatory approaches as adjuncts to anticoagulation in VT treatment. Finally, we identify key knowledge gaps and future directions that could maximize the benefit of anti-inflammatory therapies in VT. Identifying and targeting the inflammatory factors driving VT, either at the endothelial cell level or within the clot, may pave the way for new therapeutic possibilities for improving VT treatment and reducing thromboembolic complications without increasing bleeding risk.

[Value of calprotectin S100 A8/A9 in predicting the severity of Mycoplasma pneumoniae pneumonia in children]

OBJECTIVES

To investigate the role of calprotectin S100 A8/A9 complex in evaluating the condition of children with severe Mycoplasma pneumoniae pneumonia (SMPP).

METHODS

A prospective study was conducted among 136 children with Mycoplasma pneumoniae pneumonia (MPP) and 30 healthy controls. According to the severity of the condition, the children with MPP were divided into mild subgroup (40 children) and SMPP subgroup (96 children). The levels of S100 A8/A9 complex and related inflammatory factors were compared between the MPP group and the healthy control group, as well as between the two subgroups of MPP. The role of S100 A8/A9 in assessing the severity of MPP was explored.

RESULTS

The MPP group had a significantly higher level of S100 A8/A9 than the healthy control group, with a significantly greater increase in the SMPP subgroup (P<0.05). The multivariate logistic regression analysis showed that the increases in serum C reactive protein (CRP) and S100A8/A9 were closely associated with SMPP (P<0.05). The receiver operating characteristic (ROC) curve analysis showed that the combined measurement of serum S100 A8/A9 and CRP had an area under the ROC curve of 0.904 in predicting SMPP, which was significantly higher than the AUC of S100 A8/A9 or CRP alone (P<0.05), with a specificity of 0.718 and a sensitivity of 0.952.

CONCLUSIONS

S100 A8/A9 is closely associated with the severity of MPP, and the combination of S100 A8/A9 with CRP is more advantageous for assessing the severity of MPP in children.

Analysis of the value of potential biomarker S100-A8 protein in the diagnosis and pathogenesis of spinal tuberculosis

Objectives

The objective of this study is to evaluate the value of S100-A8 protein as a diagnostic marker for spinal tuberculosis and to explore its role in the potential pathogenesis of spinal tuberculosis (STB).

Methods

The peripheral blood of 100 spinal tuberculosis patients admitted to the General Hospital of Ningxia Medical University from September 2018 to June 2021 were collected as the observation group, and the peripheral blood of 30 healthy medical examiners were collected as the control group. Three samples from the observation group and three samples from the control group were selected for proteomics detection and screening of differential proteins. Kyoto Encyclopedia of Genes (KEGG) was used to enrich and analyze related signaling pathways to confirm the target protein. The serum expression levels of the target proteins were determined and compared between the two groups using enzyme-linked immunosorbent assay (ELISA). Statistical methods were used to evaluate the value of target protein as a diagnostic marker for STB. A macrophage model of Mycobacterium tuberculosis infection was constructed and S100-A8 small interfering RNA was used to investigate the molecular mechanism of the target protein.

Results

S100-A8 protein has the value of diagnosing spinal tuberculosis (AUC = 0.931, p < 0.001), and the expression level in the peripheral blood of the observation group (59.04 ± 19.37 ng/mL) was significantly higher than that of the control group (43.16 ± 10.07 ng/mL) (p < 0.05). S100-A8 protein expression showed a significant positive correlation with both CRP and ESR values (p < 0.01). Its AUCs for combined bacteriological detection, T-SPOT results, diagnostic imaging, antacid staining results, and pathological results were 0.705 (p < 0.05), 0.754 (p < 0.01), 0.716 (p < 0.01), 0.656 (p < 0.05), and 0.681 (p < 0.01), respectively. Lack of S100-A8 leads to a significant decrease in the expression levels of TLR4 and IL-17A in infected macrophages.

Conclusion

S100-A8 protein is differentially expressed in the peripheral blood of patients with spinal tuberculosis and healthy individuals and may be a novel candidate biomarker for the diagnosis of spinal tuberculosis. The feedback loop on the S100-A8-TLR4-IL-17A axis may play an important role in the inflammatory mechanism of spinal tuberculosis.

