The fibrogenic chemokine CCL18 is associated with disease severity in Erdheim-Chester disease

Pyroptosis in sepsis-associated acute kidney injury: mechanisms and therapeutic perspectives

Sepsis-associated acute kidney injury (S-AKI) is a severe complication characterized by high morbidity and mortality, driven by multi-organ dysfunction. Recent evidence suggests that pyroptosis, a form of programmed cell death distinct from apoptosis and necrosis, plays a critical role in the pathophysiology of S-AKI. This review examines the mechanisms of pyroptosis, focusing on inflammasome activation (e.g., NLRP3), caspase-mediated processes, and the role of Gasdermin D in renal tubular damage. We also discuss the contributions of inflammatory mediators, oxidative stress, and potential therapeutic strategies targeting pyroptosis, including inflammasome inhibitors, caspase inhibitors, and anti-inflammatory therapies. Lastly, we highlight the clinical implications and challenges in translating these findings into effective treatments, underscoring the need for personalized medicine approaches in managing S-AKI.

Orbital histiocytosis; From A to Z

PURPOSE

Histiocytosis is one of the most challenging diseases in medical practice. Because of the broad spectrum of clinical manifestations, systemic involvements, unknown etiology, and complex management, different types of histiocytosis are still a big question mark for us. Orbital histiocytosis is characterized by the abnormal proliferation of histiocytes in orbital tissues. It could affect the orbit, eyelid, conjunctiva, and uveal tract. Orbital histiocytosis can cause limited eye movement, proptosis, decreased visual acuity, and epiphora. In this study, we review the novel findings regarding the pathophysiology, diagnosis, and treatment of different types of histiocytosis, focusing on their orbital manifestations.

METHOD

This review was performed based on a search of the PubMed, Scopus, and Embase databases or relevant published papers regarding orbital histiocytosis on October 9th, 2023. No time restriction was proposed, and articles were excluded if they were not referenced in English.

RESULTS

391 articles were screened, most of them being case reports. The pathophysiology of histiocytosis is still unclear. However, different mutations are found to be prevalent in most of the patients. The diagnostic path can be different based on various factors such as age, lesion site, type of histiocytosis, and the stage of the disease. Some modalities, such as corticosteroids and surgery, are used widely for treatment. On the other hand, based on some specific etiological factors for each type, alternative treatments have been proposed.

CONCLUSION

Significant progress has been made in the detection of somatic molecular changes. Many case studies describe various disease patterns influencing the biological perspectives on different types of histiocytosis. It is necessary to continue investigating and clustering data from a broad range of patients with histiocytosis in children and adults to define the best ways to diagnose and treat these patients.

Performance of 68Ga-Labeled Fibroblast Activation Protein Inhibitor PET/CT in Evaluation of Erdheim-Chester Disease: A Comparison with 18F-FDG PET/CT

Erdheim-Chester disease (ECD) involves multiple organs and tissues and has diverse manifestations, which makes it difficult to distinguish lesions caused by ECD from those caused by other diseases. Variable degrees of fibrosis are present in ECD. Therefore, we conducted a prospective cohort study to explore the ability of 68Ga fibroblast activation protein inhibitor (68Ga-FAPI) PET/CT to detect lesions in ECD patients. Methods: Fourteen patients diagnosed with ECD, as confirmed by histology, were included in this study. For every patient, 68Ga-FAPI PET/CT and 18F-FDG PET/CT were conducted within 1 wk. The positive rate and SUVmax of the lesions in the involved organs were compared between the examinations. Results: The most commonly involved organs were bone (100%), heart (57.1%), lung (57.1%), kidney (42.9%), and peritoneum or omentum (35.7%); other common manifestations were intracranial infiltration (50%) and cutaneous infiltration (35.7%). 68Ga-FAPI PET/CT detected 64 of 67 lesions in 14 patients, whereas 18F-FDG PET/CT detected 51 of 67 lesions (P = 0.004). The SUVmax for 68Ga-FAPI PET/CT was significantly higher than the SUVmax for 18F-FDG PET/CT of the heart (4.9 ± 2.4 vs. 2.8 ± 1.2, respectively; P = 0.050), lung or pleura (6.8 ± 4.9 vs. 3.1 ± 1.3, respectively; P = 0.025), peritoneum or omentum (5.7 ± 3.6 vs. 2.8 ± 1.7, respectively; P = 0.032), and kidney or perinephric infiltration (4.9 ± 1.2 vs. 2.9 ± 1.1, respectively; P = 0.009). Conclusion: The detectivity of 68Ga-FAPI PET/CT is superior to that of 18F-FDG PET/CT. Moreover, 68Ga-FAPI PET/CT has a better image contrast and higher SUVmax for lesions in multiple organs including the heart, lungs, peritoneum, and kidneys. 68Ga-FAPI PET/CT is a promising tool to assess pathologic features and disease extent in ECD patients.

