Ranjit Bhardwaj

Macrophages and angiogenesis.

Macrophages are supposed to play a key role in inflammatory and tumor angiogenesis. Their importance derives from (1) their ubiquitous presence in normal and especially inflamed tissues, (2) their potential to become activated in response to appropriate stimuli, and (3) their repertoire of secretory products. By release of proteases, growth factors (bFGF, GM‐CSF, TGF‐α, IGF‐I, PDGF, VEGF/VPF, TGF‐β), and other monokines (IL‐1, IL‐6, IL‐8, TNF‐α, substance P, prostaglandins, interferons, thrombospondin 1), activated macrophages have the capability to influence each phase of the angiogenic process, such as alterations of the local extracellular matrix, induction of endothelial cells to migrate or proliferate, and inhibition of vascular growth with formation of differentiated capillaries. This review describes macrophage physiology and the influence of macrophage secretory products on the different phases of angiogenesis in vitro and in vivo. J. Lcukoc. Biol. 55: 410–422; 1994.

MACROPHAGE-DERIVED ANGIOGENESIS FACTORS.

A majority of angiogenic factors has been shown to be produced by macrophages. This review will give a concise description of their biochemical nature, their isolation from macrophages and their angiogenic activity. Among the factors with mitogenic effects on endothelial cells are basic fibroblast growth factor (bFGF), transforming growth factor-alpha (TGF-alpha) and very probably insulin-like growth factor-1 (IGF-1). Other secretory products such as angiotropin and human angiogenic factor (HAF) are nonmitogenic but promote angiogenesis by inducing migration of endothelial cells. Prostaglandins, platelet-derived growth factor (PDGF), granulocyte-macrophage- and granulocyte-colony stimulating factor (GM-CSF, G-CSF), interleukin 6 (IL-6) and angiotensin converting enzyme (ACE) have also been shown to be angiogenic, but their mode of action is still to be clearly defined. As the extracellular matrix appears to be involved in the control of angiogenesis, macrophage-derived factors that can alter this structure via degradation or via the clotting system will also be discussed. Tumor necrosis factor alpha (TNF-alpha), interleukin 1 (IL-1) and transforming growth factor-beta (TGF-beta) have complex actions on endothelial cells, and can partially inhibit angiogenesis. Among the factors which solely inhibit neovascularization are the interferons. As it is not known whether all of these factors play a role in angiogenesis in vivo attempts to detect them in situ during the course of neovascularization will be described. Finally macrophages will be discussed as cells that may not be mandatory for each phase of the angiogenic process but whose angiogenic capabilities are comprehensive and unsurpassed by any other cell.

HETERODIMERS OF THE CALCIUM-BINDING PROTEINS MRP8 AND MRP14 ARE EXPRESSED ON THE SURFACE OF HUMAN MONOCYTES UPON ADHERENCE TO FIBRONECTIN AND COLLAGEN . RELATION TO TNF-ALPHA , IL-6, AND SUPEROXIDE PRODUCTION

The 27E10 antigen is a heterodimer of MRP8 and MRP14, two Ca2+‐binding proteins related to the S‐100 protein family. Previous studies have shown that 27E10 epitope–bearing monocyte subsets are prevalent in early acute but absent in chronic inflammatory conditions. These observations further provide an impetus for identifying the cellular mechanisms responsible for the appearance of different monocyte subpopulations during inflammation. Therefore this in vitro study was carried out to investigate the influence of adhesion in inducing 27E10‐positive subsets. In adhesion assays the role of 27E10 antigen in spontaneous adherence was obvious, as a monoclonal antibody directed against the 27E10 antigen significantly inhibited the adherence of monocytes to collagen and fibronectin. In contrast, these extracellular matrix (ECM) proteins induce the cell surface expression and association of 27E10 antigen with cytoskeleton (CSK), detected by flow cytometry and confocal laser scan microscopy, respectively. Similar results were obtained on cross‐linking with specific antibodies, thus showing involvement of the integrin molecules VLA‐2 and VLA‐4. In addition, the association with CSK could be confirmed by differential detergent extraction. The observed redistribution of 27E10 antigen guided by collagen compared with fibronectin was also paralleled by an augmented release of inflammatory cytokines interleukin‐6, tumor necrosis factor α, and superoxide anions. Thus, this study demonstrates that under inflammatory conditions the interactions of extravasating monocytes with the ECM may induce an activated phenotype of monocytes marked by 27E10. J. Leukoc. Biol. 57: 63–71; 1995.

Regulation of the immune response by epidermal cytokines and neurohormones

The ability of the cellular components of the skin immune system to mount various types of immune responses is largely dependent upon their ability to release and to respond to different signals provided by immunoregulatory mediators such as cytokines and neuropeptides. In principle, almost every cytokine known so far, including interleukins (IL), interferons (IFN), tumor necrosis factors (TNF), colony stimulating factors (CSF) and several growth factors can be detected in the skin under certain physiological or pathological conditions. There is recent evidence that neuropeptides such as substance P, calcitonin-related gene product (CGRP) a.o. as well as neurohormones such as proopiomelanocortin (POMC), which is the precursor of several peptidehormones including melanocyte stimulating hormones (MSH), are present in epidermal cells, cutaneous tumors and inflammatory cells infiltrating the skin. In addition to their well known functions as neurotransmitters or hormones, these peptides have recently been recognized as potent immunomodulating agents which inhibit the production and activity of immunoregulatory and proinflammatory cytokines (IL-1, IL-2, IFN gamma) but induce the release of factors, e.g., IL-10, which downregulate immune responses. Accordingly, in animals, alpha MSH and CGRP have been shown to inhibit the induction of contact hypersensitivity reactions. Therefore, a complex network of interacting mediators including cytokines and neuropeptides within the cutaneous microenvironment are crucial elements of the induction, elicitation and regulation of cutaneous immune responses.

