Mast cells in the pathogenesis of rheumatic diseases and as potential targets for anti-rheumatic therapy

Summary:  Increasing evidence suggests that mast cells (MCs), in addition to acute allergic reactions, are involved in the pathogenesis of chronic inflammatory diseases and in particular in rheumatoid arthritis (RA). MCs reside in connective tissues and in synovial tissue of joints. They produce an array of proinflammatory mediators, tissue destructive proteases, and cytokines, most prominently tumor necrosis factor-α, which is one of the key cytokines in the pathogenesis of RA. MCs may also participate in the development of secondary or amyloid A amyloidosis, as the partial degradation of the serum amyloid A (SAA) protein by MCs leads to the generation of a highly amyloidogenic N-terminal fragment of SAA. MCs may contribute to the pathogenesis of connective tissue diseases, scleroderma, vasculitic syndromes, and systemic lupus erythematosus, although the data available are limited. Inhibition of the most important growth factor receptor of human MCs, c-Kit, by the selective tyrosine kinase inhibitor imatinib mesylate, induces apoptosis of synovial tissue MCs. As MCs are long-lived cells, induction of their apoptosis could be a feasible approach to inhibit their functions. Preliminary findings suggest that a drug that inhibits c-Kit could have anti-rheumatic activity in the treatment of patients with RA and spondyloarthropathies.     

Langerhans cells in human lung tumours: an immunohistological study

In an immunocytochemical study of 41 human lung tumours we have shown that Langerhans cells can be reliably identified using the anti-CD1 monoclonal antibody NA1/34. Langerhans cells are present in all the main varieties of human lung tumour although they are infrequent in both small cell carcinoma and carcinoid tumour. There is considerable variation in numbers of Langerhans cells in both adenocarcinomas and squamous cell carcinomas. In this study tumours were divided into those with high numbers of Langerhans cells (greater than 2 per high power field) and those with low numbers (less than 2 per high power field). Analysing these results against patient survival showed a markedly worse survival in those tumours with a high number of Langerhans cells for all the tumours as a single group and for squamous cell carcinoma as a single entity.     

Langerhans'' cells and T cells in human skin tumours: an immunohistological study

In this study normal skin and a range of skin tumours, both benign and malignant, have been examined using monoclonal antibodies to identify the distribution and morphology of Langerhans' cells and T cells, the distribution of T lymphocytes and their subsets have been analysed using monoclonal anti-T cell antibodies. The results indicated that Langerhans' cells can be reliably identified in both normal and malignant skin biopsies using monoclonal antibodies. A striking finding to emerge was that in benign skin lesions Langerhans' cells were increased, whereas in malignant tumours they were not only markedly depleted or absent but also grossly stunted and deformed in outline. The majority of lymphocytes surrounding these skin tumours were shown to be T cells with helper cells outnumbering suppressor cells by a ratio from 2 to 5:1. This study shows the usefulness of immunohistological techniques using monoclonal antibodies for examining the morphology and distribution of Langerhans' cells in skin pathology. In addition they are particularly appropriate for identifying their topographical relationships with other immunologically important cells such as T cells.     

Oestrogen and progesterone receptors in screen-detected breast carcinoma: an immunohistological study using paraffin sections

The presence of oestrogen and progesterone receptors was studied in paraffin sections of 81 screen-detected breast carcinomas using the monoclonal antibodies ER-ICA and PgR-ICA (Abbott) and the immunoperoxidase technique. The immunohistological results were compared with the results of the standard dextran-coated charcoal biochemical assay in 28 tumours which were big enough to provide tumour tissue for this assay. Sixty-three cases (78%) were oestrogen receptor positive and 62 (77%) were progesterone receptor positive. There was no statistical difference between receptor positivity in palpable or impalpable, in situ or invasive tumours. In the 28 cases where the biochemical assay was carried out, the two methods gave similar results in 23 (82%) and 21 (75%) tumours for oestrogen and progesterone receptors respectively. The majority of the remaining tumours, with one exception, were positive with immunohistology and negative with biochemistry. A good correlation was also present between the mean numerical biochemical values and the semiquantitative histological scores for both receptors. It is concluded that assessment of receptor status of small screen-detected carcinomas is feasible using routinely processed paraffin sections. There is reasonably good correlation with the results obtained by the standard dextran-coated charcoal biochemical assay, but more genuine receptor positive cases are detected by immunohistology.     

