E-cadherin is expressed by mono- and multinucleated histiocytes in cutaneous sarcoidal and foreign body granulomas

Multinucleated Giant Cells: Current Insights in Phenotype, Biological Activities, and Mechanism of Formation

Monocytes and macrophages are innate immune cells with diverse functions ranging from phagocytosis of microorganisms to forming a bridge with the adaptive immune system. A lesser-known attribute of macrophages is their ability to fuse with each other to form multinucleated giant cells. Based on their morphology and functional characteristics, there are in general three types of multinucleated giant cells including osteoclasts, foreign body giant cells and Langhans giant cells. Osteoclasts are bone resorbing cells and under physiological conditions they participate in bone remodeling. However, under pathological conditions such as rheumatoid arthritis and osteoporosis, osteoclasts are responsible for bone destruction and bone loss. Foreign body giant cells and Langhans giant cells appear only under pathological conditions. While foreign body giant cells are found in immune reactions against foreign material, including implants, Langhans giant cells are associated with granulomas in infectious and non-infectious diseases. The functionality and fusion mechanism of osteoclasts are being elucidated, however, our knowledge on the functions of foreign body giant cells and Langhans giant cells is limited. In this review, we describe and compare the phenotypic aspects, biological and functional activities of the three types of multinucleated giant cells. Furthermore, we provide an overview of the multinucleation process and highlight key molecules in the different phases of macrophage fusion.

In the Thick of It: Formation of the Tuberculous Granuloma and Its Effects on Host and Therapeutic Responses

The defining pathology of tuberculosis is the granuloma, an organized structure derived from host immune cells that surrounds infecting Mycobacterium tuberculosis. As the location of much of the bacteria in the infected host, the granuloma is a central point of interaction between the host and the infecting bacterium. This review describes the signals and cellular reprogramming that drive granuloma formation. Further, as a central point of host-bacterial interactions, the granuloma shapes disease outcome by altering host immune responses and bacterial susceptibility to antibiotic treatment, as discussed herein. This new understanding of granuloma biology and the signaling behind it highlights the potential for host-directed therapies targeting the granuloma to enhance antibiotic access and tuberculosis-specific immune responses.

E-Cadherin in Pancreatic Ductal Adenocarcinoma: A Multifaceted Actor during EMT

Epithelial-to-mesenchymal transition (EMT) is a step-wise process observed in normal and tumor cells leading to a switch from epithelial to mesenchymal phenotype. In tumors, EMT provides cancer cells with a metastatic phenotype characterized by E-cadherin down-regulation, cytoskeleton reorganization, motile and invasive potential. E-cadherin down-regulation is known as a key event during EMT. However, E-cadherin expression can be influenced by the different experimental settings and environmental stimuli so that the paradigm of EMT based on the loss of E-cadherin determining tumor cell behavior and fate often becomes an open question. In this review, we aimed at focusing on some critical points in order to improve the knowledge of the dynamic role of epithelial cells plasticity in EMT and, specifically, address the role of E-cadherin as a marker for the EMT axis.

Towards Understanding Therapeutic Failures in Masquelet Surgery: First Evidence that Defective Induced Membrane Properties are Associated with Clinical Failures

The two-stage Masquelet induced-membrane technique (IMT) consists of cement spacer-driven membrane induction followed by an autologous cancellous bone implantation in this membrane to promote large bone defect repairs. For the first time, this study aims at correlating IMT failures with physiological alterations of the induced membrane (IM) in patients. For this purpose, we compared various histological, immunohistochemical and gene expression parameters obtained from IM collected in patients categorized lately as successfully (Responders; n = 8) or unsuccessfully (Non-responders; n = 3) treated with the Masquelet technique (6 month clinical and radiologic post-surgery follow-up). While angiogenesis or macrophage distribution pattern remained unmodified in non-responder IM as compared to responder IM, we evidenced an absence of mesenchymal stem cells and reduced density of fibroblast-like cells in non-responder IM. Furthermore, non-responder IM exhibited altered extracellular matrix (ECM) remodeling parameters such as a lower expression ratio of metalloproteinase-9 (MMP-9)/tissue inhibitor of metalloproteinases (TIMP-1) mRNA as well as an important collagen overexpression as shown by picrosirius red staining. In summary, this study is the first to report evidence that IMT failure can be related to defective IM properties while underlining the importance of ECM remodeling parameters, particularly the MMP-9/TIMP-1 gene expression ratio, as early predictive biomarkers of the IMT outcome regardless of the type of bone, fracture or patient characteristics.

