Circulating TNF-RII, IP-10 and HGF are associated with severity of COVID-19 in oncologic patients.

The COVID-19 patients showed hyperinflammatory response depending on the severity of the disease but little have been reported about this response in oncologic patients that also were infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Sixty-five circulating cytokines/chemokines were quantified in 15 oncologic patients, just after SARS-CoV-2 infection and fourteen days later, and their levels were compared in patients who required hospitalisation by COVID-19 versus non-hospitalised patients. A higher median age of 72 years (range 61-83) in oncologic patients after SARS-CoV-2 infection was associated with hospitalisation requirement by COVID-19 versus a median age of 49 years (20-75) observed in the non-hospitalised oncologic patients (p = 0.008). Moreover, oncologic patients at metastatic stage or with lung cancer were significantly associated with hospitalisation by COVID-19 (p = 0.044). None of these hospitalised patients required ICU treatment. Higher basal levels of tumour necrosis factor receptor II (TNF-RII), interferon-γ (IFNγ)-induced protein 10 (IP-10) and hepatocyte growth factor (HGF) in plasma were significantly observed in oncologic patients who required hospitalisation by COVID-19. Higher TNF-RII, IP-10 and HGF levels after the SARS-CoV-2 infection in oncologic patients could be used as biomarkers of COVID-19 severity associated with hospitalisation requirements.

Variation in Leishmania chemokine suppression driven by diversification of the GP63 virulence factor.

Leishmaniasis is a neglected tropical disease with diverse outcomes ranging from self-healing lesions, to progressive non-healing lesions, to metastatic spread and destruction of mucous membranes. Although resolution of cutaneous leishmaniasis is a classic example of type-1 immunity leading to self-healing lesions, an excess of type-1 related inflammation can contribute to immunopathology and metastatic spread. Leishmania genetic diversity can contribute to variation in polarization and robustness of the immune response through differences in both pathogen sensing by the host and immune evasion by the parasite. In this study, we observed a difference in parasite chemokine suppression between the Leishmania (L.) subgenus and the Viannia (V.) subgenus, which is associated with severe immune-mediated pathology such as mucocutaneous leishmaniasis. While Leishmania (L.) subgenus parasites utilize the virulence factor and metalloprotease glycoprotein-63 (gp63) to suppress the type-1 associated host chemokine CXCL10, L. (V.) panamensis did not suppress CXCL10. To understand the molecular basis for the inter-species variation in chemokine suppression, we used in silico modeling to identify a putative CXCL10-binding site on GP63. The putative CXCL10 binding site is in a region of gp63 under significant positive selection, and it varies from the L. major wild-type sequence in all gp63 alleles identified in the L. (V.) panamensis reference genome. Mutating wild-type L. (L.) major gp63 to the L. (V.) panamensis sequence at the putative binding site impaired cleavage of CXCL10 but not a non-specific protease substrate. Notably, Viannia clinical isolates confirmed that L. (V.) panamensis primarily encodes non-CXCL10-cleaving gp63 alleles. In contrast, L. (V.) braziliensis has an intermediate level of activity, consistent with this species having more equal proportions of both alleles. Our results demonstrate how parasite genetic diversity can contribute to variation in immune responses to Leishmania spp. infection that may play critical roles in the outcome of infection.

A novel method to produce synthetic murine CXCL10 for efficient screening of functional variants.

Antitumor immune responses depend on the infiltration of solid tumors by effector T cells, a process guided by chemokines. In particular, the chemokine CXCL10 has been shown to play a critical role in mediating recruitment of CXCR3 + cytolytic T and NK cells in tumors, though its use as a therapeutic agent has not been widely explored. One of the limitations is due to the rapid inactivation of CXCL10 by dipeptidyl peptidase 4 (DPP4), a broadly expressed enzyme that is active in plasma and other bodily fluids. In the present study, we describe a novel method to produce synthetic CXCL10 that is resistant to DPP4 N-terminal truncation. Using a Fmoc solid-phase peptide synthesis approach, synthetic murine WT CXCL10 was produced, showing similar biochemical and biological properties to the recombinant protein. This synthesis method supported production of natural (amino acid substitution, insertion or deletion) and non-natural (chemical modifications) variants of CXCL10. In association with a functional screening cascade that assessed DPP4-mediated cleavage, CXCR3 signaling potency and chemotactic activity, we successfully generated 20 murine CXCL10 variants. Among those, two non-natural variants with N-methylated Leu3 (MeLeu3) and a reduced amide bond between Pro2 and Leu3 (rLeu3), respectively, showed resistance to DPP4 truncation but decreased CXCR3 signaling and chemotactic activity. Interestingly, MeLeu3 and rLeu3 CXCL10 behaved as DPP4 inhibitors, preventing the truncation of WT CXCL10. This study highlights the potential of using Fmoc solid-phase chemistry in association with biochemical and biological characterization to rapidly identify CXCL10 variants with desired properties. These novel methods unlock the opportunity to develop DPP4 resistant CXCL10 variants, as well as other chemokine substrates, while maintaining chemotactic properties.

