Targeting the CXCL12/CXCR4 pathway to reduce radiation treatment side effects.

High precision, image-guided radiotherapy (RT) has increased the therapeutic ratio, enabling higher tumor and lower normal tissue doses, leading to improved patient outcomes. Nevertheless, some patients remain at risk of developing serious side effects.In many clinical situations, the radiation tolerance of normal tissues close to the target volume limits the dose that can safely be delivered and thus the potential for tumor control and cure. This is particularly so in patients being re-treated for tumor progression or a second primary tumor within a previous irradiated volume, scenarios that are becoming more frequent in clinical practice.Various normal tissue 'radioprotective' drugs with the potential to reduce side effects have been studied previously. Unfortunately, most have failed to impact clinical practice because of lack of therapeutic efficacy, concern about concurrent tumor protection or excessive drug-related toxicity. This review highlights the evidence indicating that targeting the CXCL12/CXCR4 pathway can mitigate acute and late RT-induced injury and reduce treatment side effects in a manner that overcomes these previous translational challenges. Pre-clinical studies involving a broad range of normal tissues commonly affected in clinical practice, including skin, lung, the gastrointestinal tract and brain, have shown that CXCL12 signalling is upregulated by RT and attracts CXCR4-expressing inflammatory cells that exacerbate acute tissue injury and late fibrosis. These studies also provide convincing evidence that inhibition of CXCL12/CXCR4 signalling during or after RT can reduce or prevent RT side effects, warranting further evaluation in clinical studies. Greater dialogue with the pharmaceutical industry is needed to prioritize the development and availability of CXCL12/CXCR4 inhibitors for future RT studies.

Chemokine CXCL14; a double-edged sword in cancer development.

Cancer is a leading cause of death worldwide and imposes a substantial financial burden. Therefore, it is essential to develop cost-effective approaches to inhibit tumor growth and development. The imbalance of cytokines and chemokines play an important role among different mechanisms involved in cancer development. One of the strongly conserved chemokines that is constitutively expressed in skin epithelia is the chemokine CXCL14. As a member of the CXC subfamily of chemokines, CXCL14 is responsible for the infiltration of immune cells, maturation of dendritic cells, upregulation of major histocompatibility complex (MHC)-I expression, and cell mobilization. Moreover, dysregulation of CXCL14 in several cancers has been identified by several studies. Depending on the type or origin of the tumor and components of the tumor microenvironment, CXCL14 plays a conflicting role in cancer. Although fibroblast-derived CXCL14 has a tumor-supportive role, epithelial-derived CXCL14 mainly inhibits tumor progression. Hence, this review will elucidate what is known on the mechanisms of CXCL14 and its therapeutic approaches in tumor treatment. CXCL14 is a promising approach for cancer immunotherapy.

MiR-4513 mediates the proliferation and apoptosis of oral squamous cell carcinoma cells via targeting CXCL17.

OBJECTIVE: Emerging evidence has indicated that microRNAs (miRNAs) play crucial roles in regulating cancer carcinogenesis; however, its role in oral squamous cell carcinoma (OSCC) remains largely unknown. Our work was aimed to investigate the role of miR-4513 in regulating OSCC cells behaviors. MATERIALS AND METHODS: MiR-4513 expression in OSCC cells was analyzed by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Cell proliferation, migration, invasion, and apoptosis were analyzed by the cell counting kit-8 (CCK-8) assay, wound-healing assay, transwell invasion assay, and flow cytometry, respectively. The connections of miR-4513 and CXC ligand 17 (CXCL17) were analyzed by luciferase reporter assay and Western blot assay. RESULTS: MiR-4513 expression was found elevated in the OSCC cell lines. The downregulation of miR-4513 expression inhibits cell proliferation, migration, invasion and, at the same time, promotes apoptosis. Furthermore, we validated CXCL17 as a direct target of miR-4513. Knocking down the expression of CXCL17, inhibited the effects of miR-4513 on OSCC cell behaviors. CONCLUSIONS: Our results suggested the oncogenic role of miR-4513 in OSCC, and therefore it might be used as a target for the OSCC treatment.

Novel Paracrine Functions of Smooth Muscle Cells in Supporting Endothelial Regeneration Following Arterial Injury.

