Immature Langerhans Cells Research Articles

Transmission of Zika virus by dendritic cell subsets in skin and vaginal mucosa.

Zika virus is a member of the Flaviviridae family that has caused recent outbreaks associated with neurological malformations. Transmission of Zika virus occurs primarily via mosquito bite but also via sexual contact. Dendritic cells (DCs) and Langerhans cells (LCs) are important antigen presenting cells in skin and vaginal mucosa and paramount to induce antiviral immunity. To date, little is known about the first cells targeted by Zika virus in these tissues as well as subsequent dissemination of the virus to other target cells. We therefore investigated the role of DCs and LCs in Zika virus infection. Human monocyte derived DCs (moDCs) were isolated from blood and primary immature LCs were obtained from human skin and vaginal explants. Zika virus exposure to moDCs but not skin and vaginal LCs induced Type I Interferon responses. Zika virus efficiently infected moDCs but neither epidermal nor vaginal LCs became infected. Infection of a human full skin model showed that DC-SIGN expressing dermal DCs are preferentially infected over langerin+ LCs. Notably, not only moDCs but also skin and vaginal LCs efficiently transmitted Zika virus to target cells. Transmission by LCs was independent of direct infection of LCs. These data suggest that DCs and LCs are among the first target cells for Zika virus not only in the skin but also the genital tract. The role of vaginal LCs in dissemination of Zika virus from the vaginal mucosa further emphasizes the threat of sexual transmission and supports the investigation of prophylaxes that go beyond mosquito control.

Immune activation of vaginal human Langerhans cells increases susceptibility to HIV-1 infection

Vaginal inflammation increases the risk for sexual HIV-1 transmission but underlying mechanisms remain unclear. In this study we assessed the impact of immune activation on HIV-1 susceptibility of primary human vaginal Langerhans cells (LCs). Vaginal LCs isolated from human vaginal tissue expressed a broad range of TLRs and became activated after exposure to both viral and bacterial TLR ligands. HIV-1 replication was restricted in immature vaginal LCs as only low levels of infection could be detected. Notably, activation of immature vaginal LCs by bacterial TLR ligands increased HIV-1 infection, whereas viral TLR ligands were unable to induce HIV-1 replication in vaginal LCs. Furthermore, mature vaginal LCs transmitted HIV-1 to CD4 T cells. This study emphasizes the role for vaginal LCs in protection against mucosal HIV-1 infection, which is abrogated upon activation. Moreover, our data suggest that bacterial STIs can increase the risk of HIV-1 acquisition in women.

Corneal Langerhans cells in children with celiac disease

Celiac disease (CeD) is a common small bowel enteropathy characterized by an altered adaptive immune system and increased mucosal antigen presenting cells. This study aims to establish if quantification of corneal Langerhans cells (LCs) using corneal confocal microscopy (CCM) could act as a surrogate marker for antigen presenting cell status and hence disease activity in children with CeD. Twenty children with stable CeD and 20 age-matched controls underwent CCM and quantification of central corneal total, mature and immature LC density. There was no difference in age (11.78 ± 1.7 vs. 12.83 ± 1.91; P = 0.077) or height (1.38 ± 0.14 vs. 1.44 ± 0.13; P = 0.125). BMI (18.81 ± 3.90 vs. 22.26 ± 5.47; P = 0.031) and 25 OHD levels (43.50 ± 13.36 vs. 59.77 ± 22.45; P = 0.014) were significantly lower in children with CeD compared to controls. The total (33.33(16.67–59.37) vs. 51.56(30.21–85.42); P = 0.343), immature (33.33(16.67–52.08) vs. 44.79(29.17–82.29); P = 0.752) and mature (1.56(0–5) vs. 1.56(1.04–8.33); P = 0.752) LC density did not differ between the CeD and control groups. However, immature (r = 0.535, P = 0.015), mature (r = 0.464, P = 0.039), and total (r = 0.548, P = 0.012) LC density correlated with age. Immature (r = 0.602, P = 0.038) and total (r = 0.637, P = 0.026) LC density also correlated with tissue transglutaminase antibody (Anti-TtG) levels assessed in 12/20 subjects with CeD. There was no difference in corneal LC density between children with CeD and controls. However, the correlation between corneal LC density and anti-TtG levels suggests a relationship with disease activity in CeD and requires further study.

