Chemokine Binding to Tenascin-C Influences Chemokine-Induced Immune Cell Migration.

Tenascin-C (TNC) is a complex glycoprotein of the extracellular matrix (ECM) involved in a plethora of (patho-)physiological processes, such as oncogenesis and inflammation. Since chemokines play an essential role in both disease processes, we have investigated here the binding of TNC to some of the key chemokines, namely CCL2, CCL26, CXCL8, CXCL10, and CXCL12. Thereby, a differential chemokine-TNC binding pattern was observed, with CCL26 exhibiting the highest and CCL2 the lowest affinity for TNC. Heparan sulfate (HS), another member of the ECM, proved to be a similarly high-affinity ligand of TNC, with a Kd value of 730 nM. Chemokines use glycosa-minoglycans such as HS as co-receptors to induce immune cell migration. Therefore, we assumed an influence of TNC on immune cell chemotaxis due to co-localization within the ECM. CCL26- and CCL2-induced mobilization experiments of eosinophils and monocytes, respectively, were thus performed in the presence and the absence of TNC. Pre-incubation of the immune cells with TNC resulted in a 3.5-fold increase of CCL26-induced eosinophil chemotaxis, whereas a 1.3-fold de-crease in chemotaxis was observed when monocytes were pre-incubated with CCL2. As both chemokines have similar HS binding but different TNC binding affinities, we speculate that TNC acts as an attenuator in monocyte and as an amplifier in eosinophil mobilization by impeding CCL2 from binding to HS on the one hand, and by reinforcing CCL26 to bind to HS on the other hand.

Investigating Chemokine-Matrix Networks in Breast Cancer: Tenascin-C Sets the Tone for CCL2.

Bidirectional dialogue between cellular and non-cellular components of the tumor microenvironment (TME) drives cancer survival. In the extracellular space, combinations of matrix molecules and soluble mediators provide external cues that dictate the behavior of TME resident cells. Often studied in isolation, integrated cues from complex tissue microenvironments likely function more cohesively. Here, we study the interplay between the matrix molecule tenascin-C (TNC) and chemokine CCL2, both elevated in and associated with the progression of breast cancer and playing key roles in myeloid immune responses. We uncover a correlation between TNC/CCL2 tissue levels in HER2+ breast cancer and examine the physical and functional interactions of these molecules in a murine disease model with tunable TNC levels and in in vitro cellular and cell-free models. TNC supported sustained CCL2 synthesis, with chemokine binding to TNC via two distinct domains. TNC dominated the behavior of tumor-resident myeloid cells; CCL2 did not impact macrophage survival/activation whilst TNC facilitated an immune suppressive macrophage phenotype that was not dependent on or altered by CCL2 co-expression. Together, these data map new binding partners within the TME and demonstrate that whilst the matrix exerts transcriptional control over the chemokine, each plays a distinct role in subverting anti-tumoral immunity.

Single domain shark VNAR antibodies neutralize SARS-CoV-2 infection in vitro.

Single domain shark variable domain of new antigen receptor (VNAR) antibodies can offer a viable alternative to conventional Ig-based monoclonal antibodies in treating COVID-19 disease during the current pandemic. Here we report the identification of neutralizing single domain VNAR antibodies selected against the severe acute respiratory syndrome coronavirus 2 spike protein derived from the Wuhan variant using phage display. We identified 56 unique binding clones that exhibited high affinity and specificity to the spike protein. Of those, 10 showed an ability to block both the spike protein receptor binding domain from the Wuhan variant and the N501Y mutant from interacting with recombinant angiotensin-converting enzyme 2 (ACE2) receptor in vitro. In addition, three antibody clones retained in vitro blocking activity when the E484K spike protein mutant was used. The inhibitory property of the VNAR antibodies was further confirmed for all 10 antibody clones using ACE2 expressing cells with spike protein from the Wuhan variant. The viral neutralizing potential of the VNAR clones was also confirmed for the 10 antibodies tested using live Wuhan variant virus in in vitro cell infectivity assays. Single domain VNAR antibodies, due to their low complexity, small size, unique epitope recognition, and formatting flexibility, should be a useful adjunct to existing antibody approaches to treat COVID-19.

