Autoimmunity against melanoma differentiation-associated gene 5 induces interstitial lung disease mimicking dermatomyositis in mice.

Anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (DM) is characterized by amyopathic DM with interstitial lung disease (ILD). Patients with anti-MDA5 antibody-associated ILD frequently develop rapidly progression and present high mortality rate in the acute phase. Here, we established a murine model of ILD mediated by autoimmunity against MDA5. Mice immunized with recombinant murine MDA5 whole protein, accompanied with complete Freund's adjuvant once a week for four times, developed MDA5-reactive T cells and anti-MDA5 antibodies. After acute lung injury induced by intranasal administration of polyinosinic-polycytidylic acid [poly (I:C)] mimicking viral infection, the MDA5-immunized mice developed fibrotic ILD representing prolonged respiratory inflammation accompanied by fibrotic changes 2 wk after poly (I:C)-administration, while the control mice had quickly and completely recovered from the respiratory inflammation. Treatment with anti-CD4 depleting antibody, but not anti-CD8 depleting antibody, suppressed the severity of MDA5-induced fibrotic ILD. Upregulation of interleukin (IL)-6 mRNA, which was temporarily observed in poly (I:C)-treated mice, was prolonged in MDA5-immunized mice. Treatment with anti-IL-6 receptor antibody ameliorated the MDA5-induced fibrotic ILD. These results suggested that autoimmunity against MDA5 exacerbates toll-like receptor 3-mediated acute lung injury, and prolongs inflammation resulting in the development of fibrotic ILD. IL-6 may play a key role initiating ILD in this model.

Possible correlation between serum interleukin-8 levels and the activity of myositis in anti-NXP2 antibody-positive dermatomyositis.

Anti-nuclear matrix protein 2 (NXP2) antibody-positive dermatomyositis (DM) is characterized by extensive and severe myositis. In this study, we evaluated which cytokines/chemokines involved with the activity of the myositis. We performed quantitative immunoassays using the MILLIPLEX® Multiplex Assays Using Luminex to evaluate serum levels of interferon-γ, interleukin (IL)-1ß, IL-6, IL-8, IL-12p40, and tumor necrosis factor-α in samples collected over time from a 9-year-old female with anti-NXP2 antibody-positive DM. In our case, the serum level of IL-8 was elevated when the myositis worsened, and decreased in accordance with the improvement of myositis, suggesting that the serum IL-8 levels were correlated with the myositis activity. Serum levels of IL-8 in samples from five patients with anti-NXP2 antibody-positive DM and five patients with anti-transcriptional intermediary factor 1γ (TIF1γ) antibody-positive DM without both interstitial lung disease (ILD) and malignancy before starting treatments, along with five healthy controls, were also evaluate by an enzyme-linked immunosorbent assay. Serum IL-8 levels were significantly elevated in anti-NXP2 or anti-TIF1γ antibody-positive DM patients with myositis but not ILD, than healthy controls. It was suggested that serum levels of IL-8 correlate with the activity of myositis in DM including anti-NXP2 antibody-positive DM.

Activated Akt expression is associated with the recurrence of primary melanomas and further refines the prognostic and predictive values for relapse in acral melanomas.

A PTEN deficiency leads to the activation of phospho-Akt at serine 473 (p-Akt) and promotes the tumorigenesis of melanomas by coupling with NUAK2 amplification. We tested the prognostic impact of p-Akt and/or NUAK2 expression on the relapse-free survival (RFS) and overall survival (OS) of melanoma patients. Primary tumors from patients with acral melanomas (112), Low-cumulative sun damage (CSD) melanomas (38), and High-CSD melanomas (18) were examined using immunohistochemistry and their prognostic significance was analyzed statistically. The expression of p-Akt was found in 32.1%, 68.4%, and 55.6% of acral, Low-CSD, and High-CSD melanomas, while NUAK2 expression was found in 46.4%, 76.3%, and 50.0%, respectively. Either p-Akt or NUAK2 expression was inversely correlated with the RFS of primary melanoma patients and acral melanoma patients (p-Akt: p < .0001, p < .0001; NUAK2; p = .0005, p < .0001, respectively). Strikingly, multivariate analyses revealed that p-Akt had a significant impact on RFS (Hazard ratio = 4.454; p < .0001), while NUAK2 did not. Further subset analyses revealed that p-Akt expression had an inferior RFS of patients with acral melanomas (Hazard ratio = 4.036; p = .0005). We conclude that the expression of p-Akt has a significant impact on RFS of patients with primary melanomas and can predict the relapse of patients with acral melanomas.

