Allicin May Promote Reversal of T-Cell Dysfunction in Periodontitis via the PD-1 Pathway.

We evaluated the role of allicin in periodontitis using an in silico and in vitro design. An in silico docking analysis was performed to assess the plausible interactions between allicin and PD-L1. The cytokine profile of gingival crevicular fluid (GCF) samples obtained from periodontitis patients was estimated by cytometric bead array. CD3+ lymphocytes isolated from the peripheral blood were sorted and characterized using immunomagnetic techniques. Cultured and expanded lymphocytes were treated with the GCF samples to induce T-cell exhaustion. Optimum concentrations of allicin were added to exhausted lymphocytes to compare the expression of TIM-3 and LAG-3 gene expression at baseline and post-treatment. Allicin was found to bind to the PD-L1 molecule as revealed by the in-silico experiment, which is possibly an inhibitory interaction although not proven. GCF from periodontitis patients had significantly higher concentrations of TNF-α, CCL2, IL-6, IFN-γ, and CXCL8 than controls. GCF treatment of CD3+ lymphocytes from the periodontitis patients significantly increased expression of T-cell exhaustion markers TIM-3 and LAG-3. Allicin administration with GCF treatment resulted in significant lowering of the expression of exhaustion markers. Allicin may exert an immunostimulatory role and reverse immune-destructive mechanisms such as T-cell exhaustion.

Circ-HOMER1 enhances the inhibition of miR-1322 on CXCL6 to regulate the growth and aggressiveness of hepatocellular carcinoma cells.

Hepatocellular carcinoma (HCC) is a common liver malignancy worldwide accompanying with the high rate of recurrence. Accumulating reports have documented the significance of circular RNAs (circRNAs) in carcinogenesis and development of HCC. This study aimed to establish the mechanism underlying circ-HOMER1 involvement in HCC. To this end, we identified a binding site for miR-1322 via bioinformatics, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), and dual-luciferase reporter assays providing evidence of a direct link between circ-HOMER1 and miR-1322. Similarly, the target gene of miR-1322 was investigated. Moreover, we determined the specific function of circ-HOMER1 in HCC with the aid of qRT-PCR based on patient clinical records, Cell Counting Kit-8, acridine orange/ethidium bromide double fluorescence staining, flow cytometry, and wound-healing and transwell assays. Notably, circ-HOMER1 was upregulated in both HCC cells and tissues. This aberrant expression pattern was closely correlated with larger tumor size, higher tumor-node-metastasis stage, and poorer prognosis for the patients with HCC. Moreover, silenced circ-HOMER1 inhibited cell proliferation, migration, and invasion concomitant with the promotion of apoptosis in HCC cells, and vice versa. Mechanistically, circ-HOMER1 enhanced the inhibition of miR-1322 on CXCL6 in HCC. Furthermore, we found that circ-HOMER1 promoted HCC cell growth and aggressiveness by miR-1322/CXCL6 axis. This study may provide a potential prognostic indicator and therapeutic target for patients with HCC.

A distinct double positive IL-17A+/F+ T helper 17 cells induced inflammation leads to IL17 producing neutrophils in Type 1 reaction of leprosy patients.

Type 1 reactions (T1R) an inflammatory condition, of local skin patches in 30-40% leprosy patients during the course of MDT. IL-17A and IL-17F play an important role in regulating skin inflammation through neutrophils. In the present study, we have analyzed 18 of each T1R and Non-reactions (NR) patients through flow cytometry and qPCR. Interestingly we found that, CD3+CD4+ gated IL-17A+IL-17F+ cells were significantly high in T1R in both MLSA stimulated PBMCs and skin lesions as compared to NR leprosy patients. Hierarchical clustering analysis of gene expression showed that CXCL6, CXCL5, CCL20, CCL7, MMP13 and IL-17RB expression were significantly associated with IL-17A and IL-17F expression (Spearman r2 = 0.77 to 0.98), neutrophils and monocyte markers respectively. In this study, the inflammation noted in lesions of T1R is a different phenotype of Th17 which produce double positive IL-17A+IL17F+ and also contributes IL-17 producing neutrophils and thus would be useful for monitoring, diagnosis and treatment response before reactions episodes.

