Anti-resorptive therapy is the principal means of treating osteoporotic disorders. The two families of presently available anti-resorptive drugs, namely bisphosphonates and denosumab, dampen activity of osteoclasts by reducing their number. In consequence, these agents also arrest bone remodelling eventuating suppressed formation as well as resorption. Evidence exists that osteoclasts recruit osteoblasts to sites of bone remodelling by mobilizing chemotactic proteins from matrix and direct secretion of such proteins that attract osteoblast precursors. Thus, anti-resorptive agents, such as the cathepsin K inhibitor odanacatib, that dampen osteoclast function but not number may also preserve osteoblast recruitment by preserving the bone resorptive cell.

The inflammatory arthropathies share in common their tendency to produce marked alterations in skeletal remodelling and architecture. This review will focus on RA and the seronegative spondyloarthopathies (SpA), which share common features with respect to their tendency to produce localized bone destruction at sites of articular and peri-articular inflammation. However, there are significant differences in the skeletal pathology in these conditions, which include the unique involvement of the axial skeleton and the presence of inflammation in the extra-articular entheses in SpA. There also are differences in the pattern of bone formation and repair associated with the articular and peri-articular inflammation. This review will highlight the molecular and cellular processes that are involved in the pathogenesis of the skeletal pathology in these two forms of inflammatory arthritis with specific focus on the pathogenic mechanisms underlying the differential patterns of bone formation and repair.

IL-17 cytokines are expressed by a variety of cells and mediate host defence against extracellular pathogens. IL-17 is upregulated at sites of inflammation and can synergize with other cytokines, such as TNF-α, to amplify the inflammatory response. Activation of these signalling pathways has been hypothesized to contribute to the underlying pathogenesis of several inflammatory diseases, including psoriasis, RA, PsA and asthma. Thus the IL-17 signalling pathway is an attractive target for the development of therapeutic agents to modulate aberrant inflammatory responses. This review of the clinical development of therapeutic agents that target IL-17 signalling pathways in inflammatory diseases focuses on brodalumab, a human anti-IL-17 receptor A mAb. The cumulative findings of early clinical studies with anti-IL-17 agents, including brodalumab, secukinumab and ixekizumab, provide strong evidence for the role of IL-17 signalling in the pathophysiology of certain inflammatory diseases and support the potential use of these agents in treating these diseases.

Axial spondyloarthritis (axSpA) patients can be divided into those with structural damage in the SI joint visible on X-rays, termed radiographic axSpA or AS, and those in an earlier phase of the disease, without structural damage in the SI joint, termed non-radiographic axSpA. TNF-blockers have been shown to be highly effective in the treatment of active axSpA. Interestingly, conventional DMARDs and also non-TNF-blocker biologics targeting IL-1, IL-6 and T cells (abatacept) are not effective. Recent interest has focused on the cytokines IL-23 and IL-17 as potential treatment targets in axSpA. An open-label trial with ustekinumab showed a good efficacy in AS patients. Two placebo-controlled phase 3 trials with a mAb blocking IL-17, secukinumab, showed a good reduction in disease activity, similar to that shown for TNF blockers. Probably triggered by inflammation, new bone formation is another hallmark in AS and a potentially important treatment target. However, a previously reported inhibitory effect of NSAID treatment could not be confirmed in a recent NSAID trial.

PsA is an immune-mediated chronic inflammatory disease that affects both skin and joints; it is a heterogeneous disease characterized by synovitis, enthesitis, dactylitis and spondylitis. The impact on patients and the burden of disease are substantial. For assessment of the disease, patient-reported outcomes are increasingly important. Conventional therapy consists of NSAIDs, local and systemic CSs, and synthetic and biological DMARDs. While MTX, LEF, SSZ and CYC are the synthetic drugs mainly used, TNF-α blocking agents have represented the majority of biologics used in the last decade (infliximab, etanercept, adalimumab, certolizumab and golimumab). Treat-to-target strategies have been used successfully in PsA. This review concentrates on new developments, mainly covering biologic agents with an IL-17 inhibitor (secukinumab) and an anti-IL-23 agent (ustekinumab), but also synthetic drugs, including a novel phosphodiesterase-4 inhibitor (apremilast) and a Janus kinase inhibitor (tofacitinib) that blocks mainly Jak3 and Jak1 and, to a lesser extent, Jak2. The efficacy of some of these new agents may be even better for the skin than for the joints.