The Role of Heparan Sulfate in CCL26-Induced Eosinophil Chemotaxis.

Proinflammatory chemokine ligand 26 (CCL26, eotaxin-3) mediates transendothelial cell migration of eosinophils by binding and activating the G-protein-coupled (GPC) chemokine receptor 3 on the surface of eosinophilic cells. Here we have investigated the role of glycosaminoglycans (GAGs) as potential co-receptors in the process of CCL26-induced eosinophil chemotaxis. For this purpose, we have first identified the GAG-binding site of CCL26 by a site-directed mutagenesis approach in the form of an alanine screening. A panel of GAG-binding-deficient mutants has been designed, generated, and analyzed with respect to their binding affinities to heparan sulphate (HS) by isothermal fluorescence titration studies. This showed that basic amino acids in the α-helical part of CCL26 are strongly involved in GAG-binding. In chemotaxis experiments, we found that decreased GAG-binding affinity correlated with decreased chemotactic activity, which indicates an involvement of GAGs in eosinophil migration. This was further proven by the negative impact of heparinase III treatment and, independently, by the incubation of eosinophils with an anti heparan sulfate antibody. We finally investigated eosinophils' proteoglycan (PG) expression patterns by real-time PCR, which revealed the highest expression level for serglycin. Including an anti-serglycin antibody in CCL26-induced eosinophil migration experiments reduced the chemotaxis of these immune cells, thereby proving the dependence of eosinophil mobilization on the proteoglycan serglycin.

Development of Molecules Antagonizing Heparan Sulfate Proteoglycans.

Heparan sulfate proteoglycans (HSPGs) occur in almost every tissue of the human body and consist of a protein core, with covalently attached glycosaminoglycan polysaccharide chains. These glycosaminoglycans are characterized by their polyanionic nature, due to sulfate and carboxyl groups, which are distributed along the chain. These chains can be modified by different enzymes at varying positions, which leads to huge diversity of possible structures with the complexity further increased by varying chain lengths. According to their location, HSPGs are divided into different families, the membrane bound, the secreted extracellular matrix, and the secretory vesicle family. As members of the extracellular matrix, they take part in cell-cell communication processes on many levels and with different degrees of involvement. Of particular therapeutic interest is their role in cancer and inflammation as well as in infectious diseases. In this review, we give an overview of the current status of medical approaches to antagonize HSPG function in pathology.

Isolation and Characterization of Heparan Sulfate from Human Lung Tissues.

Glycosaminoglycans are a class of linear, highly negatively charged, O-linked polysaccharides that are involved in many (patho)physiological processes. In vitro experimental investigations of such processes typically involve porcine-derived heparan sulfate (HS). Structural information about human, particularly organ-specific heparan sulfate, and how it compares with HS from other organisms, is very limited. In this study, heparan sulfate was isolated from human lung tissues derived from five donors and was characterized for their overall size distribution and disaccharide composition. The expression profiles of proteoglycans and HS-modifying enzymes was quantified in order to identify the major core proteins for HS. In addition, the binding affinities of human HS to two chemokines-CXCL8 and CCL2-were investigated, which represent important inflammatory mediators in lung pathologies. Our data revealed that syndecans are the predominant proteoglycan class in human lungs and that the disaccharide composition varies among individuals according to sex, age, and health stage (one of the donor lungs was accidentally discovered to contain a solid tumor). The compositional difference of the five human lung HS preparations affected chemokine binding affinities to various degrees, indicating selective immune cell responses depending on the relative chemokine-glycan affinities. This represents important new insights that could be translated into novel therapeutic concepts for individually treating lung immunological disorders via HS targets.

