A relapse of pemphigus vulgaris in pemphigus herpetiformis or a phenotypic “switch”

Sir, Pemphigus herpetiformis (PH) was originally described by Jablonska et al. in 1975. Clinically, PH presents itself as a herpetiform dermatitis with immunopathological characteristics of pemphigus [1,2]. We report an exceptional case of typical pemphigus vulgaris (PV) relapsing after 36 years in PH. A 65-year-old patient, followed for PV for 36 years and treated with corticosteroid therapy with a remission for more than thirty years, consulted for pruriginous lesions evolving for the previous eight months. A dermatological examination revealed urticariform pruriginous ring lesions surmounted by small peripheral vesicles spread throughout the body (Fig. 1), sparing the mucous membranes, and without Nikolsky’s sign. After two non-specific skin biopsies, the histological examination revealed an intraepidermal bubble with acantholytic cells and eosinophilic spongiosis (Figs. 2a and 2b). Direct immunofluorescence confirmed the diagnosis of pemphigus and indirect immunofluorescence was at the upper limit. The diagnosis of a PV relapse in PH was retained and a dapsone-based treatment was initiated at a dose of 150 mg/day and stopped seven days later when met with hemolytic anemia. Oral corticosteroid therapy involving prednisone at a dose of 1 mg/kg/day was initiated but, given the persistence of the pruritus, the decision was to combine methotrexate at a dose of 12.5 mg/week. A good evolution and a decline within eight months were observed. An improved pruritus and the disappearance of the skin lesions were achieved after one month of treatment. PV and PH are two different anatomical and clinical entities of the autoimmune disease pemphigus, with distinct clinical, histopathological, and immunopathological characteristics [1,2]. Our observation documents a complete phenotypic “switch” of pemphigus with a transition from PV to PH both clinically, histologically, and immunologically. Several rare cases of PV switching to superficial pemphigus (SP) (“phenotypic switch”) have, since 1991, been reported, with a higher frequency this direction than otherwise; the transition period varies from six months to twenty years [3]. To the best of our knowledge, no case has been described of a progression from PV to PH. Having observed one firsthand, we are first to describe the case of a complete phenotypic switch from PV to PH. The mechanism of such a transition remains poorly understood and is often observed during a relapse. Some authors suggest that the effect of immunosuppressants on the desmoglein DSG3 more marked than on DSG1 could explain the relapse of PS in PH [3,4]. Future studies on the immunological factors and predictors of PV relapses after the discontinuation of treatment would be useful to better understand the mechanisms of a relapse in pemphigus, with or without a phenotypic transition.

NLRP3 Inflammasome Activation Controls Vascular Smooth Muscle Cells Phenotypic Switch in Atherosclerosis

(1) Background: Monocytes and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome orchestrate lipid-driven amplification of vascular inflammation promoting the disruption of the fibrous cap. The components of the NLRP3 inflammasome are expressed in macrophages and foam cells within human carotid atherosclerotic plaques and VSMCs in hypertension. Whether monocytes and NLRP3 inflammasome activation are direct triggers of VSMC phenotypic switch and plaque disruption need to be investigated. (2) Methods: The direct effect of oxLDL-activated monocytes in VSMCs co-cultured system was demonstrated via flow cytometry, qPCR, ELISA, caspase 1, and pyroptosis assay. Aortic roots of VSMCs lineage tracing mice fed normal or high cholesterol diet and human atherosclerotic plaques were used for immunofluorescence quantification of NLRP3 inflammasome activation/VSMCs phenotypic switch. (3) Results: OxLDL-activated monocytes reduced α-SMA, SM22α, Oct-4, and upregulation of KLF-4 and macrophage markers MAC2, F4/80 and CD68 expression as well as caspase 1 activation, IL-1β secretion, and pyroptosis in VSMCs. Increased caspase 1 and IL-1β in phenotypically modified VSMCs was detected in the aortic roots of VSMCs lineage tracing mice fed high cholesterol diet and in human atherosclerotic plaques from carotid artery disease patients who experienced a stroke. (4) Conclusions: Taken together, these results provide evidence that monocyte promote VSMC phenotypic switch through VSMC NLRP3 inflammasome activation with a likely detrimental role in atherosclerotic plaque stability in human atherosclerosis.

Case Report: Phenotypic Switch in High-Grade B-Cell Lymphoma With MYC and BCL6 Rearrangements: A Potential Mechanism of Therapeutic Resistance in Lymphoma?

Lineage switch between myeloid and lymphoid in acute leukemia is well established as a mechanism for leukemic cells to escape chemotherapy. Cross-lineage transformation is also recognized in some solid tumors on targeted therapy, such as adenocarcinomas of the lung and prostate that transforms to neuroendocrine carcinoma on targeted therapy. Now lineage plasticity is increasingly recognized in mature lymphomas, such as small B-cell lymphomas transforming to histiocytic/dendritic cell sarcoma. However, there is no report of aggressive mature B-cell lymphoma switching from one histologic category to another upon targeted therapy. We report here a case of high-grade B-cell lymphoma with MYC and BCL6 rearrangements relapsing as a high-grade plasmablastic neoplasm with MYC and BCL6 rearrangements after R-CHOP and R-EPOCH therapy. Being aware of this rare scenario will help improve our understanding of the underlying mechanisms of therapeutic resistance and progression of lymphoma.