RATIONALE: Regeneration of denuded or injured endothelium is an important component of vascular injury response. Cell-cell communication between endothelial cells and smooth muscle cells (SMCs) plays a critical role not only in vascular homeostasis but also in disease. We have previously demonstrated that PKCδ (protein kinase C-delta) regulates multiple components of vascular injury response including apoptosis of SMCs and production of chemokines, thus is an attractive candidate for a role in SMC-endothelial cells communication. OBJECTIVE: To test whether PKCδ-mediated paracrine functions of SMCs influence reendothelialization in rodent models of arterial injury. METHODS AND RESULTS: Femoral artery wire injury was performed in SMC-conditional Prkcd knockout mice, and carotid angioplasty was conducted in rats receiving transient Prkcd knockdown or overexpression. SMC-specific knockout of Prkcd impaired reendothelialization, reflected by a smaller Evans blue-excluding area in the knockout compared with the wild-type controls. A similar impediment to reendothelialization was observed in rats with SMC-specific knockdown of Prkcd. In contrast, SMC-specific gene transfer of Prkcd accelerated reendothelialization. In vitro, medium conditioned by AdPKCδ-infected SMCs increased endothelial wound closure without affecting their proliferation. A polymerase chain reaction-based array analysis identified Cxcl1 and Cxcl7 among others as PKCδ-mediated chemokines produced by SMCs. Mechanistically, we postulated that PKCδ regulates Cxcl7 expression through STAT3 (signal transducer and activator of transcription 3) as knockdown of STAT3 abolished Cxcl7 expression. The role of CXCL7 in SMC-endothelial cells communication was demonstrated by blocking CXCL7 or its receptor CXCR2, both significantly inhibited endothelial wound closure. Furthermore, insertion of a Cxcl7 cDNA in the lentiviral vector that carries a Prkcd shRNA overcame the adverse effects of Prkcd knockdown on reendothelialization. CONCLUSIONS: SMCs promote reendothelialization in a PKCδ-dependent paracrine mechanism, likely through CXCL7-mediated recruitment of endothelial cells from uninjured endothelium.

CXC family of chemokines as prognostic or predictive biomarkers and possible drug targets in colorectal cancer.

Colorectal cancer (CRC) is the third most common cancer in men and the second most common cancer in women, worldwide. In the early stages of the disease, biomarkers predicting early relapse would improve survival rates. In metastatic patients, the use of predictive biomarkers could potentially result in more personalized treatments and better outcomes. The CXC family of chemokines (CXCL1 to 17) are small (8 to 10 kDa) secreted proteins that attract neutrophils and lymphocytes. These chemokines signal through chemokine receptors (CXCR) 1 to 8. Several studies have reported that these chemokines and receptors have a role in either the promotion or inhibition of cancer, depending on their capacity to suppress or stimulate the action of the immune system, respectively. In general terms, activation of the CXCR1/CXCR2 pathway or the CXCR4/CXCR7 pathway is associated with tumor aggressiveness and poor prognosis; therefore, the specific inhibition of these receptors is a possible therapeutic strategy. On the other hand, the lesser known CXCR3 and CXCR5 axes are generally considered to be tumor suppressor signaling pathways, and their stimulation has been suggested as a way to fight cancer. These pathways have been studied in tumor tissues (using immunohistochemistry or measuring mRNA levels) or serum [using enzyme-linked immuno sorbent assay (ELISA) or multiplexing techniques], among other sample types. Common variants in genes encoding for the CXC chemokines have also been investigated as possible biomarkers of the disease. This review summarizes the most recent findings on the role of CXC chemokines and their receptors in CRC and discusses their possible value as prognostic or predictive biomarkers as well as the possibility of targeting them as a therapeutic strategy.

Identification of Potential Therapeutic Targets Among CXC Chemokines in Breast Tumor Microenvironment Using Integrative Bioinformatics Analysis.

