Digital immunohistological dissection of immune privilege collapse in syringotropic autoimmune diseases: Implication for the pathogenesis.

BACKGROUND: Syringotropic cell infiltration is a histological hallmark of some autoimmune diseases. However, its underlying mechanism remains unclear. OBJECTIVES: To assess the immune privilege (IP) of the human sweat gland (SwG) in homeostasis and in syringotropic autoimmune diseases. METHODS: We combined quantitative digital image microdissection with immunohistochemisty to analyze IP molecule expression in SwG of normal and diseased skin. The human skin organ culture model was used to examine the influence of proinflammatory conditions on IP in SwG. RESULTS: In the normal subjects (n = 10), major histocompatibility complex (MHC) class І expression was significantly reduced in SwGs compared to the epidermis. In contrast, IP-guardians, macrophage migration inhibitory factor (MIF) and alpha-melanocyte stimulating hormone (α-MSH) were upregulated in SwGs. MHC class І was upregulated in whole SwGs in lupus erythematosus (LE; n = 7) and scleroderma/morphea (Scl; n = 9), whereas differential expression was noted only in the secretory portion in Sjögren's syndrome (SjS) (n = 4). MIF expression level inversely correlated with that of MHC class I in all samples tested, and downregulation of α-MSH was detected in LE SwGs alone. The severity of inflammatory changes and MIF and ⍺-MSH expression were inversely correlated in LE. CD200 expression was decreased exclusively in atrophic stage of Scl. In a human skin organ culture model, intratissue injection of interferon-gamma up-regulated MHC class I and downregulated MIF and α-MSH. CONCLUSIONS: These findings indicate that SwGs enjoy IP. Dysregulated IP molecule expression may lead to SwG IP collapse and contribute to distinct inflammatory cell distribution in syringotropic autoimmune disorders.

Transcriptional Profiling Uncovers Human Hyalocytes as a Unique Innate Immune Cell Population.

Purpose: To decipher the transcriptional signature of macrophages of the human vitreous, also known as hyalocytes, and compare it to the profiles of other myeloid cell populations including human blood-derived monocytes, macrophages, and brain microglia. Methods: This study involves a total of 13 patients of advanced age with disorders of the vitreoretinal interface undergoing vitrectomy at the University Eye Hospital Freiburg between 2018 and 2019. Vitreal hyalocytes were analyzed by fluorescence-activated cell sorting (FACS) and isolated as CD45+CD11b+CX3CR1+Mat-Mac+ cells using a FACS-based sorting protocol. RNA extraction, library preparation and RNA sequencing were performed and the sequencing data was analyzed using the Galaxy web platform. The transcriptome of human hyalocytes was compared to the transcriptional profile of human blood-derived monocytes, macrophages and brain microglia obtained from public databases. Protein validation for selected factors was performed by immunohistochemistry on paraffin sections from three human donor eyes. Results: On average, 383 ± 233 hyalocytes were isolated per patient, resulting in 128 pg/µl ± 76 pg/µl total RNA per sample. RNA sequencing revealed that SPP1, FTL, CD74, and HLA-DRA are among the most abundantly expressed genes in hyalocytes, which was confirmed by immunofluorescence for CD74, FTL, and HLA-DRA. Gene ontology (GO) enrichment analysis showed that biological processes such as "humoral immune response," "leukocyte migration," and "antigen processing and presentation of peptide antigen" (adjusted p < 0.001) are dominating in vitreal hyalocytes. While the comparison of the gene expression profiles of hyalocytes and other myeloid cell populations showed an overall strong similarity (R2 > 0.637, p < 0.001), hyalocytes demonstrated significant differences with respect to common leukocyte-associated factors. In particular, transcripts involved in the immune privilege of the eye, such as POMC, CD46, and CD86, were significantly increased in hyalocytes compared to other myeloid cell subsets. Conclusion: Human hyalocytes represent a unique and distinct innate immune cell population specialized and adapted for the tissue-specific needs in the human vitreous. Vitreal hyalocytes are characterized by a strong expression of genes related to antigen processing and presentation as well as immune modulation. Thus, hyalocytes may represent an underestimated mediator in vitreoretinal disease and for the immune privilege of the eye.

