Receptors expressions on peripheral lymphocytes and CD4+ CD183+ as a diagnostics biomarker for rheumatoid arthritis: A case-control study in Ghana

BACKGROUND

T cell receptors play important roles in the development and progression of rheumatoid arthritis (RA). Their involvement has been reported in inflammatory autoimmune diseases. However, their role in predicting RA is still under exploration. This study evaluated the expression of CD183 (CXCR3) receptors on T-cells and other relevant biomarkers for detecting RA and determine their relationship with disease activity.

METHODS

This unmatched case-control study included 48 newly diagnosed RA patients and 30 apparent healthy controls from the orthopedic units of Komfo Anokye Teaching Hospital (KATH), Kumasi and Korle-Bu Teaching Hospital (KBTH), Accra, Ghana. Sociodemographic data was obtained, and blood samples were also collected and processed for flow cytometric analysis. Statistical analyses were done using SPSS version 26.0 and R programming language. p < .05 was considered statistically significant.

RESULTS

This study found a significant difference in age group (p < .0001), marital status (p = .0210), occupation (p = .0140), educational level (p = .0210) and religion (p = .0100) between RA patients and healthy controls. Moreover, hemoglobin level (p = .0010), waist circumference (p < .0001) and hip circumference (p = .0040) were significantly different between RA patients and controls. RA patients had significantly lower levels of CD4+ CD183+ compared with the control group (p < .001), and was positively correlated with DAS score (r = .0397, p = .789). In Receiver Operator Characteristics analysis, CD4+ CD183+ could significantly detect RA with a high area under the curve (AUC = 0.687, p = .018). At a cut-off of 0.082, CD4+ CD183+ was the best receptor biomarker for detecting RA with a sensitivity of 90.0%, specificity of 25.9%, a positive predictive value of 69.2%, and a negative predictive value of 58.3%.

CONCLUSION

CD4+ CD183+ best predict RA and is positively correlated with disease activity. CD4+ CD183+ could serve as diagnostics and disease-monitoring biomarker for RA; however, it demonstrates low specificity. Future studies should be directed on CD4+ CD183+ and other biomarkers to augment their diagnostics performances and routine management in RA.

CXCR1 Regulates Pulmonary Anti-Pseudomonas Host Defense

Pseudomonas aeruginosa is a key opportunistic pathogen causing disease in cystic fibrosis (CF) and other lung diseases such as chronic obstructive pulmonary disease (COPD). However, the pulmonary host defense mechanisms regulating anti-P. aeruginosa immunity remain incompletely understood. Here we demonstrate, by studying an airway P. aeruginosa infection model, in vivo bioluminescence imaging, neutrophil effector responses and human airway samples, that the chemokine receptor CXCR1 regulates pulmonary host defense against P. aeruginosa. Mechanistically, CXCR1 regulates anti-Pseudomonas neutrophil responses through modulation of reactive oxygen species and interference with Toll-like receptor 5 expression. These studies define CXCR1 as a novel, noncanonical chemokine receptor that regulates pulmonary anti-Pseudomonas host defense with broad implications for CF, COPD and other infectious lung diseases.

Small Molecule CXCR3 Antagonists

Chemokines and their receptors are known to play important roles in disease. More than 40 chemokine ligands and 20 chemokine receptors have been identified, but, to date, only two small molecule chemokine receptor antagonists have been approved by the FDA. The chemokine receptor CXCR3 was identified in 1996, and nearly 20 years later, new areas of CXCR3 disease biology continue to emerge. Several classes of small molecule CXCR3 antagonists have been developed, and two have shown efficacy in preclinical models of inflammatory disease. However, only one CXCR3 antagonist has been evaluated in clinical trials, and there remain many opportunities to further investigate known classes of CXCR3 antagonists and to identify new chemotypes. This Perspective reviews the known CXCR3 antagonists and considers future opportunities for the development of small molecules for clinical evaluation.

