Risk of malignancy in patients with rheumatoid arthritis after anti-tumor necrosis factor therapy: results from Korean National Health Insurance claims data

BACKGROUND/AIMS

Inhibition of tumor necrosis factor (TNF) is an effective treatment for rheumatoid arthritis (RA), but safety concerns about malignancy remain. The aim of this study was to evaluate cancer risk in RA patients treated with TNF inhibitors (TNFi), based on Korean Nationwide Health Insurance claims data.

METHODS

Patients with seropositive RA were selected from the health insurance database containing all citizens' medical information, based on both RA diagnosis codes and medications. Between 2010 and 2014, RA patients treated with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) and TNFi were enrolled and followed up. We compared the cancer incidence between patients treated with TNFi and csDMARDs using incidence rate ratios (IRRs) after adjustment for age, gender, and observational periods.

RESULTS

Of 45,423 selected patients with seropositive RA, 2,337 were treated with TNFi and 43,086 were treated with csDMARDs. The TNFi group was younger and was followed-up for a longer duration. During the observational period, 1,732 and 49 cases of cancer were detected in patients treated with csDMARDs and TNFi, respectively. Old age and male sex were associated with cancer occurrence. Adjusted IRRs for all cancers and common cancers demonstrated that cancer incidence did not differ significantly between the TNFi group and csDMARDs group (IRR = 0.913 for all cancers, p = 0.546).

CONCLUSION

This study revealed that cancer incidence was similar in RA patients treated with TNFi and csDMARDs. Anti-TNF therapy may be a safe therapeutic option for RA treatment, in terms of malignancy.

Generation of 3D Skin Organoid from Cord Blood-derived Induced Pluripotent Stem Cells

The skin is the body's largest organ and has many functions. The skin acts as a physical barrier and protector of the body and regulates bodily functions. Biomimetics is the imitation of the models, systems, and elements of nature for the purpose of solving complex human problems¹. Skin biomimetics is a useful tool for in vitro disease research and in vivo regenerative medicine. Human induced pluripotent stem cells (iPSCs) have the characteristic of unlimited proliferation and the ability of differentiation to three germ layers. Human iPSCs are generated from various primary cells, such as blood cells, keratinocytes, fibroblasts, and more. Among them, cord blood mononuclear cells (CBMCs) have emerged as an alternative cell source from the perspective of allogeneic regenerative medicine. CBMCs are useful in regenerative medicine because human leukocyte antigen (HLA) typing is essential to the cell banking system. We provide a method for the differentiation of CBMC-iPSCs into keratinocytes and fibroblasts and for generation of a 3D skin organoid. CBMC-iPSC-derived keratinocytes and fibroblasts have characteristics similar to a primary cell line. The 3D skin organoids are generated by overlaying an epidermal layer onto a dermal layer. By transplanting this 3D skin organoid, a humanized mice model is generated. This study shows that a 3D human iPSC-derived skin organoid may be a novel, alternative tool for dermatologic research in vitro and in vivo.

