Pulmonary Hypertension and the Gut Microbiome

The gut microbiome and its associated metabolites are integral to the maintenance of gut integrity and function. There is increasing evidence that its alteration, referred to as dysbiosis, is involved in the development of a systemic conditions such as cardiovascular disease (e.g., systemic hypertension, atherosclerosis). Pulmonary hypertension (PH) is a condition characterised by progressive remodelling and vasoconstriction of the pulmonary circulation, ultimately leading to right ventricular failure and premature mortality if untreated. Initial studies have suggested a possible association between dysbiosis of the microbiome and the development of PH. The aim of this article is to review the current experimental and clinical data with respect to the potential interaction between the gut microbiome and the pathophysiology of pulmonary hypertension. It will also highlight possible new therapeutic targets that may provide future therapies.

Chlamydial YAP activation in host endocervical epithelial cells mediates pro-fibrotic paracrine stimulation of fibroblasts

IMPORTANCE

Chronic or repeated infection of the female upper genital tract by C. trachomatis can lead to severe fibrotic sequelae, including tubal factor infertility and ectopic pregnancy. However, the molecular mechanisms underlying this effect are unclear. In this report, we define a transcriptional program specific to C. trachomatis infection of the upper genital tract, identifying tissue-specific induction of host YAP-a pro-fibrotic transcriptional cofactor-as a potential driver of infection-mediated fibrotic gene expression. Furthermore, we show that infected endocervical epithelial cells stimulate collagen production by fibroblasts and implicate chlamydial induction of YAP in this effect. Our results define a mechanism by which infection mediates tissue-level fibrotic pathology via paracrine signaling and identify YAP as a potential therapeutic target for the prevention of Chlamydia-associated scarring of the female genital tract.

The role of TLR2 in exercise-induced immunomodulation in normal weight individuals

Toll-like receptors (TLRs) have been targeted for therapeutic drug development for several disorders, including cardiovascular diseases (CVD), and diabetes mellitus. Daily levels physical activity (PA) has been purported to influence the systemic circulation of cytokines, affecting the overall activation of TLRs and influencing the inflammatory milieu. Objective and self-reported daily PA was tracked in 69 normal-weight adults. Freedson's cut-offs categorized daily PA intensity into the 25th lowest, medium, and top percentiles. Monocytic TLR2 expression was quantified by flow cytometry in fresh whole blood. Cross-sectional associations between flow cytometry measured TLR2⁺ subsets and clinical biomarkers were evaluated. PA increased circulation of TLR2⁺ monocytes. TLR2 expression was adversely corelated with reduced diastolic blood pressure (DBP), triglyceride (TG), and matrix metallopeptidase 9 (MMP9) levels. However, regression analysis indicated that only TG levels were independently linked with TLR2⁺ subsets in circulation in active participants. Higher daily levels of physical activity are associated with improved cardiovascular blood markers and elevated circulatory monocytic TLR2⁺ subsets. These findings suggest that TLR2 may play a role in modulating CVD risk factors in individuals leading physically active lifestyles.

Chlamydial YAP activation in host endocervical epithelial cells mediates pro-fibrotic paracrine stimulation of fibroblasts

Infection of the female genital tract by Chlamydia trachomatis can produce severe fibrotic sequelae, including tubal factor infertility and ectopic pregnancy. While infection demonstrably mediates a pro-fibrotic response in host cells, it remains unclear if intrinsic properties of the upper genital tract exacerbate chlamydial fibrosis. The relatively sterile environment of the upper genital tract is primed for a pro-inflammatory response to infection, potentially enhancing fibrosis - however, subclinical C. trachomatis infections still develop fibrosis-related sequelae. Here, we compare infection-associated and steady-state gene expression of primary human cervical and vaginal epithelial cells. In the former, we observe enhanced baseline expression and infection-mediated induction of fibrosis-associated signal factors (e.g. TGFA , IL6 , IL8 , IL20 ), implying predisposition to Chlamydia -associated pro-fibrotic signaling. Transcription factor enrichment analysis identified regulatory targets of YAP, a transcriptional cofactor induced by infection of cervical epithelial cells, but not vaginal epithelial cells. YAP target genes induced by infection include secreted fibroblast-activating signal factors; therefore, we developed an in vitro model involving coculture of infected endocervical epithelial cells with uninfected fibroblasts. Coculture enhanced fibroblast expression of type I collagen, as well as prompting reproducible (albeit statistically insignificant) induction of α-smooth muscle actin. Fibroblast collagen induction was sensitive to siRNA-mediated YAP knockdown in infected epithelial cells, implicating chlamydial YAP activation in this effect. Collectively, our results present a novel mechanism of fibrosis initiated by Chlamydia, wherein infection-mediated induction of host YAP facilitates pro-fibrotic intercellular communication. Chlamydial YAP activation in cervical epithelial cells is thus a determinant of this tissue's susceptibility to fibrosis.

Importance

Chronic or repeated infection of the female upper genital tract by C. trachomatis can lead to severe fibrotic sequelae, including tubal factor infertility and ectopic pregnancy. However, the molecular mechanisms underlying this effect are unclear. In this report, we define a transcriptional program specific to C. trachomatis infection of the upper genital tract, identifying tissue-specific induction of host YAP - a pro-fibrotic transcriptional cofactor - as a potential driver of infection-mediated fibrotic gene expression. Further, we show that infected endocervical epithelial cells stimulate collagen production by fibroblasts, and implicate chlamydial induction of YAP in this effect. Our results define a mechanism by which infection mediates tissue-level fibrotic pathology via paracrine signaling, and identify YAP as a potential therapeutic target for prevention of Chlamydia -associated scarring of the female genital tract.

