Role Of CXC Chemokine Receptor Research Articles

Risk Stratification in Acute Myeloid Leukemia Using CXCR Gene Signatures: A Bioinformatics Analysis.

The role of CXC chemokine receptors in tumors has been an increasingly researched focus in recent years. However, significant prognostic values of CXCR members in acute myeloid leukemia are yet to be explored profoundly. In this study, we firstly made an analysis of the relationship of CXCR family members and AML using samples from TCGA. Our results suggested that transcriptional expressions of CXCRs serve an important role in AML. CXCR transcript expressions, except CXCR1 expression, were significantly increased in AML. It displayed the expression pattern of CXCR members in different AML subtypes according to FAB classification. The correlations of CXCR transcript expression with different genotypes and karyotypes were also present. High CXCR2 expression was found to have a significantly worse prognosis compared with that of low CXCR2 expression, and CXCR2 was also found to be an independent prognostic factor. We also established a CXCR signature to identify high-risk subgroups of patients with AML. It was an independent prognostic factor and could become a powerful method to predict the survival rate of patients.

Prognostic and Predictive Role of CXC Chemokine Receptor 4 in Metastatic Colorectal Cancer Patients.

Colorectal cancer (CRC) is the third leading cause of cancer-related death worldwide. About 30% of patients present with metastatic disease involving predominantly the liver and a similar percentage will develop distant metastases later after removal of the primary tumor. In metastatic CRC, chemotherapies and biological drugs have prolonged survival for up to 30 months. However, there is a great need for biomarkers predictive of response and prognosis to optimize treatments. CXC chemokine receptor 4 (CXCR4) is a chemokine receptor; it binds to CXCL12 and plays a central role in colon cancer cells' growth and dissemination. CXCR4 was evaluated in CRC primary tissues by immunohistochemistry. Formalin-fixed, paraffin-embedded 4-μm tissue sections were immunostained using a biotin-streptavidin-peroxidase method and categorized into 2 semiquantitative classes: (i) absence of staining, ≤50% positive cells (negative/low) and (ii) >50% positive cells (high). Associations between clinic-pathologic variables and CXCR4 expression were evaluated using the χ test. The Kaplan-Meier product-limit method was applied to graph overall survival (OS). OS was defined as the time elapsed from diagnosis to death from any cause. Univariate analysis was carried out using the log-rank test. Cox proportional hazards regression was used to analyze the effect of several risk factors on OS. Seventy-eight primary adenocarcinomas were analyzed; 26 were categorized as negative/low and 52 as high. Age, sex, performance status, site of metastases, KRAS mutational status, type of first-line therapy, and a number of therapy lines did not correlate with CXCR4 expression. Although not significant (P=0.0533), high CXCR4 expression was more frequently localized on the right side of the colon. Significant correlations were detected with grading (P=0.0041) and response to first-line anti-epidermal growth factor receptors agents (P<0.0001), bevacizumab (P=0.0029), and chemotherapy alone (P=0.0260). At a median follow-up of 53 months, 77 deaths have been registered. Grading [hazard ratio (HR): 1.42; confidence interval (CI): 0.89-2.28; P<0.0001], KRAS mutational status (HR: 1.73; CI: 1.03-290; P=0.0133), response to first-line chemotherapy (HR: 3.39; CI: 2.10-5.48; P<0.0001), and CXCR4 expression (HR: 3.18; CI: 2.01-5.02; P<0.0001) showed prognostic power at univariate and multivariate analyses. In the present report, we show that CXCR4 expression on the primary tumor is an independent prognostic factor and correlates with response to first-line chemotherapy in metastatic CRC patients.