Dendritic reticulum cells in reactive lymph nodes and tonsils: an immunohistological study

There has recently been much interest in the patterns of follicular dendritic reticulum cells (DRC) in pathological lymph nodes, particularly in relation to the phenomenon of DRC break-up (thought to be pathognomonic of AIDS-related lymphadenopathies) and to progressive transformation of germinal centres (as a possible precursor of lymphocyte predominant Hodgkin's disease). In the present study we have immunostained twenty-nine reactive lymph nodes and five tonsils with monoclonal antibody R4/23 (DAKO-DRC) in order to evaluate the frequency of such changes in lymphoid tissue unaffected by AIDS or Hodgkin's disease. Most of the specimens contained typical secondary follicles with clearly defined germinal centres and mantle zones. There were two variants in lymph nodes showing follicular hyperplasia characterized by (i) progressive transformation of germinal centres and (ii) inclusions of nests of small lymphocytes within germinal centres. In each of these types of follicles the compact evenly-distributed meshwork of DRCs, as previously described, was seen. However there were considerable variations in DRC meshwork in each category (the pattern could not be predicted from the morphology) with examples in all three of the DRC break-up previously considered specific for the AIDS related lymphadenopathy. Since none of the lymph nodes and tonsils studied had any known relationship to either Hodgkin's disease or AIDS it is argued that none of the changes in the DRC meshwork observed are specific for these conditions.     

Oestrogen receptors in benign epithelial lesions and intraduct carcinomas of the breast: an immunohistological study

We examined 198 breast lesions, representing commonly encountered benign epithelial proliferative disorders, lobular carcinoma in situ and intraduct carcinoma, immunohistologically for oestrogen receptors (ER). A mixture of three ER monoclonal antibodies--H222, D75 and D547--was used on sections of routinely processed and paraffin-embedded tissue blocks. Over 65% of the benign and malignant lesions showed some evidence of ER expression and significant staining was recorded by two observers in 28-31% of fibroadenomas, 18-28% of ductal epithelial hyperplasias, 30-40% of sclerosing adenosis cases, 38-45% of papillomas, 60% of in situ lobular carcinomas and 42-45% of intraduct carcinomas. Apocrine metaplastic cells and myoepithelial cells showed absent or only weak staining. Amongst intraduct carcinomas, less than 20% of comedo carcinomas and over 50% of cribriform, papillary and solid variants showed significant ER staining.     

Oestrogen receptors in mucinous carcinoma of the breast: an immunohistological study using paraffin wax sections.

An immunohistological method (Shintaku-Said method) for the demonstration of oestrogen receptors in routinely processed paraffin wax embedded tissue was applied to 19 cases of mucinous carcinoma of the breast. Seventeen (89%) tumours showed variable degrees of positivity and two were negative. In eight cases the receptors were also assayed biochemically using a dextran-coated charcoal method, and the results of the two methods showed good correlation. No difference in the distribution of positive and negative cases was noted between pure and mixed mucinous tumours, and in the latter group the pattern of staining of the mucinous elements was similar to that seen in the solid elements. It is concluded that the major advantage of this method is its ability to offer for study the distribution of the receptors in individual cells and specific histological structures. The results also indicate that most mucinous carcinomas of the breast are oestrogen receptor positive, irrespective of whether they are pure or mixed type.     

Expression of prolactin receptors in normal, benign, and malignant breast tissue: an immunohistological study