Novel Anti-Inflammatory Peptides Based on Chemokine-Glycosaminoglycan Interactions Reduce Leukocyte Migration and Disease Severity in a Model of Rheumatoid Arthritis.

Inflammation is characterized by the infiltration of leukocytes from the circulation and into the inflamed area. Leukocytes are guided throughout this process by chemokines. These are basic proteins that interact with leukocytes to initiate their activation and extravasation via chemokine receptors. This is enabled through chemokine immobilization by glycosaminoglycans (GAGs) at the luminal endothelial surface of blood vessels. A specific stretch of basic amino acids on the chemokine, often at the C terminus, interacts with the negatively charged GAGs, which is considered an essential interaction for the chemokine function. Short-chain peptides based on this GAG-binding region of the chemokines CCL5, CXCL8, and CXCL12γ were synthesized using standard Fmoc chemistry. These peptides were found to bind to GAGs with high affinity, which translated into a reduction of leukocyte migration across a cultured human endothelial monolayer in response to chemokines. The leukocyte migration was inhibited upon removal of heparan sulfate from the endothelial surface and was found to reduce the ability of the chemokine and peptide to bind to endothelial cells in binding assays and to human rheumatoid arthritis tissue. The data suggest that the peptide competes with the wild-type chemokine for binding to GAGs such as HS and thereby reduces chemokine presentation and subsequent leukocyte migration. Furthermore, the lead peptide based on CXCL8 could reduce the disease severity and serum levels of the proinflammatory cytokine TNF-α in a murine Ag-induced arthritis model. Taken together, evidence is provided for interfering with the chemokine-GAG interaction as a relevant therapeutic approach.

Therapeutic strategies to target microbial protein-glycosaminoglycan interactions.

Glycans are involved in a plethora of human pathologies including infectious diseases. Especially, glycosaminoglycans (GAGs), like heparan sulfate and chondroitin sulfate, have been found to be involved in different crucial stages of microbial invasion. Here, we review various therapeutic approaches, which target the interface of host GAGs and microbial proteins and discuss their limitations and challenges for drug development.

Anti-inflammatory effects of the GAG-binding CXCL9(74-103) peptide in dinitrofluorobenzene-induced contact hypersensitivity in mice.

BACKGROUND: To recruit leucocytes to an inflammatory site, chemokine binding to glycosaminoglycans (GAGs) is critical. Therefore, strategies to interfere with this interaction, aiming at the production of anti-inflammatory agents, were developed. These include production of modified chemokines without affinity for G protein-coupled receptors but with enhanced affinity for GAGs. Such modified chemokines compete with functional chemokines for GAG binding, prevent chemokine immobilization and presentation, and inhibit leucocyte migration. In addition to modified chemokines, a GAG-binding peptide consisting of the 30 COOH-terminal residues of CXCL9, that is CXCL9(74-103), inhibited CXCL8- and monosodium urate crystal-induced neutrophil migration. OBJECTIVE: We wanted to explore whether interference with chemokine-GAG interactions by CXCL9(74-103) reduces inflammation in neutrophil-dependent dinitrofluorobenzene-induced contact hypersensitivity. METHODS: For this study, we evaluated several inflammatory parameters, including ear swelling and the levels of chemokines, cytokines, proteases and neutrophils in the ears of dinitrofluorobenzene-induced mice treated with CXCL9(74-103) or buffer. RESULTS: One intravenous injection of CXCL9(74-103), just before painting with dinitrofluorobenzene on the ear, did not affect protein levels of the major murine neutrophil attractant, that is CXCL6, in this contact hypersensitivity model. However, IL-6, CXCL1, CCL2 and matrix metalloproteinase-9 (MMP-9) protein concentrations and peroxidase activity in challenged ears were reduced. In addition, intravenous injection of the CXCL9-derived peptide led to a reduced ear swelling response, indicating that the locally produced chemokines were hindered to attract leucocytes. The inhibiting potential of CXCL9(74-103) was explained by its competition for GAG binding with CXCL1, CXCL6 and CCL3 and inhibition of transendothelial migration of neutrophils to CXCL6. CONCLUSIONS AND CLINICAL RELEVANCE: The CXCL9(74-103) peptide inhibited dinitrofluorobenzene-induced infiltration of neutrophils and neutrophil-dependent inflammation in ears. Therefore, CXCL9(74-103) may be a lead molecule for the development of therapeutic peptides or peptide derivatives that compete with functional chemokines for GAG binding.

