[Complement activation products (C3a and C5b-9) as markers of activity of dermatomyositis. Comparison with usual biochemical parameters]

INTRODUCTION

Dermatomyositis (DM) is an autoimmune disease included in the group of idiopathic inflammatory myopathies. Markers of disease activity are needed for clinical control in order to facilitate adjustment of immunomodulatory therapy. We analyzed the relationship between complement activation products (CAP) and the activity of dermatomyositis and its usefulness in the follow-up of the disease and the prediction of recrudescences related to usual biochemical parameters.

MATERIAL AND METHODS

We studied 16 patients with DM that were followed periodically. In each appointment the degree of cutaneous and muscular activity was assessed and such disease activity was correlated with plasma levels of C3a and C5b-9, measured by ELISA.

RESULTS

Though we obtained certain correlation between disease activity and plasma levels of C3a and C5b-9, the strength of such correlation was not superior to that obtained by usual biochemical markers. C3a was shown to be the most sensitive marker (100 %) with a sufficient specificity (83.3 %) in the capability to predict recrudescences.

CONCLUSIONS

C3a and, to a lesser extent C5b-9, would be useful in the identification of patients with especially active DM as well as in predicting disease recrudescences. Nevertheless they are not superior to the rest of biochemical markers as indicators of current activity.

Tissue expression and subcellular localization of the pro-survival molecule Bcl-w

Anti-apoptotic members of the Bcl-2 family, such as Bcl-w, maintain cell viability by preventing the activation of the cell death effectors, the caspases. Gene targeting experiments in mice have demonstrated that Bcl-w is required for spermatogenesis and for survival of damaged epithelial cells in the gut. Bcl-w is, however, dispensable for physiological cell death in other tissues. Here we report on the analysis of Bcl-w protein expression using a panel of novel monoclonal antibodies. Bcl-w is found in a diverse range of tissues including colon, brain and testes. A survey of transformed cell lines and purified hematopoietic cells demonstrated that Bcl-w is expressed in cells of myeloid, lymphoid and epithelial origin. Subcellular fractionation and confocal laser scanning microscopy demonstrated that Bcl-w protein is associated with intracellular membranes. The implications of these results are discussed in the context of the phenotype of Bcl-w-null mice and recent data that suggest that Bcl-w may play a role in colon carcinogenesis.

An immunohistopathologic study in cutaneous necrotizing vasculitis

In order to investigate the importance of timing in the immunophenotypical characteristics of the inflammatory infiltrate and in the adhesion molecules expression in cutaneous necrotizing vasculitis (CNV) we carried on an immunohistopathologic study. An avidin-biotin-streptavidin peroxidase technique was performed on 21 lesional skin biopsy specimens obtained sequentially at 0 to 24, 72 and 120 hours from seven patients with a CNV presenting as palpable purpura. A panel of monoclonal antibodies specific for inflammatory cells (T lymphocytes, polymorphonuclear leukocytes, macrophages, dendritic cells) and different adhesion molecules (E-selectin, ICAM-1, VCAM-1, LFA-1, VLA-4) was used. Moreover, HECA-450 monoclonal antibody was used to identify cutaneous lymphocyte antigen (CLA) in the inflammatory infiltrate. In all cases, polymorphonuclear leukocytes predominated in the early phase of CNV and their number decreased significantly with time (p = 0.0001). The T lymphocytes were present from the beginning and their number remained stable or increased slightly in time (p = 0.1), thus becoming predominant in the perivascular infiltrate in older lesions. Macrophages were scattered on interstitium since the early phase and they showed a time-dependent increase (p = 0.0003). E-selectin (ELAM-1) expression was detected at the first biopsy and it decreased depending on the age of the evolving vasculitis (p = 0.0033). The expression of CLA decreased also with time in 5 of the 7 cases (p = 0.0001). Our study supports the existence of an unique histopathologic pattern in CNV, in which the inflammatory infiltrate varies with time at the expense of the number of polymorphonuclear cells and macrophages.

The conserved SOCS box motif in suppressors of cytokine signaling binds to elongins B and C and may couple bound proteins to proteasomal degradation

The suppressors of cytokine signaling (SOCS) family of proteins act as intracellular inhibitors of several cytokine signal transduction pathways. Their expression is induced by cytokine activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway and they act as a negative feedback loop by subsequently inhibiting the JAK/STAT pathway either by direct interaction with activated JAKs or with the receptors. These interactions are mediated at least in part by the SH2 domain of SOCS proteins but these proteins also contain a highly conserved C-terminal homology domain termed the SOCS box. Here we show that the SOCS box mediates interactions with elongins B and C, which in turn may couple SOCS proteins and their substrates to the proteasomal protein degradation pathway. Analogous to the family of F-box-containing proteins, it appears that the SOCS proteins may act as adaptor molecules that target activated cell signaling proteins to the protein degradation pathway.