BACKGROUND/AIMS: Breast cancer is a common cause of cancer mortality throughout the world. The cross-talk between cancer cells and interstitial cells exerts significant effects on neoplasia and tumor development and is modulated in part by chemokines. CXC is one of four chemokine families involved in mediating survival, angiogenesis, and immunosensitization by chemoattracting leukocytes, and it incentivizes tumor cell growth, invasion and metastasis in the tumor microenvironment. However, the differential expression profiles and prognostic values of these chemokines remains to be elucidated. METHODS: In this study, we compared transcriptional CXC chemokines and survival data of patients with breast carcinoma (BC) using the ONCOMINE dataset, Kaplan-Meier Plotter, TCGA and cBioPortal. RESULTS: We discovered increased mRNA levels for CXCL8/10/11/16/17, whereas mRNA expression of CXCL1/2/3/4/5/6/7/12/14 was lower in BC patients compared to non-tumor tissues. Kaplan-Meier plots revealed that high mRNA levels of CXCL1/2/3/4/5/6/7/12/14 correlate with relapse-free survival (RFS) in all types of BC patients. Conversely, high CXCL8/10/11 predicted worse RFS in BC patients. Significantly, high transcription levels of CXCL9/12/13/14 conferred an overall survival (OS) advantage in BC patients, while high levels of CXCL8 demonstrated shorter OS in all BC sufferers. CONCLUSIONS: Integrative bioinformatics analysis suggests that CXCL8/12/14 are potential suitable targets for precision therapy in BC patients compared to other CXC chemokines.

JN-2, a C-X-C motif chemokine receptor 3 antagonist, ameliorates arthritis progression in an animal model.

Rheumatoid arthritis (RA) is a chronic autoimmune disease that is characterized by uncontrolled joint inflammation and destruction of bone and cartilage. Previous studies have shown that C-X-C motif chemokine 10 (CXCL10) has important roles in RA development and that blocking CXCL10 expression effectively inhibits arthritis progression in animal models. However, clinical study using anti-CXCL10 monoclonal antibody (MDX-1100) to block CXCL10 expression in patients with RA did not show significant effectiveness. Therefore, we turned our attention to C-X-C motif chemokine receptor 3 (CXCR3), which is a receptor for CXCL9, CXCL10, and CXCL11, to treat RA. In the present study, administration of JN-2, our newly developed CXCR3 antagonist, ameliorated the progression of arthritis in a collagen-induced arthritis animal model. JN-2 also inhibited CXCR3-induced cell migration and pro-inflammatory cytokine expression of bone marrow-derived macrophages and CD4+ T cells in vitro. In addition, we found that CXCL10 formed an auto-amplification loop through activation of NFκB. Furthermore, Phosphorylation of p65 at serine 536 played an important role in the auto-amplification of CXCL10. Overall, the present results demonstrated that JN-2 decreased inflammation by inhibiting CXCR3-enhanced cell migration and pro-inflammatory cytokine expression, which then ameliorated arthritis progression.

Suppression of Antitumor Immune Responses by Human Papillomavirus through Epigenetic Downregulation of CXCL14.

UNLABELLED: High-risk human papillomaviruses (HPVs) are causally associated with multiple human cancers. Previous studies have shown that the HPV oncoprotein E7 induces immune suppression; however, the underlying mechanisms remain unknown. To understand the mechanisms by which HPV deregulates host immune responses in the tumor microenvironment, we analyzed gene expression changes of all known chemokines and their receptors using our global gene expression data sets from human HPV-positive and -negative head/neck cancer and cervical tissue specimens in different disease stages. We report that, while many proinflammatory chemokines increase expression throughout cancer progression, CXCL14 is dramatically downregulated in HPV-positive cancers. HPV suppression of CXCL14 is dependent on E7 and associated with DNA hypermethylation in the CXCL14 promoter. Using in vivo mouse models, we revealed that restoration of Cxcl14 expression in HPV-positive mouse oropharyngeal carcinoma cells clears tumors in immunocompetent syngeneic mice, but not in Rag1-deficient mice. Further, Cxcl14 reexpression significantly increases natural killer (NK), CD4(+) T, and CD8(+) T cell infiltration into the tumor-draining lymph nodes in vivo In vitro transwell migration assays show that Cxcl14 reexpression induces chemotaxis of NK, CD4(+) T, and CD8(+) T cells. These results suggest that CXCL14 downregulation by HPV plays an important role in suppression of antitumor immune responses. Our findings provide a new mechanistic understanding of virus-induced immune evasion that contributes to cancer progression. IMPORTANCE: Human papillomaviruses (HPVs) are causally associated with more than 5% of all human cancers. During decades of cancer progression, HPV persists, evading host surveillance. However, little is known about the immune evasion mechanisms driven by HPV. Here we report that the chemokine CXCL14 is significantly downregulated in HPV-positive head/neck and cervical cancers. Using patient tissue specimens and cultured keratinocytes, we found that CXCL14 downregulation is linked to CXCL14 promoter hypermethylation induced by the HPV oncoprotein E7. Restoration of Cxcl14 expression in HPV-positive cancer cells clears tumors in immunocompetent syngeneic mice, but not in immunodeficient mice. Mice with Cxcl14 reexpression show dramatically increased natural killer and T cells in the tumor-draining lymph nodes. These results suggest that epigenetic downregulation of CXCL14 by HPV plays an important role in suppressing antitumor immune responses. Our findings may offer novel insights to develop preventive and therapeutic tools for restoring antitumor immune responses in HPV-infected individuals.

