Systematic Assessment of Chemokine Signaling at Chemokine Receptors CCR4, CCR7 and CCR10

Structural basis of chemokine recognition by the class A3 tick evasin EVA-ACA1001

Ticks produce chemokine-binding proteins, known as evasins, in their saliva to subvert the host's immune response. Evasins bind to chemokines and thereby inhibit the activation of their cognate chemokine receptors, thus suppressing leukocyte recruitment and inflammation. We recently described subclass A3 evasins, which, like other class A evasins, exclusively target CC chemokines but appear to use a different binding site architecture to control target selectivity among CC chemokines. We now describe the structural basis of chemokine recognition by the class A3 evasin EVA-ACA1001. EVA-ACA1001 binds to almost all human CC chemokines and inhibits receptor activation. Truncation mutants of EVA-ACA1001 showed that, unlike class A1 evasins, both the N- and C-termini of EVA-ACA1001 play minimal roles in chemokine binding. To understand the structural basis of its broad chemokine recognition, we determined the crystal structure of EVA-ACA1001 in complex with the human chemokine CCL16. EVA-ACA1001 forms backbone-backbone interactions with the CC motif of CCL16, a conserved feature of all class A evasin-chemokine complexes. A hydrophobic pocket in EVA-ACA1001, formed by several aromatic side chains and the unique disulfide bond of class A3 evasins, accommodates the residue immediately following the CC motif (the "CC + 1 residue") of CCL16. This interaction is shared with EVA-AAM1001, the only other class A3 evasins characterized to date, suggesting it may represent a common mechanism that accounts for the broad recognition of CC chemokines by class A3 evasins.

Systematic Assessment of Human CCR7 Signalling Using NanoBRET Biosensors Points towards the Importance of the Cellular Context

The human CC chemokine receptor 7 (CCR7) is activated by two natural ligands, CC chemokine ligand 19 (CCL19) and 21 (CCL21). The CCL19-CCL21-CCR7 axis has been extensively studied in vitro, but there is still debate over whether CCL21 is an overall weaker agonist or if the axis displays biased signalling. In this study, we performed a systematic analysis at the transducer level using NanoBRET-based methodologies in three commonly used cellular backgrounds to evaluate pathway and ligand preferences, as well as ligand bias and the influence of the cellular system thereon. We found that both CCL19 and CCL21 activated all cognate G proteins and some non-cognate couplings in a cell-type-dependent manner. Both ligands recruited β-arrestin1 and 2, but the potency was strongly dependent on the cellular system. Overall, CCL19 and CCL21 showed largely conserved pathway preferences, but small differences were detected. However, these differences only consolidated in a weak ligand bias. Together, these data suggest that CCL19 and CCL21 share mostly overlapping, weakly biased, transducer profiles, which can be influenced by the cellular context.

Identification of aneuploidy-related gene signature to predict survival in head and neck squamous cell carcinomas

BACKGROUND

To parse the characteristics of aneuploidy related riskscore (ARS) model in head and neck squamous cell carcinomas (HNSC) and their predictive ability on patient prognosis.

METHODS

Molecular subtyping of HNSC specimens was clustered by Copy Number Variation (CNV) data from The Cancer Genome Atlas (TCGA) dataset applying consistent clustering, followed by immune condition evaluation, differentially expressed genes (DEGs) analysis and DEGs function annotation. Weighted gene co-expression network analysis (WGCNA), protein-protein interaction, Univariate Cox regression analysis, least absolute shrinkage and selection operator (LASSO) and stepwise multivariate Cox regression analysis were implemented to construct an ARS model. A nomogram for clinic practice was designed by rms package. Immunotherapy evaluation and drug sensitivity prediction were also carried out.

RESULTS

We stratified HNSC patients into three different molecular subgroups, with the best prognosis in C1 cluster among 3 clusters. C1 cluster displayed greatest immune infiltration status. The most DEGs between C1 and C2 groups, mainly enriched in cell cycle and immune function. We constructed a nine-gene ARS model (ICOS, IL21R, CCR7, SELL, CYTIP, ZAP70, CCR4, S1PR4 and CD79A) that effectively differentiates between high- and low-risk patients. Patients in low ARS group showed a higher sensitivity to immunotherapy. A nomogram built by integrating ARS and clinic-pathological characteristics helped predict clinic survival benefit. Drug sensitivity evaluation found that 4/9 inhibitor drugs (MK-8776, AZD5438, PD-0332991, PHA-665752) acted on the cell cycle.

CONCLUSIONS

We classified 3 molecular subtypes for HNSC patients and established an ARS prognostic model, which offered a prospective direction for prognosis in HNSC.

Engineering broad-spectrum inhibitors of inflammatory chemokines from subclass A3 tick evasins

Chemokines are key regulators of leukocyte trafficking and attractive targets for anti-inflammatory therapy. Evasins are chemokine-binding proteins from tick saliva, whose application as anti-inflammatory therapeutics will require manipulation of their chemokine target selectivity. Here we describe subclass A3 evasins, which are unique to the tick genus Amblyomma and distinguished from "classical" class A1 evasins by an additional disulfide bond near the chemokine recognition interface. The A3 evasin EVA-AAM1001 (EVA-A) bound to CC chemokines and inhibited their receptor activation. Unlike A1 evasins, EVA-A was not highly dependent on N- and C-terminal regions to differentiate chemokine targets. Structures of chemokine-bound EVA-A revealed a deep hydrophobic pocket, unique to A3 evasins, that interacts with the residue immediately following the CC motif of the chemokine. Mutations to this pocket altered the chemokine selectivity of EVA-A. Thus, class A3 evasins provide a suitable platform for engineering proteins with applications in research, diagnosis or anti-inflammatory therapy.

