Proteasome inhibitor-associated histiocytoid Sweet's syndrome: Clinical and histological similarities to Nakajo-Nishimura syndrome suggest a potential mechanism.

Histiocytoid Sweet's syndrome (HSS) is a variant of Sweet's syndrome (SS) that clinically resembles SS but differs histologically by infiltrates, predominantly composed of immature cells of the myeloid lineage. Medications such as proteasome inhibitors have been reported to cause HSS but there has been little discussion on the underlying mechanism. Here we report two cases of HSS associated with a proteasome inhibitor. Both patients were on ixazomib for the treatment of multiple myeloma and presented with acute erythematous plaques on the upper half of the body. Pathological findings were consistent with HSS. Similarities between proteasome inhibitor-induced HSS and Nakajo-Nishimura syndrome, an inherited inflammatory disease, can be identified both clinically and histologically, suggesting a potential explanation of the mechanism behind proteasome inhibitor-associated HSS.

Neutrophilic epitheliotropism, proposed as an auto-inflammatory condition of neutrophilic urticarial dermatosis including Schnitzler syndrome, is also observed in Japanese cases.

Schnitzler syndrome (SchS) is a rare autoinflammatory disease characterized by bone pain, recurrent fever, leukocytosis, and elevated C-reactive protein, along with an urticaria-like rash and monoclonal immunoglobulin (Ig)M or IgG gammopathy. Notably, the condition is distinguished by a relatively persistent recurrent urticarial-like rash. Histopathological features observed in the skin comprise diffuse neutrophil infiltration into the dermis, absence of dermal edema, and vascular wall degeneration, all of which classify SchS as a neutrophilic urticarial dermatosis (NUD). Accumulated histological data from skin biopsies of patients with NUD have revealed a sensitive histopathological marker for NUD, acknowledged as neutrophilic epitheliotropism, which has been proposed as reflecting an autoinflammatory condition. In this report, we present three SchS patients: two men (ages 55 and 68) and a woman (age 75), all displaying neutrophilic epitheliotropism in their skin biopsy specimens. Additionally, a review of eight previously reported SchS cases in Japan identified neutrophilic epithliotropism in five cases. These findings suggest that the inclination of neutrophils toward the epithelial tissue could aid in confirming diagnoses of NUD in most cases that need to be differentiated from conventional urticaria. Consequently, we emphasize that acknowledging neutrophilic epithelial predilection as a hallmark of NUD is critical for expediting early diagnosis and appropriate treatment for SchS.

Activation of the pentose phosphate pathway in macrophages is crucial for granuloma formation in sarcoidosis.

Sarcoidosis is a disease of unknown etiology in which granulomas form throughout the body and is typically treated with glucocorticoids, but there are no approved steroid-sparing alternatives. Here, we investigated the mechanism of granuloma formation using single-cell RNA-Seq in sarcoidosis patients. We observed that the percentages of triggering receptor expressed on myeloid cells 2-positive (TREM2-positive) macrophages expressing angiotensin-converting enzyme (ACE) and lysozyme, diagnostic makers of sarcoidosis, were increased in cutaneous sarcoidosis granulomas. Macrophages in the sarcoidosis lesion were hypermetabolic, especially in the pentose phosphate pathway (PPP). Expression of the PPP enzymes, such as fructose-1,6-bisphosphatase 1 (FBP1), was elevated in both systemic granuloma lesions and serum of sarcoidosis patients. Granuloma formation was attenuated by the PPP inhibitors in in vitro giant cell and in vivo murine granuloma models. These results suggest that the PPP may be a promising target for developing therapeutics for sarcoidosis.

Tofacitinib, a suppressor of NOD2 expression, is a potential treatment for Blau syndrome.