Proteolytic chemokine cleavage as a regulator of lymphocytic infiltration in solid tumors.

In the past decade, immune-based therapies such as monoclonal antibodies against tumor epitopes or immune checkpoint inhibitors have become an integral part of contemporary cancer treatment in many entities. However, a fundamental prerequisite for the success of such therapies is a sufficient trafficking of tumor-infiltrating lymphocytes into the tumor microenvironment. This infiltration is facilitated by chemokines, a group of about 50 small proteins capable of chemotactically guiding leukocytes. Proteolytic inactivation of chemokines leading to an impaired infiltration of immune effector cells appears to be an efficient immune escape mechanism of solid cancers.The CXCR3 and CX3CR1 chemokine receptor ligands CXCL9-11 and CX3CL1, respectively, are mainly responsible for the tumor-suppressive lymphocytic infiltration into the tumor micromilieu. Their structure explains the biochemical basis of their proteolytic cleavage, while in vivo data from mouse models and patient samples shed light on the corresponding processes in cancer. The emerging roles of proteases, e.g., matrix metalloproteinases, cathepsins, and dipeptidyl peptidase 4, in chemokine inactivation define new resistance mechanisms against immunotherapies and identify attractive new targets to enhance immune intervention in cancer.

Designing an improved T-cell mobilising CXCL10 mutant through enhanced GAG binding affinity.

The chemokine CXCL10 is released by a plethora of cells, including immune and metastatic cancer cells, following stimulation with interferon-gamma. It acts via its GPC receptor on T-cells attracting them to various target tissues. Glycosaminoglycans (GAGs) are regarded as co-receptors of chemokines, which enable the establishment of a chemotactic gradient for target cell migration. We have engineered human CXCL10 towards improved T-cell mobilisation by implementing a single site-directed mutation N20K into the protein, which leads to a higher GAG binding affinity compared to the wild type. Interestingly, this mutation not only increased T-cell migration in a transendothelial migration assay, the mutant intensified T-cell chemotaxis also in a Boyden chamber set-up thereby indicating a strong role of T-cell-localised GAGs on leukocyte migration. A CXCL10 mutant with increased GAG-binding affinity could therefore potentially serve as a T-cell mobiliser in pathological conditions where the immune surveillance of the target tissue is impaired, as is the case for most solid tumors.

CXCL10/IP-10 Neutralization Can Ameliorate Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome in Rats.

The role of C-X-C motif chemokine 10 (CXCL10), a pro-inflammatory factor, in the development of acute respiratory distress syndrome (ARDS) remains unclear. In this study, we explored the role of CXCL10 and the effect of CXCL10 neutralization in lipopolysaccharide (LPS)-induced ARDS in rats. The expression of CXCL10 and its receptor chemokine receptor 3(CXCR3) increased after LPS induction. Moreover, neutralization of CXCL10 ameliorated the severity of ARDS by reducing pulmonary edema, inhibiting the release of inflammatory mediators (IFN-γ, IL-6 and ICAM-1) and limiting inflammatory cells (neutrophils, macrophages, CD8+ T cells) influx into the lung, with a reduction in CXCR3 expression in neutrophils and macrophages. Therefore, CXCL10 could be a potential therapeutic target in LPS-induced ARDS.

Identification of a fish specific chemokine CXCL_F2 in large yellow croaker (Larimichthys crocea) reveals its primitive chemotactic function.

