CD116+ fetal precursors migrate to the perinatal lung and give rise to human alveolar macrophages

Despite their importance in lung health and disease, it remains unknown how human alveolar macrophages develop early in life. Here we define the ontogeny of human alveolar macrophages from embryonic progenitors in vivo, using a humanized mouse model expressing human cytokines (MISTRG mice). We identified alveolar macrophage progenitors in human fetal liver that expressed the GM-CSF receptor CD116 and the transcription factor MYB. Transplantation experiments in MISTRG mice established a precursor–product relationship between CD34−CD116+ fetal liver cells and human alveolar macrophages in vivo. Moreover, we discovered circulating CD116+CD64−CD115+ macrophage precursors that migrated from the liver to the lung. Similar precursors were present in human fetal lung and expressed the chemokine receptor CX3CR1. Fetal CD116+CD64− macrophage precursors had a proliferative gene signature, outcompeted adult precursors in occupying the perinatal alveolar niche, and developed into functional alveolar macrophages. The discovery of the fetal alveolar macrophage progenitor advances our understanding of human macrophage origin and ontogeny.

A distinct CD115- erythro-myeloid precursor present at the maternal-embryonic interface and in the bone marrow of adult mice

During ontogeny, macrophages develop from CD115+ precursors, including erythro-myeloid progenitors (EMP). EMP arise in the embryonic yolk sac, the primary site of early haematopoiesis. In adults, CD115+ bone marrow-derived monocytes represent essential macrophage precursors. Herein, we identify a CD115- macrophage precursor within the adult bone marrow that is unrelated to the classical monocyte lineage but rather shares transcriptomic and functional characteristics of embryonic EMP. These EMPROR (for Erythro Myeloid Precursor) cells are capable of efficiently generating macrophages in disease settings. During early development, EMPROR cells were largely absent from the yolk sac but were instead found at the embryonic-maternal interface in the uterine wall. Unexpectedly, the latter site contains robust haematopoietic activity and harbours defined embryonic haematopoietic progenitor cells, including classical CD115+ EMP. Our data suggest the existence of an alternative pathway of macrophage generation in the adult. Further, we uncover a hitherto unknown site of earliest blood cell development.

Differentiation of blood monocytes and features of the cytokine status in patients with lung tuberculosis