Glycosaminoglycans are important mediators of neutrophilic inflammation in vivo.

The pro-inflammatory chemokine interleukin-8 (CXCL8) exerts its function by establishing a chemotactic gradient in infected or damaged tissues to guide neutrophil granulocytes to the site of inflammation via its G protein-coupled receptors (GPCRs) CXCR1 and CXCR2 located on neutrophils. Endothelial glycosaminoglycans (GAGs) have been proposed to support the chemotactic gradient formation and thus the inflammatory response by presenting the chemokine to approaching leukocytes. In this study, we show that neutrophil transmigration in vitro can be reduced by adding soluble GAGs and that this process is specific with respect to the nature of the glycan. To further investigate the GAG influence on neutrophil migration, we have used an engineered CXCL8 mutant protein (termed PA401) which exhibits a much higher affinity towards GAGs and an impaired GPCR activity. This dominant-negative mutant chemokine showed anti-inflammatory activity in various animal models of neutrophil-driven inflammation, i.e. in urinary tract infection, bleomycin-induced lung fibrosis, and experimental autoimmune uveitis. In all cases, treatment with PA401 resulted in a strong reduction of transmigrated inflammatory cells which became evident from histology sections and bronchoalveolar lavage. Since our CXCL8-based decoy targets GAGs and not GPCRs, our results show for the first time the crucial involvement of this glycan class in CXCL8/neutrophil-mediated inflammation and will thus pave the way to novel approaches of anti-inflammatory treatment.

Profiling the Membrane and Glycosaminoglycan-Binding Proteomes of Moraxella catarrhalis.

Moraxella catarrhalis, a Gram-negative bacterium, is an important respiratory pathogen causing acute otitis media and exacerbations of chronic obstructive pulmonary disease. Adhesion of the pathogen to human epithelial cells is mediated via bacterial membrane adhesin proteins. To identify the surface proteome of Moraxella catarrhalis, we applied different membrane protein extraction methods in combination with different proteomic technologies. Proteins from preparations of outer membrane vesicles and from carbonate extractions were analyzed using either a gel-based nano-HPLC-MS/MS technique or 2D-LC-MS/MS. Furthermore, because glycosaminoglycans (GAGs) play an important role for microbial entry into human cells, the GAG-binding membranome of Moraxella catarrhalis was investigated using a glycan-based pull-down approach. By these means, potential vaccine protein candidates that were previously selected by the ANTIGENome technology were confirmed, but importantly also novel proteins were identified as candidates.

The Positively Charged COOH-terminal Glycosaminoglycan-binding CXCL9(74-103) Peptide Inhibits CXCL8-induced Neutrophil Extravasation and Monosodium Urate Crystal-induced Gout in Mice.