Cardiovascular involvement in Erdheim-Chester diseases is associated with myocardial fibrosis and atrial dysfunction

PURPOSE

Erdheim-Chester disease (ECD) is a rare multisystem histiocytosis, whose cardiovascular involvement has not been systematically characterized so far. We aimed to systematically (qualitatively and quantitatively) describe the features of cardiovascular involvement in a large cohort of ECD patients and to evaluate its impact on myocardial fibrosis extension and cardiac function.

MATERIAL AND METHODS

Among 54 patients with biopsy-proven ECD, 29 patients (59 ± 12 years, 79% males) underwent 1.5-T CMR using a standardized protocol for qualitative and quantitative assessment of disease localization, evaluation of atrial and ventricular function, and assessment of non-dense and dense myocardial fibrosis.

RESULTS

The right atrioventricular (AV) groove was the most commonly affected cardiac site (76%) followed by the right atrial walls (63%), thoracic aorta (59%), and superior vena cava (38%). Right AV groove involvement, encasing the right ventricular artery, was associated with non-dense myocardial fibrosis in the infero-septal (20/26 patients) and the inferior (14/26 patients) mid-basal left ventricular (LV) wall. In two patients with right AV groove localization, LGE revealed myocardial infarction in the same myocardial segments. Three out of five patients with left AV groove involvement had non-dense LGE on the lateral LV mid-basal wall. Bulky right atrial pseudomass was associated with atrial dysfunction and superior and inferior vena cava stenosis.

CONCLUSIONS

In ECD patients, AV groove localization is associated with LV wall fibrosis in the downstream coronary territories, suggesting hemodynamic alterations due to coronary encasement. Conversely, atrial pseudomass ECD localizations impact on atrial contractility causing atrial dysfunction and are associated with atrio-caval junction stenosis.

Rare presentation of multiple thromboses in Erdheim-Chester disease: a case-based review

BACKGROUND

ECD is a rare non-Langerhans cell histiocytosis with diverse and heterogeneous clinical manifestations, ranging from single-lesion forms to multi-system involvement, including slowly progressing unifocal forms to rapidly evolving life-threatening disease.

CASE PRESENTATION

A female patient presented with a 2-month history of fever. Imaging revealed multiple thromboses, bone destruction, an abnormal pituitary stalk, and clinical manifestations of diabetes insipidus. Excisional biopsy of a tibial lesion was sent for microscopic examination, and subsequent immunohistochemical testing was positive for expression of CD68 and CD163, and negative for expression of the immune markers CD1a, S100, and langerin. This confirmed the diagnosis of ECD. Treatment with methylprednisolone to inhibit the immune inflammatory response along with anti-cytokine therapy with an interleukin-6 antagonist resulted in satisfactory disease control.

CONCLUSION

We report a rare case of multiple thromboses, embolism, and multiple organ involvement as the main presentation of ECD, suggesting that ECD should be considered in patients presenting with multiple thromboses associated with multisystem damage. We successfully treated our patient with glucocorticoids and interleukin-6 antagonist. This patient's response to treatment suggests that hormone therapy and cytokine/chemokine therapy may be a potential novel treatment for patients with ECD without gene mutations.