Chemokines are a superfamily of cytokines regulating immune cell migration under both inflammatory and normal physiological conditions. Currently, a number of fish specific CXC chemokines, named as CXCL_F1-5, have been identified in several species. However, understanding of their functional characteristics is still limited. In this study, we identified a fish specific chemokine CXCL_F2 (LycCXCL_F2) from large yellow croaker (Larimichthys crocea). The open reading frame (ORF) of LycCXCL_F2 is 348 nucleotides long, encoding a protein of 115 amino acids (aa). The deduced LycCXCL_F2 protein contains a 20-aa signal peptide and a 95-aa mature polypeptide. Phylogenetic analysis showed that LycCXCL_F2 fell into a major clade formed by CXCL_F2 sequences and was separated from CXCL_F1 and CXCL_F3-5 subgroups. LycCXCL_F2 mRNA transcript was constitutively expressed in various tissues, with the highest levels in spleen and head kidney. After stimulation with inactivated trivalent bacterial vaccines, LycCXCL_F2 mRNA transcription was significantly increased in both spleen and head kidney. Moreover, recombinant LycCXCL_F2 protein exhibited obvious chemotaxis to monocytes, lymphocytes and eosnophils of PBLs isolated from large yellow croaker, but could not induce the respiratory burst of macrophages. These results indicate that this fish specific CXC chemokine LycCXCL_F2 possesses primitive chemotactic activity and may play a role in immune response in large yellow croaker.

Serum soluble urokinase-type plasminogen activator receptor and interferon-γ-induced protein 10 levels correlate with significant fibrosis in chronic hepatitis B.

BACKGROUND: Hepatitis B virus (HBV) presents an important public health problem. Liver biopsy is currently the gold standard for assessing the degree of intrahepatic inflammation and for staging liver fibrosis. However, the value of liver biopsies is limited by sampling errors, understaging and interobserver variability in interpretation. There is, therefore, a need to identify novel, non-invasive serologic biomarkers for the development of new predictive models of fibrosis. METHODS: We enrolled patients with chronic hepatitis B infection (CHB) and examined the relationships between serum soluble urokinase plasminogen activator receptor (suPAR) and interferon-induced protein-10 (IP-10), and the results of liver biopsies. Healthy volunteers with normal aminotransferase levels and negative serological results for HBV, hepatitis C virus and human immunodeficiency virus were recruited as controls. RESULTS: Mean platelet volume, serum suPAR and IP-10 were significantly elevated in patients with CHB compared with controls. Median serum suPAR and IP-10 levels were significantly higher in patients with liver fibrosis compared with patients with mild fibrosis. There was no significant difference in mean platelet volume or aspartate aminotransferase-to-platelet ratio index scores between patients with mild and significant fibrosis. CONCLUSION: suPAR and IP-10 were able to distinguish between significant and mild fibrosis with good sensitivity and specificity, and may thus represent useful biomarkers for identifying patients with significant fibrosis.

Evidence for the antagonistic form of CXC-motif chemokine CXCL10 in serous epithelial ovarian tumours.

Patients with high-grade, serous epithelial ovarian carcinoma (HGSOC) are generally diagnosed with extensive peritoneal metastases, and exhibit 5-year survival rates <30%. A subset of these tumours, defined as "immunoreactive," overexpress mRNA encoding the T-cell-recruiting chemokine CXCL10 (10-kDa interferon gamma-induced protein; C-X-C motif chemokine 10). Tumour-infiltrating CD4(+) CD8(+) T-cells are a well-documented, positive prognostic indicator for HGSOC patients; paradoxically, however, patients diagnosed with HGSOC (overexpressing CXCL10 and therefore theorised to recruit T-cells) typically exhibit poor survival. Recently, an "antagonistic" CXCL10 variant was identified that inhibited leucocyte recruitment to inflamed liver in vivo (Casrouge et al., J Clin Invest 2011;121:308-17). We hypothesised that "immunoreactive" HGSOC might also express antagonistic CXCL10, interfering with leucocyte recruitment and contributing to poor patient prognosis. CXCL10 expression was analysed in HGSOC tissues grouped according to pathology, grade and FIGO stage at diagnosis, and its localisation and association with T-cells established by immunohistochemical staining in tissue microarrays. CXCL10 expression was increased in a subset of serous epithelial tumour samples; however, it did not correlate well with CD45-positive tumour infiltrate. Immunoprecipitation and de novo sequence analysis of CXCL10 identified the N-terminally cleaved, "antagonistic" variant of CXCL10 specifically in malignant tumours, and not in benign ovarian disease. The data demonstrate the presence of the antagonistic form of CXCL10 in HGSOC for the first time, and provide a partial explanation for reduced leucocyte infiltration observed in these tumours. We suggest that CXCL10 cleavage and subsequent antagonism of immune cell recruitment may be a feature of the "immunoreactive" HGSOC subtype, leading to early impairment of the immune response and subsequently worsening patient prognosis.