Introduction: Blau syndrome is a rare autosomal dominant autoinflammatory granulomatous disease caused by a mutation in the NOD2 gene. It is characterized by a clinical trial of granulomatous dermatitis, arthritis, and uveitis. Tofacitinib is a pan Janus kinase (JAK) inhibitor used for treatment of Blau syndrome and idiopathic sarcoidosis. Here, we evaluated its effect on inflammatory pathways associated with Blau syndrome. The effect of tofacitinib on downstream pathways regulated by mutant NOD2 was analyzed using luciferase assays with overexpression of NOD2 mutants. Methods: The effect of tofacitinib on the upstream pathway for the induction of NOD2 expression and proinflammatory cytokine production was assessed using monocytic cell lines differentiated from Blau syndrome patient-derived induced pluripotent stem cells. Results: Tofacitinib did not suppress the increased spontaneous transcriptional activity of NF-κB by mutant NOD2. In addition, mutant NOD2 was not involved in the transcription of ISRE and GAS, which are activated by type 1 and type 2 interferons (IFN), respectively. On the other hand, IFNγ induced the expression of NOD2, which led to the production of inflammatory cytokines by an autoinflammatory mechanism only in cells with mutant NOD2. Discussion: Tofacitinib suppressed the induction of NOD2 by IFNγ, thereby inhibiting the production of pro-inflammatory cytokines. Thus, tofacitinib showed anti-inflammatory effects through suppression of NOD2 expression. The JAK inhibitor tofacitinib is a potential therapeutic agent for Blau syndrome because it suppresses the autoinflammation seen in Blau syndrome by inhibiting the expression of NOD2.

Human RELA dominant-negative mutations underlie type I interferonopathy with autoinflammation and autoimmunity.

Inborn errors of the NF-κB pathways underlie various clinical phenotypes in humans. Heterozygous germline loss-of-expression and loss-of-function mutations in RELA underlie RELA haploinsufficiency, which results in TNF-dependent chronic mucocutaneous ulceration and autoimmune hematological disorders. We here report six patients from five families with additional autoinflammatory and autoimmune manifestations. These patients are heterozygous for RELA mutations, all of which are in the 3' segment of the gene and create a premature stop codon. Truncated and loss-of-function RelA proteins are expressed in the patients' cells and exert a dominant-negative effect. Enhanced expression of TLR7 and MYD88 mRNA in plasmacytoid dendritic cells (pDCs) and non-pDC myeloid cells results in enhanced TLR7-driven secretion of type I/III interferons (IFNs) and interferon-stimulated gene expression in patient-derived leukocytes. Dominant-negative mutations in RELA thus underlie a novel form of type I interferonopathy with systemic autoinflammatory and autoimmune manifestations due to excessive IFN production, probably triggered by otherwise non-pathogenic TLR ligands.

Similarities and differences in autoinflammatory diseases with urticarial rash, cryopyrin-associated periodic syndrome and Schnitzler syndrome.

Cryopyrin-associated periodic syndromes (CAPS) and Schnitzler syndrome (SchS) are autoinflammatory diseases that present with urticaria-like rashes. CAPS is characterized by periodic or persistent systemic inflammation caused by the dysfunction of the NLRP3 gene. With the advent of IL-1-targeted therapies, the prognosis of CAPS has improved remarkably. SchS is considered an acquired form of autoinflammatory syndrome. Patients with SchS are adults of relatively older age. The pathogenesis of SchS remains unknown and is not associated with the NLRP3 gene. Previously, the p.L265P mutation in the MYD88 gene, which is frequently detected in Waldenström macroglobulinemia (WM) with IgM gammopathy, was identified in several cases of SchS. However, because persistent fever and fatigue are symptoms of WM that require therapeutic intervention, it is a challenge to determine whether these patients truly had SchS or whether advanced WM was misidentified as SchS. There are no established treatments for SchS. The treatment algorithm proposed with the diagnostic criteria is to use colchicine as first-line treatment, and systemic administration of steroids is not recommended due to concerns about side effects. In difficult-to-treat cases, treatment targeting IL-1 is recommended. If targeted IL-1 treatment does not improve symptoms, the diagnosis should be reconsidered. We hope that the efficacy of IL-1 therapy in clinical practice will serve as a stepping stone to elucidate the pathogenesis of SchS, focusing on its similarities and differences from CAPS.