A case of anti-SAE1/2 antibody-positive dermatomyositis with extensive panniculitis: A possible cutaneous manifestation of treatment resistance.

Dermatomyositis constitutes a heterogeneous group of autoimmune inflammatory conditions with a wide variety of clinical outcomes. The symptomatic heterogeneity carries skin, muscle, and joint manifestations; pulmonary and cardiac involvements; and concomitant malignancy. Any of these symptoms often appear at different combinations and time courses, thus posing difficulty in early diagnosis and appropriate treatment choice. Recent progress in laboratory investigations explored the identification of several myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies, allowing precise characterization for a clinical perspective of the disease. MSAs can be detectable in approximately 80% of patients with whole dermatomyositis, some of which closely reflect unique clinical features in the particular disease subset(s), including the distribution and severity of organ involvement, treatment response, and prognosis. However, only limited evidence has been available in dermatomyositis-associated panniculitis, mostly that in anti- melanoma differentiation-associated protein 5 antibody-positive disease. We present a rare case of a patients with dermatomyositis with extensive panniculitis on the trunk whose serum IgG autoantibodies reacted with both subunits of small ubiquitin-like modifier activating enzymes (SAEs), SAE1 and SAE2. The onset of panniculitis coincided with increased disease activity, including disease-related skin manifestations, fever, dysphagia, and muscle weakness in the extremities. These symptoms responded well to a high dose of systemic steroid, but even upon receiving a high-dose intravenous immunoglobulin, the panniculitic lesions and pruritic erythema flared with tapering of steroid dose, further requiring tacrolimus and mycophenolate mofetil to achieve disease remission. To our knowledge, this is the third reported case of anti-SAE autoantibody-positive dermatomyositis with panniculitis. We aim to extend the understanding of the current limitation and further perspective in the clinical management of the extremely rare skin manifestation associated with dermatomyositis.

A Case of Anti-NXP2 Antibody-positive Juvenile Dermatomyositis with Characteristic Fascial Thickening on Muscle Ultrasound and Improvement with Immunotherapy.

We herein report a 12-year-old boy who presented with a fever, erythematous rash on the cheeks, back pain, and dysphagia. Blood tests revealed increased creatine kinase levels, and muscle ultrasonography (MUS) revealed characteristic fascial thickening in the lumbar paraspinal muscles, where myalgia was prominent. Sarcoplasmic expression of myxovirus-resistant protein A on a muscle biopsy and the presence of anti-nuclear matrix protein 2 (NXP2) antibodies confirmed the diagnosis of dermatomyositis. Prednisolone and intravenous immunoglobulin therapy improved the clinical and laboratory parameters as well as fascial thickening. MUS is useful for evaluating fasciitis associated with anti-NXP2 autoantibodies and monitoring therapeutic efficacy.

Eribulin mesylate exerts antitumor effects via CD103.

Eribulin mesylate (ERB) is a synthetic analog of halichondrin B, inhibiting tumor cell growth by disrupting microtubule function. Recently, anticancer drugs have been shown to not only act directly on tumor cells but also to exert antitumor effects by modifying the tumor environment. Although ERB has also been speculated to modify the tumor microenvironment including the immune response to tumors, the precise mechanism remains unclear. In our study, ERB suppressed the tumor growth of MC38 colon cancer in wildtype mice, whereas ERB failed to inhibit the tumor growth in Rag1-deficient mice which lack both B and T cells. Moreover, depletion of either CD4+ or CD8+ T cells abrogated the antitumor effect of ERB, indicating that both CD4+ and CD8+ T cells play an important role in ERB-induced antitumor effects. Furthermore, ERB treatment increased the number of tumor infiltrating lymphocytes (TILs) as well as the expression of activation markers (CD38 and CD69), immune checkpoint molecules (LAG3, TIGIT and Tim3) and cytotoxic molecules (granzyme B and perforin) in TILs. ERB upregulated E-cadherin expression in MC38. CD103 is a ligand of E-cadherin and induces T-cell activation. ERB increased the proportion of CD103+ cells in both CD4+ and CD8+ TILs. The ERB-induced antitumor effect with the increased TIL number and the increased expression of activation markers, inhibitory checkpoint molecules and cytotoxic molecules in TILs was abrogated in CD103-deficient mice. Collectively, these results suggest that ERB exerts antitumor effects by upregulation of E-cadherin expression in tumor cells and subsequent activation of CD103+ TILs.

Muscle pathology of antisynthetase syndrome according to antibody subtypes.