Macrophage Migration Inhibitory Factor Restriction of HIV-1 Transinfection from Dendritic Cells to CD4+ T Cells through the Regulation of Autophagy

At mucosal surfaces, immature resident Dendritic Cells (DC) and Langerhans Cells (LC) are among the first cell types to encounter and to be infected by HIV-1 virus (Ahmed et al., 2015, Pena-Cruz et al., 2018). LC and myeloid DCs can restrict early HIV-1 infection through active mechanisms of viral entry restriction due to their primary autophagic functions (Blanchet et al., 2010). During early-stage infection, the recognition of virus by DCs results in the release of cytokines: Interferon-stimulated genes and TGF-β have shown their contribution in the control of HIV-1 infection (Czubala et al., 2016, Soper et al., 2017).

In vivo Confocal Microscopic Evaluation of Previously Neglected Oval Cells in Corneal Nerve Vortex: An Inflammatory Indicator of Dry Eye Disease.

This study aimed to investigate the association of between previously neglected oval cells located in the corneal vortex and dry eye disease (DED). This was an observational, prospective study involving 168 patients with different degrees of DED. In vivo confocal microscopy was used to observe the corneal subbasal nerves and Langerhans cells (LCs) in the corneal vortex and periphery. Bright and oval cells were also observed in the corneal vortex. An artificial intelligence technique was used to generate subbasal nerve fiber parameters. The patients were divided into the three groups based on the presence of inflammatory cells. Group 2 patients showed a significant increase in the corneal peripheral nerve maximum length and average corneal peripheral nerve density. Patients in group 3 had more LCs than other patients. A bright and oval cell was identified in the corneal vortex, which might be a type of immature LC related to the disease severity of DED.

Tolerogenic IDO1+CD83- Langerhans Cells in Sentinel Lymph Nodes of Patients with Melanoma.

Langerhans cells (LCs) are crucial regulators of anti-cancer immune responses. Cancer, however, can alter DCs functions leading to tolerance. The enzyme indoleamine 2,3-dioxygenase (IDO1) plays a crucial role in this process. In sentinel lymph nodes (SLNs) of patients with melanoma, LCs show phenotypical and functional alterations favoring tolerance. Herein we aimed to investigate IDO1 expression in SLN LCs from patients with melanoma. We showed by immunofluorescence analysis that a portion of Langerin+ LCs, located in the SLN T cell-rich area, displayed the typical dendritic morphology and expressed IDO1. There was no significant difference in the expression of IDO between SLN with or without metastases. Double IDO1/CD83 staining identified four LCs subsets: real mature IDO1−CD83+ LCs; real immature IDO1−CD83− LCs; tolerogenic mature IDO1+CD83+ LCs; tolerogenic immature IDO1+CD83− LCs. The latter subset was significantly increased in metastatic SLNs as compared to negative ones (p < 0.05), and in SLN LCs of patients with mitotic rate (MR) > 1 in primary melanoma, as compared to MR ≤ 1 (p < 0.05). Finally, immature SLN LCs, after in vitro stimulation by inflammatory cytokines, acquired a maturation profile by CD83 up-regulation. These results provide new input for immunotherapeutic approaches targeting in vivo LC of patients with melanoma.

O-PN003. Corneal sub-basal whorl-like nerve plexus: A landmark for early and follow-up evaluation in transthyretin familial amyloid polyneuropathy

Introduction . To evaluate the quantification of corneal sub-basal whorl-like nerve plexus parameters as a sensitive and static marker in early diagnosis of small fiber neuropathy (SFN) and monitor disease progression in familial amyloid polyneuropathy (FAP) patients. Methods . Fifteen FAP patients and fifteen healthy controls underwent neurological evaluation (including clinical scales and electrophysiological tests) and corneal nerve observation. Corneal nerve fiber density (CNFD), Corneal nerve fiber branch density (CNBD), Corneal nerve fiber length (CNFL) were detected in the central cornea (conventional method) and the whorl-like inferocentral cornea (new method). The Langerhans cells (LC) density in each image was calculated. Results . Corneal parameters were significantly reduced with disease progression. Only inferior whorl length (IWL) was significantly reduced in preclinical patients (with normal SSR and CHEPs results) comparing with age matched controls. IWL, CNFL, CNBD and CNFD were significantly lower in early phase patients. LC density was significantly increased around the central whorl in early phase patients than in healthy controls (p = 0.009), and was lower in the progressive patients. Both IWL and CNFL correlated with severity of neuropathy. IWL was more significantly reduced with the progression of disease than CNFL. The area under the ROC curve to distinguish FAP with CNFL and IWL was 88.0% and 89.3%, respectively, exceeding other parameters. The coefficient of variation of the IWL value was significantly (P < 0.0001) smaller than that of the conventional method. Conclusion . The observation of corneal sub-basal whorl-like nerve plexus can detect SFN in preclinical FAP patients earlier than traditional electrophysiological methods. IWL is the most sensitive and reliable parameters and it can best discriminate FAP patients from controls. The clustering of immature LCs at the whorl area might reflect the inflammatory response of small- fiber nerves at the very early stage.