Soluble siglec-5 is a novel salivary biomarker for primary Sjogren's syndrome

Despite advances in the understanding of the pathogenesis, disease-specific biomarkers have not been included in the classification criteria for Primary Sjogren's syndrome (pSS). Based on a microarray of peripheral blood mononuclear cells (PBMCs) from patients with primary Sjogren's syndrome (pSS), we aimed to investigate whether soluble sialic acid-binding immunoglobulin-like lectin (siglec)-5 in saliva might be a biomarker for pSS. The concentration of siglec-5 in saliva and sera was determined by ELISA. Clinical parameters related with pSS were obtained from pSS registry and correlation with salivary siglec-5 level was evaluated. Receiver operating curve (ROC) analysis was performed to determine cut off value. A separate validation cohort consisted of subjects with suspicious pSS was evaluated to determine the performance. The level of salivary siglec-5 was significantly higher in pSS patients (n = 170) compared with HCs (n = 25), non SS sicca patients (n = 78) or patients with systemic lupus erythematosus (SLE) (n = 43) (1346.8 [202.8-4280.0] pg/mL, 6.08 [0-134.0] pg/mL, 195 [0-947.5] pg/mL, and 0 [0-238.7] pg/mL, median [interquartile range], P < 0.001). Salivary siglec-5 level negatively correlated with salivary flow rate (spearman's rho: -0.420, P < 0.001), and positively correlated with ocular surface score (rho: 0.331, P < 0.001) and serum immunoglobulin G level (rho = 0.202, P = 0.008). In ROC analysis, area under the curve was 0.774[0.724-0.826]. With a cut off value of 400 pg/mL, sensitivity and specificity was 0.69 and 0.70 respectively. In validation cohort (45 pSS patients and 45 non SS sicca patients), sensitivity and specificity of siglec-5 was 64.4% and 77.8%, respectively. In conclusion, the level of soluble siglec-5 is significantly higher in the saliva from pSS patients, which reflects the severity of hyposalivation and ocular surface damage. This novel salivary biomarker may provide benefits for pSS diagnosis.

Development of immunocompatible pluripotent stem cells via CRISPR-based human leukocyte antigen engineering

Pluripotent stem cell transplantation is a promising regenerative strategy for treating intractable diseases. However, securing human leukocyte antigen (HLA)-matched donor stem cells is extremely difficult. The traditional approach for generating such cells is to establish homozygous pluripotent stem cell lines. Unfortunately, because of HLA diversity, this strategy is too time-consuming to be of practical use. HLA engineering of donor stem cells has been proposed recently as a means to evade graft-versus-host rejection in stem cell allotransplantation. This approach would be advantageous in both time and cost to the traditional method, but its feasibility must be investigated. In this study, we used CRISPR/Cas9 to knockout HLA-B from inducible pluripotent stem cells (iPSCs) with heterogenous HLA-B and showed that the HLA-B knockout iPSCs resulted in less immunogenicity in HLA-B antisera than that in the control. Our results support the feasibility of HLA-engineered iPSCs in stem cell allotransplantation.

Blocking the expression of genes that regulate the immune response in therapeutic stem cells could increase the chances of success following transplantation. Discrepancies between human leukocyte antigen (HLA) genes in a patient and those in transplanted stem cells can cause a damaging immune response and transplantation failure, yet matching HLA types between donors and recipients is notoriously difficult. Ji Hyeon Ju at The Catholic University of Korea in Seoul and colleagues have used the CRISPR/Cas9 gene editing system to introduce a mutation in the HLA-B gene that prevents its expression in pluripotent stem cells derived from adult cells. These modified cells not only retain their capacity to self-renew and differentiate, they are also less likely to trigger an immune response. This promising new approach could reduce the time and cost of developing effective stem cell therapies.

Tumor-Associated Macrophages Enhance Tumor Hypoxia and Aerobic Glycolysis

Tumor hypoxia and aerobic glycolysis are well-known resistance factors for anticancer therapies. Here, we demonstrate that tumor-associated macrophages (TAM) enhance tumor hypoxia and aerobic glycolysis in mice subcutaneous tumors and in patients with non-small cell lung cancer (NSCLC). We found a strong correlation between CD68 TAM immunostaining and PET ¹⁸fluoro-deoxyglucose (FDG) uptake in 98 matched tumors of patients with NSCLC. We also observed a significant correlation between CD68 and glycolytic gene signatures in 513 patients with NSCLC from The Cancer Genome Atlas database. TAM secreted TNFα to promote tumor cell glycolysis, whereas increased AMP-activated protein kinase and peroxisome proliferator-activated receptor gamma coactivator 1-alpha in TAM facilitated tumor hypoxia. Depletion of TAM by clodronate was sufficient to abrogate aerobic glycolysis and tumor hypoxia, thereby improving tumor response to anticancer therapies. TAM depletion led to a significant increase in programmed death-ligand 1 (PD-L1) expression in aerobic cancer cells as well as T-cell infiltration in tumors, resulting in antitumor efficacy by PD-L1 antibodies, which were otherwise completely ineffective. These data suggest that TAM can significantly alter tumor metabolism, further complicating tumor response to anticancer therapies, including immunotherapy. SIGNIFICANCE: These findings show that tumor-associated macrophages can significantly modulate tumor metabolism, hindering the efficacy of anticancer therapies, including anti-PD-L1 immunotherapy.