CXCL14 antagonizes the CXCL12-CXCR4 signaling axis.

CXCL12 and CXCL14 are evolutionarily conserved members of the CXC-type chemokine family. CXCL12 binds specifically to the G-protein-coupled receptor CXCR4 to induce the migration of primordial germ cells, hematopoietic stem cells, and inflammation-associated immune cells. In addition, CXCL12-CXCR4 signaling is often enhanced in malignant tumor cells and facilitates increased proliferation as well as metastasis. Although macrophage migration inhibitory factor and extracellular ubiquitin interact with CXCR4 as agonistic factors, CXCL12 was believed to be the sole chemokine ligand for CXCR4. However, a very recent report revealed that CXCL14 binds to CXCR4 with high affinity and efficiently inhibits CXCL12-mediated chemotaxis of hematopoietic progenitor and leukemia-derived cells. CXCL14 does not directly cross-compete with CXCL12 for the CXCR4 binding but instead inactivates CXCR4 via receptor internalization. Because both CXCL12 and CXCL14 are expressed during embryogenesis and brain development in mice, these two chemokines could function in an interactive fashion. We propose that the CXCL14 gene has been conserved from fish to man due to its role in fine-tuning the strength of CXCL12-mediated signal transduction. In addition to its biological implications, the above finding will be important for designing anti-cancer compounds targeting the CXCL12-CXCR4 signaling axis. In fact, a stabilized dimeric peptide containing the C-terminal 51-77 amino acid residues of CXCL14 has been shown to have stronger CXCL12 antagonistic activity than full-length CXCL14.

CXCL16 and CXCR6 are coexpressed in human lung cancer in vivo and mediate the invasion of lung cancer cell lines in vitro.

Despite advances in early diagnosis and multimodality therapy for cancers, most of lung cancer patients have been locally advanced or metastatic at the time of diagnosis, suggesting the highly progressive characteristic of lung cancer cells. The mechanisms underling invasiveness and metastasis of lung cancer are yet to be elucidated. In the present study, immunohistochemistry was performed to detect the expression of CXCL16-CXCR6 in human lung cancer tissues. It was demonstrated that similar to CXCL12 and CXCR4, CXCL16 and CXCR6 were also coexpressed in human primary lung cancer tissues. After confirming the functional existence of CXCL16 and CXCR6 protein in A549, 95D and H292 cells by ELSA and flow cytometry analysis, we further explored the significance of CXCL16-CXCR6 axis in the biological functions of lung cancer cell lines in vitro. It was found that CXCL16 had no effects on the PCNA (proliferating cell nuclear antigen) expression of A549, 95D and H292 cells. However, both exogenous CXCL16 and CM (conditioned medium from A549, 95D or H292) significantly improved the in vitro viability and invasion of three lung cancer cell lines. The neutralizing antibody to CXCL16 or down-regulation of CXCR6 was able to inhibit the increased viability and invasiveness of A549, 95D and H292 cells stimulated by CXCL16 or CM. Our results imply that CXCL16-CXCR6 axis is involved in the regulation of viability and invasion rather than PCNA expression of lung caner cells, which opens the door for better understanding the mechanisms of lung tumor progression and metastasis.

CXCL3 is a potential target for breast cancer metastasis.

Secreted proteins are an attractive minefield for cancer drug targets. An iTRAQ-based tandem mass spectrometry approach was employed to relatively quantify proteins in the secretomes of four isogenic breast cancer cell lines with increasing metastatic potential. CXCL3 was found to be upregulated in aggressive cancer cells. SiRNA and antibody neutralization studies supported a role of CXCL3 in metastatic processes. Meta-analysis of the mRNA level of CXCL3 in 1881 breast tumors supported a role of CXCL3 in clinical breast cancer. Our results support a functional role of CXCL3 in breast cancer metastasis and as a viable target for cancer therapy.

