CXCR1 Protein Research Articles

Pyrrolidine dithiocarbamate in combination with L-N-monomethyl arginine alleviates Staphylococcus aureus infection via regulation of CXCL8/CXCR1 axis in peritoneal macrophages in vitro

The CXCL8/CXCR1 axis in conjoint with the free radicals and anti-oxidants dictates the severity of inflammation caused by the bacteria, Staphylococcus aureus. S.aureus mediated inflammatory processes is regulated by NF-κB and its product, iNOS. The objective of this study was to examine the effects of inhibition of NF-κB and iNOS on CXCL8/CXCR1, alteration in M1/M2 polarization of macrophages and associated inflammatory responses during S.aureus infection in vitro. For this, the murine peritoneal macrophages were pretreated with NF-κB inhibitor, Pyrrolidine dithiocarbamate (PDTC) and iNOS inhibitor, L-N-monomethyl arginine (LNMMA), either alone or in combination, followed by time-dependent S.aureus infection. The chemotactic migrations of macrophages were determined by the agarose spot assay. The iNOS, NF-κB and CXCR1 protein expressions were evaluated. The ROS level (superoxide, H2O2, NO) and antioxidant activities (SOD, CAT, GSH, arginase) were measured. The intra-macrophage phagoctyic activity had been analyzed by confocal microscopy. S.aureus activated macrophages showed increased iNOS expression that symbolizes M1 characterization of macrophages. The results suggest that the combination treatment of LNMMA + PDTC was effective in diminution of CXCL8 production and CXCR1 expression through downregulation of NF-κB and iNOS signaling pathway. Consequently, there was decrement in macrophage migration, reduced ROS generation, elevated antioxidant enzyme activity as well as bacterial phagocytosis at 90 min post bacterial infection. The increased arginase activity further proves the switch from pro-inflammatory M1 to anti-inflammatory M2 polarization of macrophages. Concludingly, the combination of PDTC + LNMMA could resolve S.aureus mediated inflammation through mitigation of CXCL8/CXCR1 pathway switching from M1 to M2 polarization.

CXCR1 and its downstream NF-κB inflammation signaling pathway as a key target of Guanxinning injection for myocardial ischemia/reperfusion injury.

Guanxinning Injection (GXNI) is used clinically to treat cardiac injury, but its active components and mode of action remains unclear. Therefore, a myocardial ischemia/reperfusion injury (MIRI) model-based integrated strategy including function evaluation, RNA-seq analysis, molecular docking, and cellular thermal shift assay (CETSA) was employed to elucidate the effect and mechanism of GXNI and its main ingredient on cardiac injury. These results revealed that GXNI significantly improved cardiac dysfunction and myocardial injury in I/R mice. RNA-seq analysis clarified that CXCR1-mediated interleukin-8 pathway played a critical role in MIRI. Molecular docking screening identified danshensu (DSS) as the major active components of GXNI targeting CXCR1 protein, which was confirmed in an oxygen-glucose deprivation/reoxygenation-induced cardiomyocytes damage model showing that GXNI and DSS reduced the protein expression of CXCR1 and its downstream NF-κB, COX-2, ICAM-1 and VCAM-1. CETSA and isothermal dose-response fingerprint curves confirmed that DSS combined with CXCR1 in a dose-dependent manner. Furthermore, GXNI and DSS significantly decreased the expression levels of IL-6, IL-1β and TNF-α and the number of neutrophils in post I/R myocardial tissue. In conclusion, this study revealed that GXNI and its active components DSS exert inhibitory effects on inflammatory factor release and leukocyte infiltration to improve I/R-induced myocardial injury by down-regulating CXCR1-NF-κB-COX-2/ICAM-1/VCAM-1 pathway.

Impaired capillary tube formation induced by elevated secretion of IL8 involves altered signaling via the CXCR1/PI3K/MMP2 pathway.

