Homeostatic Control of Sebaceous Glands by Innate Lymphoid Cells Regulates Commensal Bacteria Equilibrium.

Immune cells and epithelium form sophisticated barrier systems in symbiotic relationships with microbiota. Evidence suggests that immune cells can sense microbes through intact barriers, but regulation of microbial commensalism remain largely unexplored. Here, we uncovered spatial compartmentalization of skin-resident innate lymphoid cells (ILCs) and modulation of sebaceous glands by a subset of RORγt+ ILCs residing within hair follicles in close proximity to sebaceous glands. Their persistence in skin required IL-7 and thymic stromal lymphopoietin, and localization was dependent on the chemokine receptor CCR6. ILC subsets expressed TNF receptor ligands, which limited sebocyte growth by repressing Notch signaling pathway. Consequently, loss of ILCs resulted in sebaceous hyperplasia with increased production of antimicrobial lipids and restricted commensalism of Gram-positive bacterial communities. Thus, epithelia-derived signals maintain skin-resident ILCs that regulate microbial commensalism through sebaceous gland-mediated tuning of the barrier surface, highlighting an immune-epithelia circuitry that facilitates host-microbe symbiosis.

Disruption of the endopeptidase ADAM10-Notch signaling axis leads to skin dysbiosis and innate lymphoid cell-mediated hair follicle destruction.

Hair follicles (HFs) function as hubs for stem cells, immune cells, and commensal microbes, which must be tightly regulated during homeostasis and transient inflammation. Here we found that transmembrane endopeptidase ADAM10 expression in upper HFs was crucial for regulating the skin microbiota and protecting HFs and their stem cell niche from inflammatory destruction. Ablation of the ADAM10-Notch signaling axis impaired the innate epithelial barrier and enabled Corynebacterium species to predominate the microbiome. Dysbiosis triggered group 2 innate lymphoid cell-mediated inflammation in an interleukin-7 (IL-7) receptor-, S1P receptor 1-, and CCR6-dependent manner, leading to pyroptotic cell death of HFs and irreversible alopecia. Double-stranded RNA-induced ablation models indicated that the ADAM10-Notch signaling axis bolsters epithelial innate immunity by promoting ß-defensin-6 expression downstream of type I interferon responses. Thus, ADAM10-Notch signaling axis-mediated regulation of host-microbial symbiosis crucially protects HFs from inflammatory destruction, which has implications for strategies to sustain tissue integrity during chronic inflammation.

Stress-induced production of chemokines by hair follicles regulates the trafficking of dendritic cells in skin.

Langerhans cells (LCs) are epidermal dendritic cells with incompletely understood origins that associate with hair follicles for unknown reasons. Here we show that in response to external stress, mouse hair follicles recruited Gr-1(hi) monocyte-derived precursors of LCs whose epidermal entry was dependent on the chemokine receptors CCR2 and CCR6, whereas the chemokine receptor CCR8 inhibited the recruitment of LCs. Distinct hair-follicle regions had differences in their expression of ligands for CCR2 and CCR6. The isthmus expressed the chemokine CCL2; the infundibulum expressed the chemokine CCL20; and keratinocytes in the bulge produced the chemokine CCL8, which is the ligand for CCR8. Thus, distinct hair-follicle keratinocyte subpopulations promoted or inhibited repopulation with LCs via differences in chemokine production, a feature also noted in humans. Pre-LCs failed to enter hairless skin in mice or humans, which establishes hair follicles as portals for LCs.

Dysbiosis and Staphylococcus aureus Colonization Drives Inflammation in Atopic Dermatitis.

Staphylococcus aureus skin colonization is universal in atopic dermatitis and common in cancer patients treated with epidermal growth factor receptor inhibitors. However, the causal relationship of dysbiosis and eczema has yet to be clarified. Herein, we demonstrate that Adam17(fl/fl)Sox9-(Cre) mice, generated to model ADAM17-deficiency in human, developed eczematous dermatitis with naturally occurring dysbiosis, similar to that observed in atopic dermatitis. Corynebacterium mastitidis, S. aureus, and Corynebacterium bovis sequentially emerged during the onset of eczematous dermatitis, and antibiotics specific for these bacterial species almost completely reversed dysbiosis and eliminated skin inflammation. Whereas S. aureus prominently drove eczema formation, C. bovis induced robust T helper 2 cell responses. Langerhans cells were required for eliciting immune responses against S. aureus inoculation. These results characterize differential contributions of dysbiotic flora during eczema formation, and highlight the microbiota-host immunity axis as a possible target for future therapeutics in eczematous dermatitis.

Preoperative Denosumab Therapy Against Giant Cell Tumor of Bone is Associated with an Increased Risk of Local Recurrence After Curettage Surgery.