AIMS: Prolactin plays an important role in the proliferation and differentiation of normal breast epithelium, and possibly in the development of breast carcinoma. The effects of prolactin are mediated by its receptor; thus, alteration in the expression of this receptor could be important in studying the biology of breast cancer. This investigation was aimed at comparing the expression of prolactin receptors in normal, benign, and malignant breast tissue. MATERIAL/METHODS: The expression of prolactin receptors was studied in paraffin wax embedded sections of 102 breast biopsies (93 female and nine male), using the monoclonal antibody B6.2, and the avidin-biotin immunoperoxidase technique. Six biopsies were normal, 34 had benign lesions, and 62 were malignant. RESULTS: In normal cases, prolactin receptor positivity was seen only on the luminal borders of the epithelial cells lining ducts and acini. In most benign lesions, variable degrees of luminal and cytoplasmic staining were seen. Cells showing apocrine metaplasia and florid regular ductal epithelial hyperplasia were mostly negative. In malignant cases, the staining pattern was mostly cytoplasmic and heterogeneous. Forty one of the 59 carcinomas in women showed a degree of positivity involving 10-100% of the tumour cells. A significant direct correlation was found between prolactin receptor and oestrogen receptor staining when only cases that scored more than 100/300 for the latter receptor, using the H scoring system, were considered (p = 0.0207). No correlation was found between prolactin receptors and progesterone receptors, patient's age, tumour size, tumour grade, or axillary lymph node status. CONCLUSIONS: Prolactin receptors seem to be expressed at different cellular sites in normal, benign, and malignant breast epithelial cells. The receptor is expressed in more than two thirds of female breast carcinomas, suggesting that it may play a role in the pathogenesis of the disease. The positivity is correlated with moderate and strong staining for oestrogen receptors in tissue sections, but not with other prognostic factors.     

Mast cells in the human alveolar wall: an electronmicroscopic study.

Mast cells were identified by electronmicroscopy in the alveolar wall of the lung in 20 subjects (10 normal, 10 abnormal). A quantitative and qualitative study was made of the mast cells. In the normal lung there was an average concentration of 350 mast cells/mm2 of alveolar wall and in the abnormal 523/mm2. Mast cells occupied approximately 1.6-2.1% of the area of the alveolar wall. There was marked variation in the structure of the mast cell granules but no differences between those in the normal and abnormal lungs. There was evidence that constant degranulation of mast cells may be occurring in the lung. The role that alveolar mast cells may play in the vasoconstrictor response to alveolar hypoxia is discussed. It is suggested that the tachypnoea present in asthma may partly be due to release of mediators from sensitised mast cells within the alveolar wall.     

BCMA and autoantibody-producing RP105 B cells; possible new targets of B cell therapy in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease with multiple organ disorders. Although the prognosis of SLE has been recently improved, corticosteroid and immunosuppressive agents are still main treatment used in medical practice. Refractory disease and complications by the conventional drugs still remain. RP105 (CD180) is one of the toll-like receptor associated molecules. The molecule is expressed on mature B cells. Significantly increased population of RP105-negative [RP105(-)] B cells is found in SLE. RP105(-) B cells belong to highly activated and differentiated late B cells and produce autoantibodies including anti-dsDNA antibodies. RP105(-) B cells are further divided into at least 5 subsets that include novel human B cell subsets. In active SLE, subset 1 (activated B cells) and 3 (early-plasmablasts) are significantly increased compared to inactive SLE patients. Especially, subset 3 RP105(-) B cells may play an important role in pathophysiology of SLE. RP105(-) B cells from active SLE patients express preferentially BCMA (B-cell maturation antigen) compared to BAFF-R (B-cell activating factor-receptor) than normal subjects and other autoimmune diseases. In SLE, it is suggested that BAFF/APRIL (a proliferation-inducing ligand) maintain chronic activation and survival of RP105(-) B cells. The increased RP105(-) B cells may reflect the breaking of tolerance checkpoint for autoreactive B cells and finally affect autoimmunity in SLE. For the B cell therapy, especially targeting of autoantibody-producing B cells, including subset 3 of RP105(-) B cells, BCMA and RP105(-) B cell itself may be an ideal target.     

Mast cells as a possible source of Haemophilus influenzae-induced changes in plasma and lung histamine levels

Histidine decarboxylase activity and histamine levels of peritoneal mast cells were enhanced 4 days after intraperitoneal Haemophilus influenzae vaccination of rats. Incubation of the cells with propranolol (3.4 x 10(-4) M) resulted in histamine release and an increased histidine decarboxylase activity. Histidine decarboxylase activity and histamine release were more increased in the presence of propranolol in mast cells obtained from H. influenzae-vaccinated rats. An increased mediator release is also suggested by the increase of the number of peritoneal eosinophils. These data might explain the earlier observed enhanced plasma and lung histamine levels in H. influenzae-vaccinated rats.     