Gene expression pattern differences in primary human pulmonary epithelial cells infected with MERS-CoV or SARS-CoV-2.

Coronaviruses such as MERS-CoV and SARS-CoV-2 infect the human respiratory tract and can cause severe pneumonia. Disease severity and outcomes are different for these two infections: the human mortality rate for MERS-CoV and SARS-CoV-2 is over 30% and less than 10%, respectively. Here, using microarray assay, we analyzed the global alterations in gene expression induced by MERS-CoV or SARS-CoV-2 infections in primary human pulmonary epithelial cells. Overall, the number of differentially expressed genes was higher in human lung cells infected with MERS-CoV than in cells with SARS-CoV-2. Out of 44,556 genes analyzed, 127 and 50 were differentially expressed in cells infected with MERS-CoV and SARS-CoV-2, respectively (> 2-fold increase, compared to uninfected cells). Of these, only eight genes, including the one coding for CXCL8, were similarly modulated (upregulated or downregulated) by the two coronaviruses. Importantly, these results were virus-specific and not conditioned by differences in viral load, and viral growth curves were similar in human lung cells infected with both viruses. Our results suggest that these distinct gene expression profiles, detected early after infection by these two coronaviruses, may help us understand the differences in clinical outcomes of MERS-CoV and SARS-CoV-2 infections.

Pristane/Hypoxia (PriHx) Mouse as a Novel Model of Pulmonary Hypertension Reflecting Inflammation and Fibrosis.

BACKGROUND: Pulmonary arterial hypertension (PAH), particularly connective tissue disease-associated PAH (CTD-PAH), is a progressive disease and novel therapeutic agents based on the specific molecular pathogenesis are desired. In the pathogenesis of CTD-PAH, inflammation, immune cell abnormality, and fibrosis play important roles. However, the existing mouse pulmonary hypertension (PH) models do not reflect these features enough. The relationship between inflammation and hypoxia is still unclear.Methods and Results:Intraperitoneal administration of pristane, a kind of mineral oil, and exposure to chronic hypoxia were combined, and this model is referred to as pristane/hypoxia (PriHx) mice. Hemodynamic and histological analyses showed that the PriHx mice showed a more severe phenotype of PH than pristane or hypoxia alone. Immunohistological and flow cytometric analyses revealed infiltration of immune cells, including hemosiderin-laden macrophages and activated CD4+helper T lymphocytes in the lungs of PriHx mice. Pristane administration exacerbated lung fibrosis and elevated the expression of fibrosis-related genes. Inflammation-related genes such asIl6andCxcl2were also upregulated in the lungs of PriHx mice, and interleukin (IL)-6 blockade by monoclonal anti-IL-6 receptor antibody MR16-1 ameliorated PH of PriHx mice. CONCLUSIONS: A PriHx model, a novel mouse model of PH reflecting the pathological features of CTD-PAH, was developed through a combination of pristane administration and exposure to chronic hypoxia.

Molecular characterization of a new fish specific chemokine CXCL_F6 in large yellow croaker (Larimichthys crocea) and its role in inflammatory response.