The ELR(-)CXC chemokine CXCL9 is characterized by a long, highly positively charged COOH-terminal region, absent in most other chemokines. Several natural leukocyte- and fibroblast-derived COOH-terminally truncated CXCL9 forms missing up to 30 amino acids were identified. To investigate the role of the COOH-terminal region of CXCL9, several COOH-terminal peptides were chemically synthesized. These peptides display high affinity for glycosaminoglycans (GAGs) and compete with functional intact chemokines for GAG binding, the longest peptide (CXCL9(74-103)) being the most potent. The COOH-terminal peptide CXCL9(74-103) does not signal through or act as an antagonist for CXCR3, the G protein-coupled CXCL9 receptor, and does not influence neutrophil chemotactic activity of CXCL8 in vitro. Based on the GAG binding data, an anti-inflammatory role for CXCL9(74-103) was further evidenced in vivo. Simultaneous intravenous injection of CXCL9(74-103) with CXCL8 injection in the joint diminished CXCL8-induced neutrophil extravasation. Analogously, monosodium urate crystal-induced neutrophil migration to the tibiofemural articulation, a murine model of gout, is highly reduced by intravenous injection of CXCL9(74-103). These data show that chemokine-derived peptides with high affinity for GAGs may be used as anti-inflammatory peptides; by competing with active chemokines for binding and immobilization on GAGs, these peptides may lower chemokine presentation on the endothelium and disrupt the generation of a chemokine gradient, thereby preventing a chemokine from properly performing its chemotactic function. The CXCL9 peptide may serve as a lead molecule for further development of inhibitors of inflammation based on interference with chemokine-GAG interactions.

Exploring the glycosaminoglycan-protein interaction network by glycan-mediated pull-down proteomics.

Glycosaminoglycans (GAGs) are linear, highly sulfated polysaccharides expressed by almost all animal cells. They occur as soluble molecules, or form proteoglycans by being O-linked to different core proteins on the cell surface and in the extracellular matrix. Due to their ability to interact with diverse proteins and to modulate their biologic functions, GAGs are main drivers of mammalian biology. However, to the present day, the human GAG binding proteome has only been insufficiently explored. The aim of this study was therefore to investigate the human GAG binding proteome of different sources by using the major GAG classes as ligands, and to explore the GAG-binding selectivity of the human plasma proteome. For this purpose, proteins were pulled down from immobilized low molecular weight heparin, heparan sulfate, and dermatan sulfate under different conditions and were identified by nano-LC/MS². Four hundred and fifty eight human GAG binding proteins have been identified, whereas plasma proteins showed clear differences in their GAG-binding specificity/selectivity and affinity. We were able to differentiate between proteins that bound to all three glycan ligands and proteins that showed selective binding to one or two glycan ligands. Moreover, step-gradient salt elution revealed different binding affinities toward different GAG ligands. On top of proteins with well-known GAG-binding properties we have identified formerly unknown GAG binders. Functional annotation of the identified GAG-binding proteins showed clusters of proteins that are involved in a variety of biological processes. The method described here is well suited for identifying GAG-binding proteins and for comparing human subproteomes with respect to binding to different GAG classes.

PA401, a novel CXCL8-based biologic therapeutic with increased glycosaminoglycan binding, reduces bronchoalveolar lavage neutrophils and systemic inflammatory markers in a murine model of LPS-induced lung inflammation.

RATIONALE: Neutrophils play a fundamental role in a number of chronic lung diseases. Among the mediators of their recruitment to the lung, CXCL8 (IL-8) is considered to be one of the major players. CXCL8 exerts its chemotactic activity by binding to its GPCR receptors (CXCR1/R2) located on neutrophils, as well as through interactions with glycosaminoglycans (GAGs) on cell surfaces including those of the microvascular endothelium. Binding to GAG co-receptors is required to generate a solid-phase haptotactic gradient and to present IL-8/CXCL8 in a proper conformation to its receptors on circulating neutrophils. METHODS: We have engineered increased GAG-binding affinity into human CXCL8, thereby obtaining a competitive inhibitor that displaces wild-type IL-8/CXCL8 from GAGs. By additionally knocking-out the GPCR binding domain of the chemokine, we generated a dominant negative protein (dnCXCL8; PA401) with potent anti-inflammatory characteristics proven in vivo in a murine model of LPS-induced lung inflammation (Adage et al., 2015). Here we have further investigated PA401 activity in this pulmonary model by evaluating plasma changes induced by LPS on white blood cells (WBC) and a broad range of inflammatory markers, especially chemokines, by addressing immediate effects of PA401 on these parameters in healthy and LPS exposed mice. RESULTS: Aerosolized LPS induced a significant increase in bronchoalveolar lavage (BAL) neutrophils after 3 and 7h, as well as an increase in total WBC and changes in 21 of the 59 measured plasma markers, mostly belonging to the chemokine family. PA401 treatment in saline exposed mice didn't induce major changes in any of the measured parameters. When administered to LPS aerosolized mice, PA401 caused a significant normalization of KC/mCXCL1 and other inflammatory markers, as well as of blood WBC count. In addition, BAL neutrophils were significantly reduced, confirming the previously observed lung anti-inflammatory activity of PA401 in this experiment. CONCLUSIONS: PA401 is a new promising biologic therapeutic with a novel and unique mechanism of action for interfering with neutrophilic lung inflammation, that also normalizes plasma inflammatory markers.

