DNA hypomethylation silences anti-tumor immune genes in early prostate cancer and CTCs.

Cancer is characterized by hypomethylation-associated silencing of large chromatin domains, whose contribution to tumorigenesis is uncertain. Through high-resolution genome-wide single-cell DNA methylation sequencing, we identify 40 core domains that are uniformly hypomethylated from the earliest detectable stages of prostate malignancy through metastatic circulating tumor cells (CTCs). Nested among these repressive domains are smaller loci with preserved methylation that escape silencing and are enriched for cell proliferation genes. Transcriptionally silenced genes within the core hypomethylated domains are enriched for immune-related genes; prominent among these is a single gene cluster harboring all five CD1 genes that present lipid antigens to NKT cells and four IFI16-related interferon-inducible genes implicated in innate immunity. The re-expression of CD1 or IFI16 murine orthologs in immuno-competent mice abrogates tumorigenesis, accompanied by the activation of anti-tumor immunity. Thus, early epigenetic changes may shape tumorigenesis, targeting co-located genes within defined chromosomal loci. Hypomethylation domains are detectable in blood specimens enriched for CTCs.

CD1a and bound lipids drive T-cell responses in human skin disease.

In addition to serving as the main physical barrier with the outside world, human skin is abundantly infiltrated with resident αß T cells that respond differently to self, infectious, microbiome, and noxious stimuli.  To study skin T cells during infection and inflammation, experimental biologists track T-cell surface phenotypes and effector functions, which are often interpreted with the untested assumption that MHC proteins and peptide antigens drive measured responses.  However, a broader perspective is that CD1 proteins also activate human T cells, and in skin, Langerhans cells (LCs) are abundant antigen presenting cells that express extremely high levels of CD1a.  The emergence of new experimental tools, including CD1a tetramers carrying endogenous lipids, now show that CD1a-reactive T cells comprise a large population of resident T cells in human skin.  Here, we review studies showing that skin-derived αß T cells directly recognize CD1a proteins, and certain bound lipids, such as contact dermatitis allergens, trigger T-cell responses. Other natural skin lipids inhibit CD1a-mediated T-cell responses, providing an entry point for the development of therapeutic lipids that block T-cell responses. Increasing evidence points to a distinct role of CD1a in type 2 and 22 T-cell responses, providing new insights into psoriasis, contact dermatitis, and other T-cell-mediated skin diseases.

Langerhans Cell Histiocytosis or Acute Cellular Rejection?

BACKGROUND: Langerhans cell histiocytosis (LCH) is a rare malignant disorder of epidermal antigen presenting cells. It is characterized by infiltration of various tissues with dendritic cells (Langerhans cells, LC) that express CD1a or CD207 (langerin), often leading to organ dysfunction. A patient with LCH required liver transplantation (LT) for LCH-associated biliary-tract disease. Cholangiopathy developed after LT. The question arose: In this patient, did LC in damaged liver-allograft biliary epithelium signify acute cellular rejection (ACR) or recurrent LCH? METHODS: We evaluated immunohistochemical identification of LC (CD1a, CD207) in the proposita and in 14 ACR patient samples as distinguishing between ACR and recurrent LCH. RESULTS: Among 15 patient samples, 3 (20%) marked with neither antibody. Among the remaining 12 samples (80%), 4 (26.7%)-including that from the proposita-had cells marking for both antigens within bile-duct epithelium as well as in surrounding portal-tract connective tissue, 2 (13.3%) had cells marking for both antigens in one region or the other, but not in both, and 6 (40%) had cells marking for only one antigen in one region or the other. CONCLUSIONS: Immunostaining for CD1a and CD207/langerin in the setting of ACR without suspicion of LCH identifies LC in damaged bile ducts. This biomarker pairing proved not to be LCH-specific. Our findings indicate that the presence of these cells alone is insufficient to identify recurrent LCH in the allograft liver.

Immunohistochemical analysis of chronic and recurrent dermatophytosis.

