Targeting epidermal Langerhans cells by epidermal powder immunization

Immune reactions to foreign or self-antigens lead to protective immunity and, sometimes, immune disorders such as allergies and autoimmune diseases. Antigen presenting cells (APC) including epidermal Langerhans cells (LCs) play an important role in the course and outcome of the immune reactions. Epidermal powder immunization (EPI) is a technology that offers a tool to manipulate the LCs and the potential to harness the immune reactions towards prevention and treatment of infectious diseases and immune disorders.

The role of Langerhans cells in oral squamous cell carcinoma

During the initiation, promotion, and progression of multi-step carcinogenesis, changes in specific host immuno- logical factors have been observed. Although immunology of oral cancer has long been focused on antigens and lymphocytes, the fact remains that the antigen presenting cells, like the Langerhans cells （LCs） of the epithelium are initiators and modulators of the immune response. LCs as sentinels of immune response, have been investigated in several orai mucosal diseases, including cancer. Inadequate presentation of tumor antigens by host dendritic cells is one potential mechanism that allows tumor progression, tn this review, the role of LCs in OSCC is discussed. Elucidation of the role of APCs, in particular LCs, may help to better understand the mechanisms underlying anti-tumour immune responses and, improve the effectiveness of anti-cancer immunity in tumour-bearing hosts. This section focuses on the roles LCs in the immunity of cancer and how cancer bypasses the dendritic cell-mediated immune responses, are discussed. Subsequently, the effects of tumor microenviornment on LC＇s and their therapeutic implications are elaborated.

Recurrent multisystem Langerhans cell histiocytosis involving the female genitalia: A case report

BACKGROUND Langerhans cell histiocytosis(LCH)is a histiocytic proliferative disease caused by clonal proliferation of Langerhans cells,which is currently defined as an inflam-matory myeloid tumor.It is rare in adults,with an incidence of 1–2 per million,and is highly heterogeneous in clinical presentation,with unpredictable disease progression and outcome.CASE SUMMARY A 52-year-old postmenopausal female patient presented to the gynecology department in July 2023 with bilateral vulvar masses.She was diagnosed with recurrent multisystem LCH.The patient had previously been diagnosed with a single-system and single-focal LCH in October 2021 due to a right maxillofacial mass,which resolved after surgical treatment.A chemotherapy regimen was developed after multidisciplinary consultation.Six cycles of chemotherapy resulted in partial remission,and maintenance chemotherapy is currently being administered.CONCLUSION Recurrent LCH involving the bilateral vulva has been poorly reported.Compre-hensive imaging and pathological evaluation is important for diagnosis.The model of joint multidisciplinary specialist diagnosis and treatment is worthy of clinical application.

Multisystemic recurrent Langerhans cell histiocytosis misdiagnosed with chronic inflammation at the first diagnosis:A case report

BACKGROUND Langerhans cell histiocytosis(LCH)is characterized by diabetes insipidus and is an uncommon occurrence.Pathological biopsies still have a certain degree of diagnostic probability.We present a case in which LCH initially affected the pituitary gland.This resulted in a misdiagnosis of chronic inflammation upon pathological examination.CASE SUMMARY A 25-year-old female exhibited symptoms of diabetes insipidus.Magnetic resonance imaging revealed an enhanced foci in the pituitary gland.After surgical resection of the pituitary lesion,the pathological diagnosis was chronic inflam-mation.However,the patient later experienced bone destruction in the skull and lower limb bones.After the lower limb bone lesion was compared with the initial pituitary lesion,the final diagnosis was modified to LCH.The patient was treated with multiple chemotherapy courses.However,the patient’s condition gradually worsened,and she eventually passed away at home.CONCLUSION LCH should be considered when patients exhibit diabetes insipidus and absence of high signal intensity in the pituitary gland on sagittal T1-weighted image and abnormal enhancement in the pituitary region.