Glycosides from Buyang Huanwu Decoction inhibit atherosclerotic inflammation via JAK/STAT signaling pathway

BACKGROUND

Buyang Huanwu Decoction (BYHWD) has been used to treat or prevent cardiovascular disease. The prescription and its glycosides have the effects of protecting blood vessels, and resisting atherosclerosis. However, their protective mechanism of anti-atherosclerosis remains unclear.

PURPOSE

This study aims to explore whether glycosides are the main effective components of BYHWD in anti-atherosclerotic inflammation and whether their mechanism is related to the classical JAK/STAT inflammatory signaling pathway.

METHODS

UPLC-MSMS method was used to determine the main components of BYHWD and its glycosides. Network pharmacological analysis and molecular docking were used to predict the potential therapeutic targets of glycosides. Atherosclerosis model was prepared by feeding HFD in ApoE^-/- mice. The effects of glycosides on atherosclerosis were detected by blood lipids measurement, Masson staining, immunohistochemistry, immunofluorescence, western-blot and droplet digital PCR. RAW264.7 cells were used to establish foam cells model. The mechanism of glycosides anti-atherosclerotic inflammation was detected by measuring intracellular lipids, Oil Red O staining, ELISA, western-blot and droplet digital PCR.

RESULTS

1. Glycosides were absorbed into the blood through oral administrations and existed in the blood in the form of glycosides structures. 2. Glycosides attenuated hyperlipidemia, alleviated atherosclerotic lesions and inhibited inflammatory reaction. They could regulate blood lipids by decreasing TC, TG, LDL-c, increasing HDL-c level in ApoE^-/- mice, alleviating intimal area and thickness, and inhibiting atherosclerotic plaque formation, which were similar to BYHWD. 3. Glycosides anti-atherosclerotic inflammation was related to JAK/STAT signaling pathway by network pharmacology analysis. Interactions between glycosides (astragaloside IV, paeoniflorin and amygdalin) and JAK/STAT pathway-related proteins by molecular docking. 4. Glycosides alleviated atherosclerotic inflammation by decreasing the release of pro-inflammatory factors and adhesions molecules, inhibiting the activation of JAK/STAT pathway in vivo. 5. Glycosides reduced the number of foam cells and intracellular lipid content. It also prevented the inflammation of macrophages by decreasing the levels of pro-inflammatory factors, reducing the phosphorylation of JAK2, STAT1 and STAT3 in vitro.

CONCLUSION

This study demonstrated that glycosides were the main active components of BYHWD, and they could inhibit atherosclerosis by alleviating atherosclerotic inflammation. the mechanism is inhibiting the activation of JAK/STAT signaling pathway.

Atorvastatin attenuates NS1 (Non-structural protein-1) of dengue type-2 serotype-induced expressions of matrix metalloproteinases in HL-60 cells, differentiated to neutrophils: Implications for the immunopathogenesis of dengue viral disease

BACKGROUND

The dengue is a vector borne viral infection in humans. Bite of mosquito infected with a dengue virus transmits the disease. The neutrophils support more to the innate immune response by switching to infected tissues and triggering immunomodulatory mechanisms including the release of proteases and host defence peptides.

METHODS

Cell viability by MTT and trypan blue dye exclusion assay, bright field microscopy for assessment of cell morphology, cytokines measurements by ELISA, estimation of protein by Bradford assay were done. Assessments of matrix metalloproteinase genes mRNA expressions were done using real-time PCR.

RESULTS

In the present study, we have for the first time unveiled that, NS1 antigen of dengue type-2 serotype, induce and stimulate the neutrophils cells to express high levels of matrix metalloproteases. NS1 exposure of HL-60 cells differentiated to neutrophils affected cell morphology and in 24 h of exposure. We have demonstrated that, the NS1 antigen has induced MMP-2, MMP-14 and MMP-9 expressions in neutrophils in a 24hrs exposure time. NS1 exposure has also further upregulated MMP-1, MMP-13, and MMP-8 expressions in neutrophils in a 24hrs exposure time. Notably, treatment with atorvastatin concentrations downregulated the expression profile of the all matrix metalloprotease significantly. Importantly, NS1 antigen has significantly increased the IL-6, IL-13 release by the HL,60 cells which was reversed by atorvastatin. On the other hand, NS1 exposure enhanced the mRNA expressions of VEGF-A and VEGF-D which was reversed by atorvastatin. However, we found that, NS1 exposure reduced the mRNA expressions profile of VEGF-C, which was reversed by atorvastatin.

CONCLUSION

In conclusion, we report that, neutrophils associated matrix metalloprotease are involved in the pathogenesis of dengue viral disease. VEGF growth factors may also be released by the neutrophils which may subsequently participate in the endothelial dysfunctions leading to dengue shock syndrome.

When Innate Immunity Meets Angiogenesis-The Role of Toll-Like Receptors in Endothelial Cells and Pulmonary Hypertension

Toll-like receptors serve a central role in innate immunity, but they can also modulate cell function in various non-immune cell types including endothelial cells. Endothelial cells are necessary for the organized function of the vascular system, and part of their fundamental role is also the regulation of immune function and inflammation. In this review, we summarize the current knowledge of how Toll-like receptors contribute to the immune and non-immune functions of the endothelial cells.