BACKGROUND: Dermatophytosis has assumed epidemic proportions with rising resistance, recalcitrance and recurrence, especially in tropical regions. While various factors contribute to high prevalence worldwide, yet little is known about the interactions between host defence mechanisms and dermatophytes, particularly in chronic and recalcitrant dermatophytosis. OBJECTIVES: We aimed to compare the population of various immune cells in specimens of chronic recurrent dermatophytosis and those with acute superficial dermatophytosis. METHODS: We investigated the density of various immune cells-Langerhans cells (CD1a+), macrophages (CD68+), dermal dendrocytes (Factor XIIIa+) in the skin of chronic dermatophytosis patients and those with successfully resolved lesions (controls). RESULTS: Langerhans cells were significantly decreased in the epidermis of patients, both in affected and unaffected areas in comparison with controls. In the dermis, however, no differences in the density of immune cells (macrophages and fibroblasts) were observed. LIMITATIONS: The limited sample size and immune cells evaluated could be expanded further in future research. CONCLUSION: These results indicate that the decreased number of Langerhans cells could be a potential risk factor for the development of chronic and recurrent dermatophytosis.

Chemoradiotherapy and Lymph Node Metastasis Affect Dendritic Cell Infiltration and Maturation in Regional Lymph Nodes of Laryngeal Cancer.

Dendritic cells (DCs) are the most specialized antigen-presenting cells, and lymph nodes (LNs) play an important role in the DC-mediated T-cell response. We evaluated the infiltration of CD1a-positive DCs (CD1a-DCs), i.e., immature DCs, and S100-positive dendritic cells (S100-DCs), a mixture of immature and mature DCs, in 73 cases of laryngeal cancer and its regional LNs. Among them, 31 patients underwent radiotherapy (RT) or chemoradiotherapy (CRT) prior to surgery. No significant difference was found for CD1a-DC infiltration in the primary tumors, metastatic LNs and non-metastatic LNs, while S100-DCs were significantly fewer in number in the primary tumors and metastatic LNs compared to non-metastatic LNs. The cases which showed a high infiltration of S100-DCs in the metastatic LNs appeared to show a favorable prognosis, although statistical significance was not reached. In the RT/CRT group, the infiltration of the CD1a-DCs and S100-DCs was less in the primary tumors and metastatic LNs compared to the treatment-naive group. Conversely, the RT/CRT group showed higher CD1a-DC and S100-DC numbers in the non-metastatic LNs compared to the treatment-naïve group. Thus, DC maturation in metastatic LNs plays an important role in tumor immunity in laryngeal cancer, and the infiltration of DCs into the primary tumor and metastatic LNs is impaired by RT/CRT.

Problems when diagnosing cutaneous leishmaniasis: a retrospective study analyzing clinical, histopathological and immunohistochemical features.

BACKGROUND: Cutaneous leishmaniasis (CL) incidence in Switzerland is rising due to factors like migration and globalization. The aim of this work was to investigate CL frequency in Switzerland and identify clinical and histopathological difficulties in diagnosing CL in a non-endemic country. PATIENTS AND METHODS: This retrospective study evaluated the clinical and histopathological characteristics of all CL cases from two dermatopathology laboratories between 2000 and 2022. Skin biopsies were histopathologically reviewed using HE, Giemsa, and immunohistochemical stain for CD1a and a specific Leishmania antibody (LA). PCR to detect Leishmania DNA was performed if sufficient tissue was available. RESULTS: 42 cases (27 m, 15 f) were included. The correct clinical diagnosis of CL was only made in 15 (35.7%) cases. In seven (16.6%) cases, CL was missed in the initial histopathologic evaluation. Two main histopathological patterns were observed: granulomatous and pseudolymphomatous. Immunohistochemical staining with CD1a and Leishmania-specific antibody was positive in 91% and 80% of cases, respectively. Leishmania PCR was positive in 25 of 26 cases, mainly detecting Old World species. CONCLUSIONS: CL is rare in Switzerland and often misdiagnosed clinically and histopathologically. CD1a and specific Leishmania antibody stainings are useful. CL should be considered in non-healing ulcers, even without a history of travel to endemic areas.

Phospholipase activity of acyloxyacyl hydrolase induces IL-22-producing CD1a-autoreactive T cells in individuals with psoriasis.

