Kana Mizuno

Monocyte-derived multinucleated giant cells and sarcoidosis

Multinucleated giant cells (MGC) are characteristic cells in granulomatous disorders such as sarcoidosis and also formed in vitro from peripheral blood mononuclear cells by stimulation with cytokines, including interferon-gamma (IFN-gamma), interleukin-3 (IL-3), IL-4, IL-13, and granulocyte-macrophage-colony stimulating factor. In addition to such inflammatory mediators, a factor derived from the pathogens of granulomatous disorders may be necessary for MGC formation. Muramyl dipeptide (MDP), a peptidoglycan portion of bacterial cell walls present in sarcoidal lesions, is one of the candidates and can preferentially induce Langhans-type cells (LGC) in in vitro MGC formation system. Although the exact mechanisms of in vitro MGC formation remains unknown, receptors such as P2X(7), integrins, CD98, and macrophage fusion protein are considered to be involved in cell-to-cell adhesion and subsequent fusion process. Monocytes from sarcoidosis patients expressed higher levels of P2X(7) and had a higher ability to induce MGC than those from healthy controls. Attributable cells for the formation were CD14(++)CD16(-) monocytes. Therefore, CD14(++)CD16(-) monocytes may infiltrate into sarcoidal lesions and be fused to form LGC by inflammatory mediators and MDP derived from the pathogens of the disorder. Effective agents for sarcoidosis such as tranilast, allopurinol, and captopril inhibited in vitro MGC formation through inhibiting the expression of adhesion molecule and purinergic receptor. Thus, an in vitro MGC formation model would be a useful tool to understand the relevance of MGC in granulomatous disorders.

Circulating CD14+ CD16+ Monocytes Are Expanded in Sarcoidosis Patients

Sarcoidosis is a systemic disease of unknown etiology characterized by noncaseating granulomas, consisting mainly of epithelioid cells and multinucleated giant cells derived from monocyte‐macrophage lineage cells. Monocytes fall into subpopulations comprising CD14++ CD16−, and CD14+ CD16+ cells, and expansion of the later monocytes has been reported under some pathological conditions. In this study, we examined the immunophenotype of blood monocytes in patients with sarcoidosis using two‐color immunofluorescence flow cytometry. In healthy controls CD14+ CD16+ monocytes account for 5.8 ± 2.8% of monocytes. The percentage of CD14+ CD16+ monocytes was significantly higher (p <0.02) in the sarcoidosis patients (11.8 ± 4.9%) compared with those in healthy control subjects. The serum ACE levels were significantly correlated with the percentage of CD14+ CD16+ monocytes (p <0.05). In contrast, the percentage was not correlated with purinergic receptor expression of monocytes as estimated by LDH release from BzATP‐stimulated monocytes. These findings suggest that CD14+ CD16+ monocytes represent a sensitive marker for the disease activity of sarcoidosis.

Heightened ability of monocytes from sarcoidosis patients to form multi‐nucleated giant cells in vitro by supernatants of concanavalin A‐stimulated mononuclear cells

The main immunocompetent cells in sarcoidal lesions are epithelioid cells and multi‐nucleated giant cells (MGC), both of which are derived from monocyte‐macrophage lineage cells. To understand further the relevance of monocytes in sarcoidosis, we examined in vitro MGC formation using monocytes from sarcoidosis patients, patients with other granulomatous diseases (OGD) and healthy control subjects. The supernatant of concanavalin A‐stimulated peripheral blood mononuclear cells (conditioned medium) generated Langhans type‐MGC and foreign body type‐MGC from monocytes. Conditioned medium from any three groups had the same ability to form MGC from normal monocytes. On the other hand, MGC were more highly formed using monocytes from sarcoidosis patients than from other groups. When macrophages induced by treatment of monocytes with macrophage colony‐stimulating factor (M‐CSF) were used, the rate of MGC formation in sarcoidosis patients was about threefold or fourfold as much as that in OGD patients or healthy controls, respectively. Oxidized ATP inhibited MGC formation in all groups. The susceptibility of monocytes cultured in conditioned medium for 24 h to 2′‐ and 3′‐o‐(4‐benzoyl‐benzoyl)ATP‐mediated cytolysis was significantly higher in sarcoidosis patients than other groups. These findings suggest that the ability of monocytes to form MGC through P2×7 receptors is enhanced in sarcoidosis patients.

Inhibitory influences of xanthine oxidase inhibitor and angiotensin I-converting enzyme inhibitor on multinucleated giant cell formation from monocytes by downregulation of adhesion molecules and purinergic receptors

Background  Allopurinol, a xanthine oxidase inhibitor, and captopril, an inhibitor of angiotensin I‐converting enzyme, are widely used for hyperuricaemia and hypertension, respectively. There have been reported cases showing that these two agents are effective for the treatment of granulomatous diseases such as sarcoidosis, although the mode of action is not elucidated.

Sarcoidosis and molecular mimicry--important etiopathogenetic aspects: current state and future directions.