Novel Theranostic Approaches Targeting CCR4-Receptor, Current Status and Translational Prospectives: A Systematic Review

Background: With the high mortality rate of malignant tumors, there is a need to find novel theranostic approaches to provide an early diagnosis and targeted therapy. The chemokine receptor 4 (CCR4) is highly expressed in various tumors and plays an important role in tumor pathogenesis. This systematic review aims to provide a complete overview on clinical and preclinical applications of the CCR4 receptor as a target for theranostics, using a systematic approach to classify and assemble published studies performed on humans and animals, sorted by field of application and specific tumor. Methods: A systematic literature search of articles suiting the inclusion criteria was conducted on Pubmed, Scopus, Central, and Web of Science databases, including papers published from January 2006 to November 2022. Eligible studies had to be performed on humans and/or in vivo/in vitro studying CCR4 expression in tumors. The methodological quality was assessed through the Critical Appraisal Skills Programme (CASP) assessing only the studies performed on humans. Results: A total of 17 articles were screened. The articles were assessed for eligibility with the exclusion of 4 articles. Ultimately, 13 articles were selected for the qualitative analysis, and six articles were selected for the critical appraisal skills program. Conclusions: The development of new radionuclides and radiopharmaceuticals targeting CCR4 show promising results in the theranostics of CCR4 sensible tumors. Although to widen its use in clinical practice, further translation of preclinical to clinical data is needed.

The Role of G Protein-Coupled Receptor Kinase 6 Regulation in Inflammation and Pain

The G protein-coupled receptor kinase 6 is associated with inflammation and pathological pain. Impairment of GRK6 expression was described in chronic inflammatory diseases such as rheumatoid arthritis and this was shown to be accompanied by an imbalance of downstream signaling pathways. Here, we discuss novel aspects of GRK6 interaction and its impact upon hyperalgesia and inflammatory processes. In this review, we compile important findings concerning GRK6 regulation for a better pathophysiological understanding of the intracellular interaction in the context of inflammation and show clinical implications-for example, the identification of possible therapy goals in the treatment of chronic inflammatory hyperalgesia.

Swapping N-terminal regions among tick evasins reveals cooperative interactions influencing chemokine binding and selectivity

Class A tick evasins are natural chemokine-binding proteins that block the signaling of multiple chemokines from the CC subfamily through their cognate receptors, thus suppressing leukocyte recruitment and inflammation. Development of tick evasins as chemokine-targeted anti-inflammatory therapeutics requires an understanding of the factors controlling their chemokine recognition and selectivity. To investigate the role of the evasin N-terminal region for chemokine recognition, we prepared chimeric evasins by interchanging the N-terminal regions of four class A evasins, including a newly identified evasin, EVA-RPU02. We show through chemokine binding analysis of the parental and chimeric evasins that the N-terminal region is critical for chemokine binding affinity and selectivity. Notably, we found some chimeras were unable to bind certain cognate chemokine ligands of both parental evasins. Moreover, unlike any natural evasins characterized to date, some chimeras exhibited specific binding to a single chemokine. These results indicate that the evasin N terminus interacts cooperatively with the “body” of the evasin to enable optimum chemokine recognition. Furthermore, the altered chemokine selectivity of the chimeras validates the approach of engineering the N termini of evasins to yield unique chemokine recognition profiles.

Cellular Electrical Impedance as a Method to Decipher CCR7 Signalling and Biased Agonism

The human C-C chemokine receptor type 7 (CCR7) has two endogenous ligands, C-C chemokine ligand 19 (CCL19) and CCL21, displaying biased agonism reflected by a pronounced difference in the level of β-arrestin recruitment. Detecting this preferential activation generally requires the use of separate, pathway-specific label-based assays. In this study, we evaluated an alternative methodology to study CCR7 signalling. Cellular electrical impedance (CEI) is a label-free technology which yields a readout that reflects an integrated cellular response to ligand stimulation. CCR7-expressing HEK293 cells were stimulated with CCL19 or CCL21, which induced distinct impedance profiles with an apparent bias during the desensitisation phase of the response. This discrepancy was mainly modulated by differential β-arrestin recruitment, which shaped the impedance profile but did not seem to contribute to it directly. Pathway deconvolution revealed that Gαi-mediated signalling contributed most to the impedance profile, but Gαq- and Gα12/13-mediated pathways were also involved. To corroborate these results, label-based pathway-specific assays were performed. While CCL19 more potently induced β-arrestin2 recruitment and receptor internalisation than CCL21, both chemokines showed a similar level of Gαi protein activation. Altogether, these findings indicate that CEI is a powerful method to analyse receptor signalling and biased agonism.