Clinical relevance for circulating cold-inducible RNA-binding protein (CIRP) in patients with adult-onset Still's disease

Recent advances and evolving concepts in Still's disease

Still's disease is a rare inflammatory syndrome that encompasses systemic juvenile idiopathic arthritis and adult-onset Still's disease, both of which can exhibit life-threatening complications, including macrophage activation syndrome (MAS), a secondary form of haemophagocytic lymphohistiocytosis. Genetic insights into Still's disease involve both HLA and non-HLA susceptibility genes, suggesting the involvement of adaptive immune cell-mediated immunity. At the same time, phenotypic evidence indicates the involvement of autoinflammatory processes. Evidence also implicates the type I interferon signature, mechanistic target of rapamycin complex 1 signalling and ferritin in the pathogenesis of Still's disease and MAS. Pathological entities associated with Still's disease include lung disease that could be associated with biologic DMARDs and with the occurrence of MAS. Historically, monophasic, recurrent and persistent Still's disease courses were recognized. Newer proposals of alternative Still's disease clusters could enable better dissection of clinical heterogeneity on the basis of immune cell profiles that could represent diverse endotypes or phases of disease activity. Therapeutically, data on IL-1 and IL-6 antagonism and Janus kinase inhibition suggest the importance of early administration in Still's disease. Furthermore, there is evidence that patients who develop MAS can be treated with IFNγ antagonism. Despite these developments, unmet needs remain that can form the basis for the design of future studies leading to improvement of disease management.

Extracellular CIRP Induces Calpain Activation in Neurons via PLC-IP3-Dependent Calcium Pathway

Abnormal calcium homeostasis, activation of protease calpain, generation of p25 and hyperactivation of cyclin-dependent kinase 5 (Cdk5) have all been implicated in the pathogenesis of neurogenerative diseases including Alzheimer's disease. We have recently shown that extracellular cold-inducible RNA-binding protein (eCIRP) induces Cdk5 activation via p25. However, the precise molecular mechanism by which eCIRP regulates calcium signaling and calpain remains to be addressed. We hypothesized that eCIRP regulates p25 via Ca2+-dependent calpain activation. eCIRP increased calpain activity and decreased the endogenous calpain inhibitor calpastatin in Neuro 2a (N2a) cells. Calpain inhibition with calpeptin attenuated eCIRP-induced calpain activity and p25. eCIRP specifically upregulated cytosolic calpain 1, and calpain 1 silencing attenuated the eCIRP-induced increase in p25. eCIRP stimulation increased cytosolic free Ca2+, especially in hippocampal neuronal HT22 cells, which was attenuated by the eCIRP inhibitor Compound 23 (C23). Endoplasmic reticulum (ER) inositol 1,4,5-trisphosphate receptor (IP3R) inhibition using 2-aminoethoxy-diphenyl-borate or xestospongin-C (X-C), interleukin-6 receptor alpha (IL-6Rα)-neutralization, and phospholipase C (PLC) inhibition with U73122 attenuated eCIRP-induced Ca2+ increase, while Ca2+ influx across the plasma membrane remained unaffected by eCIRP. Finally, C23, IL-6Rα antibody, U73122 and X-C attenuated eCIRP-induced p25 in HT-22 cells. In conclusion, the current study uncovers eCIRP-triggered Ca2+ release from ER stores in an IL-6Rα/PLC/IP3-dependent manner as a novel molecular mechanism underlying eCIRP's induction of Cdk5 activity and potential involvement in neurodegeneration.

Serum cold-inducible RNA-binding protein levels as a potential biomarker for systemic sclerosis-associated interstitial lung disease

Systemic sclerosis (SSc) is a complex autoimmune disease characterized by fibrotic, inflammatory, and vascular dysfunction. Danger-associated molecular patterns (DAMPs)-mediated inflammasome activation has been reported to be involved in the pathogenesis of SSc. Cold-inducible RNA-binding protein (CIRP) is newly identified as a DAMP. Here we examined the clinical significance of serum levels of CIRP in 60 patients with SSc and 20 healthy control patients (HCs) using an enzyme-linked immunosorbent assay. Serum CIRP levels in diffuse cutaneous SSc (dcSSc) patients were significantly increased compared with limited cutaneous SSc (lcSSc) patients or HCs. When examining the relationship with SSc-specific parameters, serum CIRP levels with the presence of interstitial lung disease (ILD) were higher than those without ILD. In detail, serum CIRP levels correlated negatively with the percent predicted diffusing capacity for carbon monoxide and positively with levels of Krebs von den Lungen-6. In addition, elevated serum CIRP levels declined along with decreased SSc-ILD activity in patients who received immunosuppressive therapy. These results suggest that CIRP may play a role in the development of ILD in SSc. Moreover, CIRP could serve as a useful serological marker of SSc-ILD in terms of disease activity and therapeutic effects.

Interleukin-18: a biomarker with therapeutic potential in adult-onset Still's disease

INTRODUCTION

Adult-onset Still's disease (AOSD) is an autoinflammatory disease driven by the innate immune response. Given the ambiguity in clinical presentation and lack of specific diagnostic biomarkers, AOSD diagnosis is usually delayed in the early stage. Because AOSD is a rare disease with clinical heterogeneity, there is no consensus on its treatment currently. This review summarizes the current research evidence regarding the pathogenic role and the diagnostic or therapeutic potential of interleukin (IL)-18 in AOSD.