Characterization of the prognostic values of CXCR family in gastric cancer

IntroductionThe role of CXC chemokine receptors (CXCRs) in gastric cancer (GC) has been an increasing focus. However, comprehensive prognostic values of CXCR members in GC are yet to be clearly defined. MethodsMultiple public available datasets, including Kaplan-Meier (KM) plotter, oncomine, the cancer genome atlas (TCGA), SurvExpress platform and the tumor immune estimation resource (TIMER), were used for mRNA expression and prognostic characterization. Nomogram method was used for clinical model prediction. ResultsCXCR3, CXCR4 and CXCR5 displayed significantly up-regulated expression in tumor compared to normal. High mRNA expression of CXCR2 (HR = 0.77, 95%CI: 0.62–0.95, p = 0.014), CXCR3 (HR = 0.74, 95%CI: 0.61–0.90, p = 0.0024), CXCR4 (HR = 0.7, 95%CI: 0.58–0.86, p = 0.00048), CXCR5 (HR = 0.72, 95%CI: 0.59–0.87, p = 0.00093) and CXCR6 (HR = 0.66, 95%CI: 0.54–0.81, p = 4.9e−05) was significantly associated with favorable overall survival (OS). The prognostic values of CXCR members were also explored in subtypes, including HER2 status, Lauren classification, pathological stages. The low risk group of CXCR signature displayed a significantly favorable OS compared to the high risk group (HR = 3.22, 95% CI = 2.21–4.69, p = 1.057e−09). Nomogram clinical models were established for both OS (C-index: 0.692; 95%CI: 0.648–0.736) and recurrence free survival (C-index: 0.731; 95%CI: 0.675–0.786). In addition, CXCR6 and CD8+T cells featured the highest correlation (partial-cor = 0.781, p = 4.17e−77). ConclusionThis study identified distinct expression and prognostic values of CXCR members in GC using public databases.

The Expression of CXCL10/CXCR3 and Effect of the Axis on the Function of T Lymphocyte Involved in Oral Lichen Planus

The etiology of oral lichen planus (OLP) is still not clear. The purpose of this study was to explore the role of CXC chemokine receptor 3(CXCR3) and its ligand CXC motif chemokine 10(CXCL10) in the pathogenesis of OLP. We examined the expression of CXCR3 and CXCL10 in OLP patients and healthy controls by quantitative real-time PCR, Western blotting, ELISAs, and immunohistochemistry, respectively. Moreover, we detected the effects of CXCL10/CXCR3 axis on T lymphocyte migration, proliferation and apoptosis by Transwell assays, CCK8 assays, and flow cytometry. We found that the expression of CXCR3 and CXCL10 was significantly increased in OLP patients. In addition, T lymphocyte migration rate of CXCL10 stimulation group was significantly higher than that of control and CXCR3 antagonist groups. After antagonizing CXCR3, the migration ability of T lymphocytes was significantly decreased, and regardless of whether CXCL10 was added in the upper chamber culture medium, the number of migrating cells was similar. The addition of CXCL10 stimulant could stimulate the proliferation of T lymphocytes, but there was no significant difference compared with control group. After antagonizing CXCR3, the proliferation rate of T lymphocytes was significantly reduced. However, there were no significant differences in the apoptosis rates of T lymphocytes between CXCL10 stimulation group, antagonist CXCR3 group, and control group. Due to the change of expression in CXCR3 and CXCL10, and its interaction in mediating the directional migration of peripheral blood T lymphocytes, affecting the proliferation of T lymphocytes, it suggests that CXCL10/CXCR3 axis may be related to the immune mechanism of OLP.

The Role of CXC Chemokine Receptors 1-4 on Immune Cells in the Tumor Microenvironment.

Chemokines govern leukocyte migration by attracting cells that express their cognate ligands. Many cancer types show altered chemokine secretion profiles, favoring the recruitment of pro-tumorigenic immune cells and preventing the accumulation of anti-tumorigenic effector cells. This can ultimately result in cancer immune evasion. The manipulation of chemokine and chemokine-receptor signaling can reshape the immunological phenotypes within the tumor microenvironment in order to increase the therapeutic efficacy of cancer immunotherapy. Here we discuss the three chemokine-chemokine receptor axes, CXCR1/2–CXCL1-3/5-8, CXCR3–CXCL9/10/11, and CXCR4-CXCL12 and their role on pro-tumorigenic immune cells and anti-tumorigenic effector cells in solid tumors. In particular, we summarize current strategies to target these axes and discuss their potential use in treatment approaches.