S100A9 exacerbates sepsis-induced acute lung injury via the IL17-NFκB-caspase-3 signaling pathway

BACKGROUND

Sepsis-induced acute lung injury (ALI) is associated with considerable morbidity and mortality in critically ill patients. S100A9, a key endothelial injury factor, is markedly upregulated in sepsis-induced ALI; however, its specific mechanism of action has not been fully elucidated.

METHODS

The Gene Expression Omnibus database transcriptome data for sepsis-induced ALI were used to screen for key differentially expressed genes (DEGs). Using bioinformatics analysis methods such as Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein-protein interaction network analyses, the pathogenesis of sepsis-induced ALI was revealed. Intratracheal infusion of lipopolysaccharide (LPS, 10 mg/kg) induced ALI in wild-type (WT) and S100A9 knockout mice. Multiomics analyses (transcriptomics and proteomics) were performed to investigate the potential mechanisms by which S100A9 exacerbates acute lung damage. Hematoxylin-eosin, Giemsa, and TUNEL staining were used to evaluate lung injury and cell apoptosis. LPS (10 μg/mL)-induced murine lung epithelial MLE-12 cells were utilized to mimic ALI and were modulated by S100A9 lentiviral transfection. The impact of S100A9 on cell apoptosis and inflammatory responses were identified using flow cytometry and PCR. The expression of interleukin (IL)-17-nuclear factor kappa B (NFκB)-caspase-3 signaling components was identified using western blotting.

RESULTS

Six common DEGs (S100A9, S100A8, IFITM6, SAA3, CD177, and MMP9) were identified in the six datasets related to ALI in sepsis. Compared to WT sepsis mice, S100A9 knockout significantly alleviated LPS-induced ALI in mice, with reduced lung structural damage and inflammatory exudation, decreased exfoliated cell and protein content in the lung lavage fluid, and reduced apoptosis and necrosis of pulmonary epithelial cells. Transcriptomic analysis revealed that knocking out S100A9 significantly affected 123 DEGs, which were enriched in immune responses, defense responses against bacteria or lipopolysaccharides, cytokine-cytokine receptor interactions, and the IL-17 signaling pathway. Proteomic analysis revealed that S100A9 knockout alleviated muscle contraction dysfunction and structural remodeling in sepsis-induced ALI. Multiomics analysis revealed that S100A9 may be closely related to interferon-induced proteins with tetratricopeptide repeats and oligoadenylate synthase-like proteins. LPS decreased MLE12 cell activity, accompanied by high expression of S100A9. The expression of IL-17RA, pNFκB, and cleaved-caspase-3 were increased by S100A9 overexpression and reduced by S100A9 knockdown in LPS-stimulated MLE12 cells. S100A9 knockdown decreases transcription of apoptosis-related markers Bax, Bcl and caspase-3, alleviating LPS-induced apoptosis.

CONCLUSIONS

S100A9 as a key biomarker of sepsis-induced acute lung injury, and exacerbates lung damage and epithelial cell apoptosis induced by LPS via the IL-17-NFκB-caspase-3 signaling pathway.

Neutrophil Infiltration and Function in the Pathogenesis of Inflammatory Airspace Disease

Neutrophils are an important cell type often considered the body's first responders to inflammatory insult or damage. They are recruited to the tissue of the lungs in patients with inflammatory airspace diseases and have unique and complex functions that range from helpful to harmful. The uniqueness of these functions is due to the heterogeneity of the inflammatory cascade and retention in the vasculature. Neutrophils are known to marginate, or remain stagnant, in the lungs even in nondisease conditions. This review discusses the ways in which the recruitment, presence, and function of neutrophils in the airspace of the lungs are unique from those of other tissues, and the complex effects of neutrophils on pathogenesis. Inflammatory mediators produced by neutrophils, such as neutrophil elastase, proresolving mediators, and neutrophil extracellular traps, dramatically affect the outcomes of patients with disease of the lungs.

