Density of Langerhans Cells in Nonmelanoma Skin Cancers: A Systematic Review

The roles of tissue resident macrophages in health and cancer

As integral components of the immune microenvironment, tissue resident macrophages (TRMs) represent a self-renewing and long-lived cell population that plays crucial roles in maintaining homeostasis, promoting tissue remodeling after damage, defending against inflammation and even orchestrating cancer progression. However, the exact functions and roles of TRMs in cancer are not yet well understood. TRMs exhibit either pro-tumorigenic or anti-tumorigenic effects by engaging in phagocytosis and secreting diverse cytokines, chemokines, and growth factors to modulate the adaptive immune system. The life-span, turnover kinetics and monocyte replenishment of TRMs vary among different organs, adding to the complexity and controversial findings in TRMs studies. Considering the complexity of tissue associated macrophage origin, macrophages targeting strategy of each ontogeny should be carefully evaluated. Consequently, acquiring a comprehensive understanding of TRMs' origin, function, homeostasis, characteristics, and their roles in cancer for each specific organ holds significant research value. In this review, we aim to provide an outline of homeostasis and characteristics of resident macrophages in the lung, liver, brain, skin and intestinal, as well as their roles in modulating primary and metastatic cancer, which may inform and serve the future design of targeted therapies.

Basal Cell Carcinoma in Xeroderma Pigmentosa: Reduced CD1a Expression as a Sensitive Predictor of Recurrence

Xeroderma pigmentosa (XP) is a rare genetic disorder that is characterized by defective DNA repair after ultraviolet induced damage with a great tendency for recurrent cutaneous malignancies including basal cell carcinoma (BCC). BCC is frequently linked to impaired local immune response with a major role played by Langerhans cells (LCs). The current study aims at investigating LCs in BCC specimens of XP and non-XP patients, in a trial to study its possible impact on tumor recurrence. It included 48 retrospective cases of primary facial BCC (18 for XP patients and 30 for non-XP controls). Each group was subdivided, based on the 5 years follow-up data, into recurrent and non-recurrent BCC groups. LCs were assessed immunohistochemically using the sensitive marker; CD1a. Results showed significantly reduced LCs count (intratumoral, peritumoral, and in perilesional epidermis) in XP patients compared with non-XP controls ( P ˂0.001 for all). Intratumoral ( P =0.008), peritumoral ( P =0.005), and perilesional epidermal ( P =0.02) LCs mean values were significantly lower in recurrent versus non-recurrent BCC specimens. Also, within each group (XP and controls), LCs were of significantly lower means in recurrent versus non-recurrent cases ( P ≤0.001 for all). Regarding recurrent BCC cases, peritumoral LCs showed a significant positive correlation with 1ry BCC duration ( P =0.05). Also, intratumoral and peritumoral LCs correlated positively with BCC relapse interval ( P =0.04 for both). Among non-XP controls, periocular tumors had the least LCs count (22.00±3.56), whereas tumors located in the rest of the face had the greatest count (29.00±0.00) ( P =0.02). Sensitivity and specificity of LCs to predict BCC recurrence in XP patients reached 100% in intartumoral area and perilesional epidermis when cutoff points were less than 9.5 and 20.5, respectively. In conclusion; reduced LC count in primary BCC specimens of XP patients and also in normal subjects could help to predict its recurrence. Thus, it might be identified as a risk factor for relapse to apply new strict therapeutic and preventive measures. This presents new avenue for the immunosurveillance against skin cancer relapse. However, being the first study to investigate that link in XP patients recommends further research to confirm.

Galectin-9 expression clinically associated with mature dendritic cells infiltration and T cell immune response in colorectal cancer

BACKGROUND

Galectin-9 is a member of the galectin family and has been reported to have a tumor-promoting or antitumor effect in response to the immune microenvironment. However, the immunomodulatory effect of galectin-9 in colorectal cancer (CRC) remains unclear. The antigen presentation and antitumor immune effects of galectin-9 in CRC were examined in this study.

METHODS

The expression of galectin-9, dendritic cell markers (CD208 and CD1a), T-cell markers (CD3 and CD8) and mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6) was assessed using immunohistochemistry in CRC samples. The correlation between galectin-9 and immune cells or immunomodulatory factors was also evaluated via multiple gene expression databases.

RESULTS

The level of galectin-9 was decreased in mismatch repair-proficient patients compared with mismatch repair-deficient patients (p = 0.0335). GSEA showed that the regulatory mechanism of galectin-9 in CRC was related to a variety of immune pathways. Galectin-9 expression was strongly correlated with immune cell infiltration and immunomodulators (all p < 0.0001). In the relationship between galectin-9 expression and the infiltration of DCs, there was a negative correlation in CD1a + immature DCs (R = -0.263, p = 0.042). A strong positive correlation was observed in CD208 + mature DCs (R = 0.391, p < 0.01). Patients with high galectin-9 expression also exhibited abundant CD8 + T-cell and CD3 + T-cell infiltration.