Clinical outcomes and pathological characteristics of immunoglobulin G4-related ophthalmic disease versus orbital inflammatory pseudotumor

BACKGROUND/AIMS

This study investigated the clinical and pathological features of immunoglobulin G4 (IgG4)-related ophthalmic disease. To clarify the features, we compared IgG4-related ophthalmic disease and orbital inflammatory pseudotumor.

METHODS

We retrospectively reviewed the medical records of 103 patients who were initially diagnosed with orbital inflammatory pseudotumor, and identified 16 cases in which the diagnosis was based on surgical biopsy and for which data in medical records were sufficient for analysis. Immunohistochemical staining of pathological specimens for IgG and IgG4 was performed. Finally, six of IgG4-related ophthalmic disease patient and 10 of orbital inf lammatory pseudotumor patient were analyzed.

RESULTS

The IgG4-related ophthalmic disease group had more IgG4-positive plasma cells and a higher IgG4/IgG plasma cell ratio than the orbital inflammatory pseudotumor group. Collagenous fibrosis and lacrimal gland involvement were significantly more frequent in the IgG4-related ophthalmic disease group. Dense lymphocyte infiltration, obliterative phlebitis, and bilateral lesions were more frequent in IgG4-related ophthalmic disease, but the differences were not significant. The recurrence-free period was shorter in the IgG4-related ophthalmic disease group (p = 0.035).

CONCLUSION

The location of the lesion (lacrimal gland), count and ratio of IgG4-positive plasma cells, and collagenous fibrosis aid the diagnosis of IgG4-related ophthalmic disease in patients with idiopathic orbital mass-like lesions. In addition, maintenance therapy should be considered in patients with IgG4-related ophthalmic disease to prevent recurrence.

Insulin resistance is an independent predictor of erectile dysfunction in patients with gout

BACKGROUND/AIMS

Gout is associated with metabolic disorders that are important risk factors for cardiovascular disease and erectile dysfunction (ED). We aimed to identify independent predictors of ED in patients with gout.

METHODS

From August 2014 to August 2015, male outpatients who were being treated for gout in our rheumatology clinic and healthy males without any history of inflammatory disease (control group) were studied. ED was assessed in participants using the five-item version of the International Index of Erectile Function questionnaire. Insulin resistance (IR) was estimated using the homeostatic model assessment (HOMA-IR). Logistic regression analysis was performed to determine the effect of variables on ED risk in all of the study subjects and in patients with gout.

RESULTS

We analyzed 80 patients with gout and 70 healthy controls. The median age of patients with gout was 52 years and median disease duration was 120 months. Gout patients were more likely to have ED than controls (55.3% vs. 41.4%, p < 0.047). After adjustment for confounding factors, only HOMA-IR was significantly associated with ED (odds ratio [OR], 1.82; 95% confidence interval [CI], 1.05 to 3.15). Gout patients with ED were more likely to be older (p < 0.001), have higher HOMA-IR (p = 0.048), and have lower glomerular filtration rate (p = 0.038) than those without ED. Multivariate logistic regression analysis showed that HOMAIR was an independent predictor for ED (OR, 1.62; 95% CI, 1.03 to 2.82) in gout patients.

CONCLUSION

IR is an independent predictor of ED in patients with gout.

Sodium Chloride Aggravates Arthritis via Th17 Polarization

PURPOSE

Sodium chloride (NaCl) has been proposed as a driving factor in autoimmune diseases through the induction of pathogenic CD4⁺ T helper cells that produce interleukin-17 (Th17 cells). This study investigated the effects of NaCl on inflammatory arthritis in mice and humans.