CXCR7/CXCL12 axis is involved in lymph node and liver metastasis of gastric carcinoma.

AIMTo investigate the role of CXC chemokine receptor (CXCR)-7 and CXCL12 in lymph node and liver metastasis of gastric carcinoma.METHODSIn 160 cases of gastric cancer, the expression of CXCR7 and CXCL12 in tumor and matched tumor-adjacent non-cancer tissues, in the lymph nodes around the stomach and in the liver was detected using immunohistochemistry to analyze the relationship between CXCR7/CXCL12 expression and clinicopathological features and to determine whether CXCR7 and CXCL12 constitute a biological axis to promote lymph node and liver metastasis of gastric cancer. Furthermore, the CXCR7 gene was silenced and overexpressed in human gastric cancer SGC-7901 cells, and cell proliferation, migration and invasiveness were measured by the MTT, wound healing and Transwell assays, respectively.RESULTSCXCR7 expression was up-regulated in gastric cancer tissues (P = 0.011). CXCR7/CXCL12 expression was significantly related to high tumor stage and lymph node (r = 0.338, P = 0.000) and liver metastasis (r = 0.629, P = 0.000). The expression of CXCL12 in lymph node and liver metastasis was higher than that in primary gastric cancer tissues (χ2 = 6.669, P = 0.010; χ2 = 25379, P = 0.000), and the expression of CXCL12 in lymph node and liver metastasis of gastric cancer was consistent with the positive expression of CXCR7 in primary gastric cancer (r = 0.338, P = 0.000; r = 0.629, P = 0.000). Overexpression of the CXCR7 gene promoted cell proliferation, migration and invasion. Silencing of the CXCR7 gene suppressed SGC-7901 cell proliferation, migration and invasion. Human gastric cancer cell lines expressed CXCR7 and showed vigorous proliferation and migratory responses to CXCL12.CONCLUSIONThe CXCR7/CXCL12 axis is involved in lymph node and liver metastasis of gastric cancer. CXCR7 is considered a potential therapeutic target for the treatment of gastric cancer.

Novel Ubiquitin-derived High Affinity Binding Proteins with Tumor Targeting Properties

Targeting effector molecules to tumor cells is a promising mode of action for cancer therapy and diagnostics. Binding proteins with high affinity and specificity for a tumor target that carry effector molecules such as toxins, cytokines, or radiolabels to their intended site of action are required for these applications. In order to yield high tumor accumulation while maintaining low levels in healthy tissues and blood, the half-life of such conjugates needs to be in an optimal range. Scaffold-based binding molecules are small proteins with high affinity and short systemic circulation. Due to their low molecular complexity, they are well suited for combination with effector molecules as well as half-life extension technologies yielding therapeutics with half-lives adapted to the specific therapy. We have identified ubiquitin as an ideal scaffold protein due to its outstanding biophysical and biochemical properties. Based on a dimeric ubiquitin library, high affinity and specific binding molecules, so-called Affilin® molecules, have been selected against the extradomain B of fibronectin, a target almost exclusively expressed in tumor tissues. Extradomain B-binding molecules feature high thermal and serum stability as well as strong in vitro target binding and in vivo tumor accumulation. Application of several half-life extension technologies results in molecules of largely unaffected affinity but significantly prolonged in vivo half-life and tumor retention. Our results demonstrate the utility of ubiquitin as a scaffold for the generation of high affinity binders in a modular fashion, which can be combined with effector molecules and half-life extension technologies.