Psoriasis is a chronic inflammatory skin disease characterized by Th17 responses. Recent evidence has identified Langerhans cells to have a key role in disease pathogenesis, with constitutive high expression of CD1a and capacity to present lipid antigens to T cells. Phospholipase A2 enzymes generate neolipid antigens for recognition by CD1a-reactive T cells; however, the broader enzymatic pathways of CD1a lipid ligand generation have not been thoroughly investigated. In this study, we used immunofluorescence of skin and ELISpot analyses of CD1a-reactive T cells to investigate the role of the lipase acyloxyacyl hydrolase (AOAH) in CD1a ligand generation with relevance to the pathogenesis of psoriasis. We found that the PLA2 activity of rAOAH leads to the activation of circulating CD1a auto-reactive T cells, leading to the production of IFN-γ and IL-22. Circulating AOAH-responsive CD1a-reactive T cells from patients with psoriasis showed elevated IL-22 production. We observed that AOAH is highly expressed in psoriatic lesions compared to healthy skin. Overall, these data present a role for AOAH in generating antigens that activate circulating lipid-specific CD1a-restricted T cells and, thus, contribute to psoriatic inflammation. These findings suggest that inhibition of PLA2 activity of AOAH may have therapeutic potential for individuals with psoriasis.

Dendritic Cell Subpopulations Are Associated with Prognostic Characteristics of Breast Cancer after Neoadjuvant Chemotherapy-An Observational Study.

Breast cancer (BC) is the most prevalent malignancy in women and researchers have strived to develop optimal strategies for its diagnosis and management. Neoadjuvant chemotherapy (NAC), which reduces tumor size, risk of metastasis and patient mortality, often also allows for a de-escalation of breast and axillary surgery. Nonetheless, complete pathological response (pCR) is achieved in no more than 40% of patients who underwent NAC. Dendritic cells (DCs) are professional antigen-presenting cells present in the tumor microenvironment. The multitude of their subtypes was shown to be associated with the pathological and clinical characteristics of BC, but it was not evaluated in BC tissue after NAC. We found that highe r densities of CD123+ plasmacytoid DCs (pDCs) were present in tumors that did not show pCR and had a higher residual cancer burden (RCB) score and class. They were of higher stage and grade and more frequently HER2-negative. The density of CD123+ pCDs was an independent predictor of pCR in the studied group. DC-LAMP+ mature DCs (mDCs) were also related to characteristics of clinical relevance (i.e., pCR, RCB, and nuclear grade), although no clear trends were identified. We conclude that CD123+ pDCs are candidates for a novel biomarker of BC response to NAC.

Dendritic Cell Subpopulations Are Associated with Morphological Features of Breast Ductal Carcinoma In Situ.

Ductal carcinoma in situ (DCIS) is the preinvasive form of breast cancer (BC). It is disputed whether all cases of DCIS require extensive treatment as the overall risk of progression to BC is estimated at 40%. Therefore, the crucial objective for researchers is to identify DCIS with significant risk of transformation into BC. Dendritic cells (DC) are professional antigen presenting cells and as such play a pivotal role in the formation of immune cells that infiltrate in breast tumors. The aim of this study was to investigate the relationship between the density of DCs with different superficial antigens (CD1a, CD123, DC-LAMP, DC-SIGN) and various histopathological characteristics of DCIS. Our evaluation indicated that CD123+ and DC-LAMP+ cells were strongly associated with maximal tumor size, grading and neoductgenesis. Together with CD1a+ cells, they were negatively correlated with hormonal receptors expression. Furthermore, the number of DC-LAMP+ cells was higher in DCIS with comedo necrosis, ductal spread, lobular cancerization as well as comedo-type tumors, while CD1a+ cells were abundant in cases with Paget disease. We concluded that different subpopulations of DCs relate to various characteristics of DCIS. Of the superficial DCs markers, DC-LAMP seems particularly promising as a target for further research in this area.

Gastrointestinal Langerhans cell histiocytosis with unifocal, single-system involvement in adults: Cases report and literature review.