A combinatorial approach to biophysically characterise chemokine-glycan binding affinities for drug development.

Chemokine binding to glycosaminoglycans (GAGs) is recognised to be an important step in inflammation and other pathological disorders like tumor growth and metastasis. Although different ways and strategies to interfere with these interactions are being pursued, no major breakthrough in the development of glycan-targeting drugs has been reported so far. We have engineered CXCL8 towards a dominant-negative form of this chemokine (dnCXCL8) which was shown to be highly active in various inflammatory animal models due to its inability to bind/activate the cognate CXCL8 GPC receptors on neutrophils in combination with its significantly increased GAG-binding affinity [1]. For the development of GAG-targeting chemokine-based biopharmaceuticals, we have established a repertoire of methods which allow the quantification of protein-GAG interactions. Isothermal fluorescence titration (IFT), surface plasmon resonance (SPR), isothermal titration calorimetry (ITC), and a novel ELISA-like competition assay (ELICO) have been used to determine Kd and IC50 values for CXCL8 and dnCXCL8 interacting with heparin and heparan sulfate (HS), the proto-typical members of the GAG family. Although the different methods gave different absolute affinities for the four protein-ligand pairs, the relative increase in GAG-binding affinity of dnCXCL8 compared to the wild type chemokine was found by all methods. In combination, these biophysical methods allow to discriminate between unspecific and specific protein-GAG interactions.

New targets for glycosaminoglycans and glycosaminoglycans as novel targets.

Biological functions of a variety of proteins are mediated via their interaction with glycosaminoglycans (GAGs). The structural diversity within the wide GAG landscape provides individual interaction sites for a multitude of proteins involved in several pathophysiological processes. This 'GAG angle' of such proteins as well as their specific GAG ligands give rise to novel therapeutic concepts for drug development. Current glycomic technologies to elucidate the glycan structure-function relationships, methods to investigate the selectivity and specificity of glycan-protein interactions and existing therapeutic approaches to interfere with GAG-protein interactions are discussed.

Comparative membrane proteome analysis of three Borrelia species.

The versatility of the surface of Borrelia, the causative agent of Lyme borreliosis, is very important in host-pathogen interactions allowing bacteria to survive in ticks and to persist in a mammalian environment. To identify the surface proteome of Borrelia, we have performed a large comparative proteomic analysis on the three most important pathogenic Borrelia species, namely B. burgdorferi (strain B31), B. afzelii (strain K78), and B. garinii (strain PBi). Isolation of membrane proteins was performed by using three different approaches: (i) a detergent-based fractionation of outer membrane proteins; (ii) a trypsin-based partial shedding of outer cell surface proteins; (iii) biotinylation of membrane proteins and preparation of the biotin-labelled fraction using streptavidin. Proteins derived from the detergent-based fractionation were further sub-fractionated by heparin affinity chromatography since heparin-like molecules play an important role for microbial entry into human cells. All isolated proteins were analysed using either a gel-based liquid chromatography (LC)-MS/MS technique or by two-dimensional (2D)-LC-MS/MS resulting in the identification of 286 unique proteins. Ninety seven of these were found in all three Borrelia species, representing potential targets for a broad coverage vaccine for the prevention of Lyme borreliosis caused by the different Borrelia species.