Chemokines are a superfamily of structurally related chemotactic cytokines exerting significant roles in regulating cell migration and activation. Currently, five subgroups of fish specific CXC chemokines, named CXCL_F1-CXCL_F5, have been identified in teleost fish. However, understanding of the functions of these fish specific CXC chemokines is still limited. Here, a new member of fish specific CXC chemokines, LcCXCL_F6, was cloned from large yellow croaker Larimichthys crocea. Its open reading frame (ORF) is 369 nucleotides long, encoding a peptide of 122 amino acids (aa). The deduced LcCXCL_F6 protein contains a 19-aa signal peptide and a 103-aa mature polypeptide, which has four conserved cysteine residues (C28, C30, C56, and C72), as found in other known CXC chemokines. Phylogenetic analysis showed LcCXCL_F6 formed a separate clade with sequences from other fish species, tentatively named CXCL_F6, distinct from the clades formed by fish CXCL_F1-5 and mammalian CXC chemokines. The LcCXCL_F6 transcripts were constitutively expressed in all examined tissues and significantly up-regulated in the spleen and head kidney tissues by poly (I:C) and Vibrio alginolyticus. Its transcripts were also detected in primary head kidney leukocytes (HKLs), peripheral blood leucocytes (PBLs), and large yellow croaker head kidney (LYCK) cell line, and significantly up-regulated by poly(I:C), lipopolysaccharide (LPS), and peptidoglycan (PGN) in HKLs. Recombinant LcCXCL_F6 protein (rLcCXCL_F6) could not only chemotactically attract monocytes/macrophages and lymphocytes from PBLs, but also enhance NO release and expression of proinflammatory cytokines (TNF-α, IL-1ß, and CXCL8) in monocytes/macrophages. These results indicate that LcCXCL_F6 plays a role in mediating the inflammatory response.

CRISPR-Cas9-mediated functional dissection of 3'-UTRs.

Many studies using reporter assays have demonstrated that 3' untranslated regions (3'-UTRs) regulate gene expression by controlling mRNA stability and translation. Due to intrinsic limitations of heterologous reporter assays, we sought to develop a gene editing approach to investigate the regulatory activity of 3'-UTRs in their native context. We initially used dual-CRISPR (clustered, regularly interspaced, short palindromic repeats)-Cas9 targeting to delete DNA regions corresponding to nine chemokine 3'-UTRs that destabilized mRNA in a reporter assay. Targeting six chemokine 3'-UTRs increased chemokine mRNA levels as expected. However, targeting CXCL1, CXCL6 and CXCL8 3'-UTRs unexpectedly led to substantial mRNA decreases. Metabolic labeling assays showed that targeting these three 3'-UTRs increased mRNA stability, as predicted by the reporter assay, while also markedly decreasing transcription, demonstrating an unexpected role for 3'-UTR sequences in transcriptional regulation. We further show that CRISPR-Cas9 targeting of specific 3'-UTR elements can be used for modulating gene expression and for highly parallel localization of active 3'-UTR elements in the native context. Our work demonstrates the duality and complexity of 3'-UTR sequences in regulation of gene expression and provides a useful approach for modulating gene expression and for functional annotation of 3'-UTRs in the native context.

[The effect and mechanism of transient receptor potential M(2) in antigen-induced arthritis mice].

The purpose of this study was to explore the role and mechanism of transient receptor potential M(2) (TRPM(2)) in antigen-induced arthritis (AIA) mice. Twelve C57BL/6 mice and 12 TRPM(2) knockout mice were divided into 4 groups, includingwild type control group, wild type AIA group, TRPM(2) knockout control group and TRPM(2) knockout AIA group, with 6 mice in each group. Methylated bovine serum albumin (mBSA) was used to establish AIA mouse model. The degree of joint swelling and inflammatory cell infiltration were recorded, as well as synovial hyperplasia of the knee joints. Real-time quantitative polymerase chain reaction (PCR) was used to detect the expression of interleukin (IL)-6, IL-8, chemokine ligand 6 (CXCL-6) and tumor necrosis factor alpha (TNFα) mRNA in synovial cells of knee joints. The results showed that compared with the wild-type AIA group, the TRPM(2) knockout AIA group had more significant synovial proliferation and inflammatory cell infiltration in the synovial tissue.The neutrophil and macrophage counts rather than monocytes in the knee joints of TRPM(2) knockout AIA group were higher than those in wild-type AIA mice. The expression of IL-6, IL-8 and CXCL-6 mRNA were significantly increased in the knock out mice. In summary, TRPM(2) may inhibit inflammatory cytokines such as IL-6 and IL-8 in knee joints of AIA mice by reducing the infiltration of neutrophils and macrophages, the refore alleviates the manifestations of knee arthritis.

CXCL6-EGFR-induced Kupffer cells secrete TGF-ß1 promoting hepatic stellate cell activation via the SMAD2/BRD4/C-MYC/EZH2 pathway in liver fibrosis.