Langerin-mediated internalization of a modified peptide routes antigens to early endosomes and enhances cross-presentation by human Langerhans cells

The potential of the skin immune system to generate immune responses is well established, and the skin is actively exploited as a vaccination site. Human skin contains several antigen-presenting cell subsets with specialized functions. In particular, the capacity to cross-present exogenous antigens to CD8^＋ T cells is of interest for the design of effective immunotherapies against viruses or cancer. Here, we show that primary human Langerhans cells （LCs） were able to cross-present a synthetic long peptide （SLP） to CD8^＋ T cells. In addition, modification of this SLP using antibodies against the receptor langerin, but not dectin-1, further enhanced the cross-presenting capacity of LCs through routing of internalized antigens to less proteolytic early endosome antigen 1 ^＋ early endosomes. The potency of LCs to enhance CD8^＋ T-cell responses could be further increased through activation of LCs with the toll-like receptor 3 ligand polyinosinic：polycytidylic acid （phC）. Altogether, the data provide evidence that human LCs are able to cross-present antigens after langerin-mediated internalization. Furthermore, the potential for antigen modification to target LCs specifically provides a rationale for generating effective anti-tumor or anti-viral cytotoxic T lymphocyte responses.

Langerhans cell histiocytosis misdiagnosed as thyroid malignancy: A case report

BACKGROUND The incidence of Langerhans cell histiocytosis(LCH) is low, and involvement of the thyroid is even rarer, which results in high missed diagnosis or misdiagnosis rates.CASE SUMMARY We report a young woman with a thyroid nodule. Thyroid malignancy was suggested by fine needle aspiration, but she was eventually diagnosed with multisystem LCH, thus avoiding thyroidectomy.CONCLUSION The clinical manifestations of LCH involving the thyroid are atypical, and the diagnosis depends on pathology. Surgery is the main method for treating primary thyroid LCH, while chemotherapy is the main treatment method for multisystem LCH.

Adult localized Langerhans cell histiocytosis:A case report

BACKGROUND Langerhans cell histiocytosis(LCH)is a rare clonal proliferative disease of Langerhans cells with unknown pathogenesis.An increasing number of clinicians recognize that LCH has a wide clinical spectrum and a highly varied course.Adults rarely develop LCH.Here,we report a case of adult localized LCH.CASE SUMMARY A 32-year-old woman presented with plaques and ulcers on the vulva and crissum,accompanied by pain that persisted for more than one year.Physical examination revealed a red-infiltrating plaque with ulcerations and exudates in the vulva and crissum.Pathological examination revealed a diffuse infiltration of lymphocytes,eosinophilic granulocytes,and histiocytoid cells in the superficial dermis.Proliferative histiocytoid cells showed mild atypia,partly with kidneyshaped nuclei.Immunohistochemical examination showed that the histiocytoid cells were positive for S100 protein and CD1 and weakly positive for CD68(20%+),with a Ki-67 index of 30%.Laboratory tests did not reveal any other systemic damage.The patient was diagnosed with adult localized LCH and was prescribed oral prednisone(20 mg)once daily.The skin lesions gradually improved and are still being followed-up.CONCLUSION Adult localized LCH is rare and must be differentiated from other common conditions.

Corneal subepithelial nerve fibers in type 2 diabetes:potential biomarker of diabetic neuropathy

AIM:To observe the changes in corneal subepithelial nerve fibers(CNFs)and Langerhans cells(LCs)in patients with type 2 diabetes using corneal laser confocal microscopy(CLCM).METHODS:A total of 60 patients(64 eyes),including 40 patients with type 2 diabetes(DM group)and 20 subjects without diabetes(control group)were included with CLCM.Neuron J plugin of Image J software were used for quantitative analysis of CNF length(CNFL),CNF density(CNFD),corneal nerve branch fiber density(CNBD),main branch length density,branch length density,corneal nerve fiber tortuosity(NT)score,and LCs density.An independent samples t-test to analyze the variability between the two groups was performed,and Pearson correlation analysis was used to analyze the relationships between CNF and multiple biochemical indicators in the DM group.The predictive power of CNF for type 2 diabetes was assessed using the receiver operating characteristic(ROC)curve.RESULTS:There were significant differences in the CNFL,CNFD,and main branch length density between two groups.The results of Pearson correlation analysis showed a significant negative correlation between CNFD and the duration of diabetes as well as triglyceride levels and total cholesterol,and a significant positive correlation between CNFD and serum albumin.In addition,the NT score showed a positive correlation and urea nitrogen,similar to the positive correlation observed between LC density and glycosylated hemoglobin(HbA1c)levels.CNFD showed the highest area under the curve(AUC of ROC)value,followed by main branch length density and CNFL.The AUC of the ROC curve under the logistic regression model also demonstrated good predictive values.The cut-off values of CNFD,CNFL,and main branch length density for diabetes showed 31.25,18.85,and 12.56,respectively.CONCLUSION:In patients with type 2 diabetes,there is a notable reduction in both CNFL and CNFD.These measurements can be influenced by various blood biochemical factors.However,the compromised nerve fibers can serve as valuable indicators for predicting the onset of type 2 diabetes and also as biomarkers for detecting diabetic neuropathy and its related complications.