Summary of the current status of clinically diagnosed cases of Schnitzler syndrome in Japan.

BACKGROUND: Schnitzler syndrome is a rare disorder with chronic urticaria, and there is no report summarizing the current status in Japan. METHODS: A nationwide survey of major dermatology departments in Japan was conducted in 2019. We further performed a systematic search of PubMed and Ichushi-Web, using the keywords "Schnitzler syndrome" and "Japan" then contacted the corresponding authors or physicians for further information. RESULTS: Excluding duplicates, a total of 36 clinically diagnosed cases were identified from 1994 through the spring of 2022, with a male to female ratio of 1:1. The median age of onset was 56.5 years. It took 3.3 years from the first symptom, mostly urticaria, to reach the final diagnosis. The current status of 30 cases was ascertained; two patients developed B-cell lymphoma. SchS treatment was generally effective with high doses of corticosteroids, but symptoms sometimes recurred after tapering. Colchicine was administered in 17 cases and was effective in 8, but showed no effect in the others. Tocilizumab, used in six cases, improved laboratory abnormalities and symptoms, but lost its efficacy after several years. Rituximab, used in five cases, was effective in reducing serum IgM levels or lymphoma mass, but not in inflammatory symptoms. Four cases were treated with IL-1 targeting therapy, either anakinra or canakinumab, and achieved complete remission, except one case with diffuse large B-cell lymphoma. CONCLUSIONS: Since Schnitzler syndrome is a rare disease, the continuous collection and long-term follow-up of clinical information is essential for its appropriate treatment and further understanding of its pathophysiology.

Incomplete penetrance of NOD2 C483W mutation underlining Blau syndrome.

BACKGROUND: Blau syndrome (BS) is a rare autoinflammatory disorder with NOD2 gain-of-function mutation and characterized by autoactivation of the NFκB pathway. Classically considered a disease of high penetrance, reports on NOD2 mutations underlining BS with incomplete penetrance is limited. CASE PRESENTATION: The proband is a 9-year-old girl presented with brownish annular infiltrative plaques and symmetric boggy polyarthritis over bilateral wrists and ankles. Her skin biopsy revealed noncaseating granulomas inflammation with multinucleated giant cells. A novel C483W NOD2 mutation was identify in the proband and her asymptomatic father. Functional examinations including autoactivation of the NFκB pathway demonstrated by in vitro HEK293T NOD2 overexpression test as well as intracellular staining of phosphorylated-NFκB in patient's CD11b+ cells were consistent with BS. CONCLUSIONS: We reported a novel C483W NOD2 mutation underlining BS with incomplete penetrance. Moreover, a phosphorylated-NFκB intracellular staining assay of CD11b+ was proposed to assist functional evaluation of NFκB autoactivation in patient with BS.

Potential Benefits of TNF Targeting Therapy in Blau Syndrome, a NOD2-Associated Systemic Autoinflammatory Granulomatosis.

Blau syndrome is a systemic autoinflammatory granulomatous disease caused by mutations in the nucleotide-binding oligomerization domain 2 (NOD2) gene. NOD2 is an intracellular pathogen recognition receptor. Upon binding to muramyl dipeptide (MDP), NOD2 activates the NF-κB pathway, leading to the upregulation of proinflammatory cytokines. Clinical manifestations of Blau syndrome appear in patients before the age of four. Skin manifestations resolve spontaneously in some cases; however, joint and eye manifestations are progressive, and lead to serious complications, such as joint contracture and blindness. Currently, there is no specific curative treatment for the disease. Administration of high-dose oral steroids can improve clinical manifestations; however, treatments is difficult to maintain due to the severity of the side effects, especially in children. While several new therapies have been reported, including JAK inhibitors, anti-IL-6 and anti-IL-1 therapies, anti-TNF therapy plays a central role in the treatment of Blau syndrome. We recently performed an ex vivo study, using peripheral blood and induced pluripotent stem cells from patients. This study demonstrated that abnormal cytokine expression in macrophages from untreated patients requires IFNγ stimulation, and that anti-TNF treatment corrects the abnormalities associated with Blau syndrome, even in the presence of IFNγ. Therefore, although the molecular mechanisms by which the genetic mutations in NOD2 lead to granuloma formation remain unclear, it is possible that prior exposure to TNFα combined with IFNγ stimulation may provide the impetus for the clinical manifestations of Blau syndrome.