Infection and atherosclerosis: TLR-dependent pathways

Atherosclerotic vascular disease (ASVD) is a chronic process, with a progressive course over many years, but it can cause acute clinical events, including acute coronary syndromes (ACS), myocardial infarction (MI) and stroke. In addition to a series of typical risk factors for atherosclerosis, like hyperlipidemia, hypertension, smoking and obesity, emerging evidence suggests that atherosclerosis is a chronic inflammatory disease, suggesting that chronic infection plays an important role in the development of atherosclerosis. Toll-like receptors (TLRs) are the most characteristic members of pattern recognition receptors (PRRs), which play an important role in innate immune mechanism. TLRs play different roles in different stages of infection of atherosclerosis-related pathogens such as Chlamydia pneumoniae (C. pneumoniae), periodontal pathogens including Porphyromonas gingivalis (P. gingivalis), Helicobacter pylori (H. pylori) and human immunodeficiency virus (HIV). Overall, activation of TLR2 and 4 seems to have a profound impact on infection-related atherosclerosis. This article reviews the role of TLRs in the process of atherosclerosis after C. pneumoniae and other infections and the current status of treatment, with a view to providing a new direction and potential therapeutic targets for the study of ASVD.

Curcumin affects ox-LDL-induced IL-6, TNF-α, MCP-1 secretion and cholesterol efflux in THP-1 cells by suppressing the TLR4/NF-κB/miR33a signaling pathway

The aim of the present study was to study the molecular mechanism of how curcumin decreases the formation of ox-LDL induced human monocyte macrophage foam cells, promotes the efflux of cholesterol and reduces the secretion of inflammatory cytokines. In vitro cultured THP-1 cells were induced to become macrophages using phorbol-12-myristate-13-acetate. The cells were then pre-treated with curcumin before inducing the foam cell model by addition of oxidized low-density lipoprotein (ox-LDL). Western blot assays were used to detect expression levels of toll-like receptor (TLR)4, nuclear factor κB (NF-κB), NF-κB inhibitor α (IκBα), phosphorylated-IκBα and ATP binding cassette transporter (ABC)A1. Reverse transcription-quantitative PCR was employed to examine mRNA levels of TLR4, microRNA (miR)33a and ABCA1. ELISAs were used to detect inflammatory factors, including tumor necrosis factor (TNF)-α, monocyte chemotactic protein (MCP)-1 and interleukin (IL)-6. ox-LDL successfully induced the foam cell model, promoted phosphorylation of IκBα, promoted nuclear translocation of NF-κB, promoted the expression of TLR4 and miR33a, and promoted the secretion of TNF-α, MCP-1 and Il-6. Additionally, ox-LDL reduced the expression of ABCA1 and cholesterol efflux. However, pretreatment with curcumin increased the expression of ABCA1 and cholesterol efflux and suppressed secretion of TNF-α, MCP-1 and Il-6. TLR4 antibodies, the NF-κB blocker, PDTC, and the miR33a inhibitor also reduced the abnormal transformations induced by ox-LDL. Curcumin promoted cholesterol efflux by suppressing the TLR4/NF-κB/miR33a signaling pathway, and reduced the formation of foam cells and the secretion of inflammatory factors.

Expression of TLR-2 in hepatocellular carcinoma is associated with tumour proliferation, angiogenesis and Caspase-3 expression

AIMS

Unlike other Toll-like receptors (TLRs), the role of toll like receptor 2 (TLR-2) in the pathogenesis of chronic liver disease and hepatocellular carcinoma (HCC) is not well studied. We, therefore, set out to investigate the expression of TLR-2 in different chronic liver disease states along with other markers of cell death, cellular proliferation and tissue vascularisation METHODS AND RESULTS: Immunohistochemistry was performed on liver tissue microarrays comprising hepatitis, cirrhosis and HCC patient samples using antibodies against TLR-2, Ki-67, Caspase-3 and VEGF. This was done in order to characterise receptor expression and translocation, apoptosis, cell proliferation and vascularisation. Cytoplasmic TLR-2 expression was found to be weak in 5/8 normal liver cases, 10/19 hepatitis cases and 8/21 cirrhosis patients. Moderate to strong TLR-2 expression was observed in some cases of hepatitis and cirrhosis. Both, nuclear and cytoplasmic TLR-2 expression was present in HCC with weak intensity in 11/41 cases, and moderate to strong staining in 19/41 cases. Eleven HCC cases were TLR-2 negative. Surprisingly, both cytoplasmic and nuclear TLR-2 expression in HCC were found to significantly correlate with proliferative index (r = 0.24 and 0.37), Caspase-3 expression (r = 0.27 and 0.38) and vascularisation (r = 0.56 and 0.23). Further, nuclear TLR-2 localisation was predominant in HCC, whereas cytoplasmic expression was more prevalent in hepatitis and cirrhosis. Functionally, treatment of HUH7 HCC cells with a TLR-2 agonist induced the expression of cellular proliferation and vascularisation markers CD34 and VEGF.

CONCLUSIONS

Our results demonstrate a positive correlation between the expression of TLR-2 and other markers of proliferation and vascularisation in HCC which suggests a possible role for TLR-2 in HCC pathogenesis.

