Identification and profiling of CXCR3–CXCR4 chemokine receptor heteromer complexes

Background and Purpose

The C-X-C chemokine receptors 3 (CXCR3) and C-X-C chemokine receptors 4 (CXCR4) are involved in various autoimmune diseases and cancers. Small antagonists have previously been shown to cross-inhibit chemokine binding to CXCR4, CC chemokine receptors 2 (CCR2) and 5 (CCR5) heteromers. We investigated whether CXCR3 and CXCR4 can form heteromeric complexes and the binding characteristics of chemokines and small ligand compounds to these chemokine receptor heteromers.

Experimental Approach

CXCR3–CXCR4 heteromers were identified in HEK293T cells using co-immunoprecipitation, time-resolved fluorescence resonance energy transfer, saturation BRET and the GPCR-heteromer identification technology (HIT) approach. Equilibrium competition binding and dissociation experiments were performed to detect negative binding cooperativity.

Key Results

We provide evidence that chemokine receptors CXCR3 and CXCR4 form heteromeric complexes in HEK293T cells. Chemokine binding was mutually exclusive on membranes co-expressing CXCR3 and CXCR4 as revealed by equilibrium competition binding and dissociation experiments. The small CXCR3 agonist VUF10661 impaired binding of CXCL12 to CXCR4, whereas small antagonists were unable to cross-inhibit chemokine binding to the other chemokine receptor. In contrast, negative binding cooperativity between CXCR3 and CXCR4 chemokines was not observed in intact cells. However, using the GPCR-HIT approach, we have evidence for specific β-arrestin2 recruitment to CXCR3-CXCR4 heteromers in response to agonist stimulation.

Conclusions and Implications

This study indicates that heteromeric CXCR3–CXCR4 complexes may act as functional units in living cells, which potentially open up novel therapeutic opportunities.     

Staphylococcus aureus versus Staphylococcus epidermidis in periprosthetic joint infection—Outcome analysis of methicillin-resistant versus methicillin-susceptible strains

Periprosthetic joint infections (PJIs) are a major complication in total joint arthroplasty. Staphylococcus aureus and coagulase-negative staphylococci are known to cause the majority of all PJIs. This study aimed to analyze the eradication rates of S. aureus and S. epidermidis with methicillin susceptibility and methicillin resistance in a 2-stage therapy algorithm. Seventy-four patients with PJI caused by methicillin-resistant S. aureus (MRSA), methicillin-resistant coagulase-negative staphylococci (MRSE), methicillin-susceptible S. aureus (MSSA), and methicillin-susceptible coagulase-negative staphylococci (MSSE) were included, and the outcome was analyzed retrospectively. After a minimal follow-up of 2?years, n?=?56 patients (75.7%) were definitively free of infection. The analysis revealed significant differences between the groups, with eradication rates as follows: MSSA (92.6%), MSSE (95.2%), MRSA (80%), and MRSE (54.2%). MRSE showed a significantly lower rate of patients graded as “definitively free of infection” as compared to patients with infections caused by MSSA, MSSE, and MRSA.     

Family caregiver perspectives on social relations of elderly residents with dementia in small‐scale versus traditional long‐term care settings in the Netherlands and Belgium

Aims and objectives. To provide insight into family caregiver perspectives on social relations within the ‘caregiving triangle’ between family caregiver, professional caregiver and elderly resident with dementia. Results were compared between traditional versus small‐scale long‐term care settings in the Netherlands and Belgium. Background. Residential dementia care is shifting towards a more holistic and person‐centred approach. Until now, little is known about family caregiver perspectives. Design. A quasi‐experimental longitudinal design. Methods. This study was part of a larger research project focusing on the quality of life of residents with dementia in traditional and small‐scale settings (n = 179). This study focused on family caregivers related to these residents (n = 64). They filled in a questionnaire containing 25 items (baseline and after 12 months) related to their perspectives on the interaction within the ‘caregiving triangle’. Analyses were performed using mixed models and logistic regression. Results. Compared to traditional settings, family caregivers of relatives with dementia living in small‐scale settings had more contact with the professional caregivers, were more satisfied with this contact and felt that staff paid more attention to their feelings as family members. They also reported that staff showed better listening skills towards the residents. Furthermore, compared to those in Belgium, family caregivers in the Netherlands perceived staff to be less hurried and more accepting of help from family and felt that staff more often takes the resident seriously. Conclusion. In the move towards more person‐centred care for residents with dementia, this study finds preliminary evidence for the importance of integrating the family perspective. Relevance to clinical practice. Gaining more insight into the perspectives of family caregivers on the social relations within the ‘caregiving triangle’ may provide knowledge about the importance of the social system surrounding elderly residents with dementia and can provide pointers for future research.     