ELR-CXC chemokine antagonism and cisplatin co-treatment additively reduce H22 hepatoma tumor progression and ameliorate cisplatin-induced nephrotoxicity.

Cisplatin (cis-diamminedichloroplatinum) is one of the most commonly used agents for the chemotherapy of various types of cancers, but its use is limited by its dose-dependent side-effects (e.g., nephrotoxicity). The ELR-CXC chemokines are potent tumor growth, metastatic and angiogenic factors and can foster tumor resistance to chemotherapeutic agents. They are also potent proinflammatory agents. The aim of the present study was to evaluate the added effects of combining cisplatin chemotherapy with ELR-CXC chemokine antagonism in a mouse H22 hepatoma cancer cell model. The mice were injected with tumor cells and were then treated with cisplatin (12.5 or 2 mg/kg doses), either alone or together with the chemokine antagonist CXCL8(3-72)K11R/G31P (G31P) (50 µg/kg). At varying time-points renal function was examined using blood urea nitrogen (BUN) and serum creatinine (SCr) as read-outs for the toxic effects of cisplatin, while tumor growth and metastasis were assessed as endpoints. High-dose cisplatin therapy reduced the tumor burden by 52%, while co-delivery of G31P further augmented the tumor growth-suppressive effects of this dose of cisplatin to 71%; G31P by itself and low-dose cisplatin reduced the tumor burden by 19 and 39%, respectively. G31P also reduced the nephrotoxic effects of high-dose cisplatin to the effects observed in the low-dose cisplatin-treated animals. These data confirm the beneficial effects of combined cisplatin chemotherapy and ELR-CXC chemokine anatagonism in the context of both tumor progression and adverse side-effects.

Targeting the chemokines in cardiac repair.

Chemokines are a family of chemotactic cytokines that play an essential role in leukocyte trafficking. Upregulation of both CC and CXC chemokines is a hallmark of the inflammatory and reparative response following myocardial infarction. Release of danger signals from dying cells and damaged extracellular matrix activates innate immune pathways that stimulate chemokine synthesis. Cytokineand chemokine-driven adhesive interactions between endothelial cells and leukocytes mediate extravasation of immune cells into the infarct. CXC chemokines (such as interleukin-8) are bound to glycosaminoglycans on the endothelial surface and activate captured neutrophils, inducing expression of integrins. CC chemokines (such as monocyte chemoattractant protein (MCP)-1) mediate recruitment of proinflammatory and phagocytotic mononuclear cells into the infarct. CC Chemokines may also regulate late infiltration of the healing infarct with inhibitory leukocytes that suppress inflammation and restrain the post-infarction immune response. Non-hematopoietic cells are also targeted by chemokines; in healing infarcts, the CXC chemokine Interferon-γ inducible Protein (IP)-10 exerts antifibrotic actions, inhibiting fibroblast migration. Another member of the CXC subfamily, Stromal cell-derived Factor (SDF)-1, may protect the infarcted heart by activating pro-survival signaling in cardiomyocytes, while exerting angiogenic actions through chemotaxis of endothelial progenitors. Several members of the chemokine family may be promising therapeutic targets to attenuate adverse remodeling in patients with myocardial infarction.

Characterization of contraction-induced IL-6 up-regulation using contractile C2C12 myotubes.

Muscle contractile activity functions as a potent stimulus for acute interleukin (IL)-6 expression in working skeletal muscles. Recently, we established an "in vitro contraction model" using highly-developed contractile C2C12 myotubes by applying electric pulse stimulation (EPS). Herein, we characterize the effects of EPS-evoked contraction on IL-6 expression in contractile C2C12 myotubes. Both secretion and mRNA expression of IL-6 were significantly up-regulated by EPS in a frequency-dependent manner in contracting myotubes during a 24-h period, and the response was blunted by cyclosporine A, a calcineurin inhibitor. Longer time (~12h) was required for the induction of IL-6 after the initiation of EPS as compared to that of other contraction-inducible CXC chemokines such as CXCL1/KC, which were induced in less than 3 hours. Furthermore, these acute inducible CXC chemokines exhibited no autocrine effect on IL-6 expression. Importantly, contraction-dependent IL-6 up-regulation was markedly suppressed in the presence of high levels of glucose along with increased glycogen accumulations. Experimental manipulation of intracellular glycogen contents by modulating available glucose or pyruvate during a certain EPS period further established the suppressive effect of glycogen accumulations on contraction-induced IL-6 up-regulation, which appeared to be independent of calcineurin activity. We also document that EPS-evoked contractile activity improved insulin-responsiveness in terms of intracellular glycogen accumulations. Taken together, these data provide important insights into the regulation of IL-6 expression in response to contractile activity of muscle cells, which is difficult to examine using in vivo experimental techniques. Our present results thus expand the usefulness of our "in vitro contraction model".