CONCLUSION

Collectively, our findings provide evidence that galectin-9 may increase the antitumor immune response of patients with CRC. DCs play an important role in galectin-9-mediated antitumor immune responses, which provides further insight into the development of immunotherapy.

The Roles of Skin Langerhans Cells in Immune Tolerance and Cancer Immunity

Langerhans cells (LC) are a unique population of tissue-resident macrophages with dendritic cell (DC) functionality that form a network of cells across the epidermis of the skin. Their location at the skin barrier suggests an important role for LC as immune sentinels at the skin surface. The classification of LC as DC over the past few decades has driven the scientific community to extensively study how LC function as DC-like cells that prime T cell immunity. However, LC are a unique type of tissue-resident macrophages, and recent evidence also supports an immunoregulatory role of LC at steady state and during specific inflammatory conditions, highlighting the impact of cutaneous environment in shaping LC functionality. In this mini review, we discuss the recent literature on the immune tolerance function of LC in homeostasis and disease conditions, including malignant transformation and progression; as well as LC functional plasticity for adaption to microenvironmental cues and the potential connection between LC population heterogeneity and functional diversity. Future investigation into the molecular mechanisms that LC use to integrate different microenvironment cues and adapt immunological responses for controlling LC functional plasticity is needed for future breakthroughs in tumor immunology, vaccine development, and treatments for inflammatory skin diseases.

Microneedle-based two-step transdermal delivery of Langerhans cell-targeting immunoliposomes induces a Th1-biased immune response

Novel Coronavirus is affecting human's life globally and vaccines are one of the most effective ways to combat the epidemic. Transcutaneous immunization based on microneedle (MN) has attracted much attention because of its painlessness, rapidity, high efficiency and good compliance. In this study, CD11c monoclonal antibody-immunoliposomes (OVA@CD11c-ILP) actively targeting to Langerhans cells (LCs) were successfully prepared and were delivered by the microchannels of skin produced by MN to induce an immune response in vivo. OVA@CD11c-ILP could be targeted to LCs by conjugating CD11c monoclonal antibody to the surface of the ILP. OVA@CD11c-ILP promoted the maturation of dendritic cells (DCs) and the uptake and endocytosis of antigen by LCs. Moreover, OVA@CD11c-ILP immunization can significantly inhibit tumor growth and prolong overall survival. Furthermore, a higher antibody's titer ratio of IgG1/IgG2a indicated that the immune response stimulated by this immunization method was Th1-biased and the liposomes showed Th1-type adjuvant effect. In conclusion, the combination delivery system of immunoliposomes and microneedle can significantly improve the efficiency of antigen presentation and effectively activate cellular immune responses in the body, which is expected to be a promising transdermal immune strategy.

A robust experimental and computational analysis framework at multiple resolutions, modalities and coverages

The ability to study cancer-immune cell communication across the whole tumor section without tissue dissociation is needed, especially for cancer immunotherapy development, which requires understanding of molecular mechanisms and discovery of more druggable targets. In this work, we assembled and evaluated an integrated experimental framework and analytical process to enable genome-wide scale discovery of ligand-receptors potentially used for cellular crosstalks, followed by targeted validation. We assessed the complementarity of four different technologies: single-cell RNA sequencing and Spatial transcriptomic (measuring over >20,000 genes), RNA In Situ Hybridization (RNAscope, measuring 4-12 genes) and Opal Polaris multiplex protein staining (4-9 proteins). To utilize the multimodal data, we implemented existing methods and also developed STRISH (Spatial TRanscriptomic In Situ Hybridization), a computational method that can automatically scan across the whole tissue section for local expression of gene (e.g. RNAscope data) and/or protein markers (e.g. Polaris data) to recapitulate an interaction landscape across the whole tissue. We evaluated the approach to discover and validate cell-cell interaction in situ through in-depth analysis of two types of cancer, basal cell carcinoma and squamous cell carcinoma, which account for over 70% of cancer cases. We showed that inference of cell-cell interactions using scRNA-seq data can misdetect or detect false positive interactions. Spatial transcriptomics still suffers from misdetecting lowly expressed ligand-receptor interactions, but reduces false discovery. RNAscope and Polaris are sensitive methods for defining the location of potential ligand receptor interactions, and the STRISH program can determine the probability that local gene co-expression reflects true cell-cell interaction. We expect that the approach described here will be widely applied to discover and validate ligand receptor interaction in different types of solid cancer tumors.