MicroRNA-15a-5p acts as a tumor suppressor in histiocytosis by mediating CXCL10-ERK-LIN28a-let-7 axis

Erdheim-Chester disease (ECD) is characterized by excessive production and accumulation of histiocytes within multiple tissues and organs. ECD patients harbor recurrent mutations of genes associated with the RAS/RAF/MEK/ERK signaling pathway, particularly, the BRAFV600E mutation. Following our previous finding that miR-15a-5p is the most prominently downregulated microRNA in ECD patients compared to healthy individuals, we elucidated its role in ECD pathogenesis. Bioinformatics analysis followed by a luciferase assay showed that chemokine ligand 10 (CXCL10) is a target gene regulated by miRNA-15a-5p. This was confirmed in 24/34 ECD patients that had low expression of miR-15a-5p concurrent with upregulated CXCL10. Overexpression of miR-15a-5p in cell lines harboring BRAF or RAS mutations (Ba/F3, KG-1a and OCI-AML3) resulted in CXCL10 downregulation, followed by LIN28a and p-ERK signaling downregulation and let-7 family upregulation. Overexpression of miR-15a-5p inhibited cell growth and induced apoptosis by decreasing Bcl-2 and Bcl-xl levels. Analysis of sequential samples from 7 ECD patients treated with MAPK inhibitors (vemurafenib/cobimetinib) for 4 months showed miR-15a-5p upregulation and CXCL10 downregulation. Our findings suggest that miR-15a-5p is a tumor suppressor in ECD through the CXCL10-ERK-LIN28a-let7 axis, highlighting another layer of post-transcriptional regulation in this disease. Upregulation of miR-15a-5p in ECD patients may have a potential therapeutic role.

Interleukin-1 and Systemic Sclerosis: Getting to the Heart of Cardiac Involvement

Systemic sclerosis (SSc) is rare, severe connective tissue disease characterized by endothelial and vascular damage, immune activation, and resulting in inflammation and fibrosis of skin and internal organs, including the heart. SSc is associated with high morbidity and mortality. Cardiac involvement is frequent in SSc patients, even though often asymptomatic at early stages, and represents one of the major causes of SSc-related mortality. Heart involvement has a variable clinical presentation, and its pathogenesis is not completely understood. Myocardial fibrosis is traditionally considered the immunopathologic hallmark of heart involvement in SSc. This unique histological feature is paralleled by distinctive clinical and prognostic features. The so-called "vascular hypothesis" represents the most credited hypothesis to explain myocardial fibrosis. More recently, the prominent role of an inflammatory myocardial process has been identified as a cardinal event in the evolution to fibrosis, thus also delineating an "inflammation-driven pathway to fibrosis". The pro-inflammatory cytokine interleukin (IL)-1 has an apical and cardinal role in the myocardial inflammatory cascade and in cardiac dysfunction. The primary aim of this perspective article is: to present the emerging evidence on the role of IL-1 and inflammasome in both SSc and heart inflammation, to review the complex interplay between cellular metabolism and inflammasome activation, and to discuss the rationale for targeted inhibition of IL-1 for the treatment of SSc-heart involvement, providing preliminary experimental and clinical data to support this hypothesis.

Interleukin 1α: a comprehensive review on the role of IL-1α in the pathogenesis and treatment of autoimmune and inflammatory diseases