MATERIALS AND METHODS

Collagen-induced arthritis (CIA) mice were fed a normal or high-salt diet ad libitum, and clinical and histologic features of arthritis were evaluated. The proportion of Th17 cells in the spleens of CIA mice fed a normal or high-salt diet was evaluated by flow cytometry, and the expression of IL-17 in joints and intestines was determined by immunohistochemical staining. We also analyzed the effect of NaCl on Th17 differentiation from peripheral blood monocytes of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and evaluated the contents of sodium and IL-17 in the synovial fluid of RA and OA patients.

RESULTS

NaCl increased murine and human Th17 cell differentiation in a dose-dependent manner. Clinical and histological arthritis was more severe in the high-salt-fed CIA mice, compared to control CIA mice. The proportion of Th17 cells among splenocytes was higher in CIA mice fed a high-salt diet. Expression of synovial and intestinal IL-17 was also higher in high-salt-fed CIA mice. Comparison of synovial fluid between RA patients and OA patients revealed that Na⁺ and IL-17 were more abundant in RA synovial fluid.

CONCLUSION

This study suggests that NaCl can aggravate arthritis by affecting Th17 differentiation. Accordingly, limiting salt intake may be helpful for treating inflammatory arthritis, such as RA.

Recapitulation of methotrexate hepatotoxicity with induced pluripotent stem cell-derived hepatocytes from patients with rheumatoid arthritis

BACKGROUND

Methotrexate (MTX) is widely used for the treatment of rheumatoid arthritis (RA). The drug is cost-effective, but sometimes causes hepatotoxicity, requiring a physician's attention. In this study, we simulated hepatotoxicity by treating hepatocytes derived from RA patient-derived induced pluripotent stem cells (RA-iPSCs) with MTX.

METHODS

RA-iPSCs and healthy control iPSCs (HC-iPSCs) were established successfully. RA-iPSCs were differentiated into hepatocytes in two-dimensional (2D) monolayers and three-dimensional (3D) hepatocyte spheroid cultures; this process required growth factors such as BMP4, bFGF, HGF, and OSM. Immunofluorescence staining and flow cytometry were performed to confirm that the mature hepatocytes expressed cytokeratin 18, anti-alpha-1 antitrypsin, and albumin. MTX toxicity was evaluated via monitoring of cell viability, alanine aminotransferase, and mitochondrial status after MTX treatment in 2D and 3D cultures.

RESULTS

RA-iPSCs generated from three RA patients suffering from MTX-induced hepatotoxicity differentiated into the endoderm lineage, hepatoblasts, and hepatocytes. In 2D culture, RA-iPSC-derived hepatocytes were more sensitive to MTX than healthy controls. A 3D culture system using hepatocyte spheroids also successfully recapitulated MTX-induced hepatotoxicity. The 3D culture system had several advantages, including longer culture periods under more complex conditions.

CONCLUSIONS

A patient-derived iPSC platform could recapitulate MTX toxicity. Simulation of drug toxicity in vitro may help clinicians choose safer drugs or less toxic doses.

Korean Guideline for the Prevention and Treatment of Glucocorticoid-induced Osteoporosis

Background

To develop guidelines and recommendations to prevent and treat glucocorticoid (GC)-induced osteoporosis (GIOP) in Korea.

Methods

The Korean Society for Bone and Mineral Research and the Korean College of Rheumatology have developed this guideline based on Guidance for the Development of Clinical Practice Guidelines ver. 1.0 established by the National Evidence-Based Healthcare Collaborating Agency. This guideline was developed by adapting previously published guidelines, and a systematic review and quality assessment were performed.

Results

This guideline applies to adults aged ≥19 years who are using or plan to use GCs. It does not include children and adolescents. An initial assessment of fracture risk should be performed within 6 months of initial GC use. Fracture risk should be estimated using the fracture-risk assessment tool (FRAX) after adjustments for GC dose, history of osteoporotic fractures, and bone mineral density (BMD) results. All patients administered with prednisolone or an equivalent medication at a dose ≥2.5 mg/day for ≥3 months are recommended to use adequate calcium and vitamin D during treatment. Patients showing a moderate-to-high fracture risk should be treated with additional medication for osteoporosis. All patients continuing GC therapy should undergo annual BMD testing, vertebral X-ray, and fracture risk assessment using FRAX. When treatment failure is suspected, switching to another drug should be considered.