Identification of antisynthetase syndrome (ASS) could be challenging due to inaccessibility and technical difficulty of the serology test for the less common non-Jo-1 antibodies. This study aimed to describe ASS antibody-specific myopathology and evaluate the diagnostic utility of myofiber HLA-DR expression. We reviewed 212 ASS muscle biopsies and compared myopathologic features among subtypes. Additionally, we compared their HLA-DR staining pattern with 602 non-ASS myositis and 140 genetically confirmed myopathies known to have an inflammatory component. We used t-test and Fisher's exact for comparisons and used sensitivity, specificity, positive and negative predictive values to assess the utility of HLA-DR expression for ASS diagnosis. RNAseq performed from a subset of myositis cases and histologically normal muscle biopsies was used to evaluate interferon (IFN)-signaling pathway-related genes. Anti-OJ ASS showed prominent myopathology with higher scores in muscle fiber (4.6 ± 2.0 vs. 2.8 ± 1.8, p = 0.001) and inflammatory domains (6.8 ± 3.2 vs. 4.5 ± 2.9, p  = 0.006) than non-OJ ASS. HLA-DR expression and IFN-γ-related genes upregulation were prominent in ASS and inclusion body myositis (IBM). When dermatomyositis and IBM were excluded, HLA-DR expression was 95.4% specific and 61.2% sensitive for ASS with a positive predictive value of 85.9% and a negative predictive value of 84.2%; perifascicular HLA-DR pattern is common in anti-Jo-1 ASS than non-Jo-1 ASS (63.1% vs. 5.1%, p < 0.0001). In the appropriate clinicopathological context, myofiber HLA-DR expression help support ASS diagnosis. The presence of HLA-DR expression suggests involvement of IFN-γ in the pathogenesis of ASS, though the detailed mechanisms have yet to be elucidated.

The potential value of thallium-201 scintigraphy in the diagnosis of squamous cell carcinoma arising from extensive pyoderma.

Squamous cell carcinoma (SCC) arises from a variety of premalignant conditions, including pyoderma. However, an accurate diagnosis of SCC is sometimes challenging due to indistinguishable inflammatory lesions. Here, we present a case of SCC arising from extensive pyoderma, which was successfully diagnosed by taking advantage of thallium-201 scintigraphy. A 49-year-old man presented with an elevated tumor on his right buttock. Computed tomography (CT) and enhanced magnetic resonance imaging (MRI) identified the tumor, but many indistinguishable lesions were also found around the tumor. Histopathology revealed an atypical proliferation of keratinocytes with cancer pearls inside the tumor nests, while histopathology of nodules around the tumor revealed inflammatory tissues. Positron emission tomography CT (PET/CT) revealed an accumulation of 2-deoxy-2-[18 F]-D-glucose at the axillae and inguinal nodes, and at subcutaneous tissues in addition to the tumor. From the CT, enhanced MRI, and PET/CT analyses it was impossible to differentiate many scattered subcutaneous nodules on the trunk from SCCs. However, thallium-201 scintigraphy identified only the tumor and found no accumulation in other nodules. This finding suggests that thallium-201 scintigraphy is useful for the diagnosis of SCC by excluding false-positive signals detected by other imaging technologies.

Hepatic veno-occlusive disease accompanied by thrombotic microangiopathy developed during treatment of juvenile dermatomyositis and macrophage activation syndrome: A case report.

Hepatic veno-occlusive disease (VOD) is a complication of haematopoietic stem cell transplantation. VOD is associated with the occurrence of thrombotic microangiopathy (TMA). In haematopoietic stem cell transplantation, VOD and TMA are endothelial syndromes resulting from endothelial cell activation and dysfunction. In rheumatic disease, while TMA is not rare, there are few reports of VOD. In idiopathic myositis, only one case with VOD and TMA complications has been reported, and there are no published cases in juvenile dermatomyositis (JDM). We report a case of JDM manifesting VOD and TMA complications during the treatment for myositis and macrophage activation syndrome (MAS). A 5-year-old boy diagnosed as anti-nuclear matrix protein 2 antibody-positive JDM was complicated by MAS. He received pulsed methylprednisolone, prednisolone, and tacrolimus, but JDM and MAS progressed. He was then treated with intravenous cyclophosphamide and cyclosporine A, with improvement in myositis symptoms and MAS. After initiation of cyclophosphamide and cyclosporine A, he developed haemolysis, painful hepatomegaly, liver damage, and ascites. He was diagnosed with VOD and TMA. Cyclophosphamide and cyclosporine A were discontinued, with recovery from VOD and TMA. The patient remained well on treatment with methotrexate, without any relapse of JDM and MAS to date. The presence of vasculopathy and hypercytokinaemia because of JDM and MAS exacerbated endothelial cell damage. In the present case, we suggest that the main cause of VOD was medication with CY and CsA, which had been used to treat acute exacerbation of MAS and JDM.