English

The role of chemokines in virus-induced acute hepatic failure is not well defined. In this study, we investigated the role of CXC chemokine receptor 3 (CXCR3) and its ligands chemokine Mig/CXCL9 (monokine induced by IFN-gamma) and IP-10/CXCL10 (interferon-gamma-inducible protein 10) in the recruitment of intrahepatic lymphocytes and subsequent acute hepatic failure. Balb/cJ mice (6 to 8 weeks, female) were intraperitoneally injected with 100 PFU murine hepatitis virus strain 3 (MHV-3). The proportions and numbers of T cells and NK cells in liver, spleen, and blood as well as the expression of CXCR3 on T cells and NK cells post MHV-3 infection was analyzed by flow cytometry. The hepatic mRNA level of the CXCR3-associated chemokines (CXCL9 and CXCL10) was detected by realtime PCR. A transwell migration assay was used to assess the chemotactic effect of MHV-3-infected hepatocytes and CXCL10 on the splenic lymphocytes. Following MHV-3 infection, the number of hepatic NK cells and T cells and the frequencies of hepatic NK cells and T cells expressing CXCR3 increased markedly; however, in the spleen and peripheral blood, they both decreased significantly. Moreover, the hepatic mRNAs levels of CXCL9 and CXCL10 were significantly elevated post infection. The transwell migration assay demonstrated that MHV-3-infected hepatocytes have the capacity to attract and recruit the splenic NK cells and T cells, and CXCL10 plays a key role in lymphocyte mobilization from the spleen. These results indicate that interactions involving CXCR3 and its ligands (CXCL9 and CXCL10), especially CXCL10 may play a key role in the recruitment of intrahepatic lymphocytes and subsequent necroinflammation and acute hepatic failure. &nbsp; Key words:&nbsp;Chemokine,&nbsp;interferon gamma-inducible protein 10 (CXCL10), hepatic failure, natural killer cell, T cell.

Compartmentalized Protective and Detrimental Effects of Endogenous Macrophage Migration-Inhibitory Factor Mediated by CXCR2 in a Mouse Model of Myocardial Ischemia/Reperfusion

Here, we aimed to clarify the role of CXC chemokine receptor (CXCR) 2 in macrophage migration-inhibitory factor (MIF)-mediated effects after myocardial ischemia and reperfusion. As a pleiotropic chemokine-like cytokine, MIF has been identified to activate multiple receptors, including CD74 and CXCR2. In models of myocardial infarction, MIF exerts both proinflammatory effects and protective effects in cardiomyocytes. Similarly, CXCR2 displays opposing effects in resident versus circulating cells. Using bone marrow transplantation, we generated chimeric mice with Cxcr2(-/-) bone marrow-derived inflammatory cells and wild-type (wt) resident cells (wt/Cxcr2(-/-)), Cxcr2(-/-) cardiomyocytes and wt bone marrow-derived cells (Cxcr2(-/-)/wt), and wt controls reconstituted with wt bone marrow (wt/wt). All groups were treated with anti-MIF or isotype control antibody before they underwent myocardial ischemia and reperfusion. Blocking MIF increased infarction size and impaired cardiac function in wt/wt and wt/CXCR2(-/-) mice but ameliorated functional parameters in Cxcr2(-/-)/wt mice, as analyzed by echocardiography and Langendorff perfusion. Neutrophil infiltration and angiogenesis were unaltered by MIF blockade or Cxcr2 deficiency. Monocyte infiltration was blunted in wt/Cxcr2(-/-) mice and reduced by MIF blockade in wt/wt and Cxcr2(-/-)/wt mice. Furthermore, MIF blockade attenuated collagen content in all groups in a CXCR2-independent manner. The compartmentalized and opposing effects of MIF after myocardial ischemia and reperfusion are largely mediated by CXCR2. Although MIF confers protective effects by improving myocardial healing and function through CXCR2 in resident cells, thereby complementing paracrine effects through CD74/AMP-activated protein kinase, it exerts detrimental effects on CXCR2-bearing inflammatory cells by increasing monocyte infiltration and impairing heart function. These dichotomous findings should be considered when developing novel therapeutic strategies to treat myocardial infarction.

