[Meniscal degeneration score and NITEGE expression : immunohistochemical detection of NITEGE in advanced meniscal degeneration]

Degradation of Proteoglycans and Collagen in Equine Meniscal Tissues

Investigate meniscal extracellular matrix degradation. Equine menisci (n = 34 from 17 horses) were studied. Site-matched sections were cut and scored from three regions (ROIs; n = 102) and stained for histology, proteoglycan (safranin O and fast green), aggrecan, and collagen cleavage (NITEGE, DIPEN, and C1,2C antibodies, respectively). Picrosirius red and second harmonic generation microscopy were performed to investigate collagen ultrastructure. A total of 42 ROIs met the inclusion criteria and were included in the final analysis. The median (range) ROI histological score was 3 (0-9), providing a large spectrum of pathology. The median (range) proteoglycan score was 1 (0-3), representing superficial and central meniscal loss. The median (range) of DIPEN, NITEGE, and C1,2C scores was 1 (0-3), revealing immunostaining of the femoral and tibial surfaces. The proteoglycan scores exhibited significant positive associations with both histologic evaluation (p = 0.03) and DIPEN scores (p = 0.02). Additionally, a robust positive association (p = 0.007) was observed between the two aggrecanolysis indicators, NITEGE and DIPEN scores. A negative association (p = 0.008) was identified between NITEGE and histological scores. The C1,2C scores were not associated with any other scores. Picrosirius red and second harmonic generation microscopy (SHGM) illustrated the loss of the collagen matrix and structure centrally. Proteoglycan and collagen degradation commonly occur superficially in menisci and less frequently centrally. The identification of central meniscal proteoglycan and collagen degradation provides novel insight into central meniscal degeneration. However, further research is needed to elucidate the etiology and sequence of degradative events.

Role of pro-inflammatory interleukins in osteoarthritis: a narrative review

PURPOSE

This manuscript will summarize the role of pro-inflammatory cytokines and tackle newly discussed ones within the scope of OA pathogenesis as mentioned in the recent literature. This will allow for a better understanding of the mechanisms behind such a complicated disease.

MATERIAL AND METHODS

Relevant articles were obtained by searching key terms including "pro-inflammatory cytokines," "inflammation," "pathophysiology," "cartilage damage," and "OA" in PubMed and Google Scholar databases. The year ranges set for the selection of the articles was between 2015 -2021. Inclusion criteria was based on the relevance and contribution to the field of the study.

RESULTS

Osteoarthritis (OA) has a complex multifactorial pathophysiology which is attributed to molecular and biomechanical changes that disrupt the normal balance of synthesis and degradation of articular cartilage and subchondral bone. Pro-inflammatory cytokines, with their wide range of action and intricate signaling pathways, are the constant subject of new discoveries revolving around this inflammatory disease. The available literature indicates that some of these cytokines such as IL-33, IL-17, IL-6, and IL-22 have a direct relation to cartilage degradation, while others like IL-15, IL-1, IL-7, and IL-34 have an indirect one.

CONCLUSIONS

Inflammation has an essential role in the manifestation of osteoarthritis clinical events. Specifically, certain cytokines exhibit pro-inflammatory properties that are markedly activated during the course of the disease and notably alter the homeostasis of the joint environment. However, clinical trials and observational studies remain insufficient to navigate the varying nature of this disease in humans.

Mechanical stretching induces calcification and cartilage matrix metabolism, causing degeneration of the acetabular labrum

PURPOSE

The acetabular labrum plays an important role in joint lubrication, and damage to this structure leads to osteoarthritis. This study aimed to histologically classify the degree of degeneration of the acetabular labrum and to investigate the changes in gene expression induced by mechanical stretching.

METHODS

We obtained acetabular labrum cells from patients with hip osteoarthritis during total hip arthroplasty (n = 25). The labrum was stained with safranin O, and images were histologically evaluated using a new parameter, the red/blue (R/B) value. The samples were divided into the degenerated group (D group: n = 18) and the healthy group (H group: n = 7) in accordance with the Kellgren-Lawrence (KL) grade. The cultured acetabular labral cells were subjected to loaded uniaxial cyclic tensile strain (CTS). After CTS, changes in gene expression were examined in both groups.

RESULTS

Spearman's correlation analysis revealed that the R/B value was significantly correlated with the KL grade and the Krenn score. The expression levels of genes related to cartilage metabolism, osteogenesis and angiogenesis significantly increased after CTS in the H group, while gene expression in the D group showed weaker changes after CTS than that in the H group compared to the nonstretched control group.

CONCLUSIONS

The degree of labral degeneration could be classified histologically using the R/B value and the KL grade. Mechanical stretching caused changes in gene expression that support the pathological features of labral degeneration.