Liver fibrosis is the excessive accumulation of extracellular matrix proteins in response to the inflammatory response that accompanies tissue injury, which at an advanced stage can lead to cirrhosis and even liver failure. This study investigated the role of the CXC chemokine CXCL6 (GCP-2) in liver fibrosis. The expression of CXCL6 was found to be elevated in the serum and liver tissue of high stage liver fibrosis patients. Furthermore, treatment with CXCL6 (100 ng/mL) stimulated the phosphorylation of EGFR and the expression of TGF-ß in cultured Kupffer cells (KCs). Although treatment with CXCL6 directly did not activate the hepatic stellate cell (HSC) line, HSC-T6, HSCs cultured with media taken from KCs treated with CXCL6 or TGF-ß showed increased expression of α-SMA, a marker of HSC activation. CXCL6 was shown to function via the SMAD2/BRD4/C-MYC/EZH2 pathway by enhancing the SMAD3-BRD4 interaction and promoting direct binding of BRD4 to the C-MYC promoter and CMY-C to the EZH2 promoter, thereby inducing profibrogenic gene expression in HSCs, leading to activation and transdifferentiation into fibrogenic myofibroblasts. These findings were confirmed in a mouse model of CCl4 -induced chronic liver injury and fibrosis in which the levels of CXCL6 and TGF-ß in serum and the expression of α-SMA, SMAD3, BRD4, C-MYC, and EZH2 in liver tissue were increased. Taken together, our results reveal that CXCL6 plays an important role in liver fibrosis through stimulating the release of TGF-ß by KCs and thereby activating HSCs.

TSPAN12 is a critical factor for cancer-fibroblast cell contact-mediated cancer invasion.

Communication between cancer cells and their microenvironment controls cancer progression. Although the tumor suppressor p53 functions in a cell-autonomous manner, it has also recently been shown to function in a non-cell-autonomous fashion. Although functional defects have been reported in p53 in stromal cells surrounding cancer, including mutations in the p53 gene and decreased p53 expression, the role of p53 in stromal cells during cancer progression remains unclear. We herein show that the expression of α-smooth muscle actin (α-SMA), a marker of cancer-associated fibroblasts (CAFs), was increased by the ablation of p53 in lung fibroblasts. CAFs enhanced the invasion and proliferation of lung cancer cells when cocultured with p53-depleted fibroblasts and required contact between cancer and stromal cells. A comprehensive analysis using a DNA chip revealed that tetraspanin 12 (TSPAN12), which belongs to the tetraspanin protein family, was derepressed by p53 knockdown. TSPAN12 knockdown in p53-depleted fibroblasts inhibited cancer cell proliferation and invasion elicited by coculturing with p53-depleted fibroblasts in vitro, and inhibited tumor growth in vivo. It also decreased CXC chemokine ligand 6 (CXCL6) secretion through the ß-catenin signaling pathway, suggesting that cancer cell contact with TSPAN12 in fibroblasts transduced ß-catenin signaling into fibroblasts, leading to the secretion of CXCL6 to efficiently promote invasion. These results suggest that stroma-derived p53 plays a pivotal role in epithelial cancer progression and that TSPAN12 and CXCL6 are potential targets for lung cancer therapy.

CXCL16 regulates renal injury and fibrosis in experimental renal artery stenosis.

Recent studies have shown that inflammation plays a critical role in the initiation and progression of hypertensive kidney disease, including renal artery stenosis. However, the signaling mechanisms underlying the induction of inflammation are poorly understood. We found that CXCL16 was induced in the kidney in a murine model of renal artery stenosis. To determine whether CXCL16 is involved in renal injury and fibrosis, wild-type and CXCL16 knockout mice were subjected to renal artery stenosis induced by placing a cuff on the left renal artery. Wild-type and CXCL16 knockout mice had comparable blood pressure at baseline. Renal artery stenosis caused an increase in blood pressure that was similar between wild-type and CXCL16 knockout mice. CXCL16 knockout mice were protected from RAS-induced renal injury and fibrosis. CXCL16 deficiency suppressed bone marrow-derived fibroblast accumulation and myofibroblast formation in the stenotic kidneys, which was associated with less expression of extracellular matrix proteins. Furthermore, CXCL16 deficiency inhibited infiltration of F4/80(+) macrophages and CD3(+) T cells in the stenotic kidneys compared with those of wild-type mice. Taken together, our results indicate that CXCL16 plays a pivotal role in the pathogenesis of renal artery stenosis-induced renal injury and fibrosis through regulation of bone marrow-derived fibroblast accumulation and macrophage and T-cell infiltration.