Small Nerve Fiber Damage and Langerhans Cells in Type 1 and Type 2 Diabetes and LADA Measured by Corneal Confocal Microscopy.

PurposeIncreased corneal and epidermal Langerhans cells (LCs) have been reported in patients with diabetic neuropathy. The aim of this study was to quantify the density of LCs in relation to corneal nerve morphology and the presence of diabetic neuropathy and to determine if this differed in patients with type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), and latent autoimmune diabetes of adults (LADA).MethodsPatients with T1DM (n = 25), T2DM (n = 36), or LADA (n = 23) and control subjects (n = 23) underwent detailed assessment of peripheral neuropathy and corneal confocal microscopy. Corneal nerve fiber density (CNFD), branch density (CNBD), length (CNFL) and total, immature and mature LC densities were quantified.ResultsLower CNFD (P < 0.001), CNBD (P < 0.0001), and CNFL (P < 0.0001) and higher LC density (P = 0.03) were detected in patients with T1DM, T2DM, and LADA compared to controls. CNBD was inversely correlated with mature (r = –0.5; P = 0.008), immature (r = –0.4; P = 0.02) and total (r = –0.5; P = 0.01) LC density, and CNFL was inversely correlated with immature LC density (r = –0.4; P = 0.03) in patients with T1DM but not in patients with T2DM and LADA.ConclusionsThis study shows significant corneal nerve loss and an increase in LC density in patients with T1DM, T2DM, and LADA. Furthermore, increased LC density correlated with corneal nerve loss in patients with T1DM.

CSF1R Is Required for Differentiation and Migration of Langerhans Cells and Langerhans Cell Histiocytosis.

Langerhans cell histiocytosis (LCH) is a rare disorder characterized by tissue accumulation of CD1a+CD207+ LCH cells. In LCH, somatic mutations of the BRAF V600E gene have been detected in tissue LCH cells, bone marrow CD34+ hematopoietic stem cells, circulating CD14+ monocytes, and BDCA1+ myeloid dendritic cells (DC). Targeting BRAF V600E in clonal Langerhans cells (LC) and their precursors is a potential treatment option for patients whose tumors have the mutation. The development of mouse macrophages and LCs is regulated by the CSF1 receptor (CSF1R). In patients with diffuse-type tenosynovial giant cell tumors, CSF1R inhibition depletes tumor-associated macrophages (TAM) with therapeutic efficacy; however, CSF1R signaling in LCs and LCH has not been investigated. We found through IHC and flow cytometry that CSF1R is normally expressed on human CD1a+CD207+ LCs in the epidermis and stratified epithelia. LCs that were differentiated from CD14+ monocytes, BDCA1+ DCs, and CD34+ cord blood progenitors expressed CSF1R that was downregulated upon maturation. Immature LCs migrated toward CSF1, but not IL34. Administration of the c-FMS/CSF1R kinase inhibitors GW2580 and BLZ945 significantly reduced human LC migration. In LCH clinical samples, LCH cells (including BRAF V600E cells) and TAMs retained high expression of CSF1R. We also detected the presence of transcripts for its ligand, CSF1, but not IL34, in all tested LCH cases. CSF1R and CSF1 expression in LCH, and their role in LC migration and differentiation, suggests CSF1R signaling blockade as a candidate rational approach for treatment of LCH, including the BRAF V600E and wild-type forms of the disease.

Syndecan 4 Upregulation on Activated Langerhans Cells Counteracts Langerin Restriction to Facilitate Hepatitis C Virus Transmission.