Введение. При клинической манифестации туберкулеза легких альвеолярные макрофаги накапливают микобактерии и перестают выполнять свои эффекторные функции. Это связано с конверсией их провоспалительного фенотипа М1 в противовоспалительный М2, что способствует хронизации инфекции. Научная гипотеза исследования предполагает влияние цитокинового статуса организма на поляризацию моноцитов в крови в процессе их миграции к очагу воспаления, определяя дифференцировку и пути активации макрофагов в тканях. Цель исследования - оценка иммунофенотипа моноцитов крови и исследование in vitro уровня секреции иммунорегуляторных цитокинов мононуклеарными лейкоцитами периферической крови у больных с различными клиническими формами туберкулеза легких. Методика. Обследовано 65 пациентов с впервые выявленным туберкулезом легких. Материалом исследования служили венозная кровь и мононуклеарные лейкоциты периферической крови. Исследование иммунофенотипа моноцитов проводили методом проточной цитометрии (цитофлуориметр Cytoflex, Becman Coulter, США) в цельной крови с использованием моноклональных антител («eВioscience», США). Обработку полученных данных проводили с помощью программы «CytExpert 2.0». Определяли количество клеток экспрессирующих поверхностные маркеры: CD14, CD163, CD204 и HLA-DR. Содержание цитокинов (IL-2, IL-10, TGFβ) в супернатантах клеточных культур оценивали с помощью твердофазного иммуноферментного анализа (ELISA). Результаты. Полученные результаты позволяют предположить, что при общем снижении численности циркулирующих CD14-позитивных моноцитов крови у больных туберкулезом легких, независимо от его клинической формы сохраняется высокая экспрессия маркеров активации клеток как по провоспалительному фенотипу М1 (HLA-DR-позитивные моноциты), так и противовоспалительному фенотипу М2 (CD163-позитивные моноциты). При диссеминированной форме заболевания повышается количество противовоспалительных CD204-позитивных моноцитов, предшественников М2-макрофагов, что свидетельствует о доминировании супрессорного типа иммунного ответа. Анализ цитокинового статуса in vitro показал, что течение болезни сопровождается угнетением эффекторных иммунных реакций и повышением уровня противовоспалительных цитокинов. Выявленные изменения в равной степени могут быть как причиной, так и следствием дефицита секреции IL-2. Показано также, что уровень секреции медиаторов с супрессорными эффектами (IL-10, TGFβ) меняется в зависимости от клинической формы заболевания и чувствительности возбудителя к противотуберкулезным препаратам: гиперсекреция IL-10 отмечается у больных с инфильтративным лекарственно-чувствительным, а TGFβ - при диссеминированном лекарственно-устойчивом туберкулезе легких. Заключение. Особенности дифференциации моноцитов крови у больных туберкулезом легких позволили прийти к заключению, что предшественники макрофагов - моноциты, уже в кровотоке начинают экспрессировать маркеры, характерные для разных по функциям М1- и М2-макрофагов, c поляризацией в направлении М2-иммунофенотипа. Следовательно, при развитии туберкулеза легких реализуются механизмы цитокиновой регуляции, подавляющие активацию врожденного иммунитета, что, возможно, является причиной хронизации воспалительного процесса в легких и формирования иммунодефицита индуцированного Mycobacterium tuberculosis. In clinical manifestation of pulmonary tuberculosis, alveolar macrophages perform as a reservoir where they accumulate mycobacteria and lose their effector functions due to the pathological conversion of macrophage pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, which provides transition to chronic infection. The study hypothesis suggested that the cytokine status, as evaluated by leukocyte secretion of cytokines in vitro, influences the monocyte polarization in the blood during their migration to the inflammatory focus, thereby determining differentiation and pathways of macrophage activation in tissues. The aim of this work was to assess the immunophenotype of blood monocytes and the in vitro secretion of immunoregulatory cytokines by mononuclear peripheral blood leukocytes from patients with different clinical forms of pulmonary tuberculosis taking into account the pathogen sensitivity to major anti-tuberculosis drugs. Methods. 65 patients with newly diagnosed pulmonary tuberculosis were evaluated. The study material was venous blood and peripheral blood mononuclear leukocytes. Monocyte immunophenotype was determined in whole blood by flow cytometry on a Cytoflex flow cytometer (Becman Coulter, USA) with monoclonal antibodies (eBioscience, USA). Results were processed with a CytExpert 2.0 software. The number of cells expressing surface markers, CD14, CD163, CD204 and HLA-DR, was determined. Content of cytokines (IL-2, IL-10, TGFβ) in supernatants of cell cultures was measured by enzyme-linked immunosorbent assay (ELISA). Results of the study were processed with a SPSS v.11.0 standard software package. Results. The study results suggested that with an overall decrease in the number of circulating CD14-positive blood monocytes in patients with pulmonary tuberculosis regardless of its clinical form, high expression of cell activation markers remained both for the pro-inflammatory M1 phenotype (HLA-DR-positive monocytes) and the anti-inflammatory M2 phenotype (CD163-positive monocytes). In disseminated tuberculosis, the number of anti-inflammatory CD204-positive monocytes, M2 macrophage precursors, increases indicating predomination of the immunosuppressive response. In vitro analysis of the cytokine status showed that tuberculosis progression is accompanied by inhibition of effector immune responses and increases in anti-inflammatory cytokine concentrations in vitro. These changes may be equally either a cause or a consequence of deficient IL-2 secretion. We also found that the secretion of mediators with suppressor effects (IL-10, TGFβ) varied depending on both the clinical form of tuberculosis and the pathogen sensitivity to anti-TB drugs; IL-10 hypersecretion was observed in patients with drug-sensitive, infiltrative tuberculosis whereas TGFβ hypersecretion was observed in disseminated, drug-resistant tuberculosis. Conclusion. Features of blood monocyte differentiation in patients with pulmonary tuberculosis allowed us to conclude that monocytes, the macrophage precursors, start expressing markers for different functions of M1 and M2 macrophages with polarization toward the M2 immunophenotype already in the bloodstream. Therefore, in the development of pulmonary tuberculosis, cytokine regulation mechanisms become involved in suppressing the activation of innate immunity, which possibly causes chronic inflammation in the lungs and formation of Mtb-induced immunodeficiency.

