Increased angiogenesis and cellular proliferation as hallmarks of the synovium in chronic septic arthritis

CD38: An Immunomodulatory Molecule in Inflammation and Autoimmunity

CD38 is a molecule that can act as an enzyme, with NAD-depleting and intracellular signaling activity, or as a receptor with adhesive functions. CD38 can be found expressed either on the cell surface, where it may face the extracellular milieu or the cytosol, or in intracellular compartments, such as endoplasmic reticulum, nuclear membrane, and mitochondria. The main expression of CD38 is observed in hematopoietic cells, with some cell-type specific differences between mouse and human. The role of CD38 in immune cells ranges from modulating cell differentiation to effector functions during inflammation, where CD38 may regulate cell recruitment, cytokine release, and NAD availability. In line with a role in inflammation, CD38 appears to also play a critical role in inflammatory processes during autoimmunity, although whether CD38 has pathogenic or regulatory effects varies depending on the disease, immune cell, or animal model analyzed. Given the complexity of the physiology of CD38 it has been difficult to completely understand the biology of this molecule during autoimmune inflammation. In this review, we analyze current knowledge and controversies regarding the role of CD38 during inflammation and autoimmunity and novel molecular tools that may clarify current gaps in the field.

Primarily treated patients versus referred patients in the treatment of native septic arthritis of digits: a retrospective comparative study

BACKGROUND

Septic arthritis of digits needs urgent treatment. When treatments delayed or insufficient, patients may be referred to the upper-level hospital due to uncontrolled infection. We reviewed the treatment history of referred patients and compared the microorganisms and the clinical course of both primary and referred patients as relevant studies are rare.

METHODS

In this retrospective review of consecutive case series, 45 patients (primary, n = 11; referred, n = 34) were treated with multiple irrigation and debridement. Cefazolin was used as empiric antibiotics, then changed according to microbiologic study. Previously used antibiotics, treatment delay, surgical history of the referred patients were reviewed. Identified microorganisms, required surgical intervention, hospital stay, radiologic outcome, functional outcomes were compared between both groups.

RESULTS

In the referred patients, methicillin-resistant Staphylococcus aureus (MRSA) was commonly found and cefazolin was susceptible in only 15% of the cases. Longer hospital stay, prolonged antibiotic therapy, more surgical intervention including flap surgery was required to treat the referred patients. Postoperative pain was not severe in daily activities, but the final range of motion was significantly less in the referred patients compared to the primary patients.

CONCLUSIONS

This study suggests that in the treatment of uncontrolled septic arthritis of the digits, antibiotic agents covering MRSA may shorten the duration of antibiotic therapy in areas of high MRSA incidence. Besides, more number of I & D including flap surgery may be required for the referred patients compared with the primary patients. These findings can help the surgeon in setting up a treatment plan or in counseling of referred patients with uncontrolled septic arthritis of the digits.

Clinical Applications of Synovial Biopsy

The synovial tissue is a primary target of multiple diseases characterized by different pathogenic mechanisms, including infective, deposition, neoplastic, and chronic immune-inflammatory pathologies. Synovial biopsy can have a relevant role in differential diagnosis of specific conditions in clinical practice, although its exploitation remains relatively limited. In particular, no validated synovial-tissue-derived biomarkers are currently available in the clinic to aid in the diagnosis and management in most frequent forms of chronic inflammatory arthropathies, namely rheumatoid arthritis (RA) and the spondyloarthritides (SpA). In this brief review, we will discuss the current spectrum of clinical applications of synovial biopsy in routine rheumatologic care and will provide an analysis of the perspectives for its potential exploitation in patients with chronic inflammatory arthritides.

Endoglin (CD105) expression differentiates between aseptic loosening and periprosthetic joint infection after total joint arthroplasty

The differentiation between aseptic loosening and periprosthetic joint infection (PJI) after total joint arthroplasty is essential for successful therapy. A better understanding of pathogenesis of aseptic loosening and PJI may help to prevent or treat these complications. Previous investigations revealed an increased vascularization in the periprosthetic membrane in cases of PJI via PET signals. Based on these findings our hypothesis was that PJI is associated with an increased neovascularization in the periprosthetic membrane.