Effects of Shenkangling intervention on the MAPK pathway in rats with doxorubicin-induced nephropathy.

Shenkangling plays a role of Yishenhuoxue effect for the treatment of children with nephrotic syndrome. The aim of this study was to investigate the effects of Shenkangling intervention on the mitogen-activated protein kinase (MAPK) pathway in rats with Adriamycin-induced nephropathy (AN) and its underlying mechanism of action. Nephrosis was induced in healthy Sprague-Dawley rats by doxorubicin and the rats were untreated or treated with prednisone, simvastatin, Shenkangling, or a combination thereof. Using real-time PCR, the mRNA expression levels of Chemokine (C-X-C motif) ligand 16 (CXCL16), A Disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), and ADAM17 in the renal tissues of these rats were found to be decreased by the various treatments compared to those in the untreated doxorubicin-induced nephrosis rats. To quantify the activation of the MAPK pathway, western blotting was used to detect the phosphorylation levels of MAPK pathway-associated proteins (p38, ERK1/2, SAPK/JNK) and nuclear factor (NF)-κB p65, which were reduced by the various treatments compared to those in the untreated doxorubicin-induced rats. Serum levels of transforming growth factor (TGF)-ß1, tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6, quantified by ELISA, were decreased by the various treatments compared to the levels in the untreated doxorubicin-induced nephrosis rats. The rats treated with prednisone, simvastatin, and Shenkangling showed the best outcome. The Chinese medicine Shenkangling that is known for nourishing the kidney and promoting blood circulation reduced urinary protein levels, increased serum albumin levels, and reduced cholesterol levels by reducing the release of CXCL16, ADAM10, ADAM17, TGF-ß1, TNF-α, IL-1ß, IL- 6, and other inflammatory mediators and inhibiting the activation of the MAPK signaling pathway, thereby effectively improving the state of nephropathy in AN rats. These results indicate that Shenkangling can be used clinically to treat nephropathy.

The chemokine receptor CXCR6 contributes to recruitment of bone marrow-derived fibroblast precursors in renal fibrosis.

Bone marrow-derived fibroblasts in circulation are of hematopoietic origin, and they proliferate, differentiate into myofibroblasts, and express the chemokine receptor CXCR6. As chemokines mediate the trafficking of circulating cells to sites of injury, we studied the role of CXCR6 in mouse models of renal injury. Significantly, the kidney of CXCR6 knockout mice accumulated fewer bone marrow-derived fibroblasts in response to injury, expressed less profibrotic chemokines and cytokines, displayed fewer myofibroblasts, and expressed less α-smooth muscle actin in the obstructed kidneys compared with wild-type (WT) mice. CXCR6 deficiency inhibited total collagen deposition and suppressed the expression of collagen I and fibronectin in the obstructed kidneys. Furthermore, WT mice engrafted with CXCR6(-/-) bone marrow cells displayed fewer bone marrow-derived fibroblasts in the kidneys with obstructive injury and showed less severe renal fibrosis compared with WT mice engrafted with CXCR6(+/+) bone marrow cells. Transplant of WT bone marrow into CXCR6(-/-) recipients restored recruitment of myeloid fibroblasts and susceptibility to fibrosis. Hematopoietic fibroblasts migrate into injured kidney and proliferate and differentiate into myofibroblasts. Thus, CXCR6, together with other chemokines and their receptors, may have important roles in the recruitment of bone marrow-derived fibroblast precursors into the kidney and contribute to the pathogenesis of renal fibrosis.

HIF-1α plays a role in the chemotactic migration of hepatocarcinoma cells through the modulation of CXCL6 expression.