A rare case of langerhans cell histiocytosis of the gastrointestinal tract

Langerhans cell histiocytosis （LCH） is a group of idiopathic disorders characterized by the proliferation of specialized, bone marrow-derived langerhans cells and mature eosinophils. The clinical spectrum ranges from an acute, fulminant, disseminated disease called Letterer Siwe disease to solitary or few, indolent and chronic lesions of the bone or other organs called eosinophilic granuloma. Involvement of the gastrointestinal tract is very rare in LCH. We present the case of a 53-year-old woman referred by her primary care physician for a screening colonoscopy. A single sessile polyp, measuring 4 mm in size, was found in the rectum. Histopathological examination revealed that the lesion was relatively well circumscribed and comprised mainly a mixture of polygonal cells with moderate-to-abundant pink slightly granular cytoplasm. The nuclei within these cells had frequent grooves and were occasionally folded. Immunohistochemical staining was positive for CD la which confirmed the diagnosis of LCH. On further workup, there was no evidence of involvement of any other organ. On follow up colonoscopy one year later, there was no evidence of disease recurrence. Review of the published literature revealed that LCH presenting as solitary colonic polyp is rare. However, with the increasing rates of screening colonoscopy, more colonic polyps may be identified as LCH on histopathology. This underscores the importance of recognizing this rare condition and ensuring proper follow-up to rule out systemic disease.

Hepatic Langerhans cell histiocytosis:A review

Hepatic Langerhans cell histiocytosis(LCH)is characterized by proliferation and accumulation of Langerhans cells in the liver,causing liver dysfunction or forming a mass lesion.The liver can be involved in isolation,or be affected along with other organs.A common clinical hepatic presentation is cholestasis with pruritis,fatigue and direct hyperbilirubinemia.In late stages,there may be hypoalbuminemia.Liver biopsy may be required for the diagnosis of hepatic LCH.Histologic finding may be diverse,including lobular Langerhans cell infiltrate with mixed inflammatory background,primary biliary cholangitis-like pattern,sclerosing cholangitis-like pattern,and even cirrhosis at later stages.Because of its non-specific injury patterns with broad differential diagnosis,establishing a diagnosis of hepatic LCH can be challenging.Hepatic LCH can easily be missed unless this diagnosis is considered at the time of biopsy interpretation.A definitive diagnosis relies on positive staining with CD1a and S100 antigen.Liver involvement is a high risk feature in LCH.The overall prognosis of hepatic LCH is poor.Treating at an early stage may improve the outcome.Systemic chemotherapy is the mainstay of treatment and liver transplantation may be offered.New molecular markers involved in pathogenesis of LCH are being explored with a potential for targeted therapy.However,further studies are needed to improve outcome.

Langerhans cell histiocytosis masquerading as acute appendicitis: Case report and review

Langerhans cell histiocytosis(LCH) is a rare syndrome characterized by unifocal,multifocal unisystem,or disseminated/multi-system disease that commonly involves the bone,skin,lymph nodes,pituitary,or sometimes lung(almost exclusively in smokers) causing a variety of symptoms from rashes and bone lesions to diabetes insipidus or pulmonary infiltrates.We present a previously unreported case of gastrointestinal LCH as well as a novel characteristic lesion affecting the colon of a young woman who presented with signs and symptoms mimicking acute on chronic appendicitis.Immunohistochemical analysis of appendectomy specimen and nodular specimens on colonoscopy demonstrated S-100,CD1a,and langerin reactivity.The patient underwent systemic chemotherapy with cytarabine and demonstrated excellent response to therapy.