Relevance of leukaemia inhibitory factor to anti-melanoma differentiation-associated gene 5 antibody-positive interstitial lung disease.

OBJECTIVES: Anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive rapidly progressive interstitial lung disease (RP-ILD) is a life-threatening disease, the aetiology of which remains unclear. To detect potential diagnostic markers, a transcriptome analysis of the lung sample from a patient with anti-MDA5 antibody-positive RP-ILD was performed. METHODS: RNA sequencing analyses of an autopsy lung sample from a 74-year-old woman with anti-MDA5 antibody-positive RP-ILD was performed and compared with an age- and sex-matched normal lung sample. Genes with changes of gene expression ≥5-fold were considered differentially expressed genes and analysed by Metascape. The levels of leukaemia inhibitory factor (LIF) were measured in the serum samples from 12 cases of anti-MDA5 antibody-positive ILD, 12 cases of anti-aminoacyl tRNA synthetase (ARS) antibody-positive ILD, 10 cases of anti-transcription intermediary factor 1γ/anti-Mi-2 antibody DM and 12 healthy volunteers. RESULTS: Gene ontology enrichment analysis on the RNA sequencing data showed a strong association with antigen binding. Upregulated expressions of IL-1ß, IL-6 and LIF were also detected. Serum LIF levels were significantly elevated in anti-MDA5 antibody-positive ILD patients {median 32.4 pg/ml [interquartile range (IQR) 13.2-125.7]} when compared with anti-ARS antibody-positive ILD patients [4.9 pg/ml (IQR 3.1-19.7), P < 0.05] and DM patients [5.3 pg/ml (IQR 3.9-9.7), P < 0.05]. CONCLUSION: Our present study suggested that upregulation of LIF might be a new potential disease marker specific for anti-MDA5 antibody-positive ILD.

A Continuous Increase in CXC-Motif Chemokine Ligand 10 in a Case of Anti-Nuclear Matrix Protein-2-Positive Juvenile Dermatomyositis.

Anti-nuclear matrix protein-2 (NXP2) antibody is associated with the severe, chronic myositis phenotype in juvenile dermatomyositis (JDM). Although hyperproduction of type I interferon is considered to play an important role in JDM, sequential changes in biomarkers associated with this pathophysiology have not yet been described in detail. An 8-year-old boy who presented with muscle weakness, heliotrope rash, and Gottron's papules was diagnosed with JDM. With regard to myositis-specific autoantibodies, anti-NXP2 was detected. Although the increase of serum myogenic enzymes was modest at onset, two courses of methyl-prednisolone (mPSL) pulse therapy followed by oral prednisolone and methotrexate were insufficient to initiate remission. Therefore, additional treatment, with intravenous cyclophosphamide (IVCY) and intravenous immunoglobulin (IVIG) was required to obtain a favorable outcome. We also retrospectively evaluated serum concentration of several cytokines: interleukin (IL)-6, soluble tumor necrotizing factor receptor (sTNFR)-1, sTNFR-2, IL-18, and CXC-motif chemokine ligand (CXCL)-10. The cytokine profile of this patient at onset showed a CXCL-10-dominant pattern. Additionally, sequential evaluation of CXCL-10 revealed an aberrantly high level of CXCL-10 persistent despite two courses of mPSL pulse therapy, and the level of this cytokine only gradually decreased after initiation of IVCY and IVIG. The hyperproduction of CXCL-10, presumably reflecting the hyperproduction of type I interferon in the affected tissue, may persist for a certain period, even after the initiation of multiple courses of mPSL pulse therapy. With regard to the fact that anti-NXP2 is associated with subcutaneous calcification, our data suggest the importance of aggressive intervention in cases of anti-NXP2-positive JDM as well as the need for the development of a more pathophysiologically specific treatment.

Immune-related adverse events in various organs caused by immune checkpoint inhibitors.