MicroRNA-129-5p affects immune privilege and apoptosis of nucleus pulposus cells via regulating FADD in intervertebral disc degeneration.

Literatures indicate that microRNA-129-5p (miR-129-5p) or Fas-associated death domain (FADD) is related to intervertebral disc degeneration (IDD), but the effect of miR-129-5p/FADD axis on IDD is not studied. The study aimed to investigate whether miR-129-5p influenced immune privilege and nucleus pulposus (NP) cell apoptosis in rats with IDD via regulating FADD.A rat model with caudal IDD was established, and injected with miR-129-5p agomir or miR-129-5p antagomir to figure out the character of miR-129-5p in the cell apoptosis and inflammation in the nucleus pulposus (NP) tissues of IDD rats. NP cells were grouped as the same ways for determining proliferation, apoptosis, and senescence in NP cells of IDD rats. Annexin V-FITC/PI double staining detected the apoptosis of macrophages and CD8+ cells co-cultured via transfected NP cells. Expression of miR-129-5p, FADD, collagen I, collagen II, aggrecan and Sox-9 in NP tissues and cells were determined.Up-regulated miR-129-5p decreased FADD, collagen I and elevated collagen Ⅱ, aggrecan, and Sox-9 in NP tissues and repressed inflammation in serum and NP tissues in IDD rats. Up-regulated miR-129-5p facilitated proliferation, inhibited senescence, apoptosis, and decreased FADD, collagen I and increased collagen Ⅱ, aggrecan, and Sox-9 in NP cells of IDD rats. Elevated miR-129-5p promoted the apoptosis of macrophages and CD8+ cells.We pronounced that up-regulated miR-129-5p inhibited the apoptosis and facilitated the proliferation of NP cells, as well as the apoptosis of macrophages and CD8+ cells via decreased FADD in IDD, suggesting that miR-129-5p had a protective effect on IDD.

High frequency of inactivating tetraspanin C D37 mutations in diffuse large B-cell lymphoma at immune-privileged sites.

Tetraspanin CD37 is predominantly expressed on the cell surface of mature B lymphocytes and is currently being studied as novel therapeutic target for B-cell lymphoma. Recently, we demonstrated that loss of CD37 induces spontaneous B-cell lymphoma in Cd37-knockout mice and correlates with inferior survival in patients with diffuse large B-cell lymphoma (DLBCL). Here, CD37 mutation analysis was performed in a cohort of 137 primary DLBCL samples, including 44 primary immune-privileged site-associated DLBCL (IP-DLBCL) samples originating in the testis or central nervous system. CD37 mutations were exclusively identified in IP-DLBCL cases (10/44, 23%) but absent in non-IP-DLBCL cases. The aberrations included 10 missense mutations, 1 deletion, and 3 splice-site CD37 mutations. Modeling and functional analysis of CD37 missense mutations revealed loss of function by impaired CD37 protein expression at the plasma membrane of human lymphoma B cells. This study provides novel insight into the molecular pathogenesis of IP-DLBCL and indicates that anti-CD37 therapies will be more beneficial for DLBCL patients without CD37 mutations.

Immune privilege: failure of immunotherapy in controlling metastatic cutaneous melanoma to the eye.

This report concerns a 49-year-old female with cutaneous malignant melanoma and systemic metastases. These resolved following combination immunotherapy with ipilimumab and nivolumab. She subsequently experienced unilateral floaters, an increase in iris pigmentation and pigmentary glaucoma. The eye progressively lost vision and became painful due to iris neovascularization. The clinical diagnosis was of cutaneous melanoma metastatic to the vitreous, ciliary body and iris. Enucleation was performed for symptom control, with histopathology confirming the clinical diagnosis. The immune privilege of the eye may preclude ocular metastasis control with immunotherapy. Ocular symptoms in such patients merit referral to an ophthalmologist.