Bim: a novel member of the Bcl-2 family that promotes apoptosis

Certain members of the Bcl-2 family inhibit apoptosis while others facilitate this physiological process of cell death. An expression screen for proteins that bind to Bcl-2 yielded a small novel protein, denoted Bim, whose only similarity to any known protein is the short (nine amino acid) BH3 motif shared by most Bcl-2 homologues. Bim provokes apoptosis, and the BH3 region is required for Bcl-2 binding and for most of its cytotoxicity. Like Bcl-2, Bim possesses a hydrophobic C-terminus and localizes to intracytoplasmic membranes. Three Bim isoforms, probably generated by alternative splicing, all induce apoptosis, the shortest being the most potent. Wild-type Bcl-2 associates with Bim in vivo and modulates its death function, whereas Bcl-2 mutants that lack survival function do neither. Significantly, Bcl-xL and Bcl-w, the two closest homologues of Bcl-2, also bind to Bim and inhibit its activity, but more distant viral homologues, adenovirus E1B19K and Epstein-Barr virus BHRF-1, can do neither. Hence, Bim appears to act as a 'death ligand' which can only neutralize certain members of the pro-survival Bcl-2 sub-family.

T-cell population of primary and secondary cutaneous B-cell lymphomas does not express the cutaneous lymphocyte-associated antigen (CLA)

Primary cutaneous B-cell lymphomas (CBCL) are a group of malignant lymphomas with apparently distinct clinicopathological and immunophenotypical features. As in other B-cell lymphomas, the accompanying benign cell population in CBCL includes a variable number of T lymphocytes whose role is not well understood. In the present study we characterized the immunophenotype of these T cells and compared it with that of the reactive T-cell population in specific skin involvement by noncutaneous B-cell malignancies. Our results indicated that most T cells in both primary and secondary B-cell lymphomas were CLA+ memory/effector helper T cells which differed from the currently known CLA+ memory/effector helper T lymphocytes of the skin-associated lymphoid tissue (SALT) system. However, the endothelial CLA ligand, E-selectin, was expressed on dermal vessels. These results suggest that a B cell environment and/or a lack of epidermal involvement promote(s) the recruitment into the skin of a different, apparently less specific, subset of memory helper T cells from those seen in T-cell-mediated dermatoses.

Uncommon cutaneous manifestations of lupus erythematosus

Cutaneous manifestations of lupus erythematosus (LE) are, usually, characteristic enough to permit an easy diagnosis. However, some patients may present less typical lesions, associated or not to the classic ones. Therefore, irrespectively of the variety of LE (acute, subacute and chronic), in absence of the typical butterfly rash, erythematosquamous papules or plaques, or any of the characteristic cutaneous alterations, it is important (even though not always easy) to recognize the uncommon and/or atypical changes of the skin.

Cell adhesion molecule expression in cutaneous lesions of dermatomyositis

Chronic inflammation seems to play a major role in skin and muscle cell damage in dermatomyositis. Adhesion molecules and their ligands are fundamental in regulating inflammation. We have carried out an immunohistochemical analysis of different activation-inducible adhesion markers in 15 biopsy specimens from dermatomyositis skin lesions. Consistent findings were the increased expression of intercellular adhesion molecule-1 (ICAM-1) on endothelial cells, inflammatory cells and focally grouped keratinocytes in contact with subepidermal inflammatory infiltrates. Immunoreactivity for vascular cell adhesion molecule-1 (VCAM-1) was predominant on endothelial cells of the upper reticular dermis and dermal stellate-shaped cells. E-selectin (endothelial leukocyte adhesion molecule-1) immunoreactivity was less extensive, detected mostly on segments of vessels of the papillary dermis and upper reticular dermis, and sometimes independent of inflammation. This pattern of adhesion molecule expression is similar to that described in other immunemediated dermatoses. The up-regulation of the adhesion molecules appears to play a role in the development and perpetuation of dermatomyositis skin lesions.

