Chlamydia pneumoniae infection promotes vascular smooth muscle cell migration via c-Fos/interleukin-17C signaling

Interleukin 2 receptor subunit beta as a novel hub gene plays a potential role in the immune microenvironment of abdominal aortic aneurysms

BACKGROUND

Abdominal aortic aneurysm (AAA) is potentially life threatening and characterized by immune-inflammatory cell infiltration and extracellular matrix degradation. Currently, pharmacotherapy mainly aims to control risk factors without reversion of the dilated aorta. This study analyzed the immune-inflammatory response and identified the immune-related hub genes of AAA.

METHOD

Gene Expression Omnibus datasets (GSE57691, GSE47472 and GSE7084) were downloaded. After identification of GSE57691 differentially expressed genes (DEGs), weighted gene co-expression network analysis of the DEGs was performed. Through enrichment analysis of each module and screening in Immunology Database and Analysis Portal, immune-related hub genes were identified via protein-protein interaction (PPI) network construction and lasso regression. CIBERSORT was utilized to analyze AAA immune infiltration. The correlations between the immune-related hub genes and infiltrating immune cells were investigated. Receiver operating characteristic (ROC) curve analysis was performed to determine immune-related hub gene cutoff values, which were validated in GSE47472 and GSE7084.

RESULT

In GSE57691, 1,018 DEGs were identified. Five modules were identified in the co-expression network. The blue and green modules were found to be related to immune-inflammatory responses, and 61 immune-related genes were identified. PPI and lasso regression analyses identified FOS, IL-6 and IL2RB as AAA immune-related hub genes. CIBERSORT analysis indicated significantly increased infiltration of naive B cells, memory activated CD4 T cells, follicular helper T cells, monocytes and M1 macrophages and significantly decreased infiltration of M2 macrophages in AAA compared with normal samples. IL2RB was more strongly associated with immune infiltration in AAA than were FOS and IL6. The IL2RB area under the ROC curve (AUC) value was > 0.9 in both the training and validation set, demonstrating its strong, stable diagnostic value in AAA.

CONCLUSION

AAA and normal samples had different immune infiltration statuses. IL2RB was identified as an immune-related hub gene and a potential hub gene with significant diagnostic value in AAA.

Chlamydia pneumoniae Infection Induces Vascular Smooth Muscle Cell Migration and Atherosclerosis Through Mitochondrial Reactive Oxygen Species-Mediated JunB-Fra-1 Activation

Infection is closely related to atherosclerosis, which is a major pathological basis for cardiovascular diseases. Vascular smooth muscle cell (VSMC) migration is an important trigger in development of atherosclerosis that is associated with Chlamydia pneumoniae (C. pneumoniae) infection. However, the mechanism of VSMC migration remains unclear, and whether antioxidant could be a therapeutic target for C. pneumoniae infection-induced atherosclerosis also remains unknown. The results showed that C. pneumoniae infection mainly impaired mitochondrial function and increased the level of mitochondrial reactive oxygen species (mtROS). The expressions of protein JunB, Fra-1 and Matrix metalloproteinase 2 (MMP) evidently increased after C. pneumoniae infection, and the interaction between JunB and Fra-1 was also enhanced. After scavenging mtROS by antioxidant Mito-TEMPO, the increasing expressions of JunB, Fra-1, MMP2 and the capacity of VSMC migration induced by C. pneumoniae infection were all inhibited. In comparison with infected ApoE^-/- mice, the level of ROS in atherosclerotic lesion in ApoE^-/-TLR2^-/- mice with C. pneumoniae infection decreased. Knocking out TLR2 suppressed the expressions of JunB, Fra-1 and MMP2 in VSMCs and the formation of atherosclerotic lesion after C. pneumoniae infection. Furthermore, after using small interfering RNA to inhibit the expression of TLR2, the level of mtROS and the expressions of JunB, Fra-1 and MMP2 apparently decreased. Taken together, C. pneumoniae infection may promote VSMC migration and atherosclerosis development by increasing the level of mtROS through TLR2 to activate the JunB-Fra-1/MMP2 signaling pathway. The data provide the first evidence that antioxidant could reduce C. pneumoniae infection-induced VSMC migration and atherosclerosis.

The Effects of Porphyromonas gingivalis on Atherosclerosis-Related Cells

Atherosclerosis (AS), one of the most common types of cardiovascular disease, has initially been attributed to the accumulation of fats and fibrous materials. However, more and more researchers regarded it as a chronic inflammatory disease nowadays. Infective disease, such as periodontitis, is related to the risk of atherosclerosis. Porphyromonas gingivalis (P. gingivalis), one of the most common bacteria in stomatology, is usually discovered in atherosclerotic plaque in patients. Furthermore, it was reported that P. gingivalis can promote the progression of atherosclerosis. Elucidating the underlying mechanisms of P. gingivalis in atherosclerosis attracted attention, which is thought to be crucial to the therapy of atherosclerosis. Nevertheless, the pathogenesis of atherosclerosis is much complicated, and many kinds of cells participate in it. By summarizing existing studies, we find that P. gingivalis can influence the function of many cells in atherosclerosis. It can induce the dysfunction of endothelium, promote the formation of foam cells as well as the proliferation and calcification of vascular smooth muscle cells, and lead to the imbalance of regulatory T cells (Tregs) and T helper (Th) cells, ultimately promoting the occurrence and development of atherosclerosis. This article summarizes the specific mechanism of atherosclerosis caused by P. gingivalis. It sorts out the interaction between P. gingivalis and AS-related cells, which provides a new perspective for us to prevent or slow down the occurrence and development of AS by inhibiting periodontal pathogens.