Imaging, histopathological degree of degeneration and clinical findings - Do these correlate in patients with temporomandibular joint disorders

The gold standard for temporomandibular joint imaging is magnetic resonance imaging, although there are still pathological findings that cannot be seen in MRI but in surgery and the subsequent histological analysis only. The main goal of this investigation was to validate the MRI score used by histopathological findings as well as clinical findings. In this retrospective study 39 patients were included; 38 of which underwent unilateral and 1 underwent bilateral discectomy. MRI findings were graded according to the score by Wurm. Histopathological analysis was performed in hematoxylin-eosin staining and graded in accordance with the scores by Krenn and by Leonardi. For valuation of preoperative pain values of the temporomandibular joint operated on the numeric rating scale was utilized. Correlations were verified by Spearman-Rho. The MRI scores on average showed significantly lower scores for the discs of the operated temporomandibular joint than for the discs of the non-operated side(p<.01). No significant correlations between MRI findings, histopathological findings and pain intensities could be observed. Thus unsuspicious morphology of the TMJ and the articular disc in MRI is no guarantee for the absence of cartilage-degeneration. Further investigations utilizing T2 cartilage mapping could possibly show better correlations between the temporomandibular joint's degree of degeneration and imaging results.

Degeneration of the articular disc in the human triangular fibrocartilage complex

INTRODUCTION

Traumatic injuries of the triangular fibrocartilage complex (TFCC) are frequent reasons for ulnar wrist pain. The assessment of the extent of articular disc (AD) degeneration is important for the differentiation of acute injuries versus chronic lesions.

MATERIALS AND METHODS

The AD of the TFCC of eleven human cadaver wrists was dissected. Degeneration was analyzed according to the grading of Krenn et al. Hematoxylin-eosin was used to determine the tissue morphology. Degeneration was evaluated using the staining intensity of alcian blue, the immunohistochemistry of the proteoglycan versican and the immunoreactivity of NITEGE, an aggrecan fragment.

RESULTS

The staining homogeneity of HE decreased with higher degeneration of the AD and basophilic tissue areas were more frequently seen. Two specimens were characterized as degeneration grade 1, five specimens as grade 2, and four specimens as grade 3, respectively. Staining intensity of alcian blue increased with higher degeneration grade of the specimens. Immunoreactivity for NITEGE was detected around tissue fissures and perforations as well as matrix splits. Immunoreactivity for versican was found concentrated in the tissue around matrix fissures and lesions as well as loose connective tissue at the ulnar border of the AD. Specimens with degeneration grade 2 had the strongest immunoreactivity of NITEGE and versican. Cell clusters were observed in specimens with degeneration grade 2 and 3, which were stained by alcian blue and immunoreactive for NITEGE and versican. Increasing age of the cadaver wrists correlated with a higher degree of degeneration (p < 0.0001, r = 0.68).

CONCLUSIONS

The fibrocartilage of degenerated ADs contains NITEGE and versican. The amount of the immunoreactivity of these markers allows the differentiation of degenerative changes into three grades. The degeneration of the AD increases with age and emphasizes its important mechanical function.

Calcification of the acetabular labrum of the hip: prevalence in the general population and relation to hip articular cartilage and fibrocartilage degeneration

Background

Meniscal calcification is considered to play a relevant role in the pathogenesis of osteoarthritis of the knee. Little is known about the biology of acetabular labral disease and its importance in hip pathology. Here, we analyze for the first time the calcification of the acetabular labrum of the hip (ALH) and its relation to hip cartilage degeneration.

Methods

In this cross-sectional post-mortem study of an unselected sample of the general population, 170 ALH specimens and 170 femoral heads from 85 donors (38 female, 47 male; mean age 62.1 years) were analyzed by high-resolution digital contact radiography (DCR) and histological degeneration grade. The medial menisci (MM) from the same 85 donors served as an intra-individual reference for cartilage calcification (CC). Scanning electron microscopy (SEM), energy dispersive analysis (ED) and Raman spectroscopy were performed for characterization of ALH CC.

Results

The prevalence of CC in the ALH was 100% and that in the articular cartilage of the hip (ACH) was 96.5%. Quantitative analysis revealed that the amount of ALH CC was higher than that in the ACH (factor 3.0, p < 0.001) and in the MM (factor 1.3, p < 0.001). There was significant correlation between the amount of CC in the fibrocartilage of the left and right ALH (r = 0.70, p < 0.001). Independent of age, the amount of ALH CC correlated with histological degeneration of the ALH (Krenn score) (r = 0.55; p < 0.001) and the ACH (Osteoarthritis Research Society International (OARSI), r = 0.69; p < 0.001). Calcification of the ALH was characterized as calcium pyrophosphate dihydrate deposition.