Angiogenesis is a multistep process requiring endothelial cell activation, migration, proliferation and tube formation. We recently reported that elevated secretion of interlukin 8 (IL8) by myotubes (MT) from subjects with Type-2 Diabetes (T2D) reduced angiogenesis by human umbilical vein endothelial cells (HUVEC) and human skeletal muscle explants. This lower vascularization was mediated through impaired activation of the phosphatidylinositol 3-kinase (PI3K)-pathway. We sought to investigate additional signaling elements that might mediate reduced angiogenesis. HUVEC were exposed to levels of IL8 equal to those secreted by MT from non-diabetic (ND) and T2D subjects and the involvement of components in the angiogenic response pathway examined. Cellular content of reactive oxygen species and Nitrate secretion were similar after treatment with [ND-IL8] and [T2D-IL8]. CXCR1 protein was down-regulated after treatment with [T2D-IL8] (p < 0.01 vs [ND-IL8] treatment); CXCR2 expression was unaltered. Addition of neutralizing antibodies against CXCR1 and CXCR2 to HUVEC treated with IL8 confirmed that CXCR1 alone mediated the angiogenic response to IL8. A key modulator of angiogenesis is matrix metalloproteinase-2 (MMP2). MMP2 secretion was higher after treatment with [ND-IL8] vs [T2D-IL8] (p < 0.01). MMP2 inhibition reduced tube formation to greater extent with [ND-IL8] than with [T2D-IL8] (p < 0.005). The PI3K-pathway inhibitor LY294002 reduced IL8-induced MMP2 release. IL8 regulation of MMP2 release was CXCR1 dependent, as anti-CXCR1 significantly reduced MMP2 release (p < 0.05). These results suggest that high levels of IL8 secreted by T2D MT trigger reduced capillarization via lower activation of a CXCR1-PI3K pathway, followed by impaired release and activity of MMP2.

In silico prediction of the functional and structural consequences of the non-synonymous single nucleotide polymorphism A122V in bovine CXC chemokine receptor type 1.

The current study aimed to assess whether the A122V causal polymorphism promotes alterations in the functional and structural proprieties of the CXC chemokine receptor type 1 protein (CXCR1) of cattle Bos taurus by in silico analyses. Two amino acid sequences of bovine CXCR1 was selected from database UniProtKB/Swiss-Prot: a) non-polymorphic sequence (A7KWG0) with alanine (A) at position 122, and b) polymorphic sequence harboring the A122V polymorphism, substituting alanine by valine (V) at same position. CXCR1 sequences were submitted as input to different Bioinformatics' tools to examine the effects of this polymorphism on functional and structural stabilities, to predict eventual alterations in the 3-D structural modeling, and to estimate the quality and accuracy of the predictive models. The A122V polymorphism exerted tolerable and non-deleterious effects on the polymorphic CXCR1, and the predictive structural model for polymorphic CXCR1 revealed an alpha helix spatial structure typical of a receptor transmembrane polypeptide. Although higher variations in the distances between pairs of amino acid residues at target-positions are detected in the polymorphic CXCR1 protein, more than 97% of the amino acid residues in both models were located in favored and allowed conformational regions in Ramachandran plots. Evidences has supported that the A122V polymorphism in the CXCR1 protein is associated with increased clinical mastitis incidence in dairy cows. Thus, the findings described herein prove that the replacement of the alanine by valine amino acids provokes local conformational changes in the A122V-harboring CXCR1 protein, which could directly affect its post-translational folding mechanisms and biological functionality.

Identification of a novel mutation in the mechanoreceptor-encoding gene CXCR1 in patients with keloid

Keloids are skin fibroproliferative tumors characterized by locally invasive growth of fibroblasts and excessive collagen deposition. The objective of this study is to investigate the molecular basis of the keloid scar by studying the mutation of related genes. We performed gene screening of mechanoreceptors by quantitative polymerase chain reaction (qPCR), Sanger sequencing to detect the CXCR1gene mutation, and immuno-histochemistry to determine CXCR1 protein expression. Among the genes encoding mechanoreceptors, the expression of CXCR1 mRNA was significantly higher in keloid scar tissues than in the surrounding tissues of normal controls (P < 0.05). Sequencing analysis identified a novel missense mutation, c.574G > A (p.Gly192Glu). Immunohistochemistry showed heightened protein expression of CXCR1 in keloid scars as compared to controls. Our findings indicate that CXCR1 gene mutation and altered protein expression are associated with keloid scar development. Identification of the CXCR1 gene mutation might provide insights into the molecular mechanism underlying keloid scar and underscores the potential importance of mechanoreceptors in keloid scar pathogenesis.

Predicting the effects of the single nucleotide polymorphism A122V on CXC chemokine receptor type 1 of Bos taurus (Artiodactyla: Bovidae) cattle by in silico analyses