Conclusions

This guideline is intended to guide clinicians in the prevention and treatment of GIOP.

Risk factors associated with inadequate control of disease activity in elderly patients with rheumatoid arthritis: Results from a nationwide KOrean College of Rheumatology BIOlogics (KOBIO) registry

OBJECTIVE

The proportion of elderly patients with rheumatoid arthritis (RA) is continuously growing as a result of the increasing aging population. We compared disease activity between different age groups, and evaluated the clinical factors associated with high disease activity.

METHODS

This cross-sectional study analyzed the data of RA patients enrolled in the Korean College of Rheumatology Biologics registry (KOBIO-RA) between 2012 and 2014. Disease activity between elderly (age ≥ 65 years) and non-elderly patients (age < 65 years) was compared, and the association of clinical factors with high disease activity was assessed using a multivariate logistic regression model.

RESULTS

Of 1,227 patients in KOBIO-RA, 244 patients with RA were aged 65 years or over. In elderly patients, the proportion of men was higher (P = 0.012), and the duration of disease was longer (P < 0.001) compared with non-elderly patients. The elderly group showed a higher incidence of comorbidity (P < 0.001), and less use of methotrexate (P = 0.004). Assessment of disease activity using various composite measures showed a higher proportion of high disease activity in elderly patients than non-elderly patients. Longer disease duration, presence of comorbidity, and non-use of methotrexate were independently associated with high disease activity (P = 0.002, P < 0.001, and P = 0.029, respectively).

CONCLUSIONS

At enrollment of KOBIO-RA, elderly patients showed higher disease activity compared with non-elderly patients. Disease duration, use of methotrexate, and comorbidity are associated with disease activity control in Korean patients with RA.

Low bone mineral density predicts the formation of new syndesmophytes in patients with axial spondyloarthritis

Background

This study aimed to investigate whether the presence of low bone mineral density (BMD) in patients with axial spondyloarthritis (axSpA) predicts formation of new syndesmophytes over 2 years.

Methods

One hundred and nineteen patients fulfilling the imaging arm of the Assessment of SpondyloArthritis International Society axSpA criteria were enrolled. All patients were under 50 years of age. The modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) was assessed by two trained readers blinded to the patients’ data. BMD (lumbar spine, femoral neck or total hip) at baseline was assessed using dual-energy absorptiometry. Low BMD was defined as Z score ≤ − 2.0. Spinal radiographic progression was defined as worsening of the mSASSS by ≥ 2 points over 2 years. Logistic regression analyses were performed to identify predictors associated with development of new syndesmophytes and spinal radiographic progression.

Results

At baseline, 19 (16%) patients had low BMD. New syndesmophytes had developed in 22 (21%) patients at 2-year follow-up. New syndesmophyte formation after 2 years occurred more in patients with low BMD than in those with normal BMD (p = 0.047). In the multivariable analysis, current smoking, existing syndesmophytes and low BMD at baseline were associated with spinal radiographic progression (OR (95% CI) 3.0 (1.1, 7.7), 4.6 (1.8, 11.8) and 3.6 (1.2, 11.2), respectively). The presence of syndesmophytes at baseline and low BMD were predictors of new syndesmophytes over the following 2 years (OR (95% CI) 5.5 (2.0, 15.2) and 3.6 (1.1, 11.8), respectively).

Conclusions

Low BMD and existing syndesmophytes at baseline were independently associated with the development of new syndesmophytes in young axSpA patients.