Conclusion

The finding that ALH fibrocartilage is a strongly calcifying tissue is unexpected and novel. The fact that ALH calcification correlates with cartilage degeneration independent of age is suggestive of an important role of ALH calcification in osteoarthritis of the hip and renders it a potential target for the prevention and treatment of hip joint degeneration.

Labral calcification in end-stage osteoarthritis of the hip correlates with pain and clinical function

The acetabular labrum of the hip (ALH) is recognized as a clinically important structure, but knowledge about the pathophysiology of this fibrocartilage is scarce. In this prospective study we determined the prevalence of ALH calcification in patients with end-stage osteoarthritis (OA) and analyzed the relationship of cartilage calcification (CC) with hip pain and clinical function. Cohort of 80 patients (70.2 ± 7.6years) with primary OA scheduled for total hip replacement. Harris Hip Score (HHS) was recorded preoperatively. Total ALH and femoral head (FH) were sampled intraoperatively. CC of the ALH and FH was analyzed by high-resolution digital contact radiography. Histological degeneration of the ALH (Krenn-Score) and FH (OARSI-Score) was determined. Multivariate linear regression model and partial correlation analyses were performed. The prevalence of cartilage calcification both in the ALH and FH was 100%, while the amount of CC in the ALH was 1.55 times higher than in the FH (p < 0.001). There was a significant inverse regression between the amount of calcification of both the ALH and the FH and preoperative HHS (β_ALH  = -2.1, p = 0.04), (β_FH  = -2.9, p = 0.005), but pain was influenced only by ALH calcification (β_ALH  = -2.7, p = 0.008). Age-adjusted, there was a significant correlation between cartilage calcification and histological degeneration (ALH:r_s  = 0.53, p < 0.001/FH: r_s  = 0.30, p = 0.007). Fibrocartilage and articular cartilage calcification are inseparable pathological findings in end-stage osteoarthritis of the hip. Fibrocartilage calcification is associated with poor and painful hip function.

CLINICAL SIGNIFICANCE

ALH fibrocartilage appears to be particularly prone to calcification, which may explain higher pain levels in individuals with a high degree of ALH calcification independent of age and histological degeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1248-1255, 2018.

A Porcine Animal Model for Early Meniscal Degeneration - Analysis of Histology, Gene Expression and Magnetic Resonance Imaging Six Months after Resection of the Anterior Cruciate Ligament

BACKGROUND/OBJECTIVE

The menisci of the mammalian knee joint balance the incongruence between femoral condyle and tibial plateau and thus menisci absorb and distribute high loads. Degeneration processes of the menisci lead to pain syndromes in the knee joint. The origin of such degenerative processes on meniscal tissue is rarely understood and may be described best as an imbalance of anabolic and catabolic metabolism. A standardized animal model of meniscal degeneration is needed for further studies. The aim of the current study was to develop a porcine animal model with early meniscal degeneration.

MATERIAL AND METHODS

Resection of the anterior cruciate ligament (ACLR) was performed on the left knee joints of eight Göttingen minipigs. A sham operation was carried out on the right knee joint. The grade of degeneration was determined 26 weeks after the operation using histology and magnetic resonance imaging (MRI). Furthermore, the expression of 14 genes which code for extracellular matrix proteins, catabolic matrix metalloproteinases and inflammation mediators were analyzed.

RESULTS

Degenerative changes were detected by a histological analysis of the medial meniscus after ACLR. These changes were not detected by MRI. In terms of their gene expression profile, these degenerated medial menisci showed a significantly increased expression of COL1A1.

CONCLUSION

This paper describes a new animal model for early secondary meniscal degeneration in the Göttingen minipig. Histopathological evidence of the degenerative changes could be described. This early degenerative changes could not be seen by NMR imaging.

Comparative immunohistochemical evaluation of the zonal distribution of extracellular matrix and inflammation markers in human meniscus in osteoarthritis and rheumatoid arthritis

The purpose of our study was to analyze the distribution of the major extracellular matrix glycosaminoglycan hyaluronan (HA), its receptor CD44 and cells which influence (re)modeling of the extracellular matrix (T- and B-cells, macrophages, endothelial cells) in menisci obtained from patients suffering from rheumatoid arthritis or osteoarthritis in order to analyze whether these markers could be useful to differentiate between both arthropathies. Human menisci were sampled from patients undergoing total knee arthroplasty. Histological staining (H&E, PAS/Alcian Blue for neutral and charged carbohydrate residues) and (immuno)histochemistry were performed for detection of HA, CD44, sphingosine-1-phosphate receptor 1 (EDG-1) as a marker for endothelial cells, CD3 as a marker for T-cells, CD20 as a marker for B-cells and CD68 as a marker for macrophages. The extracellular matrix in the vascularized zone showed higher amounts of HA as well as acid carbohydrate residues in comparison to the poorly vascularized zones of the meniscus in both disease entities. EDG-1 positive endothelial cells were present in all zones, with fewer cells being detected in the inner zones of the rheumatoid menisci than in the osteoarthritic ones. Macrophages, T- and B-cells as well as CD44-positive cells were more prominent in the vascularized zone of the meniscus than in the poorly vascularized central zone. The distribution patterns of the extracellular matrix components as well as the CD44-positive cells and the inflammation markers in the peripheral zone resembled the distribution in synovial tissue, indicating that both synovia and meniscus were involved in pathological changes in osteoarthritis and rheumatoid arthritis.