The interleukin (IL)-1 family member IL-1α is a ubiquitous and pivotal pro-inflammatory cytokine. The IL-1α precursor is constitutively present in nearly all cell types in health, but is released upon necrotic cell death as a bioactive mediator. IL-1α is also expressed by infiltrating myeloid cells within injured tissues. The cytokine binds the IL-1 receptor 1 (IL-1R1), as does IL-1β, and induces the same pro-inflammatory effects. Being a bioactive precursor released upon tissue damage and necrotic cell death, IL-1α is central to the pathogenesis of numerous conditions characterized by organ or tissue inflammation. These include conditions affecting the lung and respiratory tract, dermatoses and inflammatory skin disorders, systemic sclerosis, myocarditis, pericarditis, myocardial infarction, coronary artery disease, inflammatory thrombosis, as well as complex multifactorial conditions such as COVID-19, vasculitis and Kawasaki disease, Behcet's syndrome, Sjogren Syndrome, and cancer. This review illustrates the clinical relevance of IL-1α to the pathogenesis of inflammatory diseases, as well as the rationale for the targeted inhibition of this cytokine for treatment of these conditions. Three biologics are available to reduce the activities of IL-1α; the monoclonal antibody bermekimab, the IL-1 soluble receptor rilonacept, and the IL-1 receptor antagonist anakinra. These advances in mechanistic understanding and therapeutic management make it incumbent on physicians to be aware of IL-1α and of the opportunity for therapeutic inhibition of this cytokine in a broad spectrum of diseases.

Histiocytic disorders: insights into novel biology and implications for therapy of Langerhans cell histiocytosis and Erdheim-Chester disease

Langerhans cell histiocytosis (LCH) and Erdheim-Chester disease (ECD) are caused by mutations of the MAPK pathway, most often BRAFV600E, in myeloid dendritic cells that lead to some overlapping and other unique presentations of the two diseases. LCH occurs in both children and adults, but ECD is primarily found in the latter. The challenges in diagnosing these conditions relates to the rarity of the conditions and that they mimic diseases that are more widely understood, such as certain rashes; bone, lung, and renal diseases; and other malignancies. The histopathology of LCH is definitive, but not so for ECD. Treatment with BRAF and MEK inhibitors has become one of the important advances in the care of these patients.

Erdheim-Chester disease

Erdheim-Chester disease (ECD) is characterized by the infiltration of tissues by foamy CD68+CD1a- histiocytes, with 1500 known cases since 1930. Mutations activating the MAPK pathway are found in more than 80% of patients with ECD, mainly the BRAFV600E activating mutation in 57% to 70% of cases, followed by MAP2K1 in close to 20%. The discovery of BRAF mutations and of other MAP kinase pathway alterations, as well as the co-occurrence of ECD with LCH in 15% of patients with ECD, led to the 2016 revision of the classification of histiocytoses in which LCH and ECD belong to the "L" group. Both conditions are considered inflammatory myeloid neoplasms. Ten percent of ECD cases are associated with myeloproliferative neoplasms and/or myelodysplastic syndromes. Some of the most striking signs of ECD are the long bone involvement (80%-95%), as well as the hairy kidney appearance on computed tomography scan (63%), the coated aorta (40%), and the right atrium pseudo-tumoral infiltration (36%). Central nervous system involvement is a strong prognostic factor and independent predictor of death. Interferon-α seems to be the best initial treatment of ECD. Since 2012, more than 200 patients worldwide with multisystem or refractory ECD have benefitted from highly effective therapy with BRAF and MEK inhibitors. Targeted therapies have an overall, robust, and reproducible efficacy in ECD, with no acquired resistance to date, but their use may be best reserved for the most severe manifestations of the disease, as they may be associated with serious adverse effects and as-yet-unknown long-term consequences.

Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare but increasingly recognized multi-system disorder. Its diagnosis and treatment require integration of clinical information, imaging studies, and pathology studies. Of note, ECD can now be defined as a clonal myeloid disorder due to mutations which activate mitogen-activated protein kinase (MAPK) pathways and where an inflammatory milieu is important in the pathogenesis and clinical manifestations of the disease. Biopsy demonstrating characteristic histopathologic features in addition to clinical and radiographic features, most often sclerosing long bone involvement, is required to establish a diagnosis. Detection of somatic MAPK pathway mutations can also assist in the differential diagnosis of ECD and related histiocytic neoplasms. Also, genetic analysis establishing BRAF and RAS mutational status is critical in all ECD patients, as these features will impact therapy with MAPK inhibition. Therapy is recommended at diagnosis in all patients, except for those patients with minimally symptomatic disease. Prospective therapeutic trials are essential to furthering therapeutic progress in ECD.