Recovery of Altered Diabetic Myofibroblast Heterogeneity and Gene Expression Associated with CD301b+ Macrophages

Diabetic wound healing is associated with impaired function and reduced numbers of myofibroblasts, a heterogeneous cell population with varying capacities to promote repair. To determine how diabetes alters myofibroblast composition, we performed flow cytometry and spatial tissue analysis of myofibroblast subsets throughout the healing process in diabetic (db/db) and control (db/+) mouse skin. We observed reduced numbers of profibrotic SCA1+; CD34+; CD26+ myofibroblasts in diabetic wounds five days after injury, with decreased expression of fibrosis-associated genes compared to myofibroblasts from db/+ mouse wounds. While the abundance of myofibroblasts remained reduced in db/db mouse wounds compared to controls, the altered myofibroblast heterogeneity and gene expression in diabetic mice was improved seven days after injury. The natural correction of myofibroblast composition and gene expression in db/db wound beds temporally corresponds with a macrophage phenotypic switch. Correlation analysis from individual wound beds revealed that wound healing in control mice is associated with CD206+ macrophages, while the rescued myofibroblast phenotypes in diabetic wounds are correlated with increased CD301b+ macrophage numbers. These data demonstrate how diabetes impacts specific subsets of myofibroblasts and indicate that signaling capable of rescuing impaired diabetic wound healing could be different from signals that regulate wound healing under nonpathological conditions.

Restoration of 5-methoxytryptophan protects against atherosclerotic chondrogenesis and calcification in ApoE−/− mice fed high fat diet

Background Toll-like receptor-2 (TLR2) promotes vascular smooth muscle cell (VSMC) transdifferentiation to chondrocytes and calcification in a p38 MAPK-dependent manner. Vascular 5-methoxytryptophan (5-MTP) is a newly identified factor with anti-inflammatory actions. As 5-MTP targets p38 MAPK for its actions, we postulated that 5-MTP protects against vascular chondrogenesis and calcification. Methods High-fat diet-induced advanced atherosclerosis in mice were performed to investigate the effect of 5-MTP on atherosclerotic lesions and calcification. VSMCs were used to determine the role of 5-MTP in VSMC chondrogenic differentiation and calcification. Alizarin red S and Alcian blue staining were used to measure VSMC calcification and chondrogenic differentiation, respectively. Results 5-MTP was detected in aortic tissues of ApoE−/− mice fed control chow. It was reduced in ApoE−/− mice fed high-fat diet (HFD), but was restored in ApoE−/−Tlr2−/− mice, suggesting that HFD reduces vascular 5-MTP production via TLR2. Intraperitoneal injection of 5-MTP or its analog into ApoE−/− mice fed HFD reduced aortic atherosclerotic lesions and calcification which was accompanied by reduction of chondrogenesis and calcium deposition. Pam3CSK4 (Pam3), ligand of TLR2, induced SMC phenotypic switch to chondrocytes. Pretreatment with 5-MTP preserved SMC contractile proteins and blocked Pam3-induced chondrocyte differentiation and calcification. 5-MTP inhibited HFD-induced p38 MAPK activation in vivo and Pam3-induced p38 MAPK activation in SMCs. 5-MTP suppressed HFD-induced CREB activation in aortic tissues and Pam3-induced CREB and NF-κB activation in SMCs. Conclusions These findings suggest that 5-MTP is a vascular arsenal against atherosclerosis and calcification by inhibiting TLR2–mediated SMC phenotypic switch to chondrocytes and the consequent calcification. 5-MTP exerts these effects by blocking p38 MAPK activation and inhibiting CREB and NF-κB transactivation activity.

NLRP3 Inflammasome Mediates Immune-Stromal Interactions in Vasculitis

Rationale: NLRP3 (NLR family pyrin domain containing 3) activation and IL-1β (interleukin-1β) production are implicated in Kawasaki disease (KD) pathogenesis; however, a detailed and complete characterization of the molecular networks and cellular subsets involved in the development of cardiovascular lesions is still lacking. Objective: Here, in a murine model of KD vasculitis, we used single-cell RNA sequencing and spatial transcriptomics to determine the cellular landscape of inflamed vascular tissues. Methods and Results: We observe infiltrations of innate and adaptive immune cells in murine KD cardiovascular lesions, associated with increased expression of Nlrp3 and Il1b . Monocytes, macrophages, and dendritic cells were the main sources of IL-1β, whereas fibroblasts and vascular smooth muscle cells (VSMCs) expressed high levels of IL-1 receptor. VSMCs type 1 surrounding the inflamed coronary artery undergo a phenotype switch to become VSMCs type 2, which are characterized by gene expression changes associated with decreased contraction and enhanced migration and proliferation. Genetic inhibition of IL-1β signaling on VSMCs efficiently attenuated the VSMCs type 2 phenotypic switch and the development of cardiovascular lesions during murine KD vasculitis. In addition, pharmacological inhibition of NLRP3 prevented the development of cardiovascular inflammation. Conclusions: Our studies unravel the cellular diversity involved in IL-1β production and signaling in murine KD cardiovascular lesions and provide the rationale for therapeutic strategies targeting NLRP3 to inhibit cardiovascular lesions associated with KD.