New onset sarcoidosis following biologic treatment in patients with seronegative inflammatory arthritis: A case series and systematic literature review

OBJECTIVE

To report cases of new onset sarcoidosis upon biologic (bDMARDs) treatment administration in patients with seronegative inflammatory arthritis in a real-life cohort, alongside a systematic literature review (SLR) on this topic.

METHODS

We performed a retrospective analysis on clinical records of patients with seronegative arthritis followed up in a monocentric cohort who underwent bDMARDs treatment due to the underlying rheumatic disease and described any newly diagnosed sarcoidosis in this cohort. Only ascertained cases with available radiological and/or histological documentation were considered. A SLR on new-onset sarcoidosis in seronegative arthritis receiving bDMARDs was performed across MEDLINE (through PubMed), Scopus and Ovid (Cochrane, Embase) electronic databases using appropriate strings.

RESULTS

In our cohort, 4 new-onset cases of sarcoidosis were reported among patients with seronegative inflammatory arthritis receiving biologics. Three out of 4 patients were receiving anti-tumor necrosis factor alpha (TNFα) while 1 patient was on secukinumab (anti-IL17A) prior to sarcoidosis onset. The SLR disclosed 46 new-onset sarcoidosis cases upon biological treatment for seronegative arthritis, of whom 43 occurred during treatment with anti-TNFα, while 3 during anti-IL-17A therapy. In our cohort as well as in the majority of cases reported in the SLR, sarcoidosis presented with lymph nodal and lung involvement and displayed a benign course with spontaneous resolution in about 1 fourth of the cases.

CONCLUSION

The use of biologics may relate to the onset of sarcoidosis; hence, clinicians must remain aware of the potential occurrence or reactivation of sarcoidosis when starting biologic treatment in patients with inflammatory arthritis, performing adequate patient assessment and surveillance. Since TNFα inhibitors may represent a therapeutic option for sarcoidosis, further evaluation on larger cohorts is needed to investigate any causal link with the development of sarcoidosis.

Circulating osteoprotegerin and soluble RANKL: do they have a future in clinical practice?

The discovery of the signalling system consisting of receptor activator of nuclear factor-KB ligand (RANKL), its receptor RANKL and its decoy receptor osteoprotegerin (OPG) has been a key step in the understanding of pathophysiology of the bone microenvironment and has provided pharmacological targets for new anti-resorptive drugs. The system is central to the interactions among bone, vascular and immune cells. OPG and a soluble form of RANKL (sRANKL) are present in the blood stream. The measurement of their concentrations offers insights into the regulatory mechanisms of the system and the possibility of using new markers in a number of diseases. Besides bone metabolic disorders, the list includes malignancies, rheumatic and cardiovascular diseases. However, apparent discrepancies in the outcome of studies point to a number of caveats: lack of control of pre-analytical and analytical variables; paucity of data on the metabolic removal of the molecules; the cross sectional design of most studies comparing patients with healthy subjects. Finally, circulating OPG and sRANKL derive from several sources, and their concentrations may be alterated by different coexisting pathological processes. In the absence of tissue-specific isoforms, diagnostic or prognostic significance may be suggested from data obtained in large cohorts, but is still of limited usefulness in single patients.

[Pathophysiological significance and clinical utility of circulating osteoprotegerin]

Osteoprotegerin (OPG) belongs to the tumor necrosis factor receptor superfamily and acts as a decoy receptor for the receptor activator of NF-kappaB ligand (RANKL), preventing its binding to RANK. Since 1997, the RANKL/RANK/OPG system has been intensively investigated in the fields of bone, immune and cardiovascular system pathophysiology. Specific anti-OPG antibodies have been developed, allowing for the measurement of OPG and, more recently, of soluble RANKL in both physiological and pathological conditions, often yielding unexpected results. When considering circulating OPG measurements, it should be borne in mind that this receptor is ubiquitously expressed, and that circulating levels do reflect the production by a number of tissues. Moreover, strikingly different values of circulating OPG have been reported. The aim of this paper is to summarize the available data on circulating OPG levels in a number of conditions; the pathophysiological significance and potential clinical utility will be emphasized.