Anti-TNF treatment corrects IFN-γ-dependent proinflammatory signatures in Blau syndrome patient-derived macrophages.

BACKGROUND: Blau syndrome (BS) is an autoinflammatory disease associated with mutations in nucleotide-binding oligomerization domain 2. Although treatments with anti-TNF agents have been reported to be effective, the underlying molecular mechanisms remain unclear. OBJECTIVE: We aimed to elucidate the mechanisms of autoinflammation in patients with BS and to clarify how anti-TNF treatment controls the disease phenotype at the cellular level in clinical samples. METHODS: Macrophages were differentiated from monocytes of 7 BS patients, and global transcriptional profiles of 5 patients were analyzed with or without IFN-γ stimulation. Macrophages were also generated from BS-specific induced pluripotent stem cells (iPSCs), and their transcriptome was examined for comparison. RESULTS: Aberrant inflammatory responses were observed upon IFN-γ stimulation in macrophages from untreated BS patients, but not in those from patients treated with anti-TNF. iPSC-derived macrophages carrying a disease-associated mutation also showed IFN-γ-dependent accelerated inflammatory responses. Comparisons of peripheral blood- and iPSC-derived macrophages revealed the upregulation of nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) targets in unstimulated macrophages as a common feature. CONCLUSIONS: IFN-γ stimulation is one of the key signals driving aberrant inflammatory responses in BS-associated macrophages. However, long-term treatment with anti-TNF agents ameliorates such abnormalities even in the presence of IFN-γ stimulation. Our data thus suggest that preexposure to TNF or functionally similar cytokines inducing NF-κB-driven proinflammatory signaling during macrophage development is a prerequisite for accelerated inflammatory responses upon IFN-γ stimulation in BS.

Refractory serum immunoglobulin M elevation during anti-interleukin (IL)-1- or IL-6-targeted treatment in four patients with Schnitzler syndrome.

Schnitzler syndrome is characterized by chronic urticarial rash, neutrophilic dermal infiltrate, recurrent fever, bone pain, elevated C-reactive protein, and neutrophilic leukocytosis. The pathophysiology of Schnitzler syndrome is unknown, but it is considered to be an acquired form of an autoinflammatory disease because of the resemblance to clinical phenotypes of cryopyrin-associated periodic syndrome, in which a gain-of-function mutation in NLRP3 causes overexpression of interleukin (IL)-1ß. Schnitzler syndrome is generally accompanied by a monoclonal immunoglobulin (Ig)M gammopathy with a long-term risk of lymphoproliferation that is possibly associated with an MYD88 mutation. Herein, we present the following four patients with Schnitzler syndrome: a 63-year-old woman; a 65-year-old man; a 43-year-old woman; and a 63-year-old woman. Each patient fulfilled the Strasbourg diagnostic criteria, but none of the patients had any mutation in NLRP3 or MYD88 detected in their peripheral blood. Although approved treatment options for Schnitzler syndrome are lacking, our patients were treated with IL-1-targeted therapy (anakinra or canakinumab) or anti-IL-6 (tocilizumab). The acute inflammatory clinical manifestations improved completely with canakinumab and partially with anakinra and tocilizumab, but the serum IgM levels were gradually increased in all patients, even during treatment. To determine whether treatment with anti-IL-1ß or IL-6 prevents conversion to a hematopoietic disorder, further collection of cases and long-term follow-up will be needed.