Membrane attack complex deposits in cutaneous lesions of dermatomyositis

BACKGROUND AND DESIGN

The presence of membrane attack complex of complement (MAC) deposits in the intramuscular vasculature of biopsy specimens taken from patients with dermatomyositis (DM) has been implicated in the pathogenesis of this myopathy. The purpose of this study was to investigate the presence of MAC deposition in the skin lesions of patients with DM. Using immunohistochemical methods, we examined 22 biopsy specimens from lesional skin, six biopsy specimens from uninvolved skin, and 12 muscle biopsy specimens from patients with DM for the presence of MAC and vitronectin and CD59, two regulatory proteins of complement.

RESULTS

The deposition of MAC was demonstrated in a large percentage of biopsy specimens obtained from the lesional skin of patients with DM. Deposits were found along the dermoepidermal junction in 19 (86%) of 22 biopsy specimens. Deposits on the vessel walls of the dermis were found in 17 (77%) of 22 biopsy specimens; but only in six of these biopsy specimens (27%) were deposits present in more than 10% of blood vessels. In contrast, deposits along the dermoepidermal junction and the vessel walls of the dermis were absent in specimens from uninvolved skin. In 12 muscle biopsy specimens obtained simultaneously from these patients, MAC deposits were found on the vessel walls in nine (75%), but only in six (50%) were deposits found in more than 10% of the intramuscular vessels. The pattern of vitronectin immunoreactivity in skin and muscle biopsy specimens obtained from patients with DM was similar to MAC deposits. The expression of CD59 was normal in all skin and muscle biopsy specimens.

CONCLUSIONS

The deposition of MAC was found in a high percentage of biopsy specimens from the lesional skin of patients with DM; it was absent in uninvolved skin. These findings suggest that the complement system may be involved in the pathogenesis of the skin lesions of DM.

Immunopathologic study of skin lesions in dermatomyositis

To determine the phenotype of skin infiltrates in affected and uninvolved skin from patients with dermatomyositis, immunohistochemical studies with 10 murine monoclonal antibodies were carried out on 25 skin biopsy specimens. Dermal infiltrates consisted predominantly of HLA-DR-expressing macrophages and T lymphocytes, especially of the CD4 subset. B lymphocytes, as defined by positive staining for Leu-12, were absent. Epidermal Langerhans cells were absent or decreased in some areas of affected skin but the total number was normal. OKT6+ cells were present in some dermal mononuclear infiltrates in close contact with lymphocytes. We observed reduced HLA-DR positivity of dermal capillary endothelia. These findings are apparently different from dermatomyositis muscle infiltrates but are similar to those in skin affected by cutaneous lupus erythematosus. Our observations support the concept that, in autoimmune diseases, cellular infiltrates may be more organ-specific than disease-specific.

Control of prostanoid synthesis: role of reincorporation of released precursor fatty acids

Prostanoid synthesis is limited by the availability of free arachidonic acid. This polyunsaturated fatty acid is liberated by phospholipases and usually is an intermediate of the deacylation-reacylation cycle of membrane phospholipids. In rat peritoneal macrophages, ethylmercurisalicylate (merthiolate) or N-ethylmaleimide (NEM) dose dependently inhibited the incorporation of arachidonic acid into cellular phospholipids, at lower concentrations specifically into phosphatidylcholine. Furthermore, merthiolate could be shown to be a rather selective inhibitor of lysophosphatidylcholine acyltransferase. In contrast, phospholipase A2 activity was not affected over a wide dose range. Consequently, macrophages showed a large increase in prostanoid synthesis (prostaglandin E, prostacyclin and thromboxane) in the presence of both lysophosphatide acyltransferase inhibiting agents. Similar results were obtained with human platelets, in which merthiolate increased the release of thromboxane. Addition of free arachidonic acid also enhanced prostanoid synthesis in macrophages. At optimal concentrations, merthiolate had no further augmenting effect. It is concluded that the rate of prostanoid synthesis is not only controlled by phospholipase A2 activity, but rather by the activity of the reacylating enzymes, mainly lysophosphatide acyltransferase.

[The Zinsser-Cole-Engman syndrome. A contribution to congenital poikilodermias as well as a contribution to familial pancytopenias]

The Zinser-Cole-Engman-syndrome (Dyskeratosis congenita), which is characterized by the cardinal symptoms pigmentatio reticularis, onychodystrophia and leukoplakia oris, is discussed as a clinical entity, which is different from Fanconi's anemia and Braun-Falco-Marghescu-syndrome. A review of the literature is given.