BACKGROUND/AIMS: Hypoxia promotes the progression and metastasis of hepatocellular carcinoma (HCC). Hypoxia inducible factor-α (HIF-1α) regulates the expression of various chemokines involved in tumor growth, angiogenesis and metastasis. METHODS: The role of HIF-1α in HCC tumor growth and invasion and the prognosis of patients with HCC was investigated in cell lines and patient samples. HIF-1α mRNA and protein levels were assessed by qRT-PCR and western blotting. Silencing of HIF-1α downregulated the expression of granulocyte chemotactic protein-2 (GCP-2)/CXCL6, a CXC ELR+ chemokine, in HCC cells, and a luciferase assay showed that HIF-1α binds to a hypoxia response element in the promoter of CXCL6 and regulates its transcription. Induction of HIF-1α by hypoxia promoted the migration and invasion of HCC cells in vitro, and this effect was suppressed by an anti-CXCL6 antibody. RESULTS: HIF-1α is upregulated in HCC cell lines and tissues and its effect on promoting invasion and metastasis is mediated by its direct interaction with the pro-angiogenic chemokine CXCL6. CXCL6 expression was associated with poor prognosis of HCC patients. CONCLUSION: HIF-1α promotes HCC progression and metastasis by upregulating CXCL6 transcription in HCC cells, providing a potential novel therapeutic target for the treatment of HCC.

The chemokine CXCL6 restricts human trophoblast cell migration and invasion by suppressing MMP-2 activity in the first trimester.

STUDY QUESTION: Can the chemokine CXCL6 affect trophoblast cell migration and invasion in human first-trimester placenta? SUMMARY ANSWER: Chemokine CXCL6 inhibits trophoblast cell migration and invasion by suppressing matrix metalloproteinase (MMP)-2 activity in human first-trimester placenta. WHAT IS KNOWN ALREADY: Several chemokines including CXCL8, CXCL12, CXCL14, CXCL16, CX3CL1, CCL14 and CCL4 can promote or inhibit trophoblast cell migration and invasion in human first-trimester placenta. STUDY DESIGN, SIZE, DURATION: We used the trophoblast cell line HTR8/SVneo cells, primary trophoblast cells and villi explants to investigate the effect of rhCXCL6 on trophoblast cell migration and invasion. PARTICIPANTS/MATERIALS, SETTING, METHODS: First, the CXCL6 RNA transcript level was detected in HTR8/SVneo cells derived from human first-trimester, second-trimester and third-trimester placenta by RT-PCR. Protein expression of CXCL6 and its receptors was tested in first-trimester placenta by immunohistochemistry. Secreted CXCL6 protein was detected in HTR8/SVneo cell supernatants by enzyme-linked immunosorbent assay. Secondly, the effect of rhCXCL6 on HTR8/SVneo cell proliferation was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Thirdly, the effect of rhCXCL6 on cell migration and invasion of HTR8/SVneo cells, primary trophoblast cells and villi explants was tested by transwell migration and invasion assays, respectively. Last, MMP-2 and MMP-9 activity in the supernatants of HTR8/SVneo and primary trophoblast cells treated by rhCXCL6 in the invasion assay was assessed by gelatin zymography. MAIN RESULTS AND THE ROLE OF CHANCE: Abundance of the CXCL6 RNA transcript increased with pregnancy development. CXCL6 and its receptor were expressed in several cells at the human maternal-fetal interface. RhCXCL6 inhibited trophoblast cell migration and invasion by suppressing MMP-2 activity. LIMITATIONS, REASONS FOR CAUTION: These experiments are only in vitro. WIDER IMPLICATIONS OF THE FINDINGS: According to the literature, CXCL6 could promote tumour cell migration and invasion by accelerating MMP-9 activity. However, CXCL6 inhibited trophoblast cell migration and invasion by suppressing MMP-2 activity in human first-trimester interface. These data suggest that strict regulation of CXCL6 is required for normal migration and invasion of cells, such as those involved at the maternal-fetal interface.

TWEAK (tumor necrosis factor-like weak inducer of apoptosis) activates CXCL16 expression during renal tubulointerstitial inflammation.