Application of Cord Blood and Cord Blood-Derived Induced Pluripotent Stem Cells for Cartilage Regeneration

Regeneration of articular cartilage is of great interest in cartilage tissue engineering since articular cartilage has a low regenerative capacity. Due to the difficulty in obtaining healthy cartilage for transplantation, there is a need to develop an alternative and effective regeneration therapy to treat degenerative or damaged joint diseases. Stem cells including various adult stem cells and pluripotent stem cells are now actively used in tissue engineering. Here, we provide an overview of the current status of cord blood cells and induced pluripotent stem cells derived from these cells in cartilage regeneration. The abilities of these cells to undergo chondrogenic differentiation are also described. Finally, the technical challenges of articular cartilage regeneration and future directions are discussed.

Establishment of a complex skin structure via layered co-culture of keratinocytes and fibroblasts derived from induced pluripotent stem cells

Background

Skin is an organ that plays an important role as a physical barrier and has many other complex functions. Skin mimetics may be useful for studying the pathophysiology of diseases in vitro and for repairing lesions in vivo. Cord blood mononuclear cells (CBMCs) have emerged as a potential cell source for regenerative medicine. Human induced pluripotent stem cells (iPSCs) derived from CBMCs have great potential for allogenic regenerative medicine. Further study is needed on skin differentiation using CBMC-iPSCs.

Methods

Human iPSCs were generated from CBMCs by Sendai virus. CBMC-iPSCs were differentiated to fibroblasts and keratinocytes using embryonic body formation. To generate CBMC-iPSC-derived 3D skin organoid, CBMC-iPSC-derived fibroblasts were added into the insert of a Transwell plate and CBMC-iPSC-derived keratinocytes were seeded onto the fibroblast layer. Transplantation of 3D skin organoid was performed by the tie-over dressing method.

Results

Epidermal and dermal layers were developed using keratinocytes and fibroblasts differentiated from cord blood-derived human iPSCs, respectively. A complex 3D skin organoid was generated by overlaying the epidermal layer onto the dermal layer. A humanized skin model was generated by transplanting this human skin organoid into SCID mice and effectively healed skin lesions.

Conclusions

This study reveals that a human skin organoid generated using CBMC iPSCs is a novel tool for in-vitro and in-vivo dermatologic research.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0958-2) contains supplementary material, which is available to authorized users.

Clinical and Laboratory Characteristics and Mortality in Korean Patients with Systemic Sclerosis: A Nationwide Multicenter Retrospective Cohort Study

Objective.

We aimed to investigate demographic and clinical features and predictors of mortality in Korean patients with systemic sclerosis (SSc).

Methods.

We performed a retrospective multicenter medical chart review in Korean patients diagnosed with SSc from 1986 to 2016 at 11 university hospitals representing each geographic area of Korea. SSc patients were defined according to the American College of Rheumatology preliminary classification criteria and subtyped as limited cutaneous (lcSSc) or diffuse cutaneous (dcSSc) SSc.

Results.

We enrolled 751 patients (female, 86.7%; mean age at diagnosis, 48.9 yrs). The most common organ involvement was interstitial lung disease (52.7%), followed by gastroesophageal reflux disease (32.9%) and pulmonary arterial hypertension (13.6%). Patients with lcSSc were more common than those with dcSSc (64.8 vs 35.2%), whereas anti-Scl-70 and anticentromere antibody positivity were identified in 302 (42.5%) and 175 (25.5%) patients, respectively. In the 46 (6.1%) patients who developed a malignancy, lung cancer (23.9%) was the most common diagnosis, followed by gastric (13%) and breast cancer (13%). During the study period, 57 (7.6%) patients died, and the 5- and 10-year survival rates were 94% and 87%, respectively. Increased age at diagnosis, cardiovascular involvement, and anti-Scl-70 antibody positivity were significant predictors of death.

Conclusion.

Clinical manifestations and survival rates in Korean SSc patients are similar to those of other populations. However, the prevalence of anti-Scl-70 antibody is higher in Korean SSc patients compared with whites, while the prevalence of anticentromere antibody is lower.