2020 European guideline on the management of genital molluscum contagiosum

Molluscum contagiosum is a benign viral epidermal infection associated with high risk of transmission. The guideline is focused on the sexually transmitted molluscum contagiosum. The diagnosis is clinical with characteristic individual lesions, termed ‘mollusca’, seen as dome‐shaped, smooth‐surfaced, pearly, firm, skin‐coloured, pink, yellow or white papules, 2 ‐ 5 mm in diameter with central umbilication. Dermoscopy may facilitate diagnosis. Therapeutic options are numerous, including physical treatments (cautery, curettage and cryotherapy), topical chemical treatments (e.g. podophyllotoxin and imiquimod) or waiting for spontaneous resolution in immunocompetent patients. In pregnancy, it is safe to use physical procedures (e.g. cryotherapy). Immunosuppressed patients develop severe and recalcitrant molluscum lesions that may require treatment with cidofovir, imiquimod or interferon. Patients with molluscum contagiosum infection should be offered to be screened for other sexually transmitted infections.     

Disparities of conjugating protective enzyme activities in the colon of patients with adenomas and carcinomas

AIM:To investigate the metabolic enzymatic capacity of the colon mucosa to detoxify noxious carcinogenic compounds.METHODS:We investigated the activity of 2 conjugating enzymes-the microsomal uridine glucuronosyltransferase(UGT)and the cytosomal glutathione S-transferase(GST)in the uninvolved mucosa of the colon transversum and sigmoideum in patients with adenomatous polyps and colorectal cancer.Biopsies were taken from the mucosa during colonoscopies which were done for clinical(diagnostic)reasons.After storage,the biopsy material was homogenized and after differential centrifugation the enzyme assays were performed with 4-nitrophenol(UGT)and 1-chloro 2,4-dinitrobenzene(GST)as substrates.RESULTS:About 48 patients were included of which28 had adenomas and 20 had colorectal carcinomas confirmed by histopathology.Enzyme activities were expressed as nmol/mg per minute protein for the GST and as pmol/mg per minute protein for the UGT.Analysis of variance(F-test)indicated that both enzymes were more widely distributed in adenoma than in cancer patients.The means±SD were smaller for cancer patients:GST for adenomas 268±152 vs 241±69 for carcinomas and UGT for adenomas 197±200 vs 150±86 for carcinomas.CONCLUSION:Compared to patients with adenomatous colon polyps those with colorectal carcinoma exhibited a lower capacity of detoxifying enzyme metabolism and their activities clustered over a smaller range.     

DNA content in malignant salivary gland tumours

Objective:  Our aim was to evaluate the DNA content in malignant salivary gland tumours using image cytometry and its possible relationships with clinical and morphologic findings, disease course and prognosis.
Patients and methods:  The study sample comprised 31 patients diagnosed and treated for primary malignant salivary gland tumours. Formalin-fixed, paraffin-embedded surgical specimens of all patients were Feulgen-stained for DNA content analysis by image cytometry. Statistical analysis was used to investigate possible relationships between DNA content variables and clinical and histological findings, disease course and patient survival.
Results:  Seventeen (55%) cases of our sample were graded as DNA diploid, four (13%) as DNA aneuploid and 10 (32%) as DNA multiploid. In 15 (48%) cases, the 5c exceeding rate (5cER) was higher than 1.7%. DNA ploidy correlated with N stage and tumour size. DNA ploidy and 5cER had a statistically significant prognostic influence on overall and disease-free survival in univariate analysis. However, in multivariate analysis, stage classification was the only parameter with an independent prognosis value.
Conclusion:  Abnormal DNA content is a common finding in salivary gland cancers. Our results suggest an important role of DNA content analysis in the evaluation of these tumours.