Erdheim-Chester disease: An in vivo human model of Mϕ activation at the crossroad between chronic inflammation and cancer

Erdheim-Chester disease (ECD) is a rare histiocytosis characterized by infiltration of multiple tissues by CD68⁺ foamy Mϕs (or 'histiocytes'). Clinical manifestations arise from mass-forming lesions or from tissue and systemic inflammation. ECD histiocytes harbor oncogenic mutations along the MAPK-kinase signaling pathway (BRAF^V600E in more than half of the patients), and secrete abundant pro-inflammatory cytokines and chemokines. Based on these features, ECD is considered an inflammatory myeloid neoplasm, and is accordingly managed with targeted kinase inhibitors or immunosuppressive and cytokine-blocking agents. Evidence is emerging that maladaptive metabolic changes, particularly up-regulated glycolysis, represent an additional, mutation-driven feature of ECD histiocytes, which sustains deregulated and protracted pro-inflammatory activation and cytokine production. Besides translational relevance to the management of ECD patients and to the development of new therapeutic approaches, recognition of ECD as a natural human model of chronic, maladaptive Mϕ activation instructs the understanding of Mϕ dysfunction in other chronic inflammatory conditions.

Biologic discontinuation strategies and outcomes in patients with rheumatoid arthritis

Introduction: Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease, which affects joints as well as extra-articular tissues. In the last decades, increasing targeted therapeutic options dramatically improved RA management by doubling the rate of patients achieving clinical remission. Currently, there is a need for management strategies aimed at limiting treatment-related adverse events and costs in good responders.Areas covered: Data on de-escalation of biologic drugs (especially for anti-TNF agents) are mainly available from post-hoc analyses of randomized controlled trials and from registry-based observational studies. This narrative review illustrates the rationales for dose tapering and expands to provide an overview of the efficacy of the different available strategies for reducing the exposure to biologic drugs in patients achieving a sustained clinical response. Selected studies are discussed as illustrative examples.Expert opinion: Withdrawal of biologic therapy might be attempted in limited patients with very early RA; conversely, established RA is more suitably managed with a progressive decrease of drug regimen, by either dose reduction or injection/infusion spacing. Further studies investigating potential factors predicting post-tapering disease relapse are warranted, in order to better identify the best candidates for a decreased-dose approach.

Clinical and positron emission tomography responses to long-term high-dose interferon-α treatment among patients with Erdheim-Chester disease

Background

Erdheim–Chester disease (ECD) is a rare multi-systemic form of histiocytosis. Treatment with BRAF inhibitors has markedly improved outcomes of ECD; however, this targeted therapy is expensive (estimated annual cost is $50,000). Since estimated annual cost of interferon-α (IFN-α) is only approximately $1600 in China, we retrospectively evaluated the long-term therapeutic efficacy of IFN-α and the value of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) as an assessment method among 32 ECD patients who received high dose IFN-α therapy at Peking Union Medical College Hospital.

Results

The median age at diagnosis was 48 years (range, 6–66 years). The median duration of treatment was 18.5 months (range, 1–51 months). The overall clinical response rates were 80.0%, including 33.3% complete response, 36.7% partial response and 10.0% stable disease. Thirty-one patients underwent a total of 81 scans by FDG-PET. Seventeen patients had serial FDG-PET results, nine patients had experienced a partial metabolic response at the last follow-up. The median reduction of ratios between the most active target lesion standardized uptake value (SUV) and liver SUV from baseline to last FDG-PET scan was 61.4% (range, 8.8–86.6%). Eight of thirteen patients who experienced continuous clinical improvement during follow-up had at least one target lesion SUV increased by FDG-PET which decreased in subsequent scans without changing treatment strategy. The estimated 3-year progression-free survival (PFS) and overall survival (OS) were 64.1 and 84.5%, respectively. Central nervous system (CNS) involvement was the only predictor for poor PFS and OS.