Current cancer immunotherapies target immune checkpoint molecules such as the inhibitory receptor programmed cell death-1 (PD-1), one of its ligands, programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4), a competitive ligand for CD28 binding to stimulatory receptors CD80 and CD86. Multiple biological drugs use monoclonal antibodies targeting PD-1, PD-L1 and CTLA-4 as cancer immunotherapies. These are termed immune checkpoint inhibitors (ICIs). However, activation of the immune system by ICIs can induce the development of immune-related adverse events (irAEs), which can affect multiple organ systems. The most frequent irAEs are cutaneous and mimic various types of spontaneous skin disorders. Most irAEs are classified as autoimmune conditions mediated by ICI-activated CD8+ cytotoxic T cells, some of which are also related to activated B cells and production of pathogenic antibodies. Interestingly, blockade of CTLA-4 mainly induces activation of T cells and inhibition of Treg cells. On the other hand, the mechanisms underlying anti-PD-1/PD-L1 ICI-induced irAEs are more complicated. PD-1 is a receptor expressed on T and B cells, which binds not only PD-L1, but also PD-L2. The role of PD-L1 is dominant in Th1 and Th17 immunity, while PD-L2 works mainly in Th2 immunity. Better understanding of the mechanisms underlying irAEs will allow for better management of irAEs and improve outcomes and quality of life in cancer patients.

Differential Involvement of Programmed Cell Death Ligands in Skin Immune Responses.

PD-1 is an immunoregulatory receptor that can bind PD-L1 or PD-L2 expressed on stimulated antigen-presenting cells. In this study, isolated antigen-presenting cells (macrophages and dendritic cells) were cultured with IFN-γ, IL-4, or IL-17A, and the expression of PD-L1 and PD-L2 was compared by flow cytometry. Strong upregulation of PD-L1 expression was observed on IFN-γ stimulation of both antigen-presenting cells as well as in response to IL-17A stimulation of macrophages compared with the expression in unstimulated controls. In contrast, only stimulation with IL-4 could upregulate PD-L2 expression on both antigen-presenting cells. Therefore, experiments were performed in murine models, including DNFB-induced contact hypersensitivity, calcipotriol-induced atopic dermatitis-like skin inflammation, and imiquimod-induced psoriasis-like dermatitis models, to trigger IFN-γ‒mediated T helper type (Th)1-, IL-4‒mediated Th2-, and IL-17A‒mediated Th17-type responses, respectively. In both Th1- and Th17-type immunity models, changes in ear thickness were more severe in Pd-l1‒deficient mice than in wild-type or Pd-l2‒deficient mice. In the Th2-type immunity model, changes in thickness in Pd-l2‒deficient mice were more severe than that in wild-type or Pd-l1‒deficient mice. Collectively, PD-L1 has predominant roles in Th1 and Th17 type immunity, whereas PD-L2 is involved in Th2-type immunity.

Anti-nuclear matrix protein 2 antibody-positive inflammatory myopathies represent extensive myositis without dermatomyositis-specific rash.

OBJECTIVES: Myositis-specific autoantibodies (MSAs) define distinct clinical subsets of idiopathic inflammatory myopathies (IIMs). The anti-nuclear matrix protein 2 (NXP2) antibody, a MSA detected in juvenile/adult IIMs, has been reported to be associated with a high risk of subcutaneous calcinosis, subcutaneous oedema and internal malignancies. The study aimed to clarify the clinical features of anti-NXP2 antibody-positive IIMs in detail. METHODS: This was a multicentre retrospective observational study on 76 anti-NXP2 antibody-positive patients. The antibody was detected via a serological assay using immunoprecipitation and western blotting. The patients were selected from 162 consecutive Japanese patients with IIMs. RESULTS: The cohort of anti-NXP2 antibody-positive IIMs included 29 juvenile patients and 47 adult patients. Twenty-seven (35.5%) patients presented with polymyositis phenotype without dermatomyositis-specific skin manifestations (heliotrope rash or Gottron sign/papules); this was more common in the adults than children (48.9% vs 15.8%, P < 0.01). Nine (11.8%) patients had subcutaneous calcinosis, and 20 (26.3%) patients had subcutaneous oedema. In addition, the proportion of patients with muscle weakness extending to the distal limbs was high (36 patients [47.4%]) in this cohort. Adult patients had a higher prevalence of malignancy than the general population (age-standardized incidence ratio of malignancies: 22.4). CONCLUSION: Anti-NXP2 antibody-positive IIMs, which include dermatomyositis sine dermatitis, are characterized by atypical skin manifestations and extensive muscular involvement.

Dermatomyositis: Muscle Pathology According to Antibody Subtypes.