BACKGROUND: Langerhans cell histiocytosis (LCH) is characterized by unifocal, multifocal single-system, or multi-system disease that occurs in all age groups, while it primarily attacks pediatric patients. Solitary gastrointestinal (GI) LCH in adults is exceedingly rare, so we aimed to investigate GI LCH in adults with unifocal single-system involvement and clarified the clinicopathologic characteristics of this disease. METHODS: Two cases of solitary GI LCH in adults were presented, and the clinicopathologic features of this diagnosis in the literature were reviewed. RESULTS: The main diagnostic feature of LCH is the morphologic identification of the characteristic Langerhans cells with prominent nuclear grooves and abundant eosinophilic cytoplasm, accompanied by a variable number of lymphocytes, eosinophils, and plasma cells. The distinctive cells expressed S100, CD1a, and langerin (CD207) on immunohistochemistry. BRAF V600E mutations were detected in the two patients. CONCLUSIONS: Gastrointestinal Langerhans cell histiocytosis in adults with unifocal, single-system involvement is extremely rare. Most patients were asymptomatic and usually a small solitary polyp in GI tract can be observed under routine endoscopy. Although the overall prognosis of unifocal single-system LCH is favorable, long-term follow-up is still necessary to rule out systemic disease.

Immunolocalization of CD1a expressing dendritic cells in sinonasal polyposis.

Sinonasal polyps are benign projections of edematous nasal mucosa lined by respiratory epithelium. Langerhans cells (LCs) belonging to the dendritic cell family located in respiratory epithelium are involved in antigen presentation and maintenance of local immunological homeostasis. This study aims to elucidate the morphology and distribution of CD1a positive LCs in normal nasal mucosa and compare the same with polypoid nasal mucosa by immunohistochemistry. Normal nasal mucosa (n = 20) was obtained from patients who underwent septoplasty for deviated nasal septum. Polypoid nasal mucosa (n = 22) was obtained from patients with chronic rhinosinusitis (CRS) or allergic fungal rhinosinusitis who underwent excision of nasal polyps. The tissues obtained were processed for immunohistochemistry and stained with CD1a-EP80 Rabbit monoclonal antibody. In the tissues studied, CD1a positive LCs were observed in both the epithelium and lamina propria. Different morphological subtypes of LCs were noted in the epithelium. The cells were distributed adjacent to walls of subepithelial capillaries and cysts. The median number of CD1a positive LCs was significantly higher in polypoid category (13.5 per mm2) as compared with normal nasal mucosa (2.5per mm2) (p = .001). Presence of CD1a positive LCs in polypoid nasal mucosa hints at a critical immunological role in the etiopathogenesis of nasal polyps.

Infiltration of CD1a-positive dendritic cells in advanced laryngeal cancer correlates with unfavorable outcomes post-laryngectomy.

BACKGROUND: The prognosis of advanced laryngeal cancer is unfavorable despite advances in multidisciplinary therapy. Dendritic cells (DCs) play a central role in antitumor immunity. Tumor-infiltrating CD1a+ DCs have been reported to be associated with clinical outcomes in carcinomas of various organs, but the clinical impact of CD1a+ DCs in laryngeal cancer remains to be unequivocally established. METHODS: We retrospectively analyzed the cases of 57 patients with Stage III or IV laryngeal cancer who underwent a total laryngectomy. Immunohistochemistry detection of CD1a, S100 and CD8 was performed on representative resected specimens. CD1a+ DCs, S100+ DCs and CD8+ cytotoxic T-lymphocytes (CTLs) were evaluated, and the cases divided into high and low groups according to the cut-off of the median values for each of these 3 parameters. RESULTS: Compared to the CD1a-low group, the CD1a-high group had more advanced cases and showed significantly worse disease-specific survival (DSS) (P = 0.008) and overall survival (OS) (P = 0.032). The analyses of S100 DCs and CD8+ CTLs revealed no significant impact on clinical outcomes. However, multivariate analysis revealed that infiltration of CD1a+ DCs was an independent unfavorable prognostic factor for both DSS (P = 0.009) and OS (P = 0.013). CONCLUSIONS: Our results demonstrated that the infiltration of CD1a+ DCs was associated with unfavorable clinical outcomes in patients with advanced laryngeal cancer who underwent a total laryngectomy as the initial treatment.

