Amelioration of lymphoid hyperplasia and hypergammaglobulinemia in lupus-prone mice (gld) by Fas-ligand gene transfer

Ability of trichloroethylene metabolite to promote immune pathology is strain-specific

Chronic low-level exposure to the environmental pollutant trichloroethylene has been shown to promote autoimmune disease in association with CD4(+) T-lymphocyte activation in lupus-prone MRL(+/+) mice. One of the primary metabolites of trichloroethylene, trichloroacetaldehyde hydrate (TCAH), was similarly shown to increase the percentage of IFNgamma-producing CD4(+) T-lymphocytes when added to the drinking water of MRL(+/+) mice. In addition, TCAH-treated MRL(+/+) mice developed skin inflammation and alopecia. In the present study TCAH was tested for its ability to accelerate the development of alopecia in C3H/HeJ mice which tend to develop the disorder spontaneously late in life. In contrast to MRL(+/+) mice, C3H/HeJ mice treated with TCAH did not develop alopecia at an increased rate. In addition, TCAH did not promote the expansion of activated IFNgamma-producing CD4(+) T-lymphocytes in C3H/HeJ mice. CD4(+) T-lymphocytes from TCAH-treated C3H/HeJ mice, unlike their MRL(+/+) counterparts, did not become resistant to activation-induced apoptosis following in vivo exposure to TCAH. Taken together, it appears that the ability of TCAH to promote immune-mediated pathology is strain-specific and may require an autoimmune-prone genetic background.

Exposure to a metabolite of the environmental toxicant, trichloroethylene, attenuates CD4+ T cell activation-induced cell death by metalloproteinase-dependent FasL shedding

Long-term exposure to the environmental contaminant trichloroethylene (TCE) in drinking water has been shown to promote autoimmune disease in association with the expansion of activated CD4+ T cells. The effects of TCE on CD4+ T cells were linked in the present study to the ability of TCE metabolite, trichloroacetaldehyde hydrate (TCAH), to inhibit activation-induced cell death (AICD) in CD4+ T cells. TCAH attenuated AICD in CD4+ T cells by decreasing FasL (CD178) expression but not by altering Fas (CD95) expression or by interfering with Fas-signaling events following direct engagement of the Fas receptor. The TCAH-induced decrease in FasL expression did not appear to be mediated at the transcriptional level but was instead due to increased shedding of FasL from the surface of the CD4+ T cells. The ability of TCAH to cleave FasL and thereby decrease AICD appeared to be mediated by metalloproteinases and correlated with a TCAH-induced increase in matrix metalloproteinase-7. Thus, this study presents the novel finding that the environmental contaminant TCE works via its metabolite TCAH to attenuate AICD by increasing metalloproteinase activity that cleaves FasL from CD4+ T cells. This represents a mechanism by which an environmental trigger inhibits AICD in CD4+ T cells and may thereby promote CD4+ T cell-mediated autoimmune disease.

New therapies in systemic lupus erythematosus

A new understanding of the pathogenesis of autoimmunity, the mechanisms of action of older drugs, the advent of target-specific biological therapies and pharmacogenomics has created multiple treatment options for the patient with systemic lupus erythematosus. These include topical therapies, more selective non-steroidal anti-inflammatory agents, hormonal interventions and a new generation of immune suppressives. Currently available strategies also include the use of intravenous gamma globulin, apheresis, stem-cell transplantation and antileprosy preparations alone or in combination with immune suppressives. A handful of biologicals have been studied in clinical trials. After two decades without new options for lupus patients practitioners now have a full menu of improved therapeutic options.

Genetics of systemic lupus erythematosus. Clinical implications

Rheumatic diseases have long been recognized as having complex inheritance patterns. It has recently been estimated that over 100 genes may be implicated in the SLE disease process. Identification of these genes has led to a greater understanding of the etiopathogenesis of SLE and is beginning to lead to new types of interventions directed at correcting aberrant biological processes.

Progress in the treatment of proliferative lupus nephritis

Lupus nephritis is often well developed at the time of diagnosis. High-dose corticosteroids are universally accepted as the initial approach to the control of severe inflammation in the kidney. Long-term disease control and the minimization of iatrogenic risk usually require adjunctive therapies that target the more fundamental immunoregulatory disturbances of lymphoid cells. Of the available cytotoxic drugs, cyclophosphamide is currently among the most effective, although it cannot be considered ideal in terms of efficacy or toxicity. New prospects for the treatment of proliferative lupus nephritis include novel immunosuppressive agents (e.g. mycophenolate, cyclosporine, fludarabine), combination chemotherapy (e.g. cyclophosphamide plus fludarabine), and sequential chemotherapy (e.g. cyclophosphamide-azathioprine), immunological reconstitution using intensive cytoreductive chemotherapy (with or without stem cell rescue), co-stimulatory molecule inhibition (e.g. humanized anti-CD154 monoclonal antibody, CTLA4-Ig). Gene therapy remains an attractive prospect, but its feasibility clearly depends on the further definition of lupus-promoting genes and the availability of methods to establish stable expression of disease-corrective genes in the appropriate lymphoid cells.

Control of apoptosis of cardiovascular fibroblasts: a novel drug target

Adequate control of survival or programmed cell death (apoptosis) of cardiovascular cells appears as an important drug target. While prevention of apoptotic death of cardiomyocytes has been assessed in detail, selective induction of apoptosis of vascular smooth muscle cells or fibroblasts could also be of relevance. Thus, induction of apoptosis of vascular smooth muscle cells by p65 NF-kappa B and Bcl-xL antisense oligonucleotides or p53 overexpression could be useful for limiting vascular lesions associated with restenosis. Although fibroblasts represent the majority of cardiac cells, few attempts were made to induce fibroblast apoptosis in disorders associated with excessive collagen deposition and fibrosis. It is hypothesized that early interference with fibroblast proliferation after myocardial infarction or inflammatory heart disease limits fibrosis which further impairs cardiac performance. A candidate approach could involve growth factor analogues which are known to induce fibroblast apoptosis when an incomplete growth stimulus persists.