Sexually transmitted Hepatitis C virus (HCV) infections and high reinfections are a major concern amongst men who have sex with men (MSM) living with HIV-1 and HIV-negative MSM. Immune activation and/or HIV-1 coinfection enhance HCV susceptibility via sexual contact, suggesting that changes in immune cells or external factors are involved in increased susceptibility. Activation of anal mucosal Langerhans cells (LCs) has been implicated in increased HCV susceptibility as activated but not immature LCs efficiently retain and transmit HCV to other cells. However, the underlying molecular mechanism of transmission remains unclear. Here we identified the Heparan Sulfate Proteoglycan Syndecan 4 as the molecular switch, controlling HCV transmission by LCs. Syndecan 4 was highly upregulated upon activation of LCs and interference with Heparan Sulfate Proteoglycans or silencing of Syndecan 4 abrogated HCV transmission. These data strongly suggest that Syndecan 4 mediates HCV transmission by activated LCs. Notably, our data also identified the C-type lectin receptor langerin as a restriction factor for HCV infection and transmission. Langerin expression abrogated HCV infection in HCV permissive cells, whereas langerin expression on the Syndecan 4 expressing cell line strongly decreased HCV transmission to a target hepatoma cell line. These data suggest that the balanced interplay between langerin restriction and Syndecan 4 transmission determines HCV dissemination. Silencing of langerin enhanced HCV transmission whereas silencing Syndecan 4 on activated LCs decreased transmission. Blocking Heparan Sulfate Proteoglycans abrogated HCV transmission by LCs ex vivo identifying Heparan Sulfate Proteoglycans and Syndecan 4 as potential targets to prevent sexual transmission of HCV. Thus, our data strongly suggest that the interplay between receptors promotes or restricts transmission and further indicate that Syndecan 4 is the molecular switch controlling HCV susceptibility after sexual contact.

CD1a+ and CD207+ cells are reduced in oral submucous fibrosis and oral squamous cell carcinoma.

Background The objective of this study investigated the distribution of immature dendritic cells (DCs), Langerhans cells and plasmacytoid DCs in oral submucous fibrosis (OSMF), OSMF associated with oral squamous cell carcinoma (OSMF-OSCC), oral leukoplakia (OL), and oral squamous cell carcinoma (OSCC). Material and Methods Fourteen cases of OSMF, 9 of OSMF-OSCC, 8 of OL¸ 45 of OSCC and 8 of normal epithelium were retrospectively retrieved and their diagnoses confirmed. Immunoreactions against CD1a, CD207 e CD303 were performed and the number of positive cells quantified. Results A significant decrease of CD1a+ was found in OSMF (p≤0.05), OSMF-OSCC (p ≤ 0.01), and OSCC (p ≤ 0.001) when compared to normal epithelium. For CD207+ the significance decrease was observed in OSMF-OSCC (p ≤ 0.05), and OSCC (p ≤ 0.01) when compared with normal epithelium, and in OSMF when compared with OL (p ≤ 0.05). There was no significant difference for CD303, but increased in CD303+ was observed in OSCC when compared with normal epithelium. Conclusions The decrease in the number of CD1a+ and CD207+ cells may be associate to the development of oral OSCC, and in OPMDs they might be indicators of malignant transformation. Key words:Premalignant lesions, oral submucous fibrosis, oral squamous cell carcinoma, immune response.

Sexually transmitted founder HIV-1 viruses are relatively resistant to Langerhans cell-mediated restriction.

A single HIV-1 variant establishes infection of the host after sexual contact. Identifying the phenotypic characteristics of these Transmitted Founder (T/F) viruses is important to understand the restriction mechanisms during transmission. Langerhans cells (LCs) are the mucosal dendritic cell subset that has been shown to have a protective role in HIV-1 transmission. Immature LCs efficiently capture and degrade HIV-1 via langerin-mediated restriction. Here we have investigated the capacity of T/F HIV-1 strains to infect mucosal Langerhans cells (LCs). Notably, most T/F variants efficiently infected immature LCs derived from skin and vaginal tissue in contrast to chronic HIV-1 laboratory strains. Next we screened a panel of T/F viruses and their matched 6-month consensus sequence viruses. Interestingly most T/F variants infected immature LCs whereas donor-matched 6-month consensus sequence viruses had lost the ability to infect LCs. However, we also identified 6-month consensus sequence viruses that had retained an ability to infect LCs similar to that of the donor-matched T/F virus. Moreover, some T/F viruses and 6-month consensus sequence viruses were unable to infect immature LCs. Further analyses indicated that T/F viruses are less sensitive to langerin-mediated restriction. These data suggest that T/F HIV-1 variants have the ability to infect immature LCs, which will facilitate transmission.