Temporal and spatial distributions of CXC chemokine receptor 4 after spinal cord injury in Wistar rats

Objective To investigate the temporal and spatial distributions and the role of CXC chemokine receptor 4 (CXCR4) in the process of recovery after spinal cord injury (SCI) in Wistar rats.Methods Adult female Wistar rats (n =80) were randomly divided into eight groups:the groups of 1,2,3,4,7,14,28 days after SCI and control group (n =10 eacb).Immunohistochemical technique and hematoxylin-eosin staining technique were used to examine the changes of CXCR4 temporal and spatial distributions in the spinal cord of Wistar rats.Results After SCI in rats,the expression of CXCR4 in neurons,glial cells,macrophages and ependymal cells in spinal cord gray matter was increased,especially in neurons and macrophages.The number of the CXCR4 positive cells near the injury site was significantly greater than that in the rostral and caudal regions,while the gray matter contained more CXCR4 positive cells than white matter.Twenty-four h after SCI in rats,the expression of CXCR4 was increased (145 ± 3.46)/mm2,and on the 3rd day,the CXCR4 expression in the spinal cord gray matter reached the peak [(181.5 ±6.73)/mm2].Conclusion CXCR4 was widely expressed and presented characteristics of temporal and spatial distributions after SPI in rats. Key words: Spinal cord injury; CXC chemokine receptor 4

Role of CXC Chemokine Receptor–2 in a Murine Model of Bronchopulmonary Dysplasia

The contribution of neutrophils and CXC chemokines to the pathogenesis of bronchopulmonary dysplasia is not well defined. The transgenic expression of IL-1β in the pulmonary epithelium causes lung inflammation and disrupts alveolar development in infant mice. To study the hypothesis that CXC chemokine receptor-2 (CXCR2) is a mediator of inflammatory lung injury, we compared lung development in IL-1β-expressing mice with wild-type (IL-1β/CXCR2(+/+)) or null (IL-1β/CXCR2(-/-)) CXCR2 loci. CXCR2 deficiency abolished the transmigration of neutrophils into the alveolar lumen in IL-1β-expressing mice, but did not alter the number of neutrophils in the parenchyma. The deletion of CXCR2 increased the alveolar chord length and reduced the survival of mice when IL-1β was expressed from the pseudoglandular to the alveolar stages. The capillary configuration was highly abnormal in both IL-1β/CXCR2(+/+) and IL-1β/CXCR2(-/-) lungs, but in very different ways. The cellular area of the parenchyma and the total capillary area of IL-1β/CXCR2(+/+) and IL-1β/CXCR2(-/-) mice were smaller than those of control/CXCR2(+/+) and control/CXCR2(-/-) mice, but the ratio of capillary area to cellular area was similar in all four genotypes. When IL-1β was expressed during the saccular stage, IL-1β/CXCR2(-/-) mice had smaller alveolar chord lengths and better survival than did IL-1β/CXCR2(+/+) mice. Independent of the timing of IL-1β expression, IL-1β increased alveolar septal thickness in mice with wild-type CXCR2 loci, but not in CXCR2 null mice. Depending on the developmental stage at the time of the inflammatory insult, inhibition of the CXCR2 pathway may exert opposite effects on alveolar septation in the neonatal lung.