CXCL10 decreases GP73 expression in hepatoma cells at the early stage of hepatitis C virus (HCV) infection.

Golgi protein 73 (GP73), which is up-regulated in hepatocellular carcinoma (HCC), has recently been identified as a novel serum marker for HCC diagnosis. Several reports also noted the increased levels of GP73 expression in chronic liver disease in patients with acute hepatitis of various etiologies, chronic Hepatitis C virus (HCV) infection and alcoholic liver disease. The molecular mechanisms of GP73 expression in HCV related liver disease still need to be determined. In this study, we aimed to evaluate the effect of HCV infection on GP73 expression. GP73 was highly expressed in Huh7, Hep3B, 293T and HUVEC cells, and was low-expressed in HepG2 cells. HCV infection led to down-regulation of GP73 in Huh7 and HepG2/CD81 cells at the early stage of infection. CXCL10 decreased GP73 expression in Huh7 and HepG2 cells. Up-regulation of GP73 was noted in hepatocytes with cytopathic effect at advanced stage of HCV infection, and further research is needed to determine the unknown factors affecting GP73 expression. In conclusion, our study provided additional evidence for the roles of GP73 in liver disease.

Study on characteristics of chemokine CXCL10 gene cloned from cDNA expression library of Ujumqin sheep.

Chemokines were a major regulator of body's inflammatory and immune responses. In this study, the cDNA fragment of chemokine CXC ligand 10 (CXCL10) was cloned from the Ujumqin sheep ear marginal tissue cDNA expression library; the CXCL10 gene had 103 amino acids and a molecular weight of 11.47 kDa, and it shared a high homology among cattle, sheep, and goat, while a low homology compared with mouse. The CXCL10 protein had 4 conservative cysteine residues, located in 28, 30, 55, and 72 sites. The expression pattern and intracellular distribution of recombinant CXCL10 proteins in Ujumqin sheep fibroblast cells showed that there were green fluorescence signals both in cytoplasm and nucleolus after 24 h of transfection, the number of positive cells was increased with time, the peak level of fluorescence signal was reached after 48 h of transfection and the transfection efficiency was 33.3%; there was a significant decrease in fluorescence intensity after 72 h of transfection. Expression of recombinant CXCL10 gene in Escherichia coli had a time- and temperature-dependency on the amount of protein expression, and a small quantity of inducer was needed.

An IP-10 (CXCL10)-derived peptide inhibits angiogenesis.

Angiogenesis plays a critical role in processes such as organ development, wound healing, and tumor growth. It requires well-orchestrated integration of soluble and matrix factors and timely recognition of such signals to regulate this process. Previous work has shown that newly forming vessels express the chemokine receptor CXC receptor 3 (CXCR3) and, activation by its ligand IP-10 (CXCL10), both inhibits development of new vasculature and causes regression of newly formed vessels. To identify and develop new therapeutic agents to limit or reverse pathological angiogenesis, we identified a 21 amino acid fragment of IP-10, spanning the α-helical domain residues 77-98, that mimic the actions of the whole IP-10 molecule on endothelial cells. Treatment of the endothelial cells with the 22 amino acid fragment referred to as IP-10p significantly inhibited VEGF-induced endothelial motility and tube formation in vitro, properties critical for angiogenesis. Using a Matrigel plug assay in vivo, we demonstrate that IP-10p both prevented vessel formation and induced involution of nascent vessels. CXCR3 neutralizing antibody was able to block the inhibitory effects of the IP-10p, demonstrating specificity of the peptide. Inhibition of endothelial function by IP-10p was similar to that described for IP-10, secondary to CXCR3-mediated increase in cAMP production, activation of PKA inhibiting cell migration, and inhibition of VEGF-mediated m-calpain activation. IP-10p provides a novel therapeutic agent that inhibits endothelial cell function thus, allowing for the modulation of angiogenesis.

The protective effect of 3-deoxysappanchalcone on in vitro influenza virus-induced apoptosis and inflammation.