Sustained Surface ICAM-1 Expression and Transient PDGF-B Production by Phorbol Myristate Acetate-Activated THP-1 Cells Harboring Blau Syndrome-Associated NOD2 Mutations.

OBJECTIVES: Blau syndrome is a distinct class of autoinflammatory syndrome presenting with early-onset systemic granulomatosis. Blau syndrome-causing NOD2 mutations located in the central nucleotide-oligomerization domain induce ligand-independent basal NF-κB activation in an in vitro reporter assay. However, the precise role of this signaling on granuloma formation has not yet been clarified. METHODS: Blau syndrome-causing NOD2 mutations were introduced into human monocytic THP-1 cells, and their morphological and molecular changes from parental cells were analyzed. Identified molecules with altered expression were examined in the patient's lesional skin by immunostaining. RESULTS: Although the production of proinflammatory cytokines was not altered without stimulation, mutant NOD2-expressing THP-1 cells attached persistently to the culture plate after stimulation with phorbol myristate acetate. Sustained surface ICAM-1 expression was observed in association with this phenomenon, but neither persistent ICAM-1 mRNA expression nor impaired ADAM17 mRNA expression was revealed. However, the transient induction of PDGF-B mRNA expression was specifically observed in stimulated THP-1 derivatives. In the granulomatous skin lesion of a Blau syndrome patient, ICAM-1 and PDGF-B were positively immunostained in NOD2-expressing giant cells. CONCLUSIONS: Sustained surface ICAM-1 expression and transient PDGF-B production by newly differentiating macrophages harboring mutant NOD2 might play a role in granuloma formation in Blau syndrome.

NOD2 Mutation-Associated Case with Blau Syndrome Triggered by BCG Vaccination.

We describe a patient who developed multiple granulomatous skin lesions after Bacille de Calmette et Guérin (BCG) vaccination without significant effect by topical corticosteroid, followed by painless cystic tumors on the bilateral knees and hands and inflammatory changes on ophthalmologic examination. A functional mutation in NOD2 was detected by a genetic analysis, and he was diagnosed as sporadic Blau syndrome. Since NOD2 acts as a sensor for the BCG component, it is possible that BCG vaccination may trigger granuloma formation in Blau syndrome patients with such genetic background.

Blau Syndrome: NOD2-related systemic autoinflammatory granulomatosis.

Blau Syndrome, or early-onset sarcoidosis, is hereditary juvenile-onset systemic granulomatosis. Clinical symptoms appear before the age of four years and mainly affect the skin, joints, and eyes. The symptoms are progressive and cause severe complications, such as joint destruction and blindness. Although tumor necrosis factor alpha (TNFα) antagonists are effective for controlling some of the symptoms of Blau Syndrome, there is no specific curative treatment. Heterozygous mutations in nucleotide-binding oligomerization domain 2 (NOD2) were identified as the cause of Blau Syndrome onset. NOD2 is an intracellular pathogen recognition receptor, the ligand of which is muramyl dipeptide (MDP) found in bacterial cell walls. Upon binding to MDP, NOD2 activates the NF-κB pathway, which leads to upregulation of proinflammatory cytokines. However, the detailed molecular mechanisms by which disease associated NOD2 mutations lead to autoinflammation and granuloma formation are still unclear. To clarify the relationship between disease associated NOD2 mutations and the inflammatory response, we established induced pluripotent stem (iPS) cells from Blau Syndrome patients. Functional analyses using these iPS cells suggested that IFNγ is a critical mediator of the inflammatory manifestations in this disease. This experimental finding is supported by the clinical observation that bacillus Calmette-Guesrin (BCG) vaccination is sometimes associated with disease onset, since IFNγ is a major cytokine associated with BCG-mediated immune responses. Further investigation of NOD2 signaling and accumulation of clinical cases are essential to elucidate the mechanisms of Blau Syndrome and develop an effective treatment for patients.

Clinical characteristics and treatment of 50 cases of Blau syndrome in Japan confirmed by genetic analysis of the NOD2 mutation.