Initial Assessment of the Role of CXC Chemokine Receptor 4 after Polytrauma

CXC chemokine receptor (CXCR)-4 agonists have been shown to attenuate inflammation and organ injury in various disease models, including trauma/hemorrhage. The pathophysiological role of CXCR4 during the early response to tissue injury, however, remains unknown. Therefore, we investigated the effects of AMD3100, a drug that antagonizes binding of stromal cell-derived factor (SDF)-1α and ubiquitin to CXCR4 during the initial response to polytrauma in pigs. Fifteen minutes before polytrauma (femur fractures/lung contusion; control: sham), 350 nmol/kg AMD3100, equimolar AMD3100 and ubiquitin (350 nmol/kg each) or vehicle were administered intravenously. After a 60-min shock period, fluid resuscitation was performed for 360 min. Ubiquitin binding to peripheral blood mononuclear cells was significantly reduced after intravenous AMD3100. SDF-1α plasma levels increased transiently >10-fold with AMD3100 in all animals. In injured animals, AMD3100 increased fluid requirements to maintain hemodynamics and enhanced increases in peripheral blood granulocytes, lymphocytes and monocytes, compared with its effects in uninjured animals. Cytokine release from leukocytes in response to Toll-like receptor (TLR)-2 and TLR-4 activation was increased after in vitro AMD3100 treatment of normal whole blood and after in vivo AMD3100 administration in animals subjected to polytrauma. Coadministration of AMD3100/ubiquitin reduced lactate levels, prevented AMD3100-induced increases in fluid requirements and sensitization of the tumor necrosis factor (TNF)-α and interleukin (IL)-6 release upon TLR-2/4 activation, but did not attenuate increases in leukocyte counts and SDF-1α plasma levels. Our findings suggest that CXCR4 controls leukocyte mobilization after trauma, regulates leukocyte reactivity toward inflammatory stimuli and mediates protective effects during the early phase of trauma-induced inflammation.

Acceleration of diabetes development in CXC chemokine receptor 3 (CXCR3)-deficient NOD mice

The aim of this study was to understand the role of CXC chemokine receptor 3 (CXCR3), a T-helper 1(Th1) type chemokine receptor, in the pathogenesis of type 1 diabetes. We observed the incidence of diabetes in Cxcr3 homozygous knockout mice. We compared the expression pattern of various cytokines and chemokines and the frequency of FOXP3(+) cells in the pancreas and pancreatic lymph nodes from Cxcr3 ( -/- ) NOD mice and wild-type NOD mice. In addition, we observed the migration ability of CXCR3(+)CD4(+) cells to pancreatic islets upon adoptive transfer. Finally, we examined whether Cxcr3 (+) regulatory T cells (Tregs) actually suppressed the onset of diabetes in vivo. Cxcr3 ( -/- ) NOD mice developed spontaneous diabetes earlier than did wild-type NOD mice. In Cxcr3 ( -/- ) NOD mice, Tregs were more frequent in pancreatic lymph nodes and less frequent in pancreatic islets than in wild-type NOD mice. While transferred CXCR3(-)CD4(+) cells from wild-type NOD mice did not infiltrate pancreatic islets of NOD-severe combined immunodeficiency (SCID) mice, CXCR3(+)CD4(+) cells from the same mice migrated into the recipient islets and contained Forkhead box P3 (FOXP3) upon adoptive transfer. Moreover, CD4(+)CD25(+) cells from wild-type NOD mice suppressed and delayed the onset of diabetes compared with those from Cxcr3 ( -/- ) NOD mice in a cyclophosphamide-induced diabetes model system. The mechanism of accelerated diabetes onset in Cxcr3 ( -/- ) NOD mice was considered to be due to the lack of hybrid Tregs (CXCR3(+)FOXP3(+)CD4(+) cells), which could effectively migrate into and regulate Th1 inflammation in local lesions under Cxcr3 knockout conditions.