Interaction of murine dendritic cells with collagen up-regulates allostimulatory capacity, surface expression of heat stable antigen, and release of cytokines.

In vivo, dendritic cells (DC) reside in direct proximity to extracellular matrix (ECM) proteins. Because ECM proteins affect morphology and function of a number of cell types, this study investigated potential effects of ECM proteins on functional properties of DC. DC were generated from murine bone marrow cultures, supplemented with granulocyte‐macrophage colony‐stimulating factor, and subsequently cultured on tissue culture plates coated with various ECM proteins. Among the ECM proteins tested, collagen (COL) up‐regulated the T cell stimulatory capacity of DC. This effect was accompanied by sustained surface expression of the co‐stimulatory molecule heat stable antigen on DC and by enhanced release of interleukin‐1 and interleukin‐6, respectively. Because fibronectin or solubilized COL were unable to cause similar changes in DC phenotype or function, we conclude that adherence to COL interferes specifically with DC function. These data suggest that ECM proteins may be involved in regulation of DC phenotype as well as in their functional activation. J. Leukoc. Biol. 60: 465–472; 1996.

Expression of a glycoprotein of the carcinoembryonic antigen family in normal and neoplastic sebaceous glands

BACKGROUND Carcinoembryonic antigen (CEA) is a well-known marker for sweat gland differentiation in adnexal neoplasms. OBJECTIVE The aim of this study was to examine the expression of glycoproteins of the CEA family, that is, CEA-180, nonspecific cross-reacting antigens (NCAs), and biliary glycoprotein (BGP), in sebaceous glands and in neoplasms with sebaceous differentiation. METHODS Normal adult and fetal skin, hyperplasias, hamartomas, and neoplasms with sebaceous or follicular differentiation were stained immunohistochemically with a panel of polyclonal and monoclonal antibodies highly specific for CEA-180, NCAs, and BGP. Double immunostaining was performed to correlate the CEA expression with that of epithelial membrane antigen (EMA), a glycoprotein consistently found in differentiating sebocytes. RESULTS Whereas sweat glands coexpressed CEA, NCAs, BGP, and EMA, sebaceous glands were exclusively labeled with the antibodies recognizing BGP or EMA. Staining of the sebaceous glands was restricted to mature sebocytes, sparing immature cells. At the ultrastructural level immunoreactivity for BGP and EMA was demonstrable in the golgi area, in small vesicles, and along the cell membranes. During fetal development BGP was not found until the sebaceous glands matured. The expression of BGP and EMA was highly conserved in reactive, hamartomatous, and neoplastic proliferations of adnexal structures with sebaceous differentiation. CONCLUSION The expression of BGP, a CEA glycoprotein, in differentiating sebocytes accounts for the reactivity of many anti-CEA antibodies with sebaceous glands and thus disqualifies the CEA family as a monospecific marker for sweat gland differentiation.

Neoplasms with sweat gland differentiation express various glycoproteins of the carcinoembryonic antigen (CEA) family

Carcinoembryonic antigen (CEA) is a well‐established marker for sweat gland differentiation in adnexal neoplasms. In contrast to previous assumptions, CEA does not represent a single oncofetal antigen but comprises a family of homologous glycoproteins, i.e. the classical CEA‐180, biliary glycoprotein (BGP), and non‐specific crossreacting antigens (NCA). The aim of the study was to evaluate the distribution of the respective glycoproteins of the CEA family in sweat gland neoplasms, as compared to normal sweat glands. A panel of mono‐specific antibodies was applied to a total of 83 samples of hyperplastic and cystic alterations of sweat glands, sweat gland neoplasms, and cutaneous metastases of different origin. Within a single group of neoplasms the immunohistochemical profile was rather consistent. Staining for both CEA‐180 and NCA‐90 indicated ductal differentiation of both eccrine and apocrine glands. Co‐expression of CEA‐180, NCA‐90, and BGP was consistent with differentiation towards the secretory part of eccrine glands or the transitional portion of proximal ducts. Neoplasms with signs of apocrine secretion showed a preferential immunoreactivity for NCA‐90 and BGP. In conclusion, a specification of the members of the CEA family may be of some value in the differential diagnosis of adnexal neoplasms, but not in the discrimination of sweat gland carcinoma from metastatic carcinoma.

Carcinoembryonic Antigen and Related Glycoproteins in Psoriasis

Psoriasis is a benign but hyperproliferative skin disease. Psoriatic basal cells show a phenotype similar to that of normal skin, while psoriatic suprabasal cells exhibit a qualitatively altered keratinization pathway, resulting in the absence of the granular layer. These cells further show an abnormal expression of cellular differentiation antigens, which does not lead to tumor development. This immunohistological study demonstrates the appearance of carcinoembryonic antigen (CEA) in psoriatic suprabasal cells below the parakeratotic layer, while other markers such as CEA-related antigens, the nonspecific cross-reacting antigens and alpha-fetoprotein are not expressed. CEA is absent in normal skin, lichen planus, ichthyosis vulgaris and allergic dermatitis. Our data support the notion that dedifferentiation of psoriatic suprabasal keratinocytes is due to the reactivation of early developmental patterns of differentiation in this disease.