The CXCR4/SDF-1 chemokine axis: a potential therapeutic target for bone metastases?

Chemokines and chemokine receptors play diverse roles in homeostasis. The chemokine stromal cell-derived factor 1 (SDF-1) and its receptor CXCR4 have critical functions in the immune, circulatory, and central nervous systems and have also been implicated in tumor biology and metastasis. Here we review the current data regarding the role of the CXCR4/SDF-1 chemokine axis in the development of bone metastases, derived from tumor models of breast or prostate cancers. There is substantial evidence that CXCR4 and SDF-1 directly influence the survival and proliferation of tumor cells. In regards to bone metastases, the CXCR4/SDF-1 axis also appears to facilitate tumor cell recruitment to the bone marrow microenvironment via a homing mechanism. This makes disruption of the chemokine axis an attractive therapeutic target for the prevention of tumor cell spread to bone. However, within the bone microenvironment, SDF-1 and CXCR4 appear to have conflicting roles. While genetic disruption of CXCR4 enhances osteoclast activity and therefore stimulates tumor cell growth in the bone - likely via release of bone-derived growth factors - SDF-1 has been shown to have either a stimulatory effect or no effect on osteoclasts. In short, the effects of the CXCR4/SDF-1 axis on tumor cell growth within the bone are not yet fully defined. Further, there are theoretical risks that blockade of this chemokine axis could impair immune function or mobilize tumor cells leading to other sites of metastasis. As such, caution should be taken when designing therapeutic strategies targeting this chemokine axis.

A novel ELR-CXC chemokine antagonist reduces intestinal ischemia reperfusion-induced mortality, and local and remote organ injury.

BACKGROUND: Neutrophil sequestration plays an important role in mediating local and remote organ injury induced by ischemia and reperfusion (I/R). The Glu-Leu-Arg (ELR)-CXC subfamily of chemokines, all CXCR1 or CXCR2 ligands, are primary agonists for such neutrophil recruitment. Herein, we assessed the effects of a combined CXCR1/CXCR2 antagonist, CXCL8((3-72))K11R/G31P (G31P), on neutrophilic local (gut) and distant organ injury and outcomes after superior mesenteric artery I/R in rats. METHODS: Male Sprague-Dawley rats (n=6-10) were subjected to either sham treatment or superior mesenteric artery ischemia for 1h; all animals received either saline or G31P (500 mug/kg, s.c.) and were euthanized for assessment after either 2 or 5h of arterial reperfusion. Survival and gut pathology, and pulmonary neutrophils were assessed directly, while bronchoalveolar lavage (BAL) fluid total protein levels and red blood cell (RBC) numbers were determined by protein assay and direct counting. Expression of inflammatory mediators in the lung and jejunum was measured by quantitative RT-PCR, colorimetric or gel zymography assays. RESULTS: Sham treatment animals suffered no discernible gut or pulmonary pathology. At 2 and 5h after reperfusion, the survival levels of the saline-treated I/R injury animals were 80% and 50%, respectively, while all G31P-treated animals survived. I/R injury led to substantial villous pathology within the jejunum, and G31P significantly reduced these pathology scores as well as neutrophil infiltration of the jejunal lamina propria and lung parenchyma, and vascular leakage into the airways (BAL protein). The tissue injury increased expression of myeloperoxidase and matrix metalloproteinase (MMP)-2 and MMP-9 in the gut tissues, but G31P treatment did not significantly affect this response. Intestinal I/R increased expression of IL-1, IL-6, GRO, and MIP-2 in the ischemic jejunum and the lung tissues, but here too G31P treatment had no palliative effects on these responses. CONCLUSION: These results suggest that full-spectrum ELR-CXC chemokine antagonism has significant protective effects against I/R-induced local and remote organ injury.