Solitary Langerhans cell histiocytosis of frontal lobe: a case report and literature review

The brain parenchymal Langerhans cell histiocytosis （LCH） without systemic disease or lytic skull lesions is extremely rare. We report a 23-year-old male presenting with new onset 1 hour seizure with loss of consciousness 20 days prior to admission, and recurrent seizure 2 weeks later. Brain magnetic resonance imaging （MRI） showed an irregularly mass with enhancement involving the right frontal lobe. Microscopically, the lesion was characterized by sheets of Langerhans cells in addition to reactive inflammatory elements. Immunohistochemically, Langerhans cells were positive for Langerin, CDla and S-100 protein. The patient received no chemotherapy or radiotherapy after surgery. After 24 months of follow-up, no recurrence or other systemic lesions were observed. Although there is no standard treatment for solitary cerebral LCH, the prognosis generally appears to be good.

Current perspectives on the role of liver transplantation for Langerhans cell histiocytosis:A narrative review

Langerhans cell histiocytosis(LCH)is a malignant disease of the histiocytes involving various organ systems.The spectrum of liver involvement in LCH ranges from mild transaminitis to end-stage liver disease.The hallmark of hepatic LCH is secondary sclerosing cholangitis,which manifests due to a progressive destruction of the biliary tree by malignant histiocytes.Chemotherapy remains the mainstay of treatment for active LCH.Early recognition,diagnosis and a systematic approach to the management of LCH can ameliorate the disease process.Nonetheless,the liver involvement in these patients may progress despite the LCH being in remission.Liver transplantation(LT)remains central in the management of such patients.Various facets of the management of LCH,especially those with liver involvement remain unclear.Furthermore,aspects of LT in LCH with regards to the indication,timing and post-LT management,including immunosuppression and adjuvant therapy,remain undefined.This review summarises the current evidence and discusses the practical aspects of the role of LT in the management of LCH.

A NEW LOOK AT LANGERHANS CELL HISTIOCYTOSIS: REVIEW OF A SERIES OF 55 CASES

Objective: Langerhans cell histiocytosis (LCH) has been well described only in children. We analyzed the characteristics, reactivation, and outcome of LCH in a cohort of 55 patients across all ages. Methods: We reviewed the records of all patients with LCH treated at a single institute between Jan. 1974 and May 1998. Results: The 55 patients were 2 to 67 years of age (median, 31 years) at the time of diagnosis, and 85.5% were male. Forty patients (72.7%) had single-system LCH; Fifteen (27.3%) had multisystem disease. The head and neck was the most frequent tumor site (63.6%). LCH was not found in organs at risk of involvement (liver, spleen, bone marrow, and lungs). The frequency of bony invasion (23.6% overall) differed significantly according to age ≤15 years (66.7%) vs. age >15 years (11.6%) (P=0.0005). At a median follow-up of 12 years, no patient died of LCH. The 5, 10-year survival estimates were 100%. The 5, 10-year disease-free survival estimates were 70.9% and 58.4%. The 5-year disease-free survival estimate was 58.3% for age ≤ 15 years vs. 74.4% for age >15 years (P=0.83) and 75% for single-system disease vs. 60% for multisystem disease (P=0.13). LCH was reactivated in 43.6% of patients, with a median of 14 months (range, 2-180 months). Three patients with recurrent disease experienced spontaneous remission. At the time of the most recent follow-up, 23.6% of survivors had active disease. Conclusion: LCH is not found exclusively in children and adolescents. The frequency of bone invasion is inversely related to age. Reactivation is very common regardless of the type of treatment, but the prognosis is generally good.

Langerhans cell histiocytosis involving only the thymus in an adult: A case report

BACKGROUND Langerhans cell histiocytosis(LCH)is a rare disease of unknown etiology.LCH involving the thymus is mainly seen in pediatric patients and is extremely rare in adults.In this report,we describe a rare case of LCH originating from the thymus in an adult.CASE SUMMARY A 56-year-old man was admitted in April 2022 with complaints of intermittent dizziness since 2020,which had worsened in the previous 10 d.The physical chest examination was negative,and there was a history of hypertension for>2 years.Chest computed tomography showed a nodular soft tissue density shadow in the anterior mediastinum measuring approximately 13 mm×9 mm×8 mm.Postoperative pathological findings confirmed the diagnosis of LCH.CONCLUSION It is challenging to differentiate LCH involving the thymus from thymoma in imaging features.Pathological biopsy remains the gold standard when an anterior mediastinal occupying lesion is found.