Trauma of Peripheral Innervation Impairs Content of Epidermal Langerhans Cells

Langerhans cells represent the first immune cells that sense the entry of external molecules and microorganisms at the epithelial level in the skin. In this pilot case-study, we evaluated Langerhans cells density and progression of epidermal atrophy in permanent spinal cord injury (SCI) patients suffering with either lower motor neuron lesions (LMNSCI) or upper motor neuron lesions (UMNSCI), both submitted to surface electrical stimulation. Skin biopsies harvested from both legs were analyzed before and after 2 years of home-based Functional Electrical Stimulation for denervated degenerating muscles (DDM) delivered at home (h-bFES) by large anatomically shaped surface electrodes placed on the skin of the anterior thigh in the cases of LMNSCI patients or by neuromuscular electrical stimulation (NMES) for innervated muscles in the cases of UMNSCI persons. Using quantitative histology, we analyzed epidermal thickness and flattening and content of Langerhans cells. Linear regression analyses show that epidermal atrophy worsens with increasing years of LMNSCI and that 2 years of skin electrostimulation reverses skin changes, producing a significant recovery of epidermis thickness, but not changes in Langerhans cells density. In UMNSCI, we did not observe any statistically significant changes of the epidermis and of its content of Langerhans cells, but while the epidermal thickness is similar to that of first year-LMNSCI, the content of Langerhans cells is almost twice, suggesting that the LMNSCI induces an early decrease of immunoprotection that lasts at least 10 years. All together, these are original clinically relevant results suggesting a possible immuno-repression in epidermis of the permanently denervated patients.

Role of Group 1 CD1-Restricted T Cells in Host Defense and Inflammatory Diseases

Group 1 CD1-restricted T cells are members of the unconventional T cell family that recognize lipid antigens presented by CD1a, CD1b, and CD1c molecules. Although they developmentally mirror invariant natural killer T cells, they have diverse antigen specificity and functional capacity, with both anti-microbial and autoreactive targets. The role of group 1 CD1-restricted T cells has been best established in Mycobacterium tuberculosis (Mtb) infection in which a wide variety of lipid antigens have been identified and their ability to confer protection against Mtb infection in a CD1 transgenic mouse model has been shown. Group 1 CD1-restricted T cells have also been implicated in other infections, inflammatory conditions, and malignancies. In particular, autoreactive group 1 CD1-restricted T cells have been shown to play a role in several skin inflammatory conditions. The prevalence of group 1 CD1 autoreactive T cells in healthy individuals suggests the presence of regulatory mechanisms to suppress autoreactivity in homeostasis. The more recent use of group 1 CD1 tetramers and mouse models has allowed for better characterization of their phenotype, functional capacity, and underlying mechanisms of antigen-specific and autoreactive activation. These discoveries may pave the way for the development of novel vaccines and immunotherapies that target group 1 CD1-restricted T cells.

Immunohistochemical analysis of the aggregation of CD1a-positive dendritic cells in resected specimens and its association with surgical outcomes for patients with gallbladder cancer

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We examined CD1a-positive dendritic cell (CD1a-DC) infiltration in gallbladder cancer.

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The group with high CD1a-DC infiltration had fewer patients with distant metastasis.

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A high level of CD1a-DC infiltration was associated with longer overall survival.

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High CD1a-DC infiltration was also associated with longer disease-specific survival.

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S100-DC and tumor-infiltrating lymphocyte statuses were without effect on survival.

Gallbladder cancer (GBC) is an aggressive malignancy with a poor prognosis. Antigen-presenting dendritic cells (DCs) play a central role in antitumor immunity. DCs expressing CD1a (CD1a-DCs) are considered immature DCs. The aim of this study was to evaluate the clinical impact of CD1a-DC infiltration into GBC tissue. Seventy-five patients with GBC (excluding non-invasive and intramucosal cancer) were enrolled. Immunohistochemistry for CD1a, S100 and CD8 was performed using representative surgically resected specimens. The cases were divided into a high CD1a-DC group (27 cases, 36%) and low CD1a-DC group (48 cases, 64%) according to the degree of CD1a-DC infiltration/aggregation. The high CD1a-DC group contained fewer patients with distant metastasis (P = 0.039) and more patients given postoperative chemotherapy (P = 0.038). The high CD1a-DC group had significantly longer overall survival (P = 0.001) and disease-specific survival (P = 0.002) than the low CD1a-DC group. In contrast, S100-DC and CD8+ tumor-infiltrating lymphocyte statuses were without effect on OS or DSS. The results of multivariate analyses indicated that the degree of infiltration/aggregation of CD1a-DCs was an independent prognostic factor associated with a favorable prognosis after surgery.