Chlamydia pneumoniae Influence on Cytokine Production in Steroid-Resistant and Steroid-Sensitive Asthmatics

Medications for asthma management consisting of inhaled corticosteroids act by controlling symptoms. However, some patients do not respond to steroid treatment due to immunological factors at the cytokine level. Chlamydia pneumoniae (C. pneumoniae) infection is strongly implicated in asthma pathogenesis, causing altered immune responses. We investigated the association of C. pneumoniae serostatus with the production of certain cytokines by peripheral blood mononuclear cells (PBMCs) of steroid-resistant and -sensitive asthmatic patients. Our most important findings are the following: In the case of C. pneumoniae seropositive patients we detected pronounced spontaneous interleukin (IL)-10 secretion and, in the case of steroid-resistant patients, IL-10 secretion was at a significantly higher level as compared with in-sensitive patients (p < 0.01). Furthermore, steroid-resistant seropositive patients produced a significantly higher level of IL-10 spontaneously and under antigen stimulation as compared with steroid-resistant seronegative individuals (p < 0.05). Concerning spontaneous TNF-α secretion by C. pneumoniae seropositive asthmatics, we observed that steroid-resistant patients produced significantly more of this cytokine than steroid-sensitive patients. In the steroid-resistant patients’ sera, a remarkably high MMP-9 concentration was associated with C. pneumoniae seronegativity. Our study revealed that the differences in the cytokine production in steroid-sensitive and -resistant asthmatic patients can be influenced by their C. pneumoniae serostatus.

Transcriptome sequencing reveals fibrotic associated-genes involved in bovine mammary fibroblasts with Staphylococcus aureus

Bovine mammary fibrosis represents a considerable health problem of cows, primarily indicated by lactation failure. Staphylococcus aureus (S. aureus) can cause mammary damage, this multifactorial disease necessitates to identify how and to what extent molecular pathogen defense mechanisms prevent bacterial infections in bovine mammary gland. In this study, we have aimed to determine the transcriptional responses in bovine mammary fibroblasts (BMFBs) induced by S. aureus using bioinformatics analysis to determine whether mRNA expression profile changes between BMFBs activation and quiescence. Established primary BMFBs obtained from healthy Holstein bovine were induced 10⁶ CFU/mL heat-inactivated S. aureus and total RNA was isolated 6 h after treatment. The 574 DEGs were involved in gene ontology (GO) that were immune response, apoptotic process, extracellular region, receptor binding, endopeptidase activity and protein kinase activity et al. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, distinct pathway contained signaling molecules common to various inflammatory and fibrotic pathways were Pathways in cancer, Cytokine-cytokine receptor interaction, PI3K-Akt signaling pathway, TNF signaling pathway, MAPK signaling pathway and Toll-like receptor signaling pathway. The BMFBs was treated with heat-inactivated S. aureus (10⁶ CFU/mL) and also with pharmacological inhibitors of ERK1/2, P38 MAPK and JNK. The MMP-2 activity were examined gelatin zymography, MMP-2, TIMP-1, -2 and PLAU/PAI-1 protein expression were examined in vitro by western blot. The MMP-2 activity was significantly inhibited by simultaneous inhibition of ERK1/2, P38 MAPK and JNK, and MMP-2, TIMP-1,-2 and PLAU/PAI-1 protein expression were significantly decreased by inhibiting ERK1/2, P38 MAPK or JNK. This suggested a crosstalk between the ERK1/2, P38 MAPK or JNK signaling pathways in regulating extracellular matrix metabolism in the BMFBs with S. aureus. Our study complement our initial study on S. aureus-induced responses by fibrosis-associated genes in BMFBs. This may lead to development of novel therapeutic targets to control bovine mammary fibrosis induced by S. aureus.

Mutual Regulation of TLR/NLR and CEACAM1 in the Intestinal Microvasculature: Implications for IBD Pathogenesis and Therapy

BACKGROUND

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) displays multiple activities, among which pathogen binding and angiogenesis are particularly prominent. These same functions are also exerted by Toll- and NOD-like receptors (TLRs and NLRs), which are critical mediators of innate immune responses. We investigated whether a functional inter-relationship exists between CEACAM1 and TLRs and NLRs and its potential impact on induction of intestinal angiogenesis.

METHODS

This hypothesis was tested using human intestinal microvascular endothelial cells, a unique cell population exposed to microbial products under physiological and pathological conditions.

RESULTS

The results show that activation of TLR2/4, TLR4, NOD1, and NOD2 by specific bacterial ligands selectively and differentially upregulates the levels of cellular and soluble CEACAM1 produced by intestinal microvascular endothelial cells. The results also show that CEACAM1 regulates the migration, transmigration, and tube formation of these endothelial cells and mediates vessel sprouting induced by specific TLR and NLR bacterial ligands. Combined, these results demonstrate a close and reciprocal regulatory interaction between CEACAM1 and bacterial products in mediating multiple functions essential to new vessel formation in the gut mucosa.

CONCLUSIONS

A coordinated and reciprocal interaction of CEACAM1 and microbiota-derived factors is necessary to optimize angiogenesis in the gut mucosa. This suggests that a coordination of endogenous and exogenous innate immune responses is necessary to promote intestinal angiogenesis under physiological and inflammatory conditions such as inflammatory bowel disease.

Chlamydia pneumoniae infection promotes monocyte transendothelial migration by increasing vascular endothelial cell permeability via the tyrosine phosphorylation of VE-cadherin

Migration of monocytes into the subendothelial layer of the intima is one of the critical events in early atherosclerosis. Chlamydia pneumoniae (C. pneumoniae) infection has been shown to promote monocyte transendothelial migration (TEM). However, the exact mechanisms have not yet been fully clarified. In this study, we tested the hypothesis that C. pneumoniae infection increases vascular endothelial cell (VEC) permeability and subsequent monocyte TEM through stimulating the tyrosine phosphorylation of vascular endothelial-cadherin (VE-cadherin). Here, we demonstrated that C. pneumoniae infection promoted monocyte TEM in a TEM assay possibly by increasing the permeability of a VEC line EA.hy926 cell as assessed by measuring the passage of FITC-BSA across a VEC monolayer. Subsequently, Western blot analysis showed that C. pneumoniae infection induced VE-cadherin internalization. Our further data revealed that Src-mediated VE-cadherin phosphorylation at Tyr658 was involved in C. pneumoniae infection-induced internalization of VE-cadherin, VEC hyperpermeability and monocyte TEM. Taken together, our data indicate that C. pneumoniae infection promotes monocyte TEM by increasing VEC permeability via the tyrosine phosphorylation and internalization of VE-cadherin in VECs.