Influenza virus is one of the most important causes of acute respiratory disease. Viral infection and viral replication activate multiple cell signalling pathways. Apoptosis of infected cells and immune response against viral replication, which are generally considered to be protective mechanisms, are also probably mediated by viruses, which lead to severe health problems. We previously reported that 3-deoxysappanchalcone (3-DSC), a compound that is isolated from Caesalpinia sappan, exhibited in vitro anti-influenza activity. In the present study, we further identified that 3-DSC inhibited viral genomic replication and transcription only at a relatively high concentration. We then evaluated the effect of 3-DSC on the regulation of virus-induced cellular apoptosis. 3-DSC ameliorated virus-induced DNA fragmentation in a concentration-dependent manner, which tends to be a consequence of its inhibition of upstream caspase activation. 3-DSC also protected host cells against influenza-induced inflammation by suppressing CCL5 and CXCL10 secretions in endothelial cells and reducing the production of IL-6 and IL-1ß in monocytes/macrophages. In conclusion, our results demonstrate that anti-influenza virus mechanisms of 3-DSC involved anti-apoptosis and anti-inflammation activities in vitro. Moreover, 3-DSC could be a promising drug candidate for influenza treatment.

Lipocalin-2 Is a chemokine inducer in the central nervous system: role of chemokine ligand 10 (CXCL10) in lipocalin-2-induced cell migration.

The secreted protein lipocalin-2 (LCN2) has been implicated in diverse cellular processes, including cell morphology and migration. Little is known, however, about the role of LCN2 in the CNS. Here, we show that LCN2 promotes cell migration through up-regulation of chemokines in brain. Studies using cultured glial cells, microvascular endothelial cells, and neuronal cells suggest that LCN2 may act as a chemokine inducer on the multiple cell types in the CNS. In particular, up-regulation of CXCL10 by JAK2/STAT3 and IKK/NF-κB pathways in astrocytes played a pivotal role in LCN2-induced cell migration. The cell migration-promoting activity of LCN2 in the CNS was verified in vivo using mouse models. The expression of LCN2 was notably increased in brain following LPS injection or focal injury. Mice lacking LCN2 showed the impaired migration of astrocytes to injury sites with a reduced CXCL10 expression in the neuroinflammation or injury models. Thus, the LCN2 proteins, secreted under inflammatory conditions, may amplify neuroinflammation by inducing CNS cells to secrete chemokines such as CXCL10, which recruit additional inflammatory cells.

Modelling of the membrane receptor CXCR3 and its complexes with CXCL9, CXCL10 and CXCL11 chemokines: putative target for new drug design.

The chemokines play a key role in immune and inflammatory responses by promoting recruitment and activation of different subpopulations of leukocytes. These comprise over 50 proteins grouped into four classes, in basis to the arrangement of conserved cysteine residues within the sequence. CXCL9, CXCL10 and CXCL11 are the members of the family of ELR-CXC chemokines and bind the same CXCR3 receptor. During the past few years, several studies have demonstrated a pathogenetic role of CXCR3 and its ligands in many human inflammatory diseases. The blockade of CXCR3 interactions with its ligands has been suggested as a possible therapeutic target for the treatment of these diseases. Therefore, we modelled the three-dimensional structure of CXCL9 and CXCR3, and, successively, of the CXCL9/CXCR3 complex in comparison to CXCL10/CXCR3 and CXCL11/CXCR3 complexes. We have then shown the structural determinants of these interactions and their physico-chemical features. Finally, the interaction residues involved in the formation of the complexes have been highlighted and analyzed in order to be used for drug design.

Stromal cell-derived factors 1alpha and 1beta, inflammatory protein-10 and interferon-inducible T cell chemo-attractant are novel substrates of dipeptidyl peptidase 8.

N-terminal truncation of chemokines by proteases including dipeptidyl peptidase (DP) IV significantly alters their biological activity; generally ablating cognate G-protein coupled receptor engagement and often generating potent receptor antagonists. DP8 is a recently recognised member of the prolyl oligopeptidase gene family that includes DPIV. Since DPIV is known to process chemokines we surveyed 27 chemokines for cleavage by DP8. We report DP8 cleavage of the N-terminal two residues of IP10 (CXCL10), ITAC (CXCL11) and SDF-1 (CXCL12). This has implications for DP8 substrate specificity. Chemokine cleavage and inactivation may occur in vivo upon cell lysis and release of DP8 or in the inactivation of internalized chemokine/receptor complexes.