Clinical, Histopathological and Immunohistochemistry Evaluation of Reactive Cutaneous Histiocytosis in Canine in Western Amazonia

Background: Canine reactive cutaneous histiocytosis (RCH) is an immuneproliferative disease of skin histiocytes and is uncommon in occurrence. Its description in the literature is scarce and clinical studies are limited by the insufficient characterization of the patients' pathological findings. The objective of this report is to describe the clinical, histological and immunohistochemical findings of a case of canine reactive cutaneous histiocytosis in the state of Acre, Amazonia, Brazil.Case: It was attended at the Federal University of Acre, a 7-year-old male American pit bull terrier dog with nodular, allopecic and ulcerated lesions in the dorsal region of the ear, with purulent discharge and exacerbated painful tenderness. The animal was domiciled on the bank of the river Acre, municipality of Rio Branco, state of Acre, and suffered frequent parasitism by sandflies, especially in the head region. In the histopathological evaluation, hyperplastic cells were found, a large ulcerated area with the presence of fibrin and neutrophilic infiltrate in the epidermis. In the dermal layer, an inflammatory reaction pattern was identified, with the presence of fibrous connective tissue, dilated blood vessels and edema, however little defined. There was an intense presence of histiocytes with anisocytosis, in addition to neutrophils, plasma cells and lymphocytes in the perivascular and perianexal region. In immunohistochemistry, lysozyme and cell markers CD1a and Thy1 were detected, but negative result for E-cadherin and CD11d. The immunosuppressive therapy indicated with prednisolone, plus cephalexin for secondary infections and topical treatment, with clinical remission within two years. Discussion: Although the etiopathogenesis of RCH is poorly understood, it is believed that, in addition to the genetic factor, the disease is triggered by an antigenic trigger on the skin, such as dogs susceptible to ticks and sandflies. The accumulation of defense cells in the skin tissue, against the antigenic stimulus, generates primarily an inflammatory process too. Immune maladjustment of dendritic cells and leukocytes occurs in the walls of dermal vessels, as well as exacerbated recruitment of histiocytes, characteristics seen in cell morphology analyzes. In RCH, the proliferation of histiocytes between collagen fibers and the infiltration of round cells in the dermis are indicative of the disease, as evidenced in this report. The immunohistochemistry is the method of choice, which allows establishing the cellular origin that triggered the disease, although the characterization of a differentiation cluster is underused in veterinary medicine. In this context, we seek to identify histiocytes, which comprise the group of cells derived from CD34 +, macrophage precursors, dendritic and Langerhans cells of the epithelial tissue, which act as antigen presenters. It can be concluded that canine RCH is an uncommon disease resulting from an inflammatory process of the dermis with difficult to identify immune dysregulation. Differential diagnosis with systemic histiocytosis, cutaneous histiocytoma, histiocytic sarcoma, as well as leishmaniasis and mycobacteriosis, are fundamental through histopathological, serological and immunohistochemical evaluations, to establish the definitive diagnosis of the disease, as well as the prognosis, and to better direct the therapeutic approach of the case.

Defining murine monocyte differentiation into colonic and ileal macrophages

Monocytes are circulating short-lived macrophage precursors that are recruited on demand from the blood to sites of inflammation and challenge. In steady state, classical monocytes give rise to vasculature-resident cells that patrol the luminal side of the endothelium. In addition, classical monocytes feed macrophage compartments of selected organs, including barrier tissues, such as the skin and intestine, as well as the heart. Monocyte differentiation under conditions of inflammation has been studied in considerable detail. In contrast, monocyte differentiation under non-inflammatory conditions remains less well understood. Here we took advantage of a combination of cell ablation and precursor engraftment to investigate the generation of gut macrophages from monocytes. Collectively, we identify factors associated with the gradual adaptation of monocytes to tissue residency. Moreover, comparison of monocyte differentiation into the colon and ileum-resident macrophages revealed the graduated acquisition of gut segment-specific gene expression signatures.

Defining Monocyte Differentiation into Colonic and Ileal Macrophages

Monocytes are circulating short-lived macrophage precursors that are recruited on demand from the blood to sites of inflammation and challenge. In steady state, classical monocytes give rise to vasculature-resident cells that patrol the luminal side of the endothelium. In addition, classical monocytes feed macrophage compartments of selected organs, including barrier tissues, such as the skin and intestine, as well as the heart. Monocyte differentiation under conditions of inflammation has been studied in considerable detail. In contrast, monocyte differentiation under non-inflammatory conditions remains less well understood. Here we took advantage of a combination of cell ablation and precursor engraftment to investigate the generation of gut macrophages from monocytes. Collectively, we identify factors associated with the gradual adaptation of monocytes to tissue residency. Moreover, comparison of monocyte differentiation into the colon and ileum-resident macrophages revealed the graduated acquisition of gut segment-specific gene expression signatures.