The different dosages of estrogen affect endometrial fibrosis and receptivity, but not SDF-1/CXCR4 axis in the treatment of intrauterine adhesions

OBJECTIVE

The study was to evaluate whether fibrotic markers, endometrial receptivity markers and SDF-1/CXCR4 had been changed in the treatment of intrauterine adhesions (IUAs) by different dosages of estrogen.

STUDY DESIGN

A total of 39 patients with IUAs were treated with EV 4 mg or 9 mg randomly post-surgery. TGF-β1/MMP-9, VEGF/αvβ3 and SDF-1/CXCR4 were detected in endometrial tissue before and after treatment by real-time PCR and Western blot.

RESULTS

TGF-β1 and MMP-9 expression significantly decreased after treatment for 3 months than before (p < .05), the falling range was larger with EV 4 mg than 9 mg in the mild-moderate degree IUAs (p < .05); Integrin avβ3 expression significantly increased after treatment for 3 months than before (p < .05), the variation range was larger with EV 4 mg than 9 mg (p < .05); CXCR4 expression had no significant change after treatment 3 months compared to that before treatment (p > .05). SDF-1 presented an upward tendency at early phase, and it came back to the level of pre-surgery. But there were no significant difference between treatment with 4 mg and 9 mg in the rate of menstrual restoration and pregnancy follow-up 3 months after the treatment.

CONCLUSIONS

Endometrium fibrosis may be inhibited and endometrium receptivity may be improved by estrogen with moderate dosage therapy. Compared to the large one, it seems to be advantageous.

Lipopolysaccharide-binding protein is associated with arterial stiffness in patients with type 2 diabetes: a cross-sectional study

BACKGROUND

Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase reactant that mediates immune responses triggered by LPS. Recent evidence indicates the association of circulating LBP levels with obesity, diabetes, and cardiovascular diseases. In this study, we aimed to investigate the relationship between serum LBP levels and arterial stiffness in patients with type 2 diabetes.

METHODS

A total of 196 patients with type 2 diabetes, including 101 men and 95 women, were enrolled in this cross-sectional study. Fasting serum LBP levels were determined by enzyme-linked immunosorbent assay. Arterial stiffness was assessed by measuring the aortic pulse wave velocity (PWV).

RESULTS

The mean values of serum LBP and aortic PWV were 18.2 μg/mL and 1194 cm/s, respectively. Serum LBP levels were positively correlated with body mass index, triglycerides, high-sensitivity C-reactive protein, and insulin resistance index and were negatively correlated with high-density lipoprotein cholesterol. They were, however, not significantly correlated with aortic PWV in univariate analyses. Multivariate analysis revealed that serum LBP levels were independently and positively associated with aortic PWV (β = 0.135, p = 0.026) after adjusting for age, sex, body mass index, albumin, high-sensitivity C-reactive protein, and other cardiovascular risk factors. Further analyses revealed that the impact of serum LBP levels on aortic PWV was modified by sex, and the association between serum LBP levels and aortic PWV was found to be significant only in men.

CONCLUSIONS

Serum LBP levels are associated with arterial stiffness, independent of obesity and traditional cardiovascular risk factors, especially in men with type 2 diabetes. This study indicates a potential role of the LPS/LBP-induced innate immunity in the development and progression of arterial stiffness in type 2 diabetes.

Toll like receptor 4: an important molecule in recognition and induction of appropriate immune responses against Chlamydia infection

Chlamydia species are obligate intracellular pathogens causing different infectious diseases particularly asymptomatic genital infections and are also responsible for a wide range of complications. Previous studies showed that there are different immune responses to Chlamydia species and their infections are limited to some cases. Moreover, Chlamydia species are able to alter immune responses through modulating the expression of some immune system related molecules including cytokines. Toll like receptors (TLRs) belonge to pathogen recognition receptors (PRRs) and play vital roles in recognition of microbes and stimulation of appropriate immune responses. Therefore, it appears that TLRs may be considered as important sensors for recognition of Chlamydia and promotion of immune responses against these bacterial infections. Accordingly, TLR4 detects several microbial PAMPs such as bacterial lipopolysacharide (LPS) and subsequently activates transcription from pro-inflammatory cytokines in both MYD88 and TRIF pathways dependent manner. The purpose of this review is to provide the recent data about the status and major roles played by TLR4 in Chlamydia species recognition and promotion of immune responses against these infections and also the relationship between TLR4 activities and pathogenesis of Chlamydia infections.