INTRODUCTION: Denosumab has been shown to be highly effective at suppressing the progression of giant cell tumor of bone (GCTB). However, recent studies have observed a potential increased risk of local recurrence after surgery following the use of denosumab, raising concerns on the use of this agent against GCTB in combination with surgery. METHODS: We retrospectively reviewed the medical records of 234 patients with GCTB who were surgically treated at multiple institutions from 1990 to 2017. Patient background, tumor characteristics, treatment methods, local recurrence-free survival rate, distant metastasis rate, oncologic outcome, and limb function at final follow-up were analyzed and compared between cases treated with and without denosumab. RESULTS: The 3-year local recurrence-free survival rate was significantly lower in patients who underwent preoperative denosumab therapy (35.3%) compared with those treated without denosumab (79.9%) (P < 0.001). Among patients who were preoperatively treated with denosumab, those who had a local recurrence all underwent curettage surgery. CONCLUSIONS: Preoperative denosumab therapy in combination with curettage surgery was significantly associated with an increased risk of local recurrence in Campanacci grade 3 tumors. Our data suggest that clinicians seeing GCTB patients should be aware to this increased risk when planning preoperative denosumab therapy.

Risk assessment of femoral pathological fracture in prostate cancer patients by computed tomography analysis.

INTRODUCTION: Prostate cancer often forms osteoblastic lesions that appear as a high-dense shadow upon X-ray. Although the lesions may seem to increase bone strength, pathological fracture occurs in one in four patients with prostate cancer. The aim of this study is to elucidate the factors that may increase the risk of pathological fracture in patients with prostate cancer metastases in the proximal femur by analyzing computed tomography data. MATERIALS AND METHODS: Computed tomography data of the femur of 62 prostate cancer patients were retrospectively analyzed. The patients were divided into three groups based on the presence or absence of femoral metastatic lesions and pathological fracture. Surgical specimens of the proximal femur collected from patients who had a pathological fracture were histologically analyzed. RESULTS: Bone density in the marrow area was increased in all cases with metastases compared with those with no metastases. Contrarily, the cortical bone density at the medial trochanter region was significantly lower in patients who had pathological fractures in the proximal femur than those who did not. Accordingly, histological analysis of the surgical specimens revealed that the affected cortical bone was osteopenic without any apparent new bone formation. CONCLUSION: These results indicate that prostate cancer is less effective in inducing bone formation in the cortex than in the marrow and that the decrease in the cortical bone density at the medial trochanter region leads to an increased risk of pathological fracture. Therefore, a previously undocumented risk factor for pathological fracture in prostate cancer patients is presented.

Regulation of osteoarthritis development by ADAM17/Tace in articular cartilage.

INTRODUCTION: A disintegrin and metalloproteinase 17 (Adam17), also known as TNFα-converting enzyme (Tace), is a membrane-anchored protein involved in shedding of TNF, IL-6 receptor, ligands of epidermal growth factor receptor (EGFR), and Notch receptor. This study aimed to examine the role of Adam17 in adult articular cartilage and osteoarthritis (OA) pathophysiology. MATERIALS AND METHODS: Adam17 expression was examined in mouse knee joints during OA development. We analyzed OA development in tamoxifen-inducible chondrocyte-specific Adam17 knockout mice of a resection of the medial meniscus and medial collateral ligament (medial) model, destabilization of the medial meniscus (DMM) model, and aging model. We analyzed downstream pathways by in vitro experiments, and further performed intra-articular administration of an Adam17 inhibitor TAPI-0 for surgically induced mouse OA. RESULTS: Adam17 expression in mouse articular cartilage was increased by OA progression. In all models, Adam17 knockout mice showed ameliorated progression of articular cartilage degradation. Adam17 knockout decreased matrix metallopeptidase 13 (Mmp13) expression in both in vivo and in vitro experiments, whereas Adam17 activation by phorbol-12-myristate-13-acetate (PMA) increased Mmp13 and decreased aggrecan in mouse primary chondrocytes. Adam17 activation enhanced release of soluble TNF and transforming growth factor alpha, a representative EGF ligand, from mouse primary chondrocytes, while it did not change release of soluble IL-6 receptor or nuclear translocation of Notch1 intercellular domain. Intra-articular administration of the Adam17 inhibitor ameliorated OA progression. CONCLUSIONS: This study demonstrates regulation of OA development by Adam17, involvement of EGFR and TNF pathways, and the possibility of Adam17 as a therapeutic target for OA.

Cell-autonomous FLT3L shedding via ADAM10 mediates conventional dendritic cell development in mouse spleen.