Repair and regeneration of the alveolar epithelium in lung injury

Considerable progress has been made in understanding the function of alveolar epithelial cells in a quiescent state and regeneration mechanism after lung injury. Lung injury occurs commonly from severe viral and bacterial infections, inhalation lung injury, and indirect injury sepsis. A series of pathological mechanisms caused by excessive injury, such as apoptosis, autophagy, senescence, and ferroptosis, have been studied. Recovery from lung injury requires the integrity of the alveolar epithelial cell barrier and the realization of gas exchange function. Regeneration mechanisms include the participation of epithelial progenitor cells and various niche cells involving several signaling pathways and proteins. While alveoli are damaged, alveolar type II (AT2) cells proliferate and differentiate into alveolar type I (AT1) cells to repair the damaged alveolar epithelial layer. Alveolar epithelial cells are surrounded by various cells, such as fibroblasts, endothelial cells, and various immune cells, which affect the proliferation and differentiation of AT2 cells through paracrine during alveolar regeneration. Besides, airway epithelial cells also contribute to the repair and regeneration process of alveolar epithelium. In this review, we mainly discuss the participation of epithelial progenitor cells and various niche cells involving several signaling pathways and transcription factors.

S100A8 is a prognostic signature and associated with immune response in diffuse large B-cell lymphoma

Background

S100A8, a calcium-binding protein belonging to the S100 family, is involved in immune responses and multiple tumor pathogens. Diffuse large B-cell lymphoma (DLBCL) is one of the most common types of B-cell lymphoma and remains incurable in 40% of patients. However, the role of S100A8 and its regulation of the immune response in DLBCL remain unclear.

Methods

The differential expression of S100A8 was identified via the GEO and TCGA databases. The prognostic role of S100A8 in DLBCL was calculated using the Kaplan-Meier curve. The function enrichment of differentially expressed genes (DEGs) was explored through GO, KEGG, GSEA, and PPI analysis. In our cohort, the expression of S100A8 was verified. Meanwhile, the biological function of S100A8 was applied after the inhibition of S100A8 in an in vitro experiment. The association between S100A8 and immune cell infiltration and treatment response in DLBCL was analyzed.

Results

S100A8 was significantly overexpressed and related to a poor prognosis in DLBCL patients. Function enrichment analysis revealed that DEGs were mainly enriched in the IL-17 signaling pathway. Our cohort also verified this point. In vitro experiments suggested that inhibition of S100A8 should promote cell apoptosis and suppress tumor growth. Single-cell RNA sequence analysis indicated that S100A8 might be associated with features of the tumor microenvironment (TME), and immune infiltration analyses discovered that S100A8 expression was involved in TME. In terms of drug screening, we predicted that many drugs were associated with preferable sensitivity.

Conclusion

Elevated S100A8 expression is associated with a poor prognosis and immune infiltration in DLBCL. Inhibition of S100A8 could promote cell apoptosis and suppress tumor growth. Meanwhile, S100A8 has the potential to be a promising immunotherapeutic target for patients with DLBCL.

Integrative study of pulmonary microbiome, transcriptome and clinical outcomes in Mycoplasma pneumoniae pneumonia

BACKGROUND

This study aimed to investigate the interactions among three core elements of respiratory infection-pathogen, lung microbiome, and host response-and their avocation with the severity and outcomes of Mycoplasma pneumoniae pneumonia (MPP) in children.

METHODS

We prospectively collected bronchoalveolar lavage fluid from a cohort of 41 children with MPP, including general MPP (GMPP) and complicated MPP (CMPP), followed by microbiome and transcriptomic analyses to characterize the association among pathogen, lung microbiome, and host response and correlate it with the clinical features and outcomes.

RESULTS

The lung microbiome of patients with CMPP had an increased relative abundance of Mycoplasma pneumoniae (MP) and reduced alpha diversity, with 76 differentially expressed species. Host gene analysis revealed a key module associated with neutrophil function and several inflammatory response pathways. Patients with a high relative abundance of MP, manifested by a specific lung microbiome and host response type, were more prone to CMPP and had a long imaging recovery time.

CONCLUSION

Patients with CMPP have a more disrupted lung microbiome than those with GMPP. MP, lung microbiome, and host response interacts with each other and are closely related to disease severity and outcomes in children with MPP.

