Use of anti-thymocyte globulin in the management of refractory systemic autoimmune diseases

Apoptotic effects of antilymphocyte globulins on human pro-inflammatory CD4+CD28- T-cells

Background

Pro-inflammatory, cytotoxic CD4⁺CD28⁻ T-cells with known defects in apoptosis have been investigated as markers of premature immuno-senescence in various immune-mediated diseases. In this study we evaluated the influence of polyclonal antilymphocyte globulins (ATG-Fresenius, ATG-F) on CD4⁺CD28⁻ T-cells in vivo and in vitro.

Principal Findings

Surface and intracellular three colour fluorescence activated cell sorting analyses of peripheral blood mononuclear cells from 16 consecutive transplant recipients and short-term cell lines were performed. In vivo, peripheral levels of CD3⁺CD4⁺CD28⁻ T-cells decreased from 3.7±7.1% before to 0±0% six hours after ATG-F application (P = 0.043) in 5 ATG-F treated but not in 11 control patients (2.9±2.9% vs. 3.9±3.0%). In vitro, ATG-F induced apoptosis even in CD4⁺CD28⁻ T-cells, which was 4.3-times higher than in CD4⁺CD28⁺ T-cells. ATG-F evoked apoptosis was partially reversed by the broad-spectrum caspase inhibitor benzyloxycarbonyl (Cbz)-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD-fmk) and prednisolon-21-hydrogensuccinate. ATG-F triggered CD25 expression and production of pro-inflammatory cytokines, and induced down-regulation of the type 1 chemokine receptors CXCR-3, CCR-5, CX3CR-1 and the central memory adhesion molecule CD62L predominately in CD4⁺CD28⁻ T-cells.

Conclusion

In summary, in vivo depletion of peripheral CD3⁺CD4⁺CD28⁻ T-cells by ATG-F in transplant recipients was paralleled in vitro by ATG-F induced apoptosis. CD25 expression and chemokine receptor down-regulation in CD4⁺CD28⁻ T-cells only partly explain the underlying mechanism.

Immune depletion with cellular mobilization imparts immunoregulation and reverses autoimmune diabetes in nonobese diabetic mice

OBJECTIVE

The autoimmune destruction of beta-cells in type 1 diabetes results in a loss of insulin production and glucose homeostasis. As such, an immense interest exists for the development of therapies capable of attenuating this destructive process through restoration of proper immune recognition. Therefore, we investigated the ability of the immune-depleting agent antithymocyte globulin (ATG), as well as the mobilization agent granulocyte colony-stimulating factor (GCSF), to reverse overt hyperglycemia in the nonobese diabetic (NOD) mouse model of type 1 diabetes.

RESEARCH DESIGN AND METHODS

Effects of each therapy were tested in pre-diabetic and diabetic female NOD mice using measurements of glycemia, regulatory T-cell (CD4+CD25+Foxp3+) frequency, insulitis, and/or beta-cell area.

RESULTS

Here, we show that combination therapy of murine ATG and GCSF was remarkably effective at reversing new-onset diabetes in NOD mice and more efficacious than either agent alone. This combination also afforded durable reversal from disease (>180 days postonset) in animals having pronounced hyperglycemia (i.e., up to 500 mg/dl). Additionally, glucose control improved over time in mice subject to remission from type 1 diabetes. Mechanistically, this combination therapy resulted in both immunological (increases in CD4-to-CD8 ratios and splenic regulatory T-cell frequencies) and physiological (increase in the pancreatic beta-cell area, attenuation of pancreatic inflammation) benefits.

CONCLUSIONS

In addition to lending further credence to the notion that combination therapies can enhance efficacy in addressing autoimmune disease, these studies also support the concept for utilizing agents designed for other clinical applications as a means to expedite efforts involving therapeutic translation.

Treatment of refractory Wegener's granulomatosis with antithymocyte globulin (ATG): an open study in 15 patients

BACKGROUND

A subset of patients with Wegener's granulomatosis does not respond sufficiently to cyclophosphamide and glucocorticosteroids or suffers of intolerable side effects. Anecdotal data suggest that antithymocyte globulin (ATG) may be a treatment option for these patients. We now describe 15 patients treated with ATG for refractory Wegener's granulomatosis.

METHODS

Fifteen patients with histologically proven active refractory Wegener's granulomatosis (seven unresponsive to cyclophosphamide, eight intolerant) were treated with ATG by a protocol (SOLUTION protocol) designed by the European Vasculitis Study (EUVAS) Group.

RESULTS

Before ATG administration, patients had received a mean of 5.2 (range 2 to 7) different therapeutic approaches including glucocorticosteroids and cyclophosphamide in all and experimental therapies in six, without control of disease activity [2.8 (range 1 to 7) relapses during a disease duration of 63.2 (range 18 to 180) months]. Thirteen of 15 patients showed a favorable response to ATG with partial (N= 9) or complete (N= 4) remission. During a follow-up of 21.8 (range 6 to 68) months, seven patients relapsed after a mean of 8.4 (range 2 to 24) months (five minor and two major relapses). Six patients are free of relapse for 22.3 (range 7 to 64) months. Two patients died, 1 and 3 days following the first dose of ATG, due to pulmonary hemorrhage and infection (one each). Although further immunosuppressive treatment was required in all surviving patients, a less intensive regimen could be applied in 12. Beside fever and chills associated with the first gift of ATG, ATG was well tolerated, with infections being observed in five cases and serum sickness in two.

CONCLUSION

Anti-T-cell-directed treatment with ATG may be a therapeutic option for severe refractory Wegener's granulomatosis if simultaneous infections and fluid overload have been ruled out. In patients with alveolar hemorrhage, ATG should only be used under special caution.

Life-threatening complications of systemic sclerosis

Pulmonary arterial hypertension is common in patients with SSc. Fig. 1 shows the diagnostic and therapeutic approach to PAH in SSc. Doppler echocardiography may suggest the diagnosis, but RHC is necessary to confirm PAH and to measure vasoreactivity. Therapy is directed at the underlying connective tissue disease. Vasoreactive patients often benefit from therapy with high-dose calcium-channel [figure: see text] blockers, but most patients are not vasoreactive. Intravenous epoprostenol and oral endothelin-1 receptor antagonists improve hemodynamic measurements and symptoms in SSc-associated PAH. The therapy of right ventricular failure is focused on vasodilators, inotