The aim of this study was to compare different antigen retrieval methods to improve the outcome of immunohistochemistry (IHC) performed on osteoarthritic (OA) cartilage obtained from total knee replacement operation. A voluminous and dense extracellular matrix of articular cartilage inhibits antibody penetration, and therefore, proteins present at low concentrations and masked during fixation may need antigen retrieval to enhance an IHC outcome. We focused on the IHC detection of a minor but diagnostically promising cartilage glycoprotein, CILP-2 (cartilage intermediate layer protein 2), to demonstrate the effect of four different protocols: (1) heat-induced epitope retrieval (HIER), (2) proteolytic-induced epitope retrieval applying proteinase K and hyaluronidase (PIER), (3) HIER combined with PIER, and (4) no antigen retrieval (control). A semi-quantitative staining assessment based on the CILP-2 staining extent was applied. Out of the tested antigen retrieval protocols, the best CILP-2 IHC staining results were achieved by PIER. Combining PIER with HIER did not improve CILP-2 staining in the given experimental setting. Rather the opposite, the application of heat reduced the positive effect of PIER on CILP-2 staining and resulted in the frequent detachment of sections from the slides. Our findings emphasize the need for proper adaptation of antigen retrieval protocols for IHC to maximize the quantitative evaluation of minor matrix proteins in OA articular cartilage samples.

Pathological cleavage of type II collagen (Col2) and generation of Col2 neoepitopes can serve as useful molecular markers of the progression of osteoarthritis (OA). One of such potential biomarkers is type II collagen neoepitope C2C. The aim of this study was to correlate the degree of articular cartilage damage in OA patients with C2C expression in histological samples of tissues removed during total knee replacement. Cartilage samples were obtained from 27 patients ranging in age from 55 to 66 years. In each patient, medial and lateral tibia plateau samples were analyzed according to the OARSI histopathology grading system. The C2C expression was evaluated on histological slides by semi-quantitative analysis using ImageJ Fiji 2.14.0 software. Spearman’s rank correlation analysis revealed a positive weak correlation (rho = 0.289, p = 0.0356) between the histological grade of tissue damage and the percentage of C2C staining. In addition, a highly significant positive correlation (rho = 0.388, p = 0.0041) was discovered between the osteoarthritis score (combining the histological grade of damage with the OA macroscopic stage) and the percentage of C2C staining in the samples. The C2C expression was detected in all the regions of the articular cartilage (i.e., the superficial zone, mid zone, deep zone and tidemark area, and the zone of calcified cartilage). Our findings imply that local expression of C2C correlates with the articular cartilage damage in OA-affected knees. This confirms that C2C can be used as a prospective marker for assessing pathological changes in the OA course and OA clinical trials.

Pathological cleavage of collagen type II (Col2) and generation of Col2 neoepitopes can be good molecular markers of progression of osteoarthritis (OA). One of such potential biomarkers is collagen type II neoepitope C2C. The aim of this study was to correlate the degree of articular cartilage damage in OA patients with C2C expression in histological samples of tissues removed during total knee replacement. Cartilage samples were obtained from 27 patients aged from 55 to 66. In each patient medial and lateral tibia plateau samples were analyzed according to the OARSI histopathology grading system. C2C expression was evaluated on histological slides by semi-quantitative analysis using ImageJ Fiji software. Spearman´s rank correlation analysis showed significant positive correlation (rho=0.289, P=0.0356) between the histological grade of tissue damage and the percentage of C2C staining. In addition, highly significant positive correlation (rho=0.388, P=0.0041) was found between osteoarthritis score (combining the histological grade of damage with the OA macroscopic stage) and the percentage of C2C staining in the samples. The C2C expression was found in all the regions of the articular cartilage (i.e. the superficial zone, mid zone, deep zone and tidemark area and the zone of calcified cartilage). Our study suggests that local expression of C2C correlates with the cartilage damage in the knee affected by OA. This further assures that C2C can be a perspective marker for evaluation of pathological processes in OA course and OA clinical trials.

The present study aims to investigate the expression of the follicle-stimulating hormone receptor (FSHR) in the human vulva to see if follicle-stimulating hormone (FSH) could potentially impact the function of vulvar tissue. Vulvar tissue was obtained from three patients during surgery due to squamous cell carcinoma. Immunohistochemistry was used for the detection of the FSHR. Positive immunoreaction for FSHR was present in the tissue samples of all patients. It was detected in all layers of the epithelium, in the fibroblasts of subepithelial connective tissue and in the walls of blood vessels in the vulva. By now, several studies have shown that, besides testes and ovaries, FSHR is also present in many extragonadal tissues. As well as in many cases, FSH actions in those organs are also suggested. Up to now, no studies have confirmed the expression of the FSHR in the vulva. Based on the present results, it is possible that FSH is involved in the regulation of vulvar tissue function. Further studies are indicated.