The Balance Between Metalloproteinases and TIMPs: Critical Regulator of Microvascular Endothelial Cell Function in Health and Disease

Endothelial cells (EC), especially the microvascular EC (MVEC), have critical functions in health and disease. For example, healthy MVEC provide a barrier between the fluid and protein found within the blood, and the surrounding tissue. Following tissue injury or infection, the microvascular barrier is often disrupted due to activation and dysfunction of the MVEC. Multiple mechanisms promote MVEC activation and dysfunction, including stimulation by cytokines, mechanical interaction with activated leukocytes, and exposure to harmful leukocyte-derived molecules, which collectively result in a loss of MVEC barrier function. However, MVEC activation is also critical to facilitate recruitment of inflammatory cells, such as neutrophils (PMNs) and monocytes, into the injured or infected tissue. Metalloproteinases, including the matrix metalloproteinases (MMPs) and the closely related, a disintegrin and metalloproteinases (ADAMs), have been implicated in regulating both MVEC barrier function, through cleavage of adherens and tight junctions proteins between adjacent MVEC and through degradation of the extracellular matrix, as well as PMN-MVEC interaction, through shedding of cell surface PMN receptors. Moreover, the tissue inhibitors of metalloproteinases (TIMPs), which collectively inhibit most MMPs and ADAMs, are critical regulators of MVEC activation and dysfunction through their ability to inhibit metalloproteinases and thereby promote MVEC stability. However, TIMPs have been also found to modulate MVEC function through metalloproteinase-independent mechanisms, such as regulation of vascular endothelial growth factor signaling. This chapter is focused on examining the role of the metalloproteinases and TIMPs in regulation of MVEC function in both health and disease.

Quercetin attenuates atherosclerotic inflammation and adhesion molecule expression by modulating TLR-NF-κB signaling pathway

Adhesion molecules expressed by activated endothelial cells play key role in regulating leukocyte trafficking to sites of inflammation. The present study attempted to explore whether the polyphenolic flavonoid quercetin influence leukocyte endothelial attraction and the involvement of TLR-NF-κB signaling pathway in the expression of adhesion molecules involved in the early development of atherosclerosis. Quercetin at 25μM concentration significantly reduced the HUVEC expression of VCAM-1 and ICAM-1 evidently enhanced by oxLDL. In addition, quercetin significantly downregulated the mRNA expression of MCP-1 and alleviated the nuclear translocation of NF-κB p65 subunit in oxLDL induced HUVECs. Western blot and PCR analyses revealed that quercetin significantly attenuated the expression of both protein and mRNA expression of TLR2 and TLR4. Quercetin supplementation significantly decreased the inflammatory mediators like COX, 5-LOX, MPO, NOS, CRP and the mRNA expression of the cytokine; IL-6 in hypercholesterolemic diet (HCD) fed atherosclerotic rats. The results demonstrate that quercetin is effective to regulate the atherosclerotic inflammatory process by inhibiting oxLDL induced endothelial leukocyte adhesion by attenuating the TLR-NF-κB signaling pathway in endothelial cells and decrease the inflammatory process induced by HCD in rats. Therefore, quercetin acts as anti-inflammatory and anti-atherogenic agent, which may have implications for strategies attenuating endothelial dysfunction-related atherosclerosis.

Biophysical and Biochemical Outcomes of Chlamydia pneumoniae Infection Promotes Pro-atherogenic Matrix Microenvironment

Multiple studies support the hypothesis that infectious agents may be involved in the pathogenesis of atherosclerosis. Chlamydia pneumoniae is strongly implicated in atherosclerosis, but the precise role has been underestimated and poorly understood due to the complexity of the disease process. In this work, we test the hypothesis that C. pneumoniae-infected macrophages lodged in the subendothelial matrix contribute to atherogenesis through pro-inflammatory factors and by cell-matrix interactions. To test this hypothesis, we used a 3D infection model with freshly isolated PBMC infected with live C. pneumoniae and chlamydial antigens encapsulated in a collagen matrix, and analyzed the inflammatory responses over 7 days. We observed that infection significantly upregulates the secretion of cytokines TNF-α, IL-1β, IL-8, MCP-1, MMP, oxidative stress, transendothelial permeability, and LDL uptake. We also observed that infected macrophages form clusters, and substantially modify the microstructure and mechanical properties of the extracellular matrix to an atherogenic phenotype. Together, our data demonstrates that C. pneumoniae-infection drives a low-grade, sustained inflammation that may predispose in the transformation to atherosclerotic foci.

Relation between TLR4/NF-κB signaling pathway activation by 27-hydroxycholesterol and 4-hydroxynonenal, and atherosclerotic plaque instability

It is now thought that atherosclerosis, although due to increased plasma lipids, is mainly the consequence of a complicated inflammatory process, with immune responses at the different stages of plaque development. Increasing evidence points to a significant role of Toll-like receptor 4 (TLR4), a key player in innate immunity, in the pathogenesis of atherosclerosis. This study aimed to determine the effects on TLR4 activation of two reactive oxidized lipids carried by oxidized low-density lipoproteins, the oxysterol 27-hydroxycholesterol (27-OH) and the aldehyde 4-hydroxynonenal (HNE), both of which accumulate in atherosclerotic plaques and play a key role in the pathogenesis of atherosclerosis. Secondarily, it examined their potential involvement in mediating inflammation and extracellular matrix degradation, the hallmarks of high-risk atherosclerotic unstable plaques. In human promonocytic U937 cells, both 27-OH and HNE were found to enhance cell release of IL-8, IL-1β, and TNF-α and to upregulate matrix metalloproteinase-9 (MMP-9) via TLR4/NF-κB-dependent pathway; these actions may sustain the inflammatory response and matrix degradation that lead to atherosclerotic plaque instability and to their rupture. Using specific antibodies, it was also demonstrated that these inflammatory cytokines increase MMP-9 upregulation, thus enhancing the release of this matrix-degrading enzyme by macrophage cells and contributing to plaque instability. These innovative results suggest that, by accumulating in atherosclerotic plaques, the two oxidized lipids may contribute to plaque instability and rupture. They appear to do so by sustaining the release of inflammatory molecules and MMP-9 by inflammatory and immune cells, for example, macrophages, through activation of TLR4 and its NF-κB downstream signaling.