Amelioration of pathology by ELR-CXC chemokine antagonism in a swine model of airway endotoxin exposure.

Airborne organic dusts in swine confinement facilities have detrimental effects on workers health. Bacterial endotoxins (i.e., lipopolysaccharides [LPS]) that contaminate these dusts have been implicated in their pro-inflammatory effects in the airways. Exposure to such dusts induces expression of ELR-CXC chemokines (e.g., interleukin [IL]-8), prototypical neutrophil chemoattractants and activators, and neutrophilic pathology. To confirm the roles of the ELR-CXC chemokines in LPS-driven airway pathology, the authors exposed swine to bacterial LPS and tested whether blocking ELR-CXC chemokines would have beneficial effects. Delivery of the ELR-CXC chemokine antagonist CXCL8(3-74)K11R/G31P (G31P) blocked reactive oxygen intermediate production and chemotactic responses by IL-8-challenged neutrophils in vitro. In vivo, one treatment with G31P (100 microg/kg) blocked neutrophil inflammatory responses to intradermal LPS challenge for > or =2 days. It also ameliorated pathology in piglets challenged via the airway with 1 mg of Eschericia coli LPS. On physical examination the saline-treated endotoxemic animals were depressed, pyrexic, and displayed labored breathing, whereas the G31P-treated animals were bright, active, and alert and had a low-grade fever and occasional cough. The lungs of the saline-treated animals displayed evidence of pleural surface hemorrhagic consolidation, and their airways contained large numbers of neutrophils (>80%) as well as substantial amounts of tumor necrosis factor (TNF) and IL-1. The G31P treatments of the LPS-challenged piglets reduced their airway neutrophilic inflammatory responses by approximately 86% and reduced the airway TNF (approximately 70%) and IL-1 (approximately 83%) levels. These data implicates the ELR-CXC chemokines in the neutrophilic inflammation observed after airways exposure to bacterial LPS.

Potent and broad-spectrum antimicrobial activity of CXCL14 suggests an immediate role in skin infections.

The skin is constantly exposed to commensal microflora and pathogenic microbes. The stratum corneum of the outermost skin layer employs distinct tools such as harsh growth conditions and numerous antimicrobial peptides (AMPs) to discriminate between beneficial cutaneous microflora and harmful bacteria. How the skin deals with microbes that have gained access to the live part of the skin as a result of microinjuries is ill defined. In this study, we report that the chemokine CXCL14 is a broad-spectrum AMP with killing activity for cutaneous gram-positive bacteria and Candida albicans as well as the gram-negative enterobacterium Escherichia coli. Based on two separate bacteria-killing assays, CXCL14 compares favorably with other tested AMPs, including human beta-defensin and the chemokine CCL20. Increased salt concentrations and skin-typical pH conditions did not abrogate its AMP function. This novel AMP is highly abundant in the epidermis and dermis of healthy human skin but is down-modulated under conditions of inflammation and disease. We propose that CXCL14 fights bacteria at the earliest stage of infection, well before the establishment of inflammation, and thus fulfills a unique role in antimicrobial immunity.

The role of CXCL16 and its processing metalloproteinases ADAM10 and ADAM17 in the proliferation and migration of human mesangial cells.

In this study, we analyzed the regulation and functional role of CXCL16 in human mesangial cells (hMCs). We can show, that CXCL16 is constitutively expressed in hMCs and is further up-regulated by cytokine mix (IFNgamma, TNFalpha, and IL1beta). The constitutive release of CXCL16 from hMCs was rapidly induced by the stimulation with cytokines. We identified ADAM10 and ADAM17 as being responsible for the cytokine-induced shedding of CXCL16. Notably, targeting ADAM10 and ADAM17 in hMCs decreased the chemotaxis of T-Jurkat cells, whereas the inhibition of CXCL16 had no significant influence. This suggests that both proteases are important players in the recruitment of immune cells into the glomerulus, but other substrates than CXCL16 are involved in this process. Finally, we could show that the inhibition of CXCL16, ADAM10, and ADAM17 led to a strong reduction of cell proliferation and migration of hMCs. This finding could be important to develop novel diagnostic and therapeutic strategies to treat mesangial proliferative kidney diseases.