The synovial fluid fibroblast-like synoviocyte: A long-neglected piece in the puzzle of rheumatoid arthritis pathogenesis

Rheumatoid arthritis (RA) is a systemic autoimmune disease during which fibroblast-like synoviocytes (FLS) contribute to both joint inflammation and destruction. FLS represent the core component of the synovial membrane. Following inflammation of this membrane, an effusion of cell-rich synovial fluid (SF) fills the joint cavity. Unlikely, SF has been shown to contain fibroblasts with some shared phenotypic traits with the synovial membrane FLS. These cells are called SF-FLS and their origin is still unclear. They are either brought into the synovium via migration through blood vessels, or they could originate within the synovium and exist in projections of the synovial membrane. SF-FLS function and phenotype are poorly documented compared to recently well-characterized synovial membrane FLS subsets. Furthermore, no study has yet reported a SF-FLS single-cell profiling analysis. This review will discuss the origin and cellular characteristics of SF-FLS in patients with RA. In addition, recent advances on the involvement of SF-FLS in the pathogenesis of RA will be summarized. Current knowledge on possible relationships between SF-FLS and other types of fibroblasts, including synovial membrane FLS, circulating fibrocytes, and pre- inflammatory mesenchymal (PRIME) cells will also be addressed. Finally, recent therapeutic strategies employed to specifically target SF-FLS in RA will be discussed.

A Rare Case of Hypophosphataemic Osteomalacia in von Recklinghausen Neurofibromatosis

Background

Neurofibromatosis type 1 (NF1), also known as von Recklinghausen disease, is a one of the more common hereditary autosomal disorders. However, osteomalacia in neurofibromatosis type 1 is very rare tumour-induced osteomalacia; fibroblast growth factor-23 is usually implicated.

Patients and methods

We report the case of a patient with a history of von Recklinghausen neurofibromatosis who presented with hypophosphataemic osteomalacia.

Results

The patient was treated with high-dose calcitriol and oral phosphate with clinical improvement.

Conclusion

Even though it is a rare entity, we must consider the diagnosis of hypophosphataemic osteomalacia in patients with neurofibromatosis in order to deliver appropriate treatment.

LEARNING POINTS

Osteomalacia during von Recklinghausen disease is a rare presentation of an uncommon condition and has a poorly understood mechanism.The treatment of oncogenic osteomalacia includes tumour removal which, however, is not always possible.Administration of calcitriol alone is not sufficient and phosphorus intake is mandatory to improve symptoms.

THU0606 RHEUMATOID ARTHRITIS INDUCED BY ALPHA-INTERFERON THERAPY: A RARE CASE PRESENTATION

Background:

Interferon-α (IFN-α) is known for its antiviral and antiproliferative effects, used mainly for the treatment of chronic hepatitis C infection [1]. Immunomodulatory effects have been reported in patients treated with IFN-α, including hematological, immunological, rheumatological and dermatological disorders [2]. In fact, IFN-α may lead to the induction or exacerbation of autoimmune diseases such as psoriasis, systemic lupus erythematosus, and rarely rheumatoid arthritis (RA).

Objectives:

We report the case of a Caucasian who developed anticyclic citrullinated peptide antibody (anti-CCP)-positive RA following treatment of chronic hepatitis C infection with pegylated IFN-α2a.

Methods:

A 57-year-old women was diagnosed of chronic hepatitis C infection after detection of abnormal liver function. She has a genotype Ib with a high viral load: RNA was 100,000 UI/ml. Liver histology showed advanced fibrosis and portal fibrosis (A3 F4 according to metavir score). A history of blood transfusion was found. The patient was placed on a 24-week course of PEGylated -IFN-α2a 180 µg weekly and a 1000 mg daily dose of ribavirin. After two months of antiviral treatment, she developed symmetrical polyarthritis, with pain and edema in the wrists, elbows, shoulders and metacarpophalangeal joints, associated with prolonged morning stiffness. The musculoskeletal examination was notable for active synovitis of the proximal phalangeal joints, metacarpophalangeal joints, wrists, elbows. Distal interphalangeal joints were spared. She had no musculoskeletal symptoms prior to antiviral therapy. Review of systems was otherwise unremarkable. X-ray showed no remarkable findings. Ultrasonography of the hands revealed diffuse synovitis as well as tenosynovitis of the ulnar extensor tendons in both wrists. Laboratory results revealed a normal C-reactive protein, elevated liver enzymes: ALAT (alanin-aminotransferase) 119,ASAT (aspartat-aminotransferase) 66, Gamma-GT 203 and undetectable cryoglobulins. Anti-CCP was 21 IU/ml (negative < 20 IU/ml), antinuclear antibodies were positive 1280 (negative<160), rheumatoid factor was 192 (normal < 30 IU/ml).

A diagnosis of rheumatoid arthritis (RA) was made on the basis of clinical and ultra-sonographic evidence as well as Rheumatoid Factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody positivity. Moreover, an autoimmune thyroiditis was found that evolved into hypothyroidism treated with thyroxine.

Results:

The patient developed a sustained virological response as evidenced by persistent undetectable HCV RNA and normal aminotransferase activities. Upon completion of a 12-week course of antiviral therapy, The rheumatoid syndrome disappeared after cessation of IFN therapy. By that time, antinuclear antibodies were in a titre of 1 /180, rheumatoid factor and Anti-CCP were negative.

Conclusion:

The present case suggests that biological agents, affecting the cytokine network, may work as triggering factors for the development of RA in previously predisposed individuals. Screening for RF and anti-CCP may be considered before treating with IFN. In addition, a close surveillance for the occurrence of autoimmune phenomena during and after treatment should be worthy, for early diagnosis and adequate clinical management.

References:

[1]DARICE YANG,DANIEL ARKFELDandTSE-LING FONG TreatmentforChronic Hepatitis C Infection.DevelopmentofAnti-CCP-positive Rheumatoid Arthritis Following Pegylated Interferon-alpha. J Rheumatol 2010;37;1777Volume 37, no. 8. 2a

[2]Okanoue T, Sakamoto S, Itoh Y, Minami M, Yasui K, Sakamoto M, et al. Side effects of high-dose interferon therapy for chronic hepatitis C. J Hepatol 1996;25:283-91.

Disclosure of Interests:

None declared

[Osteomalacia and giant cell tumor: a rare case]

BACKGROUND

Oncogenic octeomalacia is an unusual and rare clinicopathologic syndrome characterized by mesenchymal tumors that apparently produce osteomalacia and biochemical abnormalities consisting of hypophosphatemia and normocalcemia.

AIM

We have investigated the mechanism by which a giant cell tumor of bone caused biopsy-proved osteomalacia in a 50-year-old woman.

CASE REPORT

A 50-year-old woman presented with generalized bone and pelvicrural pain, associated with fatiguability and muscle weakness. The diagnosis of osteomalacia was retained, associated with a giant cell tumor. The coexistence of giant cell tumor of bone and osteomalacia suggested the diagnosis of oncogenic osteomalacia. Resolution of the biochemical abnormalities of the syndrome after tumor resection, established this diagnosis.

CONCLUSION

oncogenic osteomalacia can be a form of vitamin-D-refractory osteomalacia due to altered vitamin D3 metabolism.