CD1A+ LANGERHANS CELLS ARE REDUCED IN ORAL SUBMUCOUS FIBROSIS AND ORAL SQUAMOUS CELL CARCINOMA

Oral submucous fibrosis (OSMF) affects mainly the Indian subcontinent and its manifestations are closely linked with the habit of chewing betel. Immune system cells such as Langerhans cells (LC) and dendritic cells (DC) are linked to the immunopathogenesis of various lesions and have been studied for their ability of recognizing precursor malignant cells and to destroy them. Objective: Verify the distribution of LC and immature DC in OSMF and oral squamous cell carcinoma (OSCC). Study design: Fourteen cases of OSFM, 9 of OSCC associated to OSMF, and 40 of OSCC were retrieved. The original diagnoses were confirmed by 2 oral pathologists, who further classified OSFM in grade I, II, and III. OSCC cases were classified as well, moderately, and poorly differentiated. Immunoreactions against CD1a were performed and the number of positive LC and DC were quantified. Results: Analysis revealed a significant decrease in the number of immature LC and DC in OSCC compared to OSCC-OSMF (P Conclusions: The results suggest that depletion of immature LC and DC would represent an important step for developing OSCC.

Revealing Homologous Clonality By Synchronous Trisomy 8 in Langerhans CELL Histiocytosis and ACUTE Myeloid Leukemia

Purpose Langerhans cell histiocytosis (LCH) is a disorder in which excess immature Langerhans cells build up in the body. Increasing reports have revealed LCH may share a common origin with myeloid-derived malignancies. Here we report a case of a 45-year-old male, diagnosed as synchronous LCH and acute myeloid leukemia (AML). Relevant tests have been performed to investigate the clonal relationship between LCH and AML. Methods The diagnosis of LCH and AML were based on skin and bone marrow biopsy respectively in Beijing Friendship Hospital, Capital Medical University. No cytotoxic drugs were used before the two diseases were diagnosed. Immunophenotyping was run by immunochemistry or flow cytometry. Karyotype analysis was carried out with G-banding, and the findings were confirmed by fluorescence in situ hybridization (FISH). Mutational analysis of BRAF, KRAS and NRAS genes were performed by ARMS-PCR. Additional gene screening was detected by next-generation sequencing (NGS). Results The case expressed CD1a, S-100, Langerin on the Langerhans cells and CD13, CD34, CD38, CD117, MPO on the leukemic blasts. No other intermingling markers was found on the LCH and AML except CD33 and CD68. Cytogenetic studies showed a karyotype with 47, XY, +8[10], and a confirmatory test revealed the existence of trisomy 8 in both skin and bone marrow lesions by FISH. Cell rate of trisomy 8 on skin, bone marrow and oral mucosa were 9%, 49% and 1%. Mutation analysis revealed KRAS c.436G&gt;A:p.A146T (exon4) in AML and LCH cells, but BRAF c.1799T&gt;A:p.V600E (exon15) only in LCH. Conclusion These findings suggest that LCH cells are derived from myeloid precursors in this case, and BRAF mutation may play an important role in pathogenesis of LCH. Disclosures No relevant conflicts of interest to declare.

Distribution of Dendritic Cells in AIDS-Associated Oral Kaposi's Sarcoma.