Conclusions

High-dose IFN-α treatment is a cost-effective option, especially for patients without CNS involvement. Single target lesion SUV elevation according to FDG-PET do not accurately demonstrate disease progression, but serial FDG-PET imaging effectively discriminate treatment response.

Anakinra Therapy for Non-cancer Inflammatory Diseases

Interleukin-1 (IL-1) is the prototypical inflammatory cytokine: two distinct ligands (IL-1α and IL-1β) bind the IL-1 type 1 receptor (IL-1R1) and induce a myriad of secondary inflammatory mediators, including prostaglandins, cytokines, and chemokines. IL-1α is constitutively present in endothelial and epithelial cells, whereas IL-1β is inducible in myeloid cells and released following cleavage by caspase-1. Over the past 30 years, IL-1-mediated inflammation has been established in a broad spectrum of diseases, ranging from rare autoinflammatory diseases to common conditions such as gout and rheumatoid arthritis (RA), type 2 diabetes, atherosclerosis, and acute myocardial infarction. Blocking IL-1 entered the clinical arena with anakinra, the recombinant form of the naturally occurring IL-1 receptor antagonist (IL-1Ra); IL-1Ra prevents the binding of IL-1α as well as IL-1β to IL-1R1. Quenching IL-1-mediated inflammation prevents the detrimental consequences of tissue damage and organ dysfunction. Although anakinra is presently approved for the treatment of RA and cryopyrin-associated periodic syndromes, off-label use of anakinra far exceeds its approved indications. Dosing of 100 mg of anakinra subcutaneously provides clinically evident benefits within days and for some diseases, anakinra has been used daily for over 12 years. Compared to other biologics, anakinra has an unparalleled record of safety: opportunistic infections, particularly Mycobacterium tuberculosis, are rare even in populations at risk for reactivation of latent infections. Because of this excellent safety profile and relative short duration of action, anakinra can also be used as a diagnostic tool for undefined diseases mediated by IL-1. Although anakinra is presently in clinical trials to treat cancer, this review focuses on anakinra treatment of acute as well as chronic inflammatory diseases.

Treating Heart Inflammation With Interleukin-1 Blockade in a Case of Erdheim-Chester Disease

Pericarditis is an inflammatory heart disease, which may be idiopathic or secondary to autoimmune or auto-inflammatory diseases and often leads to severe or life-threatening complications. Colchicine and non-steroidal anti-inflammatory drugs represent the mainstay of treatment, whereas use of corticosteroids is associated with recurrence of disease flares. While effective and safe anti-inflammatory therapies remain an unmet clinical need, emerging clinical and experimental evidence points at a promising role of inhibition of the pro-inflammatory cytokine interleukin-1 (IL-1). We thus evaluated treatment with the IL-1 receptor antagonist anakinra in a case of extremely severe pericarditis with cardiac tamponade and heart failure secondary to Erdheim-Chester disease (ECD), a rare clonal disorder of macrophages characterized by rampant inflammation and multiorgan involvement. A 62-year-old man was admitted to the Emergency Department with severe pericardial effusion requiring the creation of a pleuro-pericardial window. A whole-body contrast-enhanced computed tomography pointed at a diagnosis of ECD with involvement of the heart and pericardium and of the retroperitoneal space. Over the following days, an echocardiography revealed a closure of the pleuro-pericardial window and a relapse of the pericardial effusion. Treatment with anakinra, the recombinant form of the naturally occurring IL-1 receptor antagonist, was started at a standard subcutaneous dose of 100 mg/day. After 2 days, we observed a dramatic clinical improvement, an abrupt reduction of the inflammatory markers, and a reabsorption of the pericardial effusion. Anakinra was maintained as monotherapy, and the patient remained asymptomatic in the absence of disease flares for the following year. Recent studies point at inhibition of IL-1 activity as an attractive treatment option for patients with refractory idiopathic recurrent pericarditis. Anakinra treatment may also have a role in patients with pericarditis in the setting of systemic inflammatory disorders, such as ECD.