Tissue samples from periprosthetic membranes of the bone-implant interface were investigated histologically for inflammation, wear particles, vascularization and fibrosis. To identify vascular structures antibodies against CD 31, CD 34, factor VIII and CD 105 (endoglin) were applied for immunohistochemical investigations. According to a consensus classification of Morawietz the tissue samples were divided into four types: type I (wear particle induced type, n = 11), type II (infectious type, n = 7), type III (combined type, n = 7) and type IV (indeterminate type, n = 7).

Patients with PJI (type II) showed a pronounced infiltration of neutrophil granulocytes in the periprosthetic membrane and an enhanced neovascularization indicated by positive immunoreaction with antibodies against CD 105 (endoglin). Tissue samples classified as type I, type III and type IV showed significantly less immune reaction for CD 105.

In cases of aseptic loosening and PJI vascularization is found in different expression in periprosthetic membranes. However, in aseptic loosening, there is nearly no neovascularization with CD 105-positive immune reaction. Therefore, endoglin (CD 105) expression allows for differentiation between aseptic loosening and PJI.

Immunolocalization of Ki-67 in different periodontal conditions

BACKGROUND

Ki-67 which is a non-histone nuclear protein which is expressed in proliferating cells, during all the active phases of the cell cycle. Increased Ki-67 expression has been seen in several inflammatory and malignant conditions like diabetes, rheumatoid arthritis, atherosclerosis, pancreatitis and squamous cell carcinoma.

AIM

The aim of the present study is to analyze the expression of Ki-67 in gingival tissues by immunohistochemistry in smokers and non-smokers with healthy gingiva and chronic periodontitis.

MATERIALS AND METHODS

Gingival biopsies (n = 32) were obtained from smokers who had clinically healthy gingiva (n = 8), smokers with periodontitis (n = 8), chronic periodontitis (n = 8) and healthy gingiva (n = 8). The expression of Ki-67 was evaluated immunohistochemically.

STATISTICAL ANALYSIS USED

Mean and standard deviation were estimated for the gingival tissue extract sample for each study group. Mean values were compared between different study groups by, one way ANOVA, post hoc analysis. In this study P < 0.05 was considered as the level of significance.

RESULTS

The mean number of Ki-67 positive cells/field was higher in the smokers with periodontitis group. When the mean Ki-67 positive cells were compared between different groups, statistical significant difference was observed between healthy and both the periodontitis groups (P = 0.000) and between smokers group (P = 0.001).

CONCLUSIONS

Ki-67 was maximally expressed in smoker with periodontitis followed by chronic periodontitis patients, healthy smokers and healthy control patients which shed light on the toxic effects of tobacco in dysregulating the cell cycle and cellular proliferation. The findings of this study also help us to understand the role of the cell cycle in resolution of periodontal inflammation which is a salient feature in the pathogenesis of chronic periodontitis.

T cells from chronic bone infection show reduced proliferation and a high proportion of CD28⁻ CD4 T cells

Chronic bone infection is associated with bone resorption. From animal studies, CD3/CD28-activated T cells are known to enhance osteoclastogenesis and bone resorption. Because CD28 is expressed constitutively on T cells and its expression is down-regulated by chronic exposure to the inflammatory environment, we characterized co-stimulatory molecule expression on T cells from chronically infected patients. We used cytofluorometric techniques to phenotypically characterize T cells, its co-stimulatory molecules and perforin secretion from infected and non-infected human bones. Chronic bone infection was defined as infection lasting for more than a month. We show a higher T cell activation [human leucocyte antigen D-related (HLA-DR⁺)] in infected compared to non-infected bones: median being 16 versus 7%, P = 0·009 for CD4 T cells, and 33 versus 15%, P = 0·038 for CD8 T cells, respectively. However, T cell proliferation (Ki67⁺) was lower for CD8 T cells in infected bones: 26 versus 34%, P = 0·045. In contrast, we detected no difference in apoptosis and regulatory T cells. In infected bone, we found higher CD28-negative CD4⁺ T cells compared to non-infected bone: 20 versus 8%, respectively (P = 0·005); this T cell subset had higher CD11b expression and perforin secretion. Chronically infected human bones are characterized by an increase of CD28-negative CD4⁺ T cells, indicating long-term activated cells with cytotoxic ability. Therefore, this alteration of co-stimulatory molecules may modify interactions with osteoclasts and impact bone resorption.