Role of gut microbiota in the modulation of atherosclerosis-associated immune response

Inflammation and metabolic abnormalities are linked to each other. At present, pathogenic inflammatory response was recognized as a major player in metabolic diseases. In humans, intestinal microflora could significantly influence the development of metabolic diseases including atherosclerosis. Commensal bacteria were shown to activate inflammatory pathways through altering lipid metabolism in adipocytes, macrophages, and vascular cells, inducing insulin resistance, and producing trimethylamine-N-oxide. However, gut microbiota could also play the atheroprotective role associated with anthocyanin metabolism and administration of probiotics and their components. Here, we review the mechanisms by which the gut microbiota may influence atherogenesis.

Shikonin inhibits the cell viability, adhesion, invasion and migration of the human gastric cancer cell line MGC-803 via the Toll-like receptor 2/nuclear factor-kappa B pathway

OBJECTIVES

Shikonin is an active naphthoquinone pigment isolated from the root of Lithospermum erythrorhizon. This study was designed to explore the inhibition of Shikonin on cell viability, adhesion, migration and invasion ability of gastric cancer (GC) and its possible mechanism.

METHODS

3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed for cell viability and adhesion ability of MGC-803 cells. Cell scratch repair experiments were conducted for the determination of migration ability while transwell assay for cell invasion ability. Western blot analysis and real-time polymerase chain reaction assay were used for the detection of protein and mRNA expressions.

KEY FINDINGS

Fifty per cent inhibitory concentration of Shikonin on MGC-803 cells was 1.854 μm. Shikonin (1 μm) inhibited significantly the adhesion, invasion and migratory ability of MGC-803 cells. Interestingly, Shikonin in the presence or absence of anti-Toll-like receptor 2 (TLR2) antibody (2 μg) and nuclear factor-kappa B (NF-κB) inhibitor MG-132 (10 μm) could decrease these ability of MGC-803 cells markedly, as well as the expression levels of matrix metalloproteinases (MMP)-2, MMP-7, TLR2 and p65 NF-κB. In addition, the co-incubation of Shikonin and anti-TLR2/MG-132 has a significant stronger activity than anti-TLR2 or MG-132 alone.

CONCLUSIONS

The results indicated that Shikonin could suppress the cell viability, adhesion, invasion and migratory ability of MGC-803 cells through TLR2- or NF-κB-mediated pathway. Our findings provide novel information for the treatment of Shikonin on GC.

Berberine inhibits Chlamydia pneumoniae infection-induced vascular smooth muscle cell migration through downregulating MMP3 and MMP9 via PI3K

The mechanisms by which Chlamydia pneumoniae infection promote vascular smooth muscle cell (VSMC) migration required in the development of atherosclerosis have not yet been fully clarified. Matrix metalloproteinases (MMPs) have important roles in VSMC migration. However, it is still unknown whether MMPs are involved in C. pneumoniae infection-induced VSMC migration. In addition, whether berberine can exert its inhibitory effects on the infection-induced VSMC migration also remains unclear. Accordingly, we investigated the effects of berberine on C. pneumoniae infection-induced VSMC migration and explored the possible mechanisms involved in this process. Herein, we found that C. pneumoniae infection could induce VSMC migration through Matrigel-coated membrane (P<0.05), which can be significantly inhibited by the broad-spectrum MMP inhibitor GM6001 (P<0.05). Our results also showed that C. pneumoniae infection upregulated both mRNA and protein expressions of MMP3 and MMP9 (P<0.05). The specific phosphoinositide 3-kinase (PI3K) inhibitor LY294002 significantly suppressed the increases in MMP3 and MMP9 protein expressions induced by C. pneumoniae infection (P<0.05). Further experiments showed that berberine significantly attenuated C. pneumoniae infection-induced VSMC migration (P<0.05). Moreover, berberine suppressed the protein expressions of MMP3 and MMP9 caused by C. pneumoniae infection in a dose-dependent manner (P<0.05). C. pneumoniae infection-induced increase in the phosphorylation level of Akt at Ser473 was inhibited by the treatment with berberine (P<0.05). Taken together, our data suggest that berberine inhibits C. pneumoniae infection-induced VSMC migration by downregulating the expressions of MMP3 and MMP9 via PI3K.

Contaminated open fracture and crush injury: a murine model

Modern warfare has caused a large number of severe extremity injuries, many of which become infected. In more recent conflicts, a pattern of co-infection with Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus has emerged. We attempted to recreate this pattern in an animal model to evaluate the role of vascularity in contaminated open fractures. Historically, it has been observed that infected bones frequently appear hypovascular, but vascularity in association with bone infection has not been examined in animal models. Adult rats underwent femur fracture and muscle crush injury followed by stabilization and bacterial contamination with A. baumannii complex and methicillin-resistant Staphylococcus aureus. Vascularity and perfusion were assessed by microCT angiography and SPECT scanning, respectively, at 1, 2 and 4 weeks after injury. Quantitative bacterial cultures were also obtained. Multi-bacterial infections were successfully created, with methicillin-resistant S. aureus predominating. There was overall increase in blood flow to injured limbs that was markedly greater in bacteria-inoculated limbs. Vessel volume was greater in the infected group. Quadriceps atrophy was seen in both groups, but was greater in the infected group. In this animal model, infected open fractures had greater perfusion and vascularity than non-infected limbs.