The aim of this study was to determine if the distribution of Langerhans cells (LC) and interstitial dendritic cells (IDC) is altered in AIDS-associated oral Kaposi's sarcoma when compared to HIV-negative highly vascular oral lesions. Fifty-one cases of AIDS-associated oral Kaposi's sarcoma and 20 of highly vascular oral lesions were retrospectively retrieved. All cases of Kaposi's sarcoma were confirmed with immunoreactions against CD34 and HHV-8. Clinical data regarding sex, age and lesions location were obtained from pathology reports. Immunohistochemistry against CD207 (immature dendritic cells) and CD83 (mature dendritic cells) were done. LC were in the epithelium and IDC in the stroma. CD207+ cells predominated in the epithelium of the lesions, whereas CD83+ cells predominated in their stromal compartment. Kaposi's sarcoma had a lower CD207+ immature LC count (p=0.02) and an increased CD207+ IDC than highly vascular oral lesions (p<0.001). Moreover, Kaposi's sarcoma also showed an increased number of mature CD83+ IDC than highly vascular oral lesions (p<0.001). There were significant alterations in the distribution of LC and IDC in AIDS-associated Kaposi's sarcoma when compared to HIV-negative vascular oral lesions, suggesting that changes in their concentrations may play a role in the pathogenesis of Kaposi's sarcoma.

Eruptive Junctional Nevi Appearing During Langerhans Cell Histiocytosis Treatment.

Langerhans cell histiocytosis (LCH) is a multisystemic disorder that results from the clonal proliferation of immunophenotypically and functionally immature Langerhans cells (LC). The detection of the V600E mutation in the BRAF oncogene in LCH biopsy specimens supports previous evidence that LCH is a neoplastic disorder. This mutation is present in other cutaneous lesions including malignant melanoma and benign nevi. Single case reports of a correlation between LCH and the appearance of eruptive nevi limited to the inguinal folds after chemotherapy have previously been described in the literature. This suggested that LCH could be an additional cause of eruptive melanocytic nevi, with a specific distribution mimicking that of LCH cutaneous lesions. We present the case of a 6-year-old boy, previously treated with chemotherapy for Langerhans cell histiocytosis, with disseminated junctional nevi. Although this co-occurrence may be coincidental, the skin involvement is distinct from other previously reported clinical cases. It would be interesting to evaluate whether the BRAF mutation described in LCH cells might in fact support a genetic background for the development of nevi in these patients.LEARNING POINTSLangerhans cell histiocytosis (LCH) is a clonal neoplastic proliferation of immature Langerhans cells, with the V600E mutation in the BRAF oncogene present in approximately 60% of cases.The V600E mutation in the BRAF oncogene is also documented in other cutaneous lesions, namely malignant melanoma and benign nevi.There are case reports of a correlation between LCH and the appearance of eruptive nevi after chemotherapy, but it is not known whether the BRAF mutation described in LCH cells supports a genetic background for the development of nevi in these patients.

663 Activation of Trpv1+ nociceptive fibers stimulates an innate antiviral immune response following skin injury

Multiple innate immune signaling pathways become activated upon skin injury in order to reestablish the antimicrobial barrier, prevent infection and excessive tissue injury. Damage to the skin barrier often elicits pain and leads to activation of cutaneous nociceptive fibers. We hypothesized that nociceptors in the skin are activated upon breach of the skin barrier and contribute to the innate antiviral response to skin injury. Here, we show that pharmacological or genetic ablation of TRPV1-mediated nociception impairs the innate antiviral response to skin injury. Using resiniferatoxin-treated mice or Trpv1-/- mice in murine skin excisional wound assays, we identified that preferential ablation of Trpv1 channels reduces the transcription of IFNb (p<0.01), IL27 (p<0.05), and multiple antiviral proteins including Oas2 and Oasl2 (p<0.05) in the skin. The neuromediator N-acetyl-galactosamine (GalNAc) is present in sensory nerves and binds with high specificity to the CD301 lectin, a marker for a subset of dendritic cells that releases IL-27 in the process of skin wound repair. We here show that human THP1-derived immature dendritic cells and Langerhans cells isolated from fresh human skin express IL27 when stimulated with GalNAc (p<0.01 and p<0.001, respectively). Given the knowledge from previous work that cathelicidin LL-37 is produced within the skin following injury and complexes with nucleic acids to enhance production of type I IFNs, we tested the possibility that LL-37 could also alter GalNAc signaling. We demonstrate that LL-37 with GalNAc significantly enhances IL27 (p<0.001), IFNa4 (p<0.01), and IFNb1 (p<0.01) production. Together, our data suggest that nociception promotes skin antiviral competence through activation of antiviral signaling pathways upon wounding. Better understanding of the role of pain and itch in stimulating antimicrobial peptide and protein expression and induction following injury is relevant for improving skin repair.

HIV-1 exposure and immune activation enhance sexual transmission of Hepatitis C virus by primary Langerhans cells.