The functions and regulatory pathways of S100A8/A9 and its receptors in cancers

Inflammation primarily influences the initiation, progression, and deterioration of many human diseases, and immune cells are the principal forces that modulate the balance of inflammation by generating cytokines and chemokines to maintain physiological homeostasis or accelerate disease development. S100A8/A9, a heterodimer protein mainly generated by neutrophils, triggers many signal transduction pathways to mediate microtubule constitution and pathogen defense, as well as intricate procedures of cancer growth, metastasis, drug resistance, and prognosis. Its paired receptors, such as receptor for advanced glycation ends (RAGEs) and toll-like receptor 4 (TLR4), also have roles and effects within tumor cells, mainly involved with mitogen-activated protein kinases (MAPKs), NF-κB, phosphoinositide 3-kinase (PI3K)/Akt, mammalian target of rapamycin (mTOR) and protein kinase C (PKC) activation. In the clinical setting, S100A8/A9 and its receptors can be used complementarily as efficient biomarkers for cancer diagnosis and treatment. This review comprehensively summarizes the biological functions of S100A8/A9 and its various receptors in tumor cells, in order to provide new insights and strategies targeting S100A8/A9 to promote novel diagnostic and therapeutic methods in cancers.

miRNA, lncRNA and circRNA: targeted molecules with therapeutic promises in Mycoplasma pneumoniae infection

Mycoplasma pneumoniae (MP) is primarily recognized as a respiratory pathogen that causes community-acquired pneumonia, which can lead to acute upper and lower airway inflammation and extrapulmonary syndrome. Refractory pneumonia caused by MP can cause severe complications and even be life-threatening, particularly in infants and the elderly. It is well-known that non-coding RNAs (ncRNAs) represented by miRNAs, lncRNAs and circRNAs have been manifested to be widely involved in the regulation of gene expression. Growing evidence indicates that these ncRNAs have distinct differentiated expression in MP infection and affect multiple biological processes, playing an indispensable role in the initiation and promotion of MP infection. However, the epigenetic mechanisms involved in the development of MP infection remain unclear. This article reviews the mechanisms by which miRNAs, lncRNAs, and circRNAs mediate MP infection, such as inflammatory responses, apoptosis and pulmonary fibrosis. Focusing on miRNAs, lncRNAs and circRNAs associated with MP infection could provide new insights into this disease's early diagnosis and therapeutic approaches.

Neutrophil-derived S100A8/A9 promotes apoptosis of intestinal epithelial cells in children with duodenal ulcers

Duodenal ulcer significantly reduces quality of life and safety in children; however, the mechanism of the pathogenesis in children with duodenal ulcer remains unclear. S100A8/A9, which plays a critical role in the occurrence and development of inflammation, has attracted a lot of interest recently. Here, we identified that S100A8/A9 are highly expressed in the serum of children with duodenal ulcers, and this is of excellent diagnostic value. Animal experiments have proved that inhibition of S100A8/A9 can repair ulcer progression. In addition, further study has shown that S100A8/A9, mainly produced by neutrophil, can enhance the apoptosis of intestinal epithelial cells and promote the growth in children with duodenal ulcers. Thus, our research proves the value of S100A8/A9 in the diagnosis and treatment of children with duodenal ulcers.

Bergapten alleviates depression-like behavior by inhibiting cyclooxygenase 2 activity and NF-κB/MAPK signaling pathway in microglia

Major depressive disorder (MDD) is a common psychiatric disorder that severely affects human life and health. However, the pathological mechanism of MDD is unclear, and effective treatment strategies are urgently needed. Microglia-mediated neuroinflammation is closely associated with the pathophysiology of depression. Bergapten (BG) is a natural pharmaceutical monomer with anti-inflammatory effects; however, its role in neuroinflammation and depression remains unclear. In this study, we employed a lipopolysaccharide (LPS) injection-induced acute depression mouse model, and found that treatment with BG significantly alleviated LPS-induced depression-like behavior in mice. BG administration largely decreased the increase in microglial numbers and rescued the microglial morphological changes induced by LPS injection. Furthermore, transcriptomic changes revealed a protective role of BG in the hippocampus of mice. Mechanistically, we found that BG directly inhibited cyclooxygenase 2 (COX2) activity, and suppressed nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways in microglia. Together, these results highlight the important role of BG in microglial activation, neuroinflammation, and depression-like behavior, thus providing a new candidate drug for depression treatment.

Analysis of cytokine levels, cytological findings, and MP-DNA level in bronchoalveolar lavage fluid of children with Mycoplasma pneumoniae pneumonia

BACKGROUND

The present study was conducted to determine the inflammatory response in the lungs of children with Mycoplasma pneumoniae pneumonia (MPP).

METHODS

This study retrospectively analyzed cytokine levels, cytological findings, and M. pneumoniae (MP)-DNA level in the bronchoalveolar lavage fluid (BALF) of 96 children with MPP. The study utilized Spearman's correlation method to evaluate the contribution of BALF and blood parameters in MPP children.