Gut-adipose tissue axis in hepatic fat accumulation in humans

BACKGROUND & AIMS

Recent evidence suggests that in animals gut microbiota composition (GMC) affects the onset and progression of hepatic fat accumulation. The aim of this study was to investigate in humans whether subjects with high hepatic fat content (HHFC) differ in their GMC from those with low hepatic fat content (LHFC), and whether these differences are associated with body composition, biomarkers and abdominal adipose tissue inflammation.

METHODS

Hepatic fat content (HFC) was measured using proton magnetic resonance spectroscopy ((1)H MRS). Fecal GMC was profiled by 16S rRNA fluorescence in situ hybridization and flow cytometry. Adipose tissue gene expression was analyzed using Affymetrix microarrays and quantitative PCR.

RESULTS

The HHFC group had unfavorable GMC described by lower amount of Faecalibacterium prausnitzii (FPrau) (p<0.05) and relatively higher Enterobacteria than the LHFC group. Metabolically dysbiotic GMC associated with HOMA-IR and triglycerides (p<0.05 for both). Several inflammation-related adipose tissue genes were differentially expressed and correlated with HFC (p<0.05). In addition, the expression of certain genes correlated with GMC dysbiosis, i.e., low FPrau-to-Bacteroides ratio.

CONCLUSIONS

HHFC subjects differ unfavorably in their GMC from LHFC subjects. Adipose tissue inflammation may be an important link between GMC, metabolic disturbances, and hepatic fat accumulation.

Chlamydia pneumoniae negatively regulates ABCA1 expression via TLR2-Nuclear factor-kappa B and miR-33 pathways in THP-1 macrophage-derived foam cells

OBJECTIVES

ATP-binding cassette transporter A1 (ABCA1) is critical in exporting cholesterol from macrophages and plays a protective role in the development of atherosclerosis. This study was to determine the effects and potential mechanisms of Chlamydia pneumoniae (C. pneumoniae) on ABCA1 expression and cellular cholesterol efflux in THP-1 macrophage-derived foam cells.

METHODS AND RESULTS

C. pneumoniae significantly decreased the expression of ABCA1 and reduced cholesterol efflux. Furthermore, we found that C. pneumoniae suppressed ABCA1 expression via up-regulation of miR-33s. The inhibition of C. pneumoniae-induced NF-κB activation decreased miR-33s expression and enhanced ABCA1 expression. In addition, C. pneumoniae increased Toll-like receptor 2 (TLR2) expressions, inhibition of which by siRNA could also block NF-κB activation and miR-33s expression, and promot the expression of ABCA1.

CONCLUSION

Taken together, these results reveal that C. pneumoniae may negatively regulate ABCA1 expression via TLR2-NF-κB and miR-33 pathways in THP-1 macrophage-derived foam cells, which may provide new insights for understanding the effects of C. pneumoniae on the pathogenesis of atherosclerosis.

Simultaneous transcriptional profiling of bacteria and their host cells

We developed an RNA-Seq-based method to simultaneously capture prokaryotic and eukaryotic expression profiles of cells infected with intracellular bacteria. As proof of principle, this method was applied to Chlamydia trachomatis-infected epithelial cell monolayers in vitro, successfully obtaining transcriptomes of both C. trachomatis and the host cells at 1 and 24 hours post-infection. Chlamydiae are obligate intracellular bacterial pathogens that cause a range of mammalian diseases. In humans chlamydiae are responsible for the most common sexually transmitted bacterial infections and trachoma (infectious blindness). Disease arises by adverse host inflammatory reactions that induce tissue damage & scarring. However, little is known about the mechanisms underlying these outcomes. Chlamydia are genetically intractable as replication outside of the host cell is not yet possible and there are no practical tools for routine genetic manipulation, making genome-scale approaches critical. The early timeframe of infection is poorly understood and the host transcriptional response to chlamydial infection is not well defined. Our simultaneous RNA-Seq method was applied to a simplified in vitro model of chlamydial infection. We discovered a possible chlamydial strategy for early iron acquisition, putative immune dampening effects of chlamydial infection on the host cell, and present a hypothesis for Chlamydia-induced fibrotic scarring through runaway positive feedback loops. In general, simultaneous RNA-Seq helps to reveal the complex interplay between invading bacterial pathogens and their host mammalian cells and is immediately applicable to any bacteria/host cell interaction.

Tight control - decision-making during T cell-vascular endothelial cell interaction

Vascular endothelial cells (ECs) form the inner layer of blood vessels and exert crucial functions during immune reactions including coagulation, inflammation, and regulation of innate immunity. Importantly, ECs can interact with T cells in an antigen-specific, i.e., T cell receptor-dependent manner. In this review, we will discuss EC actions and reactions during acute inflammation and focus on the interaction of T cells with ECs at two vascular sites: the high endothelial venule (HEV) of lymph nodes, and the vascular lesion during transplant vasculopathy (TV). HEVs are characterized by a highly active endothelium that produces chemoattracting factors and expresses adhesion molecules to facilitate transit of lymphocytes into the lymph node (LN) parenchyma. Yet, T cell-EC interaction at this anatomical location results neither in T cell activation nor tolerization. In contrast, the endothelium at sites of chronic inflammation, such as solid organ transplants, can promote T cell activation by upregulation of major histocompatibility complex (MHC) and costimulatory molecules. Importantly, a major function of ECs in inflamed tissues must be the maintenance of vascular integrity including the efficient attenuation of effector T cells that may damage the vascular bed. Thus, antigen-specific T cell-EC interaction is characterized by a tightly controlled balance between immunological ignorance, immune activation, and tolerization.