Este estudo objetivou predizer bioquimicamente as estruturas primárias e secundárias da proteína receptora de quimiocina CXCR1 bovina não polimórfica e polimórfica carreando o polimorfismo A122V por análises in silico. Duas sequências da proteína CXCR1 de bovino Bos taurus foram selecionadas a partir da base de dados de sequências de proteínas UniProtKB/Swiss-Prot: a) uma sequência não polimórfica (A7KWG0), contendo o aminoácido alanina (A) na posição 122, e b) uma sequência polimórfica, apresentando o aminoácido valina (V) na mesma posição. As estruturas primárias e secundárias da proteína foram preditas empregando os programas ProtParam e Chou &amp; Fasman Protein Secondary Structure Prediction CFSSP. Diferenças nos parâmetros físicos e químicos não foram previstas a partir da estrutura primária de ambas as proteínas analisadas. A presença de um domínio helicoidal, situado nas posições 100 e 150, foi exclusivamente encontrada na proteína CXCR1 não polimórfica. Resíduos de aminoácidos de propriedades bioquímicas variáveis foram detectados na posição 122 na proteína CXCR1 dos ruminantes e humana, sugerindo que esse peptídeo é altamente polimórfico em vertebrados. Os resultados aqui descritos predizem diferenças no padrão da estrutura secundária da proteína CXCR1 bovina não polimórfica e polimórfica A122V empregando ferramentas de Bioinformática.

Type 1 Diabetes Prone NOD Mice Have Diminished Cxcr1 mRNA Expression in Polymorphonuclear Neutrophils and CD4+ T Lymphocytes.

In humans, CXCR1 and CXCR2 are two homologous proteins that bind ELR+ chemokines. Both receptors play fundamental roles in neutrophil functions such as migration and reactive oxygen species production. Mouse Cxcr1 and Cxcr2 genes are located in an insulin-dependent diabetes genetic susceptibility locus. The non obese diabetic (NOD) mouse is a spontaneous well-described animal model for insulin-dependent type 1 diabetes. In this disease, insulin deficiency results from the destruction of insulin-producing beta cells by autoreactive T lymphocytes. This slow-progressing disease is dependent on both environmental and genetic factors. Here, we report descriptive data about the Cxcr1 gene in NOD mice. We demonstrate decreased expression of mRNA for Cxcr1 in neutrophils and CD4+ lymphocytes isolated from NOD mice compared to other strains, related to reduced NOD Cxcr1 gene promoter activity. Looking for Cxcr1 protein, we next analyze the membrane proteome of murine neutrophils by mass spectrometry. Although Cxcr2 protein is clearly found in murine neutrophils, we did not find evidence of Cxcr1 peptides using this method. Nevertheless, in view of recently-published experimental data obtained in NOD mice, we argue for possible Cxcr1 involvement in type 1 diabetes pathogenesis.

Interleukin-8, a promising predictor for prognosis of pancreatic cancer

To investigate the value of interleukin-8 (IL-8), a pro-inflammatory chemokine, in predicting the prognosis of pancreatic cancer. Expression of IL-8 and its receptor CXCR1 was assessed by immunohistochemistry in pancreatic cancer and chronic pancreatitis samples. Enzyme-linked immunosorbent assay was used to detect the serum IL-8 levels in pancreatic cancer patients. Human pancreatic cancer tissues were heterotopically transplanted to the immune-deficiency mice to evaluate the effect of serum IL-8 on the tumorigenesis of the cancer samples. IL-8 and CXCR1 proteins were both over-expressed in pancreatic adenocarcinoma samples (55.6% and 65.4%, respectively) compared with the matched para-cancer tissues (25.9% and 12.3%, P < 0.01), or chronic pancreatitis (0% and 25%, P < 0.05). Serum IL-8 levels in pancreatic cancer patients (271.1 ± 187.7 ng/mL) were higher than in other digestive system tumors, such as gastric cancer (41.77 ± 9.11 ng/mL, P = 0.025), colorectal carcinoma (78.72 ± 80.60 ng/mL, P = 0.032) and hepatocellular carcinoma (59.60 ± 19.80 ng/mL, P = 0.016). In vivo tumorigenesis analysis further proved that tumor tissues from patients with higher serum IL-8 levels grew faster than those with lower IL-8 levels. IL-8 can be a fine serum marker for predicting the prognosis pancreatic cancer.

A Genetic Basis of Susceptibility to Acute Pyelonephritis

BackgroundFor unknown reasons, urinary tract infections (UTIs) are clustered in certain individuals. Here we propose a novel, genetically determined cause of susceptibility to acute pyelonephritis, which is the most severe form of UTI. The IL-8 receptor, CXCR1, was identified as a candidate gene when mIL-8Rh mutant mice developed acute pyelonephritis (APN) with severe tissue damage.Methods and FindingsWe have obtained CXCR1 sequences from two, highly selected APN prone patient groups, and detected three unique mutations and two known polymorphisms with a genotype frequency of 23% and 25% compared to 7% in controls (p<0.001 and p<0.0001, respectively). When reflux was excluded, 54% of the patients had CXCR1 sequence variants. The UTI prone children expressed less CXCR1 protein than the pediatric controls (p<0.0001) and two sequence variants were shown to impair transcription.ConclusionsThe results identify a genetic innate immune deficiency, with a strong link to APN and renal scarring.