The neurotransmitter serotonin interrupts α-synuclein amyloid maturation.

Indolic derivatives can affect fibril growth of amyloid forming proteins. The neurotransmitter serotonin (5-HT) is of particular interest, as it is an endogenous molecule with a possible link to neuropsychiatric symptoms of Parkinson disease. A key pathomolecular mechanism of Parkinson disease is the misfolding and aggregation of the intrinsically unstructured protein α-synuclein. We performed a biophysical study to investigate an influence between these two molecules. In an isolated in vitro system, 5-HT interfered with α-synuclein amyloid fiber maturation, resulting in the formation of partially structured, SDS-resistant intermediate aggregates. The C-terminal region of α-synuclein was essential for this interaction, which was driven mainly by electrostatic forces. 5-HT did not bind directly to monomeric α-synuclein molecules and we propose a model where 5-HT interacts with early intermediates of α-synuclein amyloidogenesis, which disfavors their further conversion into amyloid fibrils.

Rationally evolving MCP-1/CCL2 into a decoy protein with potent anti-inflammatory activity in vivo.

Leukocyte recruitment from the blood into injured tissues during inflammatory diseases is the result of sequential events involving chemokines binding to their GPC receptors as well as to their glycosaminoglycan (GAG) co-receptors. The induction and the crucial role of MCP-1/CCL2 in the course of diseases that feature monocyte-rich infiltrates have been validated in many animal models, and several MCP-1/CCL2 as well as CCR2 antagonists have since been generated. However, despite some of them being shown to be efficacious in a number of animal models, many failed in clinical trials, and therapeutically interfering with the activity of this chemokine is not yet possible. We have therefore generated novel MCP-1/CCL2 mutants with increased GAG binding affinity and knocked out CCR2 activity, which were designed to interrupt the MCP-1/CCL2-related signaling cascade. We provide evidence that our lead mutant MCP-1(Y13A/S21K/Q23R) exhibits a 4-fold higher affinity toward the natural MCP-1 GAG ligand heparan sulfate and that it shows a complete deficiency in activating CCR2 on THP-1 cells. Furthermore, a significantly longer residual time on GAG ligands was observed by surface plasmon resonance. Finally, we were able to show that MCP-1(Y13A/S21K/Q23R) had a mild ameliorating effect on experimental autoimmune uveitis and that a marginal effect on oral tolerance in the group co-fed with Met-MCP-1(Y13A/S21K/Q23R) plus immunogenic peptide PDSAg was observed. These results suggest that disrupting wild type chemokine-GAG interactions by a chemokine-based antagonist can result in anti-inflammatory activity that could have potential therapeutic implications.

Cytokines and Chemokines in SARS-CoV-2 Infections-Therapeutic Strategies Targeting Cytokine Storm.

The recently identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, the cause of coronavirus disease (COVID-19) and the associated ongoing pandemic, frequently leads to severe respiratory distress syndrome and pneumonia with fatal consequences. Although several factors of this infection and its consequences are not completely clear, the presence and involvement of specific chemokines is undoubtedly crucial for the development and progression of COVID-19. Cytokine storm and the often-resulting cytokine release syndrome (CRS) are pathophysiological hallmarks in COVID-19 infections related to its most severe and fatal cases. In this hyperinflammatory event, chemokines and other cytokines are highly upregulated and are therefore not fulfilling their beneficial function in the host response anymore but causing harmful effects. Here, we present the recent views on the involvement of chemokines and selected cytokines in COVID-19 and the therapeutics currently in clinical development targeting or interfering with them, discussing their potentials in the treatment of COVID-19 infections.