RESULTS

(1) A total of 96 MPP children were classified into the Low MP-DNA MPP group (BALF MP-DNA ≤ 105 copies/mL) and the High MP-DNA MPP group (BALF MP-DNA > 105 copies/mL); the Non-fever MPP group (no fever during the entire course of pneumonia) and the Fever MPP group; the Defervescence MPP group (fever had subsided at the time of bronchoscopy) and the Fervescence MPP group; and the Mild MPP group and the Severe MPP group. (2) The High MP-DNA MPP, Fever MPP, Fervescence MPP, and Severe MPP groups had higher levels of interleukin (IL)-6, IL-10, and tumor necrosis factor-α (TNF-α) in their BALF (all p < .05). (3) The proportions of neutrophils and macrophages in the BALF of the High MP-DNA MPP and Fever MPP groups increased and decreased, respectively (all p < .05). (4) In the BALF of MPP children, MP-DNA, IL-6, IL-10, TNF-α, and interferon gamma (IFN-γ) levels positively correlated with neutrophil proportion while negatively correlated with macrophage proportion (all p < .05). (5) The MP-DNA, IL-6, IL-10, TNF-α, and IFN-γ levels in the BALF of MPP children were positively correlated with the levels of C-reactive protein, procalcitonin, lactic dehydrogenase, fibrinogen, and d-dimer, while they were negatively correlated with the albumin level (all p < .05).

CONCLUSIONS

In children with MPP, the pulmonary inflammatory immune response was stronger in the High MP-DNA MPP, Fever MPP, Fervescence MPP, and Severe MPP groups. The relationship between pulmonary cytokine levels, MP-DNA load, and serum inflammatory parameters were found to be weak.

Interaction between alveolar macrophages and epithelial cells during Mycoplasma pneumoniae infection

Mycoplasma pneumoniae, as one of the most common pathogens, usually causes upper respiratory tract infections and pneumonia in humans and animals. It accounts for 10% to 40% of community-acquired pneumonia in children. The alveolar epithelial cells (AECs) are the first barrier against pathogen infections, triggering innate immune responses by recruiting and activating immune cells when pathogens invade into the lung. Alveolar macrophages (AMs) are the most plentiful innate immune cells in the lung, and are the first to initiate immune responses with pathogens invasion. The cross-talk between the alveolar epithelium and macrophages is necessary to maintain physiological homeostasis and to eradicate invaded pathogen by regulating immune responses during Mycoplasma pneumoniae infections. This review summarizes the communications between alveolar macrophages and epithelial cells during Mycoplasma pneumoniae infections, including cytokines-medicated communications, signal transduction by extracellular vesicles, surfactant associated proteins-medicated signal transmission and establishment of intercellular gap junction channels.

Morphological alterations in corneal nerves of patients with dry eye and associated biomarkers

The purposes of the present study were to (1) identify the relationship between dry eye symptoms and morphological changes in corneal subbasal nerves/ocular surfaces, and (2) discover tear film biomarkers indicating morphological changes in the subbasal nerves. This was a prospective cross-sectional study conducted between October and November 2017. Adults with dry eye disease (DED, n = 43) and healthy eyes (n = 16) were evaluated based on their subjective symptoms and ophthalmological findings. Corneal subbasal nerves were observed using confocal laser scanning microscopy. Nerve lengths, densities, branch numbers, and nerve fiber tortuosity were analyzed using ACCMetrics and CCMetrics image analysis systems; tear proteins were quantified by mass spectroscopy. Compared with the control group, the DED group had significantly lower tear breakup times (TBUT) and pain tolerance capacity, and significantly higher corneal nerve branch density (CNBD) and corneal nerve total branch density (CTBD). CNBD and CTBD showed significant negative correlations with TBUT. Six biomarkers (cystatin-S, immunoglobulin kappa constant, neutrophil gelatinase-associated lipocalin, profilin-1, protein S100-A8, and protein S100-A9) showed significant positive correlations with CNBD and CTBD. The significantly higher CNBD and CTBD in the DED group suggests that DED is associated with morphological alterations in corneal nerves. The correlation of TBUT with CNBD and CTBD further supports this inference. Six candidate biomarkers that correlate with morphological changes were identified. Thus, morphological changes in corneal nerves are a hallmark of DED, and confocal microscopy may help in the diagnosis and treatment of dry eyes.