Role of CXC Chemokine Receptor 3 Pathway in Renal Ischemic Injury

Chemokines play a major role in the recruitment of leukocytes in inflammation and in the regulation of T helper 1 (Th1)/Th2 immune responses. These mechanisms have been recognized to be important in the pathogenesis of renal ischemia-reperfusion (I/R) injury. The interaction of the CXC chemokine receptor 3 (CXCR3) receptor with its ligands is a key pathogenic pathway in promoting inflammation and in enhancing Th1 immune responses. After the induction of ischemia in the mouse model of renal ischemia, an increase in intrarenal expression of CXCR3 and its ligands was observed. Compared with the wild-type (WT) mice, CXCR3-deficient mice (CXCR3-/-) had significantly lower serum creatinine levels, better survival rate, and significantly less acute tubular necrosis and cellular infiltrates. In the kidney, intracellular staining of infiltrating cells that were recovered from kidneys revealed a lower percentage of CD4+IFN-gamma+ cells in the CXCR3-/- mice compared with the WT mice. Furthermore, adoptive transfer of WT CD3+ cells into CXCR3-/- mice before induction of I/R injury abrogated the protection of CXCR3-/- mice from I/R injury. It is concluded that CXCR3 plays an important role in orchestrating the recruitment of Th1 cells to the ischemic kidney and in mediating I/R injury and therefore may serve as a novel target for the therapy of I/R injury.

CXCR3–/– mice mount an efficient Th1 response but fail to control Leishmania major infection

Chemokines play a critical role in recruitment of leukocytes to the site of infection, which is essential for host defense. We analyzed the role of CXC chemokine receptor 3 (CXCR3) in the control of cutaneous leishmaniasis using CXCR3-/- C57BL/6 mice. We found that Leishmania major-infected CXCR3-/- mice mount an efficient Th1 response as evident by markedly increased serum levels of Th1-associated IgG2a and significant production of IFN-gamma and IL-12 by the draining lymph node cells, restrict systemic spread of infection, but fail to control parasite replication at the site of infection and develop chronic non-healing lesions. Furthermore, the inability of CXCR3-/- mice to control cutaneous L. major growth was associated with fewer CD4+ and CD8+ T cells and significantly lower levels of IFN-gamma in their lesions as compared to CXCR3+/+ mice. These results demonstrate that CXCR3 plays a critical role in the host defense against cutaneous leishmaniasis caused by L. major. Furthermore, they also suggest that the susceptibility of CXCR3-/- mice to L. major is due to impaired CD4+ and CD8+ T cell trafficking and decreased production of IFN-gamma at the site of infection rather than to their inability to mount a parasite-specific Th1 response.

Combinatorial model of chemokine involvement in glomerular monocyte recruitment: role of CXC chemokine receptor 2 in infiltration during nephrotoxic nephritis.

A sequential model involving chemokines has been proposed for leukocyte extravasation into areas of inflammation; however, site-specific aspects remain to be elucidated. Hence, we studied the role of chemokines produced by mesangial (MC) or glomerular endothelial cells (GEC) and their receptors in glomerular recruitment of monocytes. Stimulation of MC with TNF-alpha up-regulated mRNA and protein of CC and CXC chemokines but not constitutive expression of the CX(3)C chemokine fractalkine. While growth-related activity (GRO)-alpha was immobilized to MC proteoglycans, monocyte chemotactic protein (MCP)-1 was secreted into the soluble phase. Firm adhesion and sequestration of monocytes on activated MC was supported by the GRO-alpha receptor CXCR2 and to a lesser extent by CX(3)CR, whereas the MCP-1 receptor CCR2 contributed to their transendothelial chemotaxis toward activated MC. In contrast, fractalkine mRNA and protein was induced by TNF-alpha in transformed rat GEC, and both CXCR2 and CX(3)CR mediated monocyte arrest on GEC in shear flow. The relevance of these mechanisms was confirmed in a rat nephrotoxic nephritis model where acute glomerular macrophage recruitment was profoundly inhibited by blocking CXCR2 or CCR2. In conclusion, our results epitomize a combinatorial model in which chemokines play specialized roles in driving glomerular monocyte recruitment and emphasize an important role for CXCR2 in macrophage infiltration during early phases of nephrotoxic nephritis.