Conventional dendritic cells (cDCs) derive from bone marrow (BM) precursors that undergo cascades of developmental programs to terminally differentiate in peripheral tissues. Pre-cDC1s and pre-cDC2s commit in the BM to each differentiate into CD8α+/CD103+ cDC1s and CD11b+ cDC2s, respectively. Although both cDCs rely on the cytokine FLT3L during development, mechanisms that ensure cDC accessibility to FLT3L have yet to be elucidated. Here, we generated mice that lacked a disintegrin and metalloproteinase (ADAM) 10 in DCs (Itgax-cre × Adam10-fl/fl; ADAM10∆DC) and found that ADAM10 deletion markedly impacted splenic cDC2 development. Pre-cDC2s accumulated in the spleen with transcriptomic alterations that reflected their inability to differentiate and exhibited abrupt failure to survive as terminally differentiated cDC2s. Induced ADAM10 ablation also led to the reduction of terminally differentiated cDC2s, and restoration of Notch signaling, a major pathway downstream of ADAM10, only modestly rescued them. ADAM10∆DC BM failed to generate cDC2s in BM chimeric mice with or without cotransferred ADAM10-sufficient BM, indicating that cDC2 development required cell-autonomous ADAM10. We determined cDC2s to be sources of soluble FLT3L, as supported by decreased serum FLT3L concentration and the retention of membrane-bound FLT3L on cDC2 surfaces in ADAM10∆DC mice, and by demonstrating the release of soluble FLT3L by cDC2 in ex vivo culture supernatants. Through in vitro studies utilizing murine embryonic fibroblasts, we determined FLT3L to be a substrate for ADAM10. These data collectively reveal cDC2s as FLT3L sources and highlight a cell-autonomous mechanism that may enhance FLT3L accessibility for cDC2 development and survival.

Angioleiomyoma of the extremities: correlation of magnetic resonance imaging with histopathological findings in 25 cases.

OBJECTIVE: To identify the characteristic magnetic resonance imaging (MRI) findings in angioleiomyoma and to clarify its relationship with histopathological findings. MATERIALS AND METHODS: We retrospectively analyzed the MRI findings and pathological subtypes in 25 patients with subcutaneous angioleiomyoma of the extremities. Based on the previous reports, MRI findings that could be characteristic of angioleiomyoma were extracted. According to the World Health Organization classification, all cases were classified into three pathological subtypes: solid, venous, and cavernous. The relationship between MRI findings and pathological subtypes was analyzed. RESULTS: The pathological subtypes were solid (n = 10), venous (n = 11), and cavernous (n = 4). The following MRI findings were observed: (a) hypo- or iso-intense linear and/or branching structures on a T2-weighted image (positive total/solid/venous/cavernous: 19/5/10/4, respectively), which we defined as "dark reticular sign"; (b) peripheral hypointense rim on a T2-weighted image (positive total/solid/venous/cavernous: 19/7/8/4, respectively); and (c) presence of any adjacent vascular structures (positive total/solid/venous/cavernous: 6/3/3/0, respectively). Chi-square test showed a significant relationship between dark reticular sign and pathological subtypes (p = 0.0426). The dark reticular sign was found more frequently in the venous and cavernous types than in the solid type. The other MRI findings did not reveal a significant relationship between pathological subtypes. CONCLUSION: We present the largest case series exploring MRI findings in angioleiomyoma. The dark reticular sign was a characteristic MRI finding of angioleiomyoma and was seen in most of the venous and cavernous types, which may facilitate preoperative diagnosis.

Aging Aggravates the Progression of Muscle Degeneration After Rotator Cuff Tears in Mice.

PURPOSE: The purpose of this study was to evaluate the impact of aging on muscle degeneration after rotator cuff tear (RCT) in mice. METHODS: Young (12-week-old) and aged (50-to-60-week-old) female C57BL/6 mice were used (n = 29 for each group). The rotator cuff was transected, and the proximal humerus was removed to induce degeneration of the rotator cuff muscles. The mice were euthanized 4 and 12 weeks after the procedure (referred to as RCT-4wk mice and RCT-12wk mice, respectively) and compared with the sham-treated mice. The supraspinatus muscles were collected for histology, Western blot analysis, and gene expression analyses. RESULTS: There was a significant increase in fat tissue in aged RCT-4wk mice (P = .001) and aged RCT-12wk mice (P < .001) compared with sham-treated aged mice, and aged RCT-12wk mice had a significantly increased fat area ratio compared with aged RCT-4wk mice (P < .001). The fat area was significantly larger in both the aged RCT-4wk (P = .002) and RCT-12wk mice (P < .001) than in the corresponding young mice. Muscular fibrosis was significantly increased in aged RCT-12wk mice compared with aged sham-treated mice (P = .005) and young RCT-12wk mice (P = .016). There were also significant increases in the expression of perilipin and transcripts of adipogenic and fibrogenic differentiation markers in aged RCT mice compared with young RCT mice. CONCLUSION: The present results show that aging is critically involved in the pathology of muscular fatty infiltration and fibrosis after RCT, and muscular degeneration progresses over time in aged mice. CLINICAL RELEVANCE: Aging promotes the progression of muscle degeneration in a mouse RCT model. Furthermore, this study shows that muscle degeneration occurs in aged mice even without denervation and that the model described in the present study is a useful tool for studying the pathology of muscle degeneration.