TWEAK (tumor necrosis factor-like weak inducer of apoptosis) is a TNF superfamily cytokine that activates the fibroblast growth factor-inducible 14 (Fn14) receptor. Transcriptional analysis of experimental kidney tubulointerstitial inflammation showed a correlation between an upregulation of the mRNA for the transmembrane chemokine CXCL16, a T-cell chemoattractant, and Fn14 activation. Exogenous TWEAK increased mouse kidney CXCL16 expression and T-lymphocyte infiltration in vivo, processes inhibited by the NF-κB inhibitor parthenolide. Tubular cell CXCL16 was increased in a nephrotoxic tubulointerstitial inflammation model and neutralizing anti-TWEAK antibodies decreased this CXCL16 expression and lymphocyte infiltration. In human kidney biopsies with tubulointerstitial inflammation, tubular cell CXCL16 and Fn14 expressions were associated with inflammatory infiltrates. TWEAK upregulated CXCL16 mRNA expression in cultured renal tubular cells in an NF-κB-dependent manner and increased soluble and cellular CXCL16 protein. CXCL16 modestly promoted the expression of cytokines in tubular cells expressing its receptor (CXCR6) and appeared to synergize with TWEAK to promote an inflammatory response; however, it did not modulate tubular cell proliferation or survival. Thus, TWEAK upregulates the expression of the chemokine CXCL16 in tubular epithelium and this may contribute to kidney tubulointerstitial inflammation.

Overexpression of CXCL16 promotes a vulnerable plaque phenotype in Apolipoprotein E-Knockout Mice.

BACKGROUND: CXCL16 has been shown to be involved in atherosclerotic lesion development, but its role in preexisting lesions is still unclear. This study aims to assess the effect of CXCL16 on the stability of preexisting lesions. METHODS: We firstly measured plasma CXCL16 level in Apolipoprotein E-Knockout (ApoE KO) mice with either high-cholesterol diet (HCD) or normal diet (ND) by enzyme-linked immunosorbent assay (ELISA). Then, silastic collars were placed around the carotid arteries in HCD-ApoE KO mice to accelerate atherosclerotic lesions. Five weeks later, CXCL16 was overexpressed by intravenous injection of lentivirus carrying CXCL16 transgene. Two weeks after infection, lesions were stained with hematoxylin and eosin (HE) and with oil red O. Biomarkers in the lesions, such as MMPs, CCL2, VCAM-1 and TNF-α were measured by real-time polymerase chain reaction (RT-PCR), which indicate the instability of plaques. RESULTS: The level of CXCL16 in plasma was higher in HCD-ApoE KO mice as compared to ND-ApoE KO mice. Circulating CXCL16 overexpression does not affect the size of preexisting plaques, but it leads to vulnerable plaque morphology and increases the expression of markers of plaque destabilization. CONCLUSION: Systemic CXCL16 becomes much higher in atherosclerosis, and it could be a potential atherogenic biomarker. Overexpression of CXCL16 promotes the evolution of preexisting lesions to vulnerable plaques in ApoE KO mice.

Oxidized low-density lipoprotein and tissue factor are involved in monocrotaline/lipopolysaccharide-induced hepatotoxicity.

These studies were aimed at characterizing an animal model of inflammation-induced hepatotoxicity that would mimic features of idiosyncratic liver toxicity observed in humans. An attempt was made to identify oxidative damage and the involvement of coagulation system in liver after monocrotaline (MCT) administration under the modest inflammatory condition induced by lipopolysaccharide (LPS) exposure. Mice were given MCT (200 mg/kg) or an equivalent volume of sterile saline (Veh.) po followed 4 h later by ip injection of LPS (6 mg/kg) or vehicle. Mice co-treated with MCT and LPS showed increased plasma alanine aminotransferase (ALT), decrease in platelet number, and a reduction in hematocrit. Accumulation of oxidized low-density lipoprotein (ox-LDL) was remarkably higher in the liver sections of mice co-treated with MCT and LPS compared to those given MCT or LPS alone. A similar trend was observed in the expression of CXCL16 receptor in the same liver sections. Elevated expression of tissue factor (TF) and fibrinogen was also observed in the liver sections of MCT/LPS co-treated mice. The in vitro results showed that incubation of HepG2 cells with CXCL16 antibody strongly diminished uptake of ox-LDL. Expression of ox-LDL, CXCL16, and TF represents an early event in the onset of hepatotoxicity induced by MCT/LPS; thus, it may contribute to our understanding of idiosyncratic liver injury and points to potential targets for protection or intervention.