IntroductionThe significant rise in incidence of Hepatitis C virus (HCV) infection among men‐who‐have‐sex‐with‐men (MSM) living with HIV‐1 suggests that HCV under specific circumstances is transmitted via sexual contact. During sexual transmission HCV has to cross the epithelial barrier to either directly enter the blood stream or indirectly via mucosal immune cells. However, the mechanisms of sexual transmission of HCV remain unclear. We investigated the role of Langerhans cells (LCs) in HCV susceptibility during sexual contact as LCs are among the first cells in mucosal tissues to encounter invading viruses.MethodsWe investigated the phenotype of primary LCs in anal biopsies from MSM living with HIV‐1. To investigate the role of primary LCs in HCV infection and transmission, we have used both isolated primary skin LCs and the ex vivo tissue transmission model.ResultsOur data identified an important role for mucosal LCs in facilitating HCV transmission after HIV‐1 exposure or immune activation. LCs were detected within mucosal anal tissues obtained from HIV‐1 positive MSM biopsies. In order to perform functional studies, we used primary LCs from skin, which have a similar phenotype as mucosal LCs. Immature LCs were neither infected nor transmitted HCV to hepatocytes. Notably, exposure to HIV‐1 significantly increased HCV transmission by LCs in the ex vivo transmission model. HIV‐1 replication was crucial for the increased HCV transmission as HIV‐1 inhibitors significantly reduced HIV‐1‐induced HCV transmission. Moreover, tissue immune activation of LCs also increased HCV transmission to target cells.ConclusionsThus, our data strongly indicate that HIV‐1 or immune activation in MSM leads to capture of HCV by mucosal LCs, which might facilitate transmission to other cells or allow entry of HCV into the blood. This novel transmission mechanism by LCs also implicates that the activation state of LCs is an important cellular determinant for HCV susceptibility after sexual contact.

Evaluation of topical corticosteroids in children with phimosis through morphological and immunohistochemical analyses of the foreskin.

Introduction:Histopathological analysis of the foreskin has become more common in the last two decades.Objectives:This study aims to analyze the morphology of the foreskin and determine the effects of topical corticosteroid therapy on this tissue.Materials and Methods:We retrospectively evaluated forty foreskin samples from children aged from 2 years to 15 years with phimosis undergoing circumcision at our institution over a 2-year period. In the foreskin samples, we analyzed the elastic fibers (Verhoeff), epidermal thickness (hematoxylin and eosin), and Annexin 1 and Langerhans cells (LCs) (immunohistochemistry).Results:In the present study, 18 (45%) patients made use of topical corticosteroids, and 22 (55%) did not, while 4 (10%) had a history of balanoposthitis as previous complication. Forty patients were divided according to the parameter analyzed: with or without previous complication and with or without previous topical corticotherapy. Annexin 1 expression was significantly higher in group with a history of complications when compared with group without complications (P = 0.024) and lower in the group of those who used corticosteroids when compared with those who did not used corticosteroids (P = 0.364). In the analysis of all samples, the density of mature LCs was significantly higher when compared with immature LCs (P < 0.0001). The density of immature LCs was significantly higher in patients without previous complications when compared with group with complications (P = 0.028).Conclusions:These findings contribute to a better understanding of the histopathological aspects of previous complications and of treatment with corticosteroids in children with phimosis.

The multiple faces of Langerhans cell histiocytosis in childhood: A gentle reminder.

Langerhans cell histiocytosis (LCH) is a rare hematologic disorder that results from the clonal multiplication and accumulation of immature dendritic Langerhans cells. Its reported incidence rate varies, but is considered to be 2.6-8.9 per million children who are <15 years of age each year. It may affect any system or organ. The present study reported 4 pediatric LCH cases in order to highlight the heterogeneity of the initial presentation, and the pitfalls that may mislead clinicians and delay diagnosis. The clinical features, as well as the pathognomonic imaging, pathology findings and treatment options were presented. LCH may be rare, but it should always be included in the differential diagnosis of persistent eczema, unexplained skin lesions, diabetes insipidus and persistent bone pain, among others. While the debate on pathogenesis and treatment is ongoing, high index of suspicion among pediatricians, pediatric oncologists and other specialists (pathologists, dermatologists, orthopaedic surgeons, general practitioners or family physicians) is essential for early diagnosis, and optimal outcome.