Repair potential of nonsurgically delivered induced pluripotent stem cell-derived chondrocytes in a rat osteochondral defect model

Human induced pluripotent stem cells (hiPSCs) are thought to be an alternative cell source for future regenerative medicine. hiPSCs may allow unlimited production of cell types that have low turnover rates and are difficult to obtain such as autologous chondrocytes. In this study, we generated hiPSC-derived chondrogenic pellets, and chondrocytes were isolated. To confirm the curative effects, chondrogenic pellets and isolated chondrocytes were transplanted into rat joints with osteochondral defects. Isolated hiPSC-derived chondrocytes were delivered in the defect by a single intra-articular injection. The generated hiPSC-derived chondrogenic pellets had increased chondrogenic marker expression and accumulated extracellular matrix proteins. Chondrocytes were successfully isolated from the pellets. Alcian blue staining and collagen type II were detected in the cells. Chondrogenic marker expression was also increased in the isolated cells. Transplanted chondrogenic pellets and chondrocytes both had curative effects in the osteochondral defect rat model. Detection of human proteins in the joints proved that the cells were successfully delivered into the defect. Chondrogenic pellets or chondrocytes generated from hiPSCs have potential as regenerative medicine for cartilage recovery or regeneration. Chondrocytes isolated from hiPSC-derived chondrogenic pellets had curative effects in damaged cartilage. Injectable hiPSC-derived chondrocytes show the possibility of noninvasive delivery of regenerative medicine for cartilage recovery.

Kruppel-Like Factor 4 Positively Regulates Autoimmune Arthritis in Mouse Models and Rheumatoid Arthritis in Patients via Modulating Cell Survival and Inflammation Factors of Fibroblast-Like Synoviocyte

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes mild to severe joint inflammation. During RA pathogenesis, fibroblast-like synoviocytes (FLS) acquire a tumor-like phenotype and mediate cartilage destruction both directly and indirectly by producing proinflammatory cytokines and matrix metalloproteinases (MMPs). Kruppel-like factor (KLF) 4, a member of the KLF family, plays significant roles in cell survival, proliferation, and differentiation. A recent study reported increased expression of KLF4 in synovial tissue from RA patients. However, its precise role in RA in different models, including mouse autoimmune disease models, remains unclear. In this study, we examined the role of KLF4 during development of autoimmune arthritis in mouse models. To do this, we used KLF4 knockout mice rendered by ribonucleic acid (RNA)-guided endonuclease (RGEN) and performed collagen antibody-induced arthritis (CAIA). We found that deletion of KLF4 reduces inflammation induced by CAIA. In addition, we assessed collagen-induced arthritis (CIA) in control mice and KLF4-overexpressing mice generated by a minicircle vector treatment. Severity of CIA in mice overexpressing KLF4 was greater than that in mice injected with control vector. Finally, we verified the inflammatory roles of KLF4 in CIA by treating Kenpaullone which is used as KLF4 inhibitor. Next, we focused on human/mouse FLS to discover the cellular process involved in RA pathogenesis including proliferation, apoptosis, and inflammation including MMPs. In FLS, KLF4 upregulated expression of mRNA encoding proinflammatory cytokines interleukin (IL)-1β and IL-6. KLF4 also regulated expression of matrix metallopeptidase 13 in the synovium. We found that blockade of KLF4 in FLS increased apoptosis and suppressed proliferation followed by downregulation of antiapoptotic factor BCL2. Our results indicate that KLF4 plays a crucial role in pathogenesis of inflammatory arthritis in vivo, by regulating apoptosis, MMP expression, and cytokine expression by FLS. Thus, KLF4 might be a novel transcription factor for generating RA by modulating cellular process of FLS.

Intraperitoneal infusion of mesenchymal stem cell attenuates severity of collagen antibody induced arthritis