BACKGROUND AND OBJECTIVES: Discoveries of dermatomyositis-specific antibodies (DMSAs) in patients with dermatomyositis raised awareness of various myopathologic features among antibody subtypes. However, only perifascicular atrophy and perifascicular myxovirus resistant protein A (MxA) overexpression were officially included as definitive pathologic criteria for dermatomyositis classification. We aimed to demonstrate myopathologic features in MxA-positive dermatomyositis to determine characteristic myopathologic features in different DMSA subtypes. METHODS: We performed a retrospective pathology review of muscle biopsies of patients with dermatomyositis diagnosed between January 2009 and December 2020 in a tertiary laboratory for muscle diseases. We included all muscle biopsies with sarcoplasmic expression for MxA and seropositivity for DMSAs. MxA-positive muscle biopsies that tested negative for all DMSAs were included as seronegative dermatomyositis. We evaluated histologic features stratified according to 4 pathology domains (muscle fiber, inflammatory, vascular, and connective tissue) and histologic features of interest by histochemistry, enzyme histochemistry, and immunohistochemical study commonly used in the diagnosis of inflammatory myopathy. We performed ultrastructural studies of 54 available specimens. RESULTS: A total of 256 patients were included. Of these, 249 patients were positive for 1 of the 5 DMSAs (seropositive patients: 87 anti-transcription intermediary factor 1-γ [TIF1-γ], 40 anti-complex nucleosome remodeling histone deacetylase [Mi-2], 29 anti-melanoma differentiation gene 5 [MDA5], 83 anti-nuclear matrix protein 2 [NXP-2], and 10 anti-small ubiquitin-like modifier-activating enzyme [SAE] dermatomyositis) and 7 patients were negative for all 5 DMSAs (seronegative patients). Characteristic myopathologic features in each DMSA subtype were as follows: anti-TIF1-γ with vacuolated/punched out fibers (64.7%; p < 0.001) and perifascicular enhancement in HLA-ABC stain (75.9%; p < 0.001); anti-Mi-2 with prominent muscle fiber damage (score 4.9 ± 2.1; p < 0.001), inflammatory cell infiltration (score 8.0 ± 3.0; p = 0.002), perifascicular atrophy (67.5%; p = 0.02), perifascicular necrosis (52.5%; p < 0.001), increased perimysial alkaline phosphatase activity (70.0%; p < 0.001), central necrotic peripheral regenerating fibers (45.0%; p = 0.002), and sarcolemmal membrane attack complex deposition (67.5%; p < 0.001); anti-MDA5 with scattered/diffuse staining pattern of MxA (65.5%; p < 0.001) with less muscle pathology and inflammatory features; anti-NXP-2 with microinfarction (26.5%; p < 0.001); and anti-SAE and seronegative dermatomyositis with HLA-DR expression (50.0%; p = 0.02 and 57.1%; p = 0.02, respectively). DISCUSSION: We describe a comprehensive serologic-pathologic correlation of dermatomyositis primarily using MxA expression as an inclusion criterion. In our study, DMSAs were associated with distinctive myopathologic features suggesting different underlying pathobiologic mechanisms in each subtype.

Combination Treatment of Topical Imiquimod Plus Anti-PD-1 Antibody Exerts Significantly Potent Antitumor Effect.

The exact mechanisms of the imiquimod (IMQ)-induced antitumor effect have not been fully understood. Although both topical IMQ treatment and anti-PD-1 antibody may be used for primary skin lesions or skin metastases of various cancers, the efficacy of each monotherapy for these lesions is insufficient. Using a murine tumor model and human samples, we aimed to elucidate the detailed mechanisms of the IMQ-induced antitumor effect and analyzed the antitumor effect of combination therapy of topical IMQ plus anti-PD-1 antibody. Topical IMQ significantly suppressed the tumor growth of MC38 in wildtype mice. IMQ upregulated interferon γ (IFN-γ) expression in CD8+ T cells in both the lymph nodes and the tumor, and the antitumor effect was abolished in both Rag1-deficient mice and IFN-γ-deficient mice, indicating that IFN-γ produced by CD8+ T cells play a crucial role in the IMQ-induced antitumor effect. IMQ also upregulated PD-1 expression in T cells as well as PD-L1/PD-L2 expression in myeloid cells, suggesting that IMQ induces not only T-cell activation but also T-cell exhaustion by enhanced PD-1 inhibitory signaling. Combination therapy of topical IMQ plus anti-PD-1 antibody exerted a significantly potent antitumor effect when compared with each single therapy, indicating that the combination therapy is a promising therapy for the skin lesions of various cancers.