Risperidone, an atypical antipsychotic enhances the antidepressant-like effect of venlafaxine or fluoxetine: possible involvement of alpha-2 adrenergic receptors

Clinical studies have reported the beneficial outcome of addition of lower doses of risperidone to antidepressant therapy specifically with selective serotonin reuptake inhibitors (SSRIs) in the treatment of major depression. The present study, therefore, examined the beneficial effect, if any, of addition of risperidone (an atypical antipsychotic) to the antidepressant-like effect of venlafaxine (dual reuptake inhibitors of both serotonin and norepinephrine, SNRI) or fluoxetine (SSRI) in Porsolt's Forced Swim Test (FST) using male laca mice. Attempts have been made to study the involvement of alpha-2 adrenergic receptors in the mechanism of action. Immobility period was recorded for a period of 6 min. Venlafaxine (4 and 8 mg/kg, i.p.) or fluoxetine (10 and 20 mg/kg, i.p.) inhibited the immobility period in mice. Addition of risperidone (0.1 mg/kg, i.p.) potentiated the anti-immobility effect of either venlafaxine (4 and 8 mg/kg, i.p.) or fluoxetine (10 and 20 mg/kg, i.p.) in mouse FST. Furthermore, the anti-immobility effect of combination of risperidone (0.1 mg/kg, i.p) plus venlafaxine (4 mg/kg, i.p.) or fluoxetine (10 mg/kg, i.p.) was potentiated by the addition of yohimbine (2 mg/kg, i.p.), an alpha-2 adrenoceptors antagonist. The results of the present study suggest that the beneficial consequences of addition of risperidone with venlafaxine or fluoxetine in mouse forced swim test may involve alpha-2 adrenergic receptors.     

An immunohistological study of giant-cell tumour of bone: evidence for an osteoclast origin of the giant cells

Using a panel of monoclonal antibodies against a variety of lymphoid and non-lymphoid antigens the immunohistological staining pattern of giant cells from a case of giant-cell tumour of bone has been compared with that of osteoclasts from the developing ends of fetal long bones. Only EBM-11, an antibody reacting with a wide spectrum of macrophages, stained both osteoclasts and giant cells; stromal cells and osteoblasts did not react. This indicates that osteoclasts and giant cells are phenotypically and presumably functionally similar. It is argued that the osteoclasts and the tumour-derived giant cells in bone are derived from a similar mononuclear precursor.     

The differential effects of 1,25‐dihydroxyvitamin D3 on Salmonella‐induced interleukin‐8 and human beta‐defensin‐2 in intestinal epithelial cells

Salmonellosis or Salmonella, one of the most common food‐borne diseases, remains a major public health problem worldwide. Intestinal epithelial cells (IECs) play an essential role in the mucosal innate immunity of the host to defend against the invasion of Salmonella by interleukin (IL)?8 and human β‐defensin‐2 (hBD‐2). Accumulated research has unravelled important roles of vitamin D in the regulation of innate immunity. Therefore, we investigated the effects of 1,25‐dihydroxyvitamin D3 (1,25D3) on Salmonella‐induced innate immunity in IECs. We demonstrate that pretreatment of 1,25D3 results in suppression of Salmonella‐induced IL‐8 but enhancement of hBD‐2, either protein secretion and mRNA expression, in IECs. Furthermore, 1,25D3 enhanced Salmonella‐induced membranous recruitment of nucleotide oligomerization domain (NOD2) and its mRNA expression and activation of protein kinase B (Akt), a downstream effector of phosphoinositide 3‐kinase (PI3K). Inhibition of the PI3K/Akt signal counteracted the suppressive effect of 1,25D3 on Salmonella‐induced IL‐8 expression, while knock‐down of NOD2 by siRNA diminished the enhanced hBD‐2 expression. These data suggest differential regulation of 1,25D3 on Salmonella‐induced IL‐8 and hBD‐2 expression in IECs via PI3K/Akt signal and NOD2 protein expression, respectively. Active vitamin D‐enhanced anti‐microbial peptide in Salmonella‐infected IECs protected the host against infection, while modulation of proinflammatory responses by active vitamin D prevented the host from the detrimental effects of overwhelming inflammation. Thus, active vitamin D‐induced innate immunity in IECs enhances the host's protective mechanism, which may provide an alternative therapy for invasive Salmonella infection.