Autoinflammatory syndromes are disorders with an exaggerated inflammatory response, mostly in the absence of an appropriate trigger. Prototypic autoinflammatory syndromes are FMF, hyper-IgD syndrome (also known as mevalonate kinase deficiency), TNF receptor-associated periodic syndrome and cryopyrin-associated periodic syndrome. The clinical phenotypes partly overlap (with fever and acute phase response), but also differ between the various syndromes (e.g. regarding fever pattern, episodic vs chronic inflammation and accompanying clinical signs). In recent years, the genetic basis of quite a number of these relatively rare and mostly hereditary disorders has been elucidated. These genetic defects lead to either enhanced production of inflammatory mediators or to a lack of inhibition of these components of the innate immune system. Among these dysregulated inflammatory mediators, the pro-inflammatory cytokine IL-1β stands out. Hence, targeted treatment with blockers of IL-1 action, such as recombinant IL-1 receptor antagonist (IL-1Ra, anakinra) and mAb against IL-1β has met with impressive clinical results. In this article, hyper-IgD syndrome is discussed in more detail, based on 30 years of experience with this syndrome.

The combined use of MTX and biological DMARDs (bDMARDs) targeting TNF has revolutionized treatment of RA, and clinical remission becomes a realistic treatment goal. After sustained remission, discontinuation of bDMARDs without disease flare has been emerging as an important theme from the risk-benefit point of view and economic burden. According to several studies, approximately half of early RA patients could discontinue TNF-targeted bDMARDs without clinical flare and functional impairment after obtaining low disease activity or remission by treatment with bDMARDs and MTX. For established RA, however, fewer patients sustained remission or low disease activity after the discontinuation of bDMARDs, compared with early RA. The results were controversial among studies, and the percentage of patients who could successfully discontinue bDMARDs ranged from 13 to 48% at 1 year after discontinuation. From the adalimumab discontinuation without functional and radiographic damage progression following sustained remission study and the induction of remission by infliximab in RA study, deep remission at discontinuation was a key factor for maintaining the treatment holiday of bDMARDs in established RA patients. However, such early intensive treatment would have the potential for reducing drug-induced adverse effects and reducing long-term medical costs, although the risks of worsening clinical, structural and functional outcomes should be considered, with careful monitoring.

Glucocorticoids are steroid hormones that once bound to their receptor interact with the DNA binding domain. Almost 1000-2000 genes are sensitive to their effects, including immune/inflammatory response genes. However, their role in pathophysiology and therapy is still debated. We performed a literature survey using the key words glucocorticoids, inflammation, autoimmune disease, rheumatology and adrenal glands in order to define important targets for this review on glucocorticoids. Considering endogenous/exogenous glucocorticoids in chronic inflammatory diseases brought up five major points for discussion: inadequately low production of endogenous cortisol relative to systemic inflammation (the disproportion principle); changes of the systemic and local cortisol-to-cortisone shuttle (reactivation and degradation of cortisol); inflammation-induced glucocorticoid resistance; highlights of present glucocorticoid therapy; and the role of circadian rhythms in action of cortisol. Much of this information becomes understandable in the context of neurohormonal energy regulation as recently summarized. The optimization of long-term low-dose glucocorticoid therapy in chronic inflammatory diseases arises from the understanding of the above mentioned aspects. Since glucocorticoid resistance is a consequence of inflammation, adequate anti-inflammatory therapy is mandatory.

Glucocorticoids have now been used for >65 years in the treatment of RA. There is good evidence for their disease-modifying effect, especially in early RA. When used in a dosage of 7.5-10 mg/day, most adverse effects can be handled quite well, although monitoring for and awareness of infections are important. Adverse events may have been overreported, due to bias by indication, but pose an important drawback in the use of these very effective anti-inflammatory and immune-modulatory drugs. Daily dosages >7.5-10 mg and use for a prolonged period (years) of time are associated with a dose-dependent increased mortality. Still, the benefit:risk ratio for low-dosage glucocorticoid in patients with RA is acceptable and in many ways is comparable with other synthetic and biologic DMARDs.

The aim was to assess the efficacy of rituximab for the cutaneous manifestations of adult DM and JDM.

Psoriatic arthritis (PsA) is a heterogeneous, potentially severe disease. Many therapeutic agents are now available for PsA, but treatment decisions are not always straightforward. To assist in this decision making, two sets of recommendations for the management of PsA were published in 2016 by international organizations - the European League Against Rheumatism (EULAR) and the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA). In both sets of recommendations, the heterogeneity of PsA is recognized and the place of various drugs in the therapeutic armamentarium is discussed. Such agents include conventional DMARDs, such as methotrexate, and targeted therapies including biologic agents, such as ustekinumab, secukinumab and TNF inhibitors, or the targeted synthetic drug apremilast. The proposed sequential use of these drugs, as well as some other aspects of PsA management, differ between the two sets of recommendations. This disparity is partly the result of a difference in the evaluation process; the focus of EULAR was primarily rheumatological, whereas that of GRAPPA was balanced between the rheumatological and dermatological aspects of disease. In this Perspectives article, we address the similarities and differences between these two sets of recommendations and the implications for patient management.