SummarySarcoidosis is a disease of uncertainty in terms of its cause, presentation, and clinical course. The disease has a worldwide distribution and affects all ages, races, and both sex. Sarcoidosis of the skin may have an extremely heterogeneous clinical presentation, so that the definitions of ‘great imitator’ and ‘clinical chameleon’ have long been used.The factors that influence clinical picture and severity of the disease are probably linked to the etiopathogenesis of sarcoidosis, which continues to be shrouded in mystery.The current state of the art on the pathogenesis of sarcoidosis is that it is an immunological response in a genetically susceptible individual to an as-yet undefined antigenic stimulus. How exposure occurs in genetically predisposed patients is not completely clear, but the most likely explanation is that these agents or antigens are either inhaled into the lungs or enter through contact with the skin, as these are the common target organs that are constantly in contact with the environment. An autoimmune etiology of sarcoidosis could possibly occur through a process of molecular mimicry of infectious or other environmental antigens to host antigens. This could lead to a cross-mediated immune response and induction of autoimmune disease. This molecular mimicry may probably be responsible for the heterogeneous clinical presentations of the disease.Several investigations and studies have provided valuable evidence on the etiopathogenesis of sarcoidosis, which may lead to the future development of targeted and innovative treatment strategies. Nevertheless, we are still a long way from unravelling the underlying cause of this mysterious disease.ZusammenfassungDie Sarkoidose ist eine Erkrankung voll der Unsicherheiten in Bezug auf ihre Ursache, Präsentation und den klinischen Verlauf. Die Erkrankung kommt überall auf der Welt vor. Sie tritt in jedem Alter, bei allen Rassen bei Mann und Frau auf. Die Sarkoidose der Haut kann sich klinisch extrem unterschiedlich präsentieren – seit Langem wird sie daher auch als „Großer Nachahmer“ und „klinisches Chamäleon“ bezeichnet.Die Faktoren, die das klinische Bild und die Schwere der Erkrankung beeinflussen, sind wahrscheinlich mit der Ätiopathogenese der Erkrankung verbunden. Diese sind aber auch heute noch immer ungeklärt. Die aktuelle Lehrmeinung besagt, dass die Sarkoidose eine immunologische Antwort auf einen bis jetzt undefinierten antigenen Reiz in einem – genetisch bedingt – empfindlichen Individuum darstellt. Wie es zur Exposition der genetisch prädisponierten Patienten kommt ist nicht ganz klar. Die wahrscheinlichste Erklärung ist, dass diese Substanzen, beziehungsweise Antigene entweder über die Lungen inhaliert werden oder durch Kontakt mit der Haut in den Körper eintreten. Haut und Lunge sind die am häufigsten befallenen Zielorgane, die dauernd mit der Umwelt in Kontakt stehen. Eine autoimmune Ätiologie der Sarkoidose könnte möglicherweise durch einen Prozess der molekularen Mimikrie von infektiösen oder anderen Antigenen aus der Umwelt auf Wirt Antigene erklärt werden. Dadurch könnte es zu einer „cross mediated“ Immunantwort und Auslösung einer autoimmunen Erkrankung kommen. Diese molekulare Mimikrie kann möglicherweise für die unterschiedliche klinische Präsentation der Erkrankung verantwortlich sein.Verschiedene Untersuchungen und Studien haben wertvolle Evidenz in Bezug auf die Ätiopathogenese der Sarkoidose geliefert. Dadurch könnte es in der Zukunft zur Entwicklung von zielgerichteten neuen Behandlungsstrategien kommen. Heute sind wir allerdings trotz allem noch weit entfernt von der Entwirrung der zugrunde liegenden Ursache dieser geheimnisvollen Krankheit.

Muramyl dipeptide and mononuclear cell supernatant induce Langhans-type cells from human monocytes

Muramyl dipeptide (MDP) in bacterial cell walls reportedly evokes epithelioid cell granulomas. We examined its effects on multinucleated‐giant‐cell (MGC) formation from monocytes. Supernatant of concanavalin A‐stimulated peripheral blood mononuclear cells (conditioned medium) generated MGCs from monocytes. MDP significantly increased the fusion index of Langhans‐type MGCs (LGCs) but did not affect total MGCs. N‐Acetylmuramyl‐l‐alanyl‐l‐isoglutamine, an MDP analogue, had no effect on MGC formation. MGCs were produced by conditioned medium from CD14++/CD16− monocytes. MDP enhanced the LGC fusion index from CD14++/CD16− monocytes. MGCs were not produced from CD14+/CD16+ monocytes or immature dendritic cells induced by granulocyte macrophage‐colony stimulating factor (GM‐CSF) and interleukin (IL) 4 and only weakly produced from macrophage (M)‐CSF‐ or GM‐CSF‐induced macrophages. Added MDP did not generate MGCs from CD14+/CD16+ monocytes or dendritic cells but enhanced LGC formation from macrophages. Because IFN‐γ, IL‐3, and GM‐CSF reportedly are important in LGC induction, we added anti‐IFN‐γ, anti‐IL‐3, or anti‐GM‐CSF monoclonal antibody (mAb) concomitantly to the monocyte culture treated with conditioned medium alone or plus MDP. Anti‐IFN‐γ mAb completely abrogated MGC generation, whereas anti‐GM‐CSF and anti‐IL‐3 mAbs significantly inhibited LGCs. These findings suggest that CD14++/CD16− monocytes are fused to form LGCs by MDP derived from granulomatous‐disease‐causing pathogens with inflammatory mediators such as IFN‐γ, IL‐3, and GM‐CSF.