Oxidative Stress and Inflammation in SARS-CoV-2- and Chlamydia pneumoniae-Associated Cardiovascular Diseases

Throughout the years, a growing number of studies have provided evidence that oxidative stress and inflammation may be involved in the pathogenesis of infectious agent-related cardiovascular diseases. Amongst the numerous respiratory pathogens, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus responsible for the global ongoing pandemic, and Chlamydia pneumoniae, a widely known intracellular obligate bacteria, seem to have an essential role in promoting reactive oxygen species and cytokine production. The present review highlights the common oxidative and inflammatory molecular pathways underlying the cardiovascular diseases associated with SARS-CoV-2 or C. pneumoniae infections. The main therapeutic and preventive approaches using natural antioxidant compounds will be also discussed.

Insights Into Host Cell Cytokines in Chlamydia Infection

Chlamydial infection causes a number of clinically relevant diseases and induces significant morbidity in humans. Immune and inflammatory responses contribute to both the clearance of Chlamydia infection and pathology in host tissues. Chlamydia infection stimulates host cells to produce a large number of cytokines that trigger and regulate host immune responses against Chlamydia. However, inappropriate responses can occur with excessive production of cytokines, resulting in overreactive inflammatory responses and alterations in host or Chlamydia metabolism. As a result, Chlamydia persists and causes wound healing delays, leading to more severe tissue damage and triggering long-lasting fibrotic sequelae. Here, we summarize the roles of cytokines in Chlamydia infection and pathogenesis, thus advancing our understanding chlamydial infection biology and the pathogenic mechanisms involved.

Elevated c-fos expression is correlated with phenotypic switching of human vascular smooth muscle cells derived from lower limb venous varicosities

BACKGROUND

Lower limb venous varicosities (VVs) are clinically common; however, their molecular underpinnings are far from well elucidated. Previous studies have demonstrated that the phenotypic transition of vascular smooth muscle cells (VSMCs) plays a critical role in VV pathogenesis and that c-fos is upregulated in VSMCs from VVs. The present study investigated the histologic and cytologic changes in VVs and the correlation between c-fos upregulation and VSMC phenotypic switching.

METHODS

Thirty-four patients with VVs (VV group) and 13 patients undergoing coronary artery bypass using autologous great saphenous vein segments (normal vein [NV] group) were enrolled in the present study. The great saphenous veins of both groups were harvested for subsequent experiments. Hematoxylin and eosin staining was performed for vein morphologic analysis. Real-time quantitative polymerase chain reaction, immunohistochemistry, and Western blot assays were used to assess mRNA and protein expression of c-fos, α-smooth muscle actin (α-SMA), and osteopontin (OPN). Simple linear regression was used to evaluate the correlation between c-fos and OPN/α-SMA. Primary VSMCs were isolated from both groups and cultured in vitro. A cell counting kit-8 assay and scratch-wound assay were used to analyze the proliferation and migration abilities of the cells, respectively.

RESULTS

The mean age of the patients in the NV and VV groups was 61.4 ± 3.8 years and 59.5 ± 10.4 years, respectively. The vein cavities of the VV group were dilated, and the arrangement of the cells was disordered. The tunica media of the VV group was thicker than that of the NV group owing to the accumulation and proliferation of VSMCs. Significantly elevated mRNA levels of c-fos and OPN were observed in the VV group compared with the NV group, and a positive correlation was further demonstrated between the mRNA levels of c-fos and OPN/α-SMA (R², 0.5524; P < .001). The VSMCs derived from the VV group were more numerous (as shown by the cell counting kit-8 assay) and had a significantly greater migration speed (as shown by the scratch-wound assay) than those derived from the NV group. Moreover, the protein expression of c-fos was significantly upregulated in VSMCs derived from the VV group, and this change was accompanied by a decrease in α-SMA and an increase in OPN expression.

CONCLUSIONS

Both mRNA and protein expression of c-fos were upregulated in VV specimens, and the phenotypic biomarkers (OPN/α-SMA) were altered concurrently. VSMCs derived from VVs showed increased proliferation and migration abilities. Upregulation of c-fos might play a role in the phenotypic switching of VSMCs and subsequently participate in the pathogenesis of VVs.

CLINICAL RELEVANCE

C-fos is an immediate early gene owing to the transient and rapid change in its expression in response to stimuli. It is involved in the regulation of cell proliferation, cell growth, and cell movement. In the present study, varicose vein specimens showed increased mRNA and protein expression of c-fos, accompanied by altered phenotypic biomarkers. The upregulation of the c-fos gene in smooth muscle cells cultured from varicose vein specimens might be associated with phenotypic switching and functional disturbance. These results could contribute to the exploration of the molecular mechanisms underlying the pathogenesis of varicose veins and the development of new therapeutic strategies.