The role of CD1a expression in the diagnosis of cutaneous leishmaniasis, its relationship with leishmania species and clinicopathological features.

Cutaneous leishmaniasis is caused by a flagellated protozoan transmitted by the bite of a female sandfly. The clinical and demographic details of this disease, predominantly affecting immunocompetent individuals, are recognized by the WHO as a Neglected Tropical Disease. We sought to determine the usability of CD1a immunohistochemical staining to detect amastigotes especially in cases where leishmaniasis is suspected but evident amastigotes could not observed. We also evaluated the relationship between CD1a expression and leishmania subtypes. A total of 84 cases diagnosed with leishmaniasis or suspected leishmania on histo-morphological evaluation of skin biopsies were included in the study. Amastigotes were easily detected in hematoxylin eosin in 18 of 84 cases. In 23 cases, amastigotes could not detect in hematoxylin eosin sections. The immunostains for CD1a are demonstrated amastigotes in 60 of 84 cases. However, a small number of amastigotes became visible by positive staining with CD1a in 43.4% of the cases in that amastigotes could not detected in hematoxylin eosin. A statistically significant correlation was found between amastigote amount in hematoxylin eosin and CD1a expression. In addition, a significant correlation was observed between CD1a expression, age and clinical pre-diagnosis of the cases. It was observed that amastigotes were easily detected in hematoxylin eosin in Leishmania Infantum / donovani positive cases in polymerase chain reaction (PCR), and at the same time, it was found that CD1a expression was significantly higher. Using histopathology examination with CD1a staining and/or PCR methods, a diagnosis of leishmaniasis can be established and early treatment initiated. This contributes to reduce transmission and prevalence.

Highly efficient CRISPR-targeting of the murine Hipp11 intergenic region supports inducible human transgene expression.

Safe harbor loci allow predicable integration of a transgene into the genome without perturbing endogenous gene activity and for decades have been exploited in the mouse to investigate gene function, generate humanised models and create tissue specific reporter and Cre recombinase expressing lines. Herein, we show that the murine Hipp11 intergenic region can facilitate highly efficient integration of a large transgene-the human CD1A promoter and coding region-by means of CRISPR-Cas9 mediated homology directed repair. The data shows that the single copy human CD1A transgene is faithfully expressed in an inducible manner in homozygous animals in both macrophage and dendritic cells. Our results validate the Hipp11 intergenic region as being a highly amenable target site for functional transgene integration in mouse.

Tumour-Infiltrating Inflammatory Cells in Early Breast Cancer: An Underrated Prognostic and Predictive Factor?

The role of tumour-infiltrating inflammatory cells (TIICs) in the disease progression of hormone-receptor-positive breast cancer (HR+ BC) is largely unclear since it is generally regarded as the least immunogenic BC subtype. This study investigated the prognostic significance of CD1a+ dendritic cells, CD20+ B cells, CD45RO+ memory T cells and CD4+ T-helper cells in HR+ BC. One hundred and forty-six patients were treated for early stage, distant-metastases-free HR+ BC in an accelerated partial breast irradiation (APBI) phase II trial. Immunohistochemistry was used to double-stain two adjoining sets of tissue microarrays from pre-RT (radiotherapy) tumour resection samples for CD1a/CD20 and CD45RO/CD4. Cell densities of CD1a+, CD20+, CD45RO+ and CD4+ TIICs in the stromal and intraepithelial compartment were registered semiautomatically. High densities of CD20+ and CD4+ TIICs were strongly associated with reduced disease-free survival (DFS), while high stromal CD45RO+ TIIC densities were indicators of subsequent successful treatment. An immunoscore based on CD20+ and CD45RO+ TIIC densities identified three different risk groups (p < 0.001). Thus, contrary to current assumptions, intratumoural immune cell composition might be an important prognostic indicator and a possible contributing factor in the outcome of HR+ BC and should be the subject of further research. Specifically, B-cell infiltration entailed an increased relapse rate and could play an important role in disease progression.