Potential Repressive Impact of microRNA-20a on Renal Tubular Damage in Diabetic Kidney Disease by Targeting C-X-C Motif Chemokine Ligand 6.

BACKGROUND AND AIMS: C-X-C Motif Chemokine Ligand 6 (CXCL6) is an important chemokine. We attempt in this investigation to explore its role and possible mechanism in diabetic kidney disease (DKD). METHODS: By intergrating GEO data, CXCL6 expression in DKD patients and normal controls was exhibited. miRWalk website and luciferase reporter assay were used to predict and verify the upstream miRNA of CXCL6. CCK-8 assay and flow cytometry were performed to detect proliferation and apoptosis capacities. The levels of inflammatory key factors (TNF-α, IL-6 and IL-8) were measured using ELISA analysis. Expression of CXCL6, miR-20a, and JAK/STAT3 pathway-related markers were detected by qRT-PCR or western blot assays. RESULTS: CXCL6 was increased in DKD. miR-20a was identified as an upstream regulatory miRNA of CXCL6, and its expression was decreased in DKD and HG-treated HK-2 cells. miR-20a overexpression facilitated the proliferation of HG-treated HK-2 cells, whereas miR-20a depletion exhibited the opposite phenomenon. The levels of TNF-α, IL-6 and IL-8 were increased by HG treatment in HK-2 cells. CXCL6 antagonized the promoting impacts of miR-20a mimics on HG-exposed HK-2 cell proliferation. The suppressive effect of miR-20a overexpression on apoptosis and inflammatory response of HG-induced HK-2 cell was rescued by CXCL6 enhancement. The protein expression of p-JAK and p-STAT3 were reduced by miR-20a mimic while facilitated by CXCL6 overexpression in HG-stimulated HK-2 cells. CONCLUSION: These consequences hinted that miR-20a might exert a repressive impact on DKD, possibly through targeting CXCL6 and mediating JAK/STAT3 pathway, which offer new targets for DKD treatment.

Chemokine CXCL16 regulates neutrophil and macrophage infiltration into injured muscle, promoting muscle regeneration.

Only a few specific chemokines that mediate interactions between inflammatory and satellite cells in muscle regeneration have been identified. The chemokine CXCL16 differs from other chemokines because it has both a transmembrane region and active, soluble chemokine forms. Indeed, we found increased expression of CXCL16 and its receptor, CXCR6, in regenerating myofibers. Muscle regeneration in CXCL16-deficient (CXCL16KO) mice was severely impaired compared with regeneration in wild-type mice. In addition, there was decreased MyoD and myogenin expression in regenerating muscle in CXCL16KO mice, indicating impaired satellite cell proliferation and differentiation. After 1 month, new myofibers in CXCL16KO mice remained significantly smaller than those in muscle of wild-type mice. To understand how CXCL16 regulates muscle regeneration, we examined cells infiltrating injured muscle. There were more infiltrating neutrophils and fewer macrophages in injured muscle of CXCL16KO mice compared with events in wild-type mice. Moreover, absence of CXCL16 led to different expression of cytokines/chemokines in injured muscles: mRNAs of macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta, and MIP-2 were increased, whereas regulated on activation normal T cell expressed and secreted, T-cell activation-3, and monocyte chemoattractant protein-1 mRNAs were lower compared with results in muscles of wild-type mice. Impaired muscle regeneration in CXCL16KO mice also resulted in fibrosis, which was linked to transforming growth factor-beta1 expression. Thus, CXCL16 expression is a critical mediator of muscle regeneration, and it suppresses the development of fibrosis.