Multisystem involvement Langerhans cell histiocytosis in an adult:A case report

BACKGROUND Langerhans cell histiocytosis(LCH)is a rare condition wherein Langerhans cells proliferate abnormally,adversely impacting organs including lymph nodes,bones,skin,lungs,and pituitary gland.The LCH disease course varies widely among patients from a self-limiting condition to one that progresses rapidly and culminates in death.It is uncommon for multisystem LCH to be observed in adults.Herein we describe a woman suffering from multi-system LCH involvement.CASE SUMMARY A 37-year old Chinese woman was admitted to the hospital in June 2019 suffering from dyspnea that had progressed over the course of 5 years.Her medical history included:central diabetes insipidus(DI)that had been treated via radiotherapy,desmopressin acetate,and bromocriptine;bilateral pneumothorax with two surgeries having been performed to remove bullae;and autoimmune hepatitis that had been unsuccessfully treated using a combination of methylprednisolone and mycophenolate mofetil.A chest computed tomography(CT)scan revealed the presence of multiple pulmonary cysts of varying sizes.We re-analyzed right pulmonary bullae samples that had been removed in 2014,performed a systematic 18 F-FDG PET/CT analysis,and convened a multidisciplinary medical team to diagnose and treat this patient.As a result,we were able to eventually diagnose this patient with LCH that was not associated with BRAF-V600 E mutations.CONCLUSION We hope to emphasize the importance of systemic evaluation and of cooperation between multidisciplinary physicians with the goal of improving awareness and detection of this orphan disease.

Conjunctival Langerhans Cell Histiocytosis: a Case Report

LANGERHANS cell histiocytosis(LCH)is a rare disease,mainly involving the bone,skin,lung,liver,spleen,and skin.1 The heterogenenous nature of LCH makes it difficult to diagnose.Not only do the involved organs vary from case to case,but also its natural history.Herein,we describe a rare case of conjuctival LCH in an Asian woman.

Langerhans cell histiocytosis presenting as an isolated brain tumour:A case report

Langerhans cell histiocytosis(LCH)is a rare proliferative histiocyte disorder.It can affect any organ or system,especially the bone,skin,lung,and central nervous system(CNS).In the CNS,the hypothalamic-pituitary is predominantly affected,whereas the brain parenchyma is rarely affected.LCH occurring in the brain parenchyma can be easily confused with glioblastoma or brain metastases.Thus,multimodal imaging is useful for the differential diagnosis of these intracerebral lesions and detection of lesions in the other organs.CASE SUMMARY A 47-year-old man presented with a headache for one week and sudden syncope.Brain computed tomography(CT)and magnetic resonance imaging showed an irregularly shaped nodule with heterogeneous enhancement.On^(18)F-fluorodeoxyglucose(^(18)F-FDG)positron emission tomography/CT,a nodule with^(18)F-FDG uptake and multiple cysts in the upper lobes of both lungs were noted,which was also confirmed by high-resolution CT.Thus,the patient underwent surgical resection of the brain lesion for further examination.Postoperative pathology confirmed LCH.The patient received chemotherapy after surgery.No recurrence was observed in the brain at the 12-mo follow-up.CONCLUSION Multimodal imaging is useful for evaluating the systemic condition of LCH,developing treatment plans,and designing post-treatment strategies.

Two smoking-related lesions in the same pulmonary lobe of squamous cell carcinoma and pulmonary Langerhans cell histiocytosis:A case report

BACKGROUND Pulmonary Langerhans cell histiocytosis(PLCH)is a rare cystic lung disease usually affecting young adults.It is predicted that PLCH is a lung tumor precursor associated with dysfunction of the myeloid dendritic cells in the lung.CASE SUMMARY A 70-year-old male patient presented with chronic cough and sputum.He had symptoms for 5 years and described shortness of breath on exertion for the previous 3 years.He had a 60 packs/year smoking history.Computerized tomography of the thorax revealed an 11-mm nodule in the right lung lower lobe superior segment and a 7-mm nodule in the right lung lower lobe poster basal segment.Those two nodules were resected by means of right thoracoscopic surgery.Pathological evaluation revealed a squamous cell carcinoma and PLCH.CONCLUSION Coexistent squamous cell carcinoma and PLCH suggest possible association between PLCH and lung cancer.