[Pathophysiology and treatment of adult Langerhans cell histiocytosis].

Langerhans cell histiocytosis (LCH) is a rare disease characterized by tissue infiltration of clusters of CD1a+/CD207+ histiocyte-like cells and a resultant surrounding inflammatory reaction. Because of its morphological similarity to cutaneous Langerhans cells, LCH was formerly named histiocytosis X in 1987. However, its cell lineage appears closely related to myeloid dendritic cells. In 2010, BRAF-V600E was detected in biopsy specimens from the majority of LCH patients. The subsequent observation of extracellular signal-regulated kinase phosphorylation in almost all LCH samples suggested that LCH was a neoplasm provoked by activation of the mitogen-activated protein (MAP) kinase pathway. Therefore, the 2016 Revised Classification by the Histiocyte Society defined LCH as an inflammatory myeloid neoplasm. Although a series of global and domestic clinical trials have improved the prognosis of pediatric LCH patients, no standard therapy with a high level of evidence for adult cases exists. Generally, LCH patients have a favorable prognosis, but delayed diagnosis and intervention may cause severe damage to the involved organs, resulting in a poor quality of life. Here we present recent advances in the pathophysiology and treatment of LCH to enlighten the understanding of this orphan disease.

A case of S-100-negative CD1a-positive indeterminate cell histiocytosis.

Histiocytoses are a group of rare disorders characterized by a proliferation of monocytes/macrophages and dendritic cells. We present a case of a 3-year-old girl with a diffuse papular eruption without systemic symptoms demonstrating a proliferation of strongly CD1a+ histiocytes, but negative for S-100 and langerin on histopathology. Systemic work-up including bone marrow biopsy was unremarkable, and the patient received a diagnosis of CD1a+ S- 100-indeterminate cell histiocytosis.

A comparative immunohistochemical study of epidermal and dermal/perifollicular Langerhans cell concentration in discoid lupus erythematosus and lichen planopilaris: a cross-sectional study.

BACKGROUND: There are times when differentiation between discoid lupus erythematosus (DLE) and lichen planopilaris (LPP) becomes quite challenging clinicopathologically. OBJECTIVES: The aim of this study was to evaluate and compare the concentration, distribution pattern and role of Langerhans cells (LCs), identified by CD1a staining in DLE and LPP. METHODS: Twenty-five specimens of skin biopsies from patients diagnosed with LPP and DLE were included. Immunohistochemistry (IHC) staining was performed against CD1a antigen to assess and compare the concentration and distribution pattern of LCs. RESULTS: Compared with LPP, the mean number of epidermal CD1a+ cells per three high power fields was significantly lower in DLE ( p = 0.003). On the other hand, DLE cases had a significantly higher mean number of dermal/perifollicular CD1a+ cells in three high power fields than LPP cases ( p = 0.01). LIMITATIONS: A small sample size and limited IHC markers. CONCLUSIONS: There are differences in the density and distribution pattern of LCs in LPP and DLE in the epidermis and perifollicular regions. Our findings of a statistically significant decrease in LC concentration in the epidermis of DLE cases and also in the perifollicular region of LPP may serve as helpful clues in further characterization of these entities, especially in equivocal cases. However, more extensive studies are required to better understand the underlying immunopathogenesis of these diseases in providing further clues to a specific diagnosis.

It is time to beelieve the CD1a hype!

Conventional T cells have historically been linked to exacerbating allergy. By efficiently generating primarily TH 2 cells, allergens skew the immune response to produce IL-4, IL-13, and IgE. Previously, CD1a-responsive T cells were shown to functionally respond to bee and wasp venom allergens. In this issue of the European Journal of Immunology, Subramaniam et al. [Eur. J. Immunol. 2016. 46: 242-252] show that more functionally active CD1a-restricted cells are present in bee venom-allergic patients than in healthy patients. Additionally, the authors show that these cells are not as frequently found in individuals receiving venom immunotherapy. Consequently, this study implicates CD1a-reactive cells as the primary responders to venom allergy, which considerably regulate the downstream immune response.