Serum Calprotectin as a Promising Inflammatory Biomarker in Psoriatic Arthritis: a 1-Year Longitudinal Study

INTRODUCTION

There are few biomarkers correlated with psoriatic arthritis (PsA). We aimed to explore the clinical value of calprotectin (CLP) in PsA in disease activity and treatment targets.

METHODS

Serum CLP was detected by enzyme-linked immunosorbent assay (ELISA) in 71 patients with PsA, 55 patients with psoriasis (PsO), and 10 healthy controls. The association of serum CLP with disease activity index at baseline and follow-up was analyzed. Cox regression and receiver operating characteristic (ROC) analysis were used to evaluate the potential of CLP for predicting the achievement of treatment targets, including low disease activity (LDA), remission, and minimal disease activity (MDA).

RESULTS

Serum CLP levels (μg/ml) were significantly increased in patients with PsA/PsO compared with healthy controls (p < 0.001). Serum CLP levels were positively associated with psoriasis area and severity index (PASI), disease activity in psoriatic arthritis (DAPSA), and its components [including tender joint count (TJC), swollen joint count (SJC), patient's global assessment (PGA), and visual analog scale (VAS)-pain, r 0.290-0.601, all p value < 0.05]. After 1-year follow-up, the number of patients with PsA in remission and MDA increased [17 (23.9%) versus 47 (66.1%) and 21 (29.5%) versus 52 (73.2%) respectively, all p value < 0.001]. Cox regression and Kaplan-Meier survival analysis indicated that patients with lower CLP obtain LDA, MDA, and remission earlier, including remission and MDA within a year (all p-value < 0.05). ROC analysis showed the ability of serum at baseline to predict the achievement of the treatment target in 3 months [area under the curve (AUC) 0.663-0.691, all p-values < 0.05].

CONCLUSIONS

Serum CLP level was correlated with disease activity in PsA. It also possessed the ability to predict the achievement of the therapeutic target. These features of CLP would make it a useful tool in clinical work.

Identification of S100A9 as a Potential Inflammation-Related Biomarker for Radiation-Induced Lung Injury

Radiation-induced lung injury (RILI), a potentially fatal and dose-limiting complication of radiotherapy for thoracic tumors, is divided into early reversible pneumonitis and irreversible advanced-stage fibrosis. Early detection and intervention contribute to improving clinical outcomes of patients. However, there is still a lack of reliable biomarkers for early prediction and clinical diagnosis of RILI. Given the central role of inflammation in the initiation and progression of RILI, we explored specific inflammation-related biomarkers during the development of RILI in this study. Two expression profiles from the Gene Expression Omnibus (GEO) database were downloaded, in which 75 differentially expressed genes (DEGs) were screened out. Combining Gene Oncology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and protein-protein interaction (PPI) network analysis, we identified four inflammation-related hub genes in the progression of RILI-MMP9, IL-1β, CCR1 and S100A9. The expression levels of the hub genes were verified in RILI mouse models, with S100A9 showing the highest level of overexpression. The level of S100A9 in bronchoalveolar lavage fluid (BALF) and the expression of S100A9 in lung tissues were positively correlated with the degree of inflammation in RILI. The results above indicate that S100A9 is a potential biomarker for the early prediction and diagnosis of the development of RILI.

Vaccination with Mycoplasma pneumoniae membrane lipoproteins induces IL-17A driven neutrophilia that mediates Vaccine-Enhanced Disease

Bacterial lipoproteins are an often-underappreciated class of microbe-associated molecular patterns with potent immunomodulatory activity. We previously reported that vaccination of BALB/c mice with Mycoplasma pneumoniae (Mp) lipid-associated membrane proteins (LAMPs) resulted in lipoprotein-dependent vaccine enhanced disease after challenge with virulent Mp, though the immune responses underpinning this phenomenon remain poorly understood. Herein, we report that lipoprotein-induced VED in a mouse model is associated with elevated inflammatory cytokines TNF-α, IL-1β, IL-6, IL-17A, and KC in lung lavage fluid and with suppurative pneumonia marked by exuberant neutrophilia in the pulmonary parenchyma. Whole-lung-digest flow cytometry and RNAScope analysis identified multiple cellular sources for IL-17A, and the numbers of IL-17A producing cells were increased in LAMPs-vaccinated/Mp-challenged animals compared to controls. Specific IL-17A or neutrophil depletion reduced disease severity in our VED model—indicating that Mp lipoproteins induce VED in an IL-17A-dependent manner and through exuberant neutrophil recruitment. IL-17A neutralization reduced levels of TNF-α, IL-1β, IL-6, and KC, indicating that IL-17A preceded other inflammatory cytokines. Surprisingly, we found that IL-17A neutralization impaired bacterial clearance, while neutrophil depletion improved it—indicating that, while IL-17A appears to confer both maladaptive and protective responses, neutrophils play an entirely maladaptive role in VED. Given that lipoproteins are found in virtually all bacteria, the potential for lipoprotein-mediated maladaptive inflammatory responses should be taken into consideration when developing vaccines against bacterial pathogens.