The relative composition of the inflammatory infiltrate as an additional tool for synovial tissue classification

OBJECTIVES

Traditionally, differences in absolute numbers of cells expressing a certain marker (e.g., positive staining cells per mm²) have been used in immunohistological synovial tissue classification. We have begun to evaluate the relative composition of the inflammatory infiltrates, i.e. percentages of inflammatory cell types in inflammatory infiltrates, as an alternate classification tool that may potentially improve tissue diagnostics, subgrouping in clinical trials, and understanding of pathogenesis of inflammatory and noninflammatory arthropathies.

METHODS

Synovial tissue specimens (normal synovium, n=15; orthopedic arthropathies, n=6; osteoarthritis, n=26; early undifferentiated arthritis, n=10; rheumatoid arthritis, n=26; chronic septic arthritis, n=11) were stained for CD15, CD68, CD3, CD20, and CD38. Densities of cells expressing a given marker were determined in the superficial subintima. Binary and multicategory receiver operating characteristic (ROC) analysis and naïve Bayes classifier were used to compare the abilities of (1) the absolute densities of cells expressing a given marker (absolute method) with (2) the percentages of these cells in the inflammatory cell population (relative method) to differentiate among the six tissue classes.

RESULTS

The inflammatory infiltrates in normal synovium and the orthopedic arthropathies consisted almost exclusively of CD68+ and CD3+ cells. Notable fractions of CD20+ and CD38+ cells appeared in a subset of osteoarthritis samples, and increased further in early, rheumatoid and chronic septic arthritis. ROC analyses and naïve Bayes classifier ranked the absolute method above the relative method in terms of overall discriminatory ability. The relative method became slightly superior when the samples were also stratified according to the total number of inflammatory cells/mm².

CONCLUSIONS

This exploratory investigation featuring a variety of joint disorders revealed that measuring the relative proportions of inflammatory cell types may aid in synovial tissue classification if the samples are also stratified according to the intensity of inflammation.

Synovial infiltration with CD79a-positive B cells, but not other B cell lineage markers, correlates with joint destruction in rheumatoid arthritis

OBJECTIVE

The efficacy of B cell depletion in the treatment of patients with rheumatoid arthritis (RA) has revitalized interest in the pathogenic role(s) of B cells in RA. We evaluated the distribution of synovial B lineage cells and their correlation with histologic disease activity and joint destruction in RA.

METHODS

Synovial tissue samples were obtained by closed-needle biopsy from 69 Chinese patients with active RA, from 14 patients with osteoarthritis (OA), and from 15 with orthopedic arthropathies (OrthA) as disease controls. Serial tissue sections were stained immunohistochemically for CD79a (pro-B cell to plasma cell), CD20 (B cells), CD38 (plasma cells), CD21 (follicular dendritic cells), CD68 (macrophages), CD3 (T cells), and CD34 (endothelial cells). Densities of positive-staining cells were determined and correlated with histologic disease activity (Krenn 3-component synovitis score) and radiographic joint destruction (Sharp score).

RESULTS

Mean sublining CD79a-positive cell density was significantly higher in RA than in OA (p <0.001) or OrthA (p = 0.003). Receiver operating characteristic curve analysis showed that CD79a-positive cell density differentiated RA well from OA [area under the curve (AUC) = 0.79] or OrthA (AUC = 0.75). Spearman's rank order correlation showed significant correlations between sublining CD79a-positive cell density and the synovitis score (r = 0.714, p < 0.001), total Sharp score (r = 0.490, p < 0.001), and the erosion subscore (r = 0.545, p < 0.001), as well as the joint space narrowing subscore (r = 0.468, p = 0.001) in RA.

CONCLUSION

Synovial CD79a-positive B cells may be a helpful biomarker for histologic disease activity in RA and may be involved in the pathogenesis of joint destruction in RA.