AREAS COVERED

We searched the MEDLINE database using the PubMed interface and reviewed English-language literature from 1971 to 2022. This review focusing on IL-18 discusses its pathogenic role and clinical implications in AOSD.

EXPERT OPINION

NLRP3-inflammasome activation with IL-18 overproduction plays a pathogenic role in AOSD. IL-18 is closely linked to the clinical manifestations and disease activity of AOSD and may be a diagnostic biomarker. Given its pathogenic role in AOSD, IL-18 could become a potential therapeutic target. IL-18 binding protein (IL-18BP) negatively regulates the biological activity of IL-18 by inhibiting IL-18 signaling, and a clinical trial revealed that IL-18BP (Tadekinig alfa) treatment was well-tolerated and effective for AOSD. Recently, monoclonal antibodies against IL-18 have been under evaluation in a phase 1b trial.

Effects of Astragalus membranaceus on systemic lupus erythematosus in a mouse model of pregnancy

BACKGROUND

This study used astragalus membranaceus (AM) to treat systemic lupus erythematosus (SLE) model mice during pregnancy, aiming to explore the role of AM in Helper T cell 17 (Th17) differentiation and SLE during pregnancy.

METHODS

We used lipopolysaccharide to constructed the SLE mouse model. AM decoction given by intragastric administration lasted from the eighth week of the mouse age until the mouse was killed. We estimated the messenger RNA  levels of IL-17a and Rorc, counted the Th17 cell number and examined the levels of cytokines including interleukin (IL)-12, tumor necrosis factor α, interferon gamma, IL-17A in mouse serum. Periodic acid-Schiff staining and renal glomerular/tubulointerstitial (TI) score were used to evaluate the progression of lupus nephritis (LN).

RESULTS

AM treatment improved the conception rate and increased the number and average weight of fetuses in SLE mice. It significantly decreased the urinary albumin/creatinine ratios and reduced the glomerular scores and TI scores in the pregnant SLE mice. AM gavage significantly decreased the weight of spleen, mesenteric lymph node, total splenocytes and T cells, and the expression of proinflammatory factors. Furthermore, AM treatment reduced the ratio of Th17 cells and the expression levels of RORγt and IL-17A.

CONCLUSION

AM significantly improved pregnancy outcomes and inhibited lupus nephritis during pregnancy in SLE mice.

Expanding the spectrum of the hyperferritinemic syndrome, from pathogenic mechanisms to clinical observations, and therapeutic implications

From the introduction of hyperferritinemic syndrome concept, a growing body of evidence has suggested the role of ferritin as a pathogenic mediator and a relevant clinical feature in the management of patients with inflammatory diseases. From a pathogenic point of view, ferritin may directly stimulate the aberrant immune response by triggering the production of pro-inflammatory mediators in inducing a vicious pathogenic loop and contributing to the occurrence of cytokine storm syndrome. The latter has been recently defined as a clinical picture characterised by elevated circulating cytokine levels, acute systemic inflammatory symptoms, and secondary organ dysfunction beyond that which could be attributed to a normal response to a pathogen It is noteworthy that the occurrence of hyperferritinemia may be correlated with the development of the cytokine storm syndrome in the context of an inflammatory disease. In addition to adult onset Still's disease, macrophage activation syndrome, catastrophic anti-phospholipids syndrome, and septic shock, recent evidence has suggested this association between ferritin and life-threatening evolution in patients with systemic lupus erythematosus, with anti-MDA5 antibodies in the context of poly-dermatomyositis, with severe COVID-19, and with multisystem inflammatory syndrome. The possible underlying common inflammatory mechanisms, associated with hyperferritinemia, may led to the similar clinical picture observed in these patients. Furthermore, similar therapeutic strategies could be suggested inhibiting pro-inflammatory cytokines and improving long-term outcomes in these disorders. Thus, it could be possible to expand the spectrum of the hyperferritinemic syndrome to those diseases burdened by a dreadful clinical picture correlated with hyperferritinemia and the occurrence of the cytokine storm syndrome. In addition, the assessment of ferritin may provide useful information to the physicians in clinical practice to manage these patients. Therefore, ferritin may be considered a relevant clinical feature to be used as biomarker in dissecting the unmet needs in the management of these disorders. Novel evidence may thus support an expansion of the spectrum of the hyperferritinemic syndrome to these diseases burdened by a life-threatening clinical picture correlated with hyperferritinemia and the occurrence of the cytokine storm syndrome.

Adult-Onset Still's Disease: Novel Biomarkers of Specific Subsets, Disease Activity, and Relapsing Forms

Adult-onset Still’s disease (AOSD) is a systemic inflammatory disease of unknown etiology. Recent studies have demonstrated that the hallmark of AOSD is a cytokine storm, which is characterized by the excessive production of interleukin (IL)-1, IL-6, IL-18, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ), suggesting how pro-inflammatory cytokines play an important role in the pathogenesis of this disease. Actually, a certain proportion of patients (around 17–32%) with severe clinical symptoms achieves only partial remission or is resistant to both first-line corticosteroids and second-line DMARDs. These patients are defined as refractory AOSD patients, requiring higher dosage glucocorticoids, longer treatment duration, or the simultaneous introduction of immunosuppressive drugs, further leading to AOSD relapses. In this narrative review, we will analyze the latest literature data to unravel potential pathogenetic factors associated with specific patterns of AOSD disease or relapses in order to identify biomarkers that may guide clinical decisions, eventually leading to new therapeutic options.