It is unclear how systemic administration of mesenchymal stem cells (MSCs) controls local inflammation. The aim of this study was to evaluate the therapeutic effects of human MSCs on inflammatory arthritis and to identify the underlying mechanisms. Mice with collagen antibody-induced arthritis (CAIA) received two intraperitoneal injections of human bone marrow-derived MSCs. The clinical and histological features of injected CAIA were then compared with those of non-injected mice. The effect of MSCs on induction of regulatory T cells was examined both in vitro and in vivo. We also examined multiple cytokines secreted by peritoneal mononuclear cells, along with migration of MSCs in the presence of stromal cell-derived factor-1 alpha (SDF-1α) and/or regulated on activation, normal T cell expressed and secreted (RANTES). Sections of CAIA mouse joints and spleen were stained for human anti-nuclear antibodies (ANAs) to confirm migration of injected human MSCs. The results showed that MSCs alleviated the clinical and histological signs of synovitis in CAIA mice. Peritoneal lavage cells from mice treated with MSCs expressed higher levels of SDF-1α and RANTES than those from mice not treated with MSCs. MSC migration was more prevalent in the presence of SDF-1α and/or RANTES. MSCs induced CD4+ T cells to differentiate into regulatory T cells in vitro, and expression of FOXP3 mRNA was upregulated in the forepaws of MSC-treated CAIA mice. Synovial and splenic tissues from CAIA mice receiving human MSCs were positive for human ANA, suggesting recruitment of MSCs. Taken together, these results suggest that MSCs migrate into inflamed tissues and directly induce the differentiation of CD4+ T cells into regulatory T cells, which then suppress inflammation. Thus, systemic administration of MSCs may be a therapeutic option for rheumatoid arthritis.

Interrupting oral infection of Porphyromonas gingivalis with anti-FimA antibody attenuates bacterial dissemination to the arthritic joint and improves experimental arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that typically results in strong inflammation and bone destruction in the joints. It is generally known that the pathogenesis of RA is linked to cardiovascular and periodontal diseases. Though rheumatoid arthritis and periodontitis share many pathologic features such as a perpetual inflammation and bone destruction, the precise mechanism underlying a link between these two diseases has not been fully elucidated. Collagen-induced arthritis (CIA) mice were orally infected with Porphyromonas gingivalis (Pg) or Pg preincubated with an anti-FimA antibody (FimA Ab) specific for fimbriae that are flexible appendages on the cell surface. Pg-infected CIA mice showed oral microbiota disruption and increased alveolar bone loss and had synovitis and joint bone destruction. However, preincubation with FimA Ab led to a significant reduction in the severity of both oral disease and arthritis. Moreover, FimA Ab attenuated bacterial attachment and aggregation on human gingival and rheumatoid arthritis synovial fibroblasts. In addition, we discovered bacteria may utilize dendritic cells, macrophages and neutrophils to migrate into the joints of CIA mice. These results suggest that disrupting Pg fimbriae function by FimA Ab ameliorates RA.

Mesenchymal stem cells ameliorate experimental arthritis via expression of interleukin-1 receptor antagonist

Human bone marrow-derived mesenchymal stem cells (MSCs) have been observed to inhibit arthritis in experimental animal models such as collagen-induced arthritis. However, the exact anti-inflammatory mechanisms remain poorly understood. Interleukin-1 receptor antagonist (IL-1Ra) is an anti-inflammatory cytokine produced by immune and stromal cells. We postulated that MSCs could produce IL-1Ra and attenuate experimental arthritis. In this study, 5x106 MSCs were injected into the peritoneal cavity of IL-1Ra knockout (IL-1RaKO) mice. MSCs reduced the severity of the arthritis by histology and decreased pro-inflammatory cytokine levels in IL-1RaKO mice. The ratio of splenic T helper 17 (Th17) cells to regulatory T cells (Treg) was significantly decreased in MSC-injected IL-1RaKO mice. Purified splenic CD4+ T cells from mice in each of the treatment groups were cultured under Th17 polarizing conditions and analyzed by flow cytometry. Less expansion of the Th17 population was observed in the MSC-treated group. Interestingly, MSCs expressed inducible IL-1Ra against inflammatory environmental stimuli. Human recombinant IL-1Ra could suppress Th17 cells differentiation under Th17 polarizing conditions. These results indicate that IL-1Ra expressed by MSCs can inhibit Th17 polarization and decrease the immune response in IL-1RaKO mice. Therefore, MSC-derived IL-1Ra may inhibit inflammation in IL-1RaKO mice via effects on Th17 differentiation.