IN CONCLUSION

the distribution of extracellular glycoconjugates and of cells modulating their synthesis showed similar results in both arthropathies, not enabling a differentiation between rheumatoid arthritis and osteoarthritis but underlining the role of these markers in inflammation and degradation in human meniscus.

[Histopathological evaluation of the meniscus]

Menisci fulfill many functions within the complex biomechanics of the knee joint. In the case of meniscus lesions, sparing arthroscopic resection and surgical refixation are the treatments of choice. In terms of diagnosis, this means in general that histopathologic diagnostics are carried out on detached meniscus fragments of between 5 mm and 2 cm in size. A good knowledge of physiologically possible cellular and fibrous histological meniscus damage, as opposed to nonphysiological change regarded as normal with respect to age, is essential for diagnostic meniscus evaluation. The clinician expects clear statements from the pathologist regarding the severity of previous or secondary degenerative meniscus damage, the age and type of traumatic tears, and an appraisal of the relationship between trauma and meniscus damage from an insurance point of view. Close cooperation between the clinician and the pathologist allows for a fast and unambiguous correlation of anamnesis, the clinical picture, and morphological reporting such that problematic insurance cases can be clarified quickly.

Macroscopic and histopathologic analysis of human knee menisci in aging and osteoarthritis

OBJECTIVE

Meniscus lesions following trauma or associated with osteoarthritis (OA) have been described, yet meniscus aging has not been systematically analyzed. The objectives of this study were to (1) establish standardized protocols for representative macroscopic and microscopic analysis, (2) improve existing scoring systems, and (3) apply these techniques to a large number of human menisci.

DESIGN

Medial and lateral menisci from 107 human knees were obtained and cut in two different planes (triangle/cross section and transverse/horizontal section as well) in three separate locations (middle portion, anterior and posterior horns). All sections included vascular and avascular regions and were graded for (1) surface integrity, (2) cellularity, (3) matrix/fiber organization and collagen alignment, and (4) Safranin-O staining intensity. The cartilage in all knee compartments was also scored.

RESULTS

The new macroscopic and microscopic grading systems showed high inter-reader and intra-reader intraclass correlation coefficients. The major age-related changes in menisci in joints with no or minimal OA included increased Safranin-O staining intensity, decreased cell density, the appearance of acellular zones, and evidence of mucoid degeneration with some loss of collagen fiber organization. The earliest meniscus changes occurred predominantly along the inner rim. Menisci from OA joints showed severe fibrocartilaginous separation of the matrix, extensive fraying, tears and calcification. Abnormal cell arrangements included decreased cellularity, diffuse hypercellularity along with cellular hypertrophy and abnormal cell clusters. In general, the anterior horns of both medial and lateral menisci were less affected by age and OA.

CONCLUSIONS

New standardized protocols and new validated grading systems allowed us to conduct a more systematic evaluation of changes in aging and OA menisci at a macroscopic and microscopic level. Several meniscus abnormalities appear to be specific to aging in the absence of significant OA. With aging the meniscal surface can be intact but abnormal matrix organization and cellularity were observed within the meniscal substance. The increased Safranin-O staining appears to represent a shift from fibroblastic to chondrocytic phenotype during aging and early degeneration.

[Bradytrophic tissue. Its histopathological diagnosis and value in trauma surgical and orthopedic expert opinions]

Expert opinions on the musculoskeletal system are generally required for statutory or private accident insurance purposes in a variety of legal areas and with varying rules of evidence. Since they are also intended for non-medical personnel, terminology needs to be defined and must be comprehensible by all parties. Bradytrophic tissue is the most frequently evaluated aspect of the musculoskeletal system. In this context, the term"degeneration" which was formerly used has been replaced by the term"tissue structure alteration", which takes matrix changes and cellularity into consideration. Thus the significance of histopathological diagnosis of bradytrophic tissue has been put in a new light. Histopathological diagnosis is carried out on the basis of various staining methods, scores and analyses depending on the diagnostic question.