Inhibitory influences of tranilast on multinucleated giant cell formation from monocytes by supernatant of concanavalin A-stimulated mononuclear cells

Tranilast is an anti-allergic drug that inhibits the release of chemical mediators from mast cells. There have been cases-reports showing that tranilast is effective for the treatment of granulomatous diseases such as granuloma annulare and cutaneous sarcoidosis. Here we examined the in vitro effects of tranilast on the formation of multinucleated giant cells (MGCs) from human peripheral monocytes. Supernatant of concanavalin A (Con A)-stimulated mononuclear cells induced Langhans-type and foreign body-type MGCs and the addition of 10 or 100 microg/ml tranilast inhibited the formation of total MGCs and foreign body-type MGCs. Tranilast decreased the number of MGCs with 16<nuclei and increased that of MGCs with three to five nuclei. Fluorescence-activated cell sorting analysis showed that tranilast-treated monocytes had lower expressions of intercellular adhesion molecule-1 (ICAM-1). These findings suggest that tranilast is effective for cutaneous lesions in some cases of granulomatous disorders partly through a direct effect on monocyte/macrophage-lineage cells.

Elevated serum BAFF levels in patients with sarcoidosis: association with disease activity

OBJECTIVE The purpose of this study was to determine serum levels of B-cell-activating factor (BAFF) and its clinical association in patients with sarcoidosis. METHODS; Serum levels of BAFF from 37 patients and 21 healthy subjects were examined by ELISA. Serum angiotensin-converting enzyme (ACE), lysozyme and IFN-γ levels in sarcoidosis patients were also measured. Isolated monocytes cultured with IFN-γ, IL-4 or IL-10 and their expression of membrane and soluble BAFF were analysed by flow cytometry or ELISA. Peripheral B cell subsets were analysed by flow cytometry. BAFF expression in the granuloma of the skin was examined by immunohistochemistry. ANAs were determined by indirect IF using HEp-2 cells as a substrate. RESULTS Serum BAFF levels were significantly elevated in sarcoidosis patients when compared with healthy controls. The frequency of skin and eye involvement was significantly higher in patients with elevated serum BAFF than in patients with normal levels. Serum BAFF levels were correlated with serum levels of ACE, lysozyme and IFN-γ. Immunostaining of anti-BAFF in the skin revealed BAFF expression by epithelioid cells of granuloma. In vitro, IFN-γ induced membrane-bound BAFF expression on monocytes and secretion of soluble BAFF by isolated monocytes. In the peripheral blood, sarcoidosis patients showed increased naïve B cells with a reciprocal decrease in memory B cells and plasmablasts. Seventeen of 26 (65%) sarcoidosis patients exhibited ANA positivity. CONCLUSION Serum BAFF levels can be used as a surrogate marker of disease activity in sarcoidosis patients. Increased BAFF may be related to the pathogenesis of sarcoidosis.

Langhans-type and foreign-body-type multinucleated giant cells in cutaneous lesions of sarcoidosis.

Multinucleated giant cells are characteristic of a monocyte-macrophage lineage in sarcoidosis and consist of two types of cells: Langhans-type with an arcuate arrangement of nuclei and a foreign-body type with random arrangement of nuclei. To compare these cells in the cutaneous lesions of sarcoidosis, we histologically and immunohistologically examined multinucleated giant cells in 25 scar infiltrations (cutaneous sarcoidosis with foreign bodies) and 30 cutaneous lesions of sarcoidosis without foreign bodies. Regardless of the presence or absence of foreign bodies, the cutaneous lesions had both types of multinucleated giant cells, usually with a predominance of the Langhans-type, although the numbers of total multinucleated giant cells were higher in scar infiltrations than in cutaneous sarcoidosis without foreign bodies, suggesting that their frequency is influenced by the microenvironment in sarcoidal lesions such as the presence of foreign bodies. Immunohistochemical studies using surface antigens of monocyte-macrophage lineage cells and adhesion molecules indicated that both types of multinucleated giant cells are formed from monocytes rather than tissue macrophages and are phenotypically the same cells with different distributions of nuclei.

Successful treatment with narrow-band UVB therapy for a case of generalized Hailey–Hailey disease with a novel splice-site mutation in ATP2C1 gene

Hailey–Hailey disease (HHD) is a rare autosomal dominant disorder characterized by development of recurrent blisters, erosions, and crustations in the intertriginous areas. The treatment of HHD is often challenging, and various methods have been tried. We report here a case of a 45‐year‐old woman with a generalized form of HHD that was dramatically improved and well controlled by narrow‐band ultraviolet B phototherapy.