Cell damage and neutrophils promote the infection of Mycoplasma pneumoniae and inflammatory response

Mycoplasma pneumoniae (MP) is an important respiratory pathogen of human. The infection of MP can cause direct damage and immune damage in lung, resulting in Mycoplasma pneumoniae pneumonia (MPP). In this study, we aim to investigate the pathogenesis of MPP by detecting the proliferation of MP under conditions of cell damages and neutrophils in vitro. Firstly, we found the supplements of intracellular fluid, protein and RNA derived from intracellular fluid of A549 cells contribute to the survival of MP, thereby promoting the infection of MP. Cell damage can also significantly contribute to the survival of MP without supplements. At the same time, the additions of supplements contribute to apoptosis and the expression of IL-8 and IL-1β. Further, we found live neutrophils show bactericidal activity to MP, and the phagocytosis of MP promotes apoptosis of neutrophils. When co-incubated with MP and A549 cells, the proliferation of MP in the high neutrophils proportion groups were accelerated with functional decline of neutrophils, and the level of extracellular IL-1β showed a time and dose dependent manner to neutrophils. These results suggest that the release of intracellular nutrients by damaged cells and functional decline of neutrophils can promote the infection of MP and play roles in the activation of inflammatory response. Therefore, lung damage and infiltration of neutrophils would be important factors affecting the development of MPP.

Role of Interleukin-17A in the Pathomechanisms of Periodontitis and Related Systemic Chronic Inflammatory Diseases

Periodontitis is a chronic inflammatory and destructive disease caused by periodontal microbial infection and mediated by host immune response. As the main cause of loosening and loss of teeth in adults, it is considered to be one of the most common and serious oral diseases in the world. The co-existence of periodontitis and systemic chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, inflammatory bowel disease, diabetes and so on is very common. It has been found that interleukin-17A (IL-17A) secreted by various innate and adaptive immune cells can activate a series of inflammatory cascade reactions, which mediates the occurrence and development of periodontitis and related systemic chronic inflammatory diseases. In this work, we review the role of IL-17A in the pathomechanisms of periodontitis and related systemic chronic inflammatory diseases, and briefly discuss the therapeutic potential of cytokine targeted agents that modulate the IL-17A signaling. A deep understanding of the possible molecular mechanisms in the relationship between periodontitis and systemic diseases will help dentists and physicians update their clinical diagnosis and treatment ideas.

Meningitic Escherichia coli-Induced Interleukin-17A Facilitates Blood-Brain Barrier Disruption via Inhibiting Proteinase 3/Protease-Activated Receptor 2 Axis

Bacterial meningitis is a life-threatening infectious disease with high morbidity and mortality worldwide, among which meningitic Escherichia coli is a common Gram-negative pathogenic bacterium causing meningitis. It can penetrate the blood–brain barrier (BBB), invoke local inflammatory responses and consequently disrupt the integrity of the BBB. Interleukin-17A (IL-17A) is recognized as a pro-inflammatory cytokine that is released during meningitic E. coli infection. It has been reported that IL-17A is involved in several pathological tissue injuries. However, the function of IL-17A in BBB breakdown remains rarely discussed. Here, our study found that E. coli-induced IL-17A led to the degradation of tight junction proteins (TJs) and adherens junction proteins (AJs) in human brain microvascular endothelial cells (hBMECs) through inhibiting protease proteinase 3 (PRTN3)/protease-activated receptor 2 (PAR-2) axis, thus increasing the permeability of BBB. In summary, this study uncovered the involvement of IL-17A in regulating BBB integrity and proposed a novel regulatory mechanism, which could be potential therapeutic targets of E. coli meningitis.