OBJECTIVES: To collect clinical information and NOD2 mutation data on patients with Blau syndrome and to evaluate their prognosis. METHODS: Fifty patients with NOD2 mutations were analysed. The activity of each NOD2 mutant was evaluated in HEK293 cells by reporter assay. Clinical information was collected from medical records through the attending physicians. RESULTS: The study population comprised 26 males and 24 females aged 0-61 years. Thirty-two cases were sporadic, and 18 were familial from 9 unrelated families. Fifteen different mutations in NOD2 were identified, including 2 novel mutations (p.W490S and D512V); all showed spontaneous nuclear factor kappa B activation, and the most common mutation was p.R334W. Twenty-six patients had fever at relatively early timepoints in the disease course. Forty-three of 47 patients had a skin rash. The onset of disease in 9 patients was recognised after BCG vaccination. Forty-five of 49 patients had joint lesions. Thirty-eight of 50 patients had ocular symptoms, 7 of which resulted in blindness. After the diagnosis of Blau syndrome, 26 patients were treated with biologics; all were antitumour necrosis factor agents. Only 3 patients were treated with biologics alone; the others received a biologic in combination with methotrexate and/or prednisolone. None of the patients who became blind received biologic treatment. CONCLUSIONS: In patients with Blau syndrome, severe joint contractures and blindness may occur if diagnosis and appropriate treatment are delayed. Early treatment with a biologic agent may improve the prognosis.

Clinicopathological and molecular features of hereditary leiomyomatosis and renal cell cancer-associated renal cell carcinomas.

AIMS: Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant disorder caused by germline mutations in fumarate hydratase (FH). Affected families have an increased risk of renal cell carcinoma (RCC). HLRCC-associated RCC (HLRCC-RCC) is highly aggressive. Clinicopathological information of genetically diagnosed patients with HLRCC-RCC contributes to the establishment of effective therapies. METHODS: Ten Japanese patients with HLRCC-RCC were enrolled in the study. Genetic testing for FH was carried out. Somatic mutations in FH and immunohistochemical analyses of FH and B7 family ligands (PD-L1 and B7-H3) were investigated in 13 tumours. Copy number variations were evaluated in two tumours. RESULTS: All patients had FH germline mutations. Regarding histology, most tumours had type 2 papillary architecture or tubulocystic pattern or both. All tumours were FH deficient by immunohistochemistry. Ten tumours were positive for PD-L1, and 12 tumours were positive for B7-H3. Somatic mutation analysis demonstrated loss of heterozygosity of FH in 10 tumours. Copy number variation analysis revealed uniparental disomy between 1q24.2 and 1q44 encompassing FH; gain of chromosome 2 p was also common. All patients had either metastases or residual tumours. Three patients died of HLRCC-RCC and one of colon cancer, whereas the other six are currently alive, including two without recurrence. CONCLUSIONS: HLRCC-RCCs appear to have unique molecular profiles, including PD-L1 expression. One patient had complete response to immunotherapy, which may be an option for HLRCC-RCC.

Spectrum of Genetic Autoinflammatory Diseases Presenting with Cutaneous Symptoms.

Autoinflammatory diseases comprise a group of chronic disabling entities characterized by inflammation without the presence of infectious agents, auto-antibodies or antigen-specific T-cells. Many autoinflammatory diseases are caused by monogenic defects, which lead to disturbed immune signalling with release of proinflammatory mediators. In addition to interleukin-1ß and interleukin-18, interferons play a key role in the pathophysiology of these disorders. Patients with autoinflammatory diseases show a broad variety of clinical symptoms, including skin involvement. Wheals, pustules and ulcerative lesions are the most common cutaneous findings observed. Knowledge of the clinical presentation of autoinflammatory diseases is crucial for establishing the diagnosis and guiding appropriate treatment. This review focuses on the dermatological findings in selected autoinflammatory disorders based on their distinct pathomechanisms.