Cadherin Signaling in Cancer: Its Functions and Role as a Therapeutic Target

Cadherin family includes lists of transmembrane glycoproteins which mediate calcium-dependent cell-cell adhesion. Cadherin-mediated adhesion regulates cell growth and differentiation throughout life. Through the establishment of the cadherin-catenin complex, cadherins provide normal cell-cell adhesion and maintain homeostatic tissue architecture. In the process of cell recognition and adhesion, cadherins act as vital participators. As results, the disruption of cadherin signaling has significant implications on tumor formation and progression. Altered cadherin expression plays a vital role in tumorigenesis, tumor progression, angiogenesis, and tumor immune response. Based on ongoing research into the role of cadherin signaling in malignant tumors, cadherins are now being considered as potential targets for cancer therapies. This review will demonstrate the mechanisms of cadherin involvement in tumor progression, and consider the clinical significance of cadherins as therapeutic targets.

An Overview of the Derivation and Function of Multinucleated Giant Cells and Their Role in Pathologic Processes

Monocyte lineage cells play important roles in health and disease. Their differentiation into macrophages is crucial for a broad array of immunologic processes that regulate inflammation, neoplasia, and infection. In certain pathologic conditions, such as foreign body reactions and peripheral inflammatory lesions, monocytes fuse to form large, multinucleated giant cells (MGCs). Currently, our knowledge of the fusion mechanisms of monocytes and the regulation of MGC formation and function in discrete pathologies is limited. Herein, we consider the types and function of MGCs in disease and assess the mechanisms by which monocyte fusion contributes to the formation of MGCs. An improved understanding of the cellular origins and metabolic functions of MGCs will facilitate their identification and ultimately the treatment of diseases and disorders that involve MGCs.

Parsimony or poor luck: Concurrent Birt-Hogg- Dubé Syndrome and sarcoidosis

While sarcoidosis is notorious for myriad manifestations including cystic lung changes, we present a case with both Birt-Hogg-Dubé syndrome (BHD) and pulmonary sarcoidosis. BHD is a rare, autosomal dominant genetic disorder characterized by numerous thin-walled, irregular cysts, but lung function is typically normal otherwise. We present a case with confirmed BHD syndrome and concurrent granulomatous lung disease consistent with sarcoidosis. (Sarcoidosis Vasc Diffuse Lung Dis 2017; 34: 194-196).

Macrophage Epithelial Reprogramming Underlies Mycobacterial Granuloma Formation and Promotes Infection

Mycobacterium tuberculosis infection in humans triggers formation of granulomas, which are tightly organized immune cell aggregates that are the central structure of tuberculosis. Infected and uninfected macrophages interdigitate, assuming an altered, flattened appearance. Although pathologists have described these changes for over a century, the molecular and cellular programs underlying this transition are unclear. Here, using the zebrafish-Mycobacterium marinum model, we found that mycobacterial granuloma formation is accompanied by macrophage induction of canonical epithelial molecules and structures. We identified fundamental macrophage reprogramming events that parallel E-cadherin-dependent mesenchymal-epithelial transitions. Macrophage-specific disruption of E-cadherin function resulted in disordered granuloma formation, enhanced immune cell access, decreased bacterial burden, and increased host survival, suggesting that the granuloma can also serve a bacteria-protective role. Granuloma macrophages in humans with tuberculosis were similarly transformed. Thus, during mycobacterial infection, granuloma macrophages are broadly reprogrammed by epithelial modules, and this reprogramming alters the trajectory of infection and the associated immune response.

Histologic features of granulomatous skin diseases. Part 1: Non-infectious granulomatous disorders

Granulomatous disorders affecting the skin belong to a heterogeneous group of diseases. With the exception of granulomas induced by infectious agents or foreign bodies, the etiopathogenesis of granulomatous disorders is still poorly understood. The knowledge of histopathologic changes is of great importance for understanding clinical presentation and disease course.