Specificity for a CCR5 Inhibitor Is Conferred by a Single Amino Acid Residue: ROLE OF ILE198

The chemokine receptors CCR5 and CCR2b share 89% amino acid homology. CCR5 is a co-receptor for HIV and CCR5 antagonists have been investigated as inhibitors of HIV infection. We describe the use of two CCR5 antagonists, Schering-C (SCH-C), which is specific for CCR5, and TAK-779, a dual inhibitor of CCR5 and CCR2b, to probe the CCR5 inhibitor binding site using CCR5/CCR2b chimeric receptors. Compound inhibition in the different chimeras was assessed by inhibition of chemokine-induced calcium flux. SCH-C inhibited RANTES (regulated on activation, normal T cell expressed and secreted) (CCL5)-mediated calcium flux on CCR5 with an IC50 of 22.8 nM but was inactive against monocyte chemoattractant protein-1 (CCL2)-mediated calcium flux on CCR2b. However, SCH-C inhibited CCL2-induced calcium flux against a CCR5/CCR2b chimera consisting of transmembrane domains IV-VI of CCR5 with an IC50 of 55 nM. A sequence comparison of CCR5 and CCR2b identified a divergent amino acid sequence located at the junction of transmembrane domain V and second extracellular loop. Transfer of the CCR5 sequence KNFQTLKIV into CCR2b conferred SCH-C inhibition (IC50 of 122 nM) into the predominantly CCR2b chimera. Furthermore, a single substitution, R206I, conferred partial but significant inhibition (IC50 of 1023 nM) by SCH-C. These results show that a limited amino acid sequence is responsible for SCH-C specificity to CCR5, and we propose a model showing the interaction with CCR5 Ile(198).

Exploring the binding mechanisms of MIF to CXCR2 using theoretical approaches

Macrophage migration inhibitory factor (MIF) is a multi-functional protein that acts as a cytokine and as an enzyme. Recently, MIF was identified as a non-canonical ligand of G protein-coupled chemokine receptor CXCR2 with low nanomolar affinity in leukocyte arrest and chemotaxis, but the precise knowledge of the molecular determinants of the MIF-CXCR2 interface has remained unknown. Therefore, we employed homology modeling, protein-protein docking, molecular dynamics (MD) simulations, Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) binding free energy calculations and MM/GBSA binding free energy decomposition to obtain insights into the molecular recognition of MIF with CXCR2. The predicted binding pattern of MIF-CXCR2 is in good agreement with the experimental data and sheds light on the functional role of important MIF-CXCR2 interface residues in association with binding and signaling. According to our predictions, the R11A/D44A double mutations of MIF exhibit a pronounced defect in the binding affinity of MIF to CXCR2, resulting in large conformational changes. The potential two-site binding model for the MIF-CXCR2 recognition was proposed: initialized primarily by the non-polar interactions including the van der Waals and hydrophobic interactions, the N-terminal region of CXCR2 contacts the N-like loop and β-sheet of MIF (site 1), and then the ECL2 and ECL3 regions of CXCR2 form strong interactions with the pseudo-(E)LR motif and C-terminus of MIF, which induces the molecular thermodynamic motion of TMs for signal transduction (site 2). This study will extend our understanding to the binding mechanisms of MIF to CXCR2 and provide useful information for the rational design of potent inhibitors selectively targeting the MIF-CXCR2 interactions.

Design, synthesis and SAR study of novel trisubstituted pyrimidine amide derivatives as CCR4 antagonists

The design, synthesis and structure-activity relationship studies of some novel trisubstituted pyrimidine amide derivatives prepared as CCR4 antagonists are described. The activities of these compounds were evaluated by the CCR4-MDC chemotaxis inhibition assay. Compound 1, which we have previously reported as a potent antagonist of CCR4, was employed as the positive control. The results indicated that most of the synthesized compounds exhibited some chemotaxis inhibition activity against CCR4. Of these new compounds, compounds 6c, 12a and 12b, with IC₅₀ values of 0.064, 0.077 and 0.069 μM, respectively, showed higher or similar activity compared with compound 1 (IC₅₀ of 0.078 μM). These compounds provide a basis for further structural modifications. The systematic structure-activity relationship of these trisubstituted pyrimidine amide derivatives was discussed based on the obtained experimental data. The results from the SAR study may be useful for identifying more potent CCR4 antagonists.