Bone Marrow Suppression by c-Kit Blockade Enhances Tumor Growth of Colorectal Metastases through the Action of Stromal Cell-Derived Factor-1

Background. Mobilization of c-Kit⁺ hematopoietic cells (HCs) contributes to tumor vascularization. Whereas survival and proliferation of HCs are regulated by binding of the stem cell factor to its receptor c-Kit, migration of HCs is directed by stromal cell-derived factor (SDF)-1. Therefore, targeting migration of HCs provides a promising new strategy of anti-tumor therapy. Methods. BALB/c mice (n = 16) were pretreated with an anti-c-Kit antibody followed by implantation of CT26.WT-GFP colorectal cancer cells into dorsal skinfold chambers. Animals (n = 8) additionally received a neutralizing anti-SDF-1 antibody. Animals (n = 8) treated with a control antibody served as controls. Investigations were performed using intravital fluorescence microscopy, immunohistochemistry, flow cytometry and western blot analysis. Results. Blockade of c-Kit significantly enhanced tumor cell engraftment compared to controls due to stimulation of tumor cell proliferation and invasion without markedly affecting tumor vascularization. C-Kit blockade significantly increased VEGF and CXCR4 expression within the growing tumors. Neutralization of SDF-1 completely antagonized this anti-c-Kit-associated tumor growth by suppression of tumor neovascularization, inhibition of tumor cell proliferation and reduction of muscular infiltration. Conclusion. Our study indicates that bone marrow suppression via anti-c-Kit pretreatment enhances tumor cell engraftment of colorectal metastases due to interaction with the SDF-1/CXCR4 pathway which is involved in HC-mediated tumor angiogenesis.

Quantitative determination of the diagnostic accuracy of the synovitis score and its components

AIMS

To assess the diagnostic accuracy of a three-component synovitis score and to determine the relative contribution of each of its components to its overall discriminatory power.

METHODS AND RESULTS

The synovitis score was determined in 666 synovial specimens: normal synovium, n = 33; post-traumatic arthropathy (PtA), n = 29; osteoarthritis (OA), n = 221; psoriatic arthritis (PsA), n = 42; and rheumatoid arthritis (RA), n = 341. The discriminatory abilities of the score and its components were quantified with binary and multicategory receiver operating characteristic (ROC) analysis. The score differentiated all arthropathies accurately from normal tissue (area under the ROC curve, AUC: 0.87-0.98) and RA from OA or PtA (AUC: 0.85 for both), but could not distinguish well within pairs of inflammatory or degenerative arthropathies. AUCs of the intimal hyperplasia and stromal cellularity components correlated with the AUCs of the complete score markedly more strongly (r = 0.94 and 0.91, respectively) than the inflammatory infiltration component (r = 0.60). Multicategory ROC analysis ranked the score several-fold higher than any of its components, and the components in the order stromal cellularity>intimal hyperplasia>infiltration.

CONCLUSION

Combining three distinct histological parameters into a three-component score produces greatly increased overall diagnostic power. The discriminatory ability of the score stems more from measuring proliferative than infiltrative aspects of synovitis.

Elevated serum glucose-6-phosphate isomerase correlates with histological disease activity and clinical improvement after initiation of therapy in patients with rheumatoid arthritis

OBJECTIVE

To determine serum glucose-6-phosphate isomerase (GPI) concentrations in patients with rheumatoid arthritis (RA), and to test whether they correlate with objective measures of disease activity.

METHODS

Sera from 116 patients with RA, 69 patients with non-RA rheumatic diseases, and 101 healthy controls were analyzed. Levels of soluble serum GPI were measured by ELISA. Histological disease activity was determined with the synovitis score in synovial needle biopsies from 58 of the 116 patients with RA. Thirty-one of the 58 synovium samples were stained for CD68, CD3, CD20, CD38, CD79a, and CD34 by immunohistochemistry. Demographic data were collected, as well as serological and clinical variables that indicate RA disease activity, for Spearman correlation analysis.

RESULTS

Serum GPI level correlated positively with the synovitis score (r = 0.278, p = 0.034). Significantly higher soluble GPI levels were detected in the RA sera compared with sera from healthy controls and the non-RA disease controls (2.25 ± 2.82 vs 0.03 ± 0.05 and 0.19 ± 0.57 μg/ml, respectively; p < 0.0001). The rate of serum GPI positivity was significantly higher in the RA patients than in the non-RA disease controls (64.7% vs 10.1%; p < 0.0001). Spearman analysis showed no significant correlation between serum GPI level and Disease Activity Score in 28 joints at baseline. After initiation of antirheumatic treatments, GPI levels decreased significantly (2.81 ± 3.12 vs 1.44 ± 2.09 μg/ml; p = 0.016), paralleling improvement of the disease activity indices.

CONCLUSION

Elevated serum GPI may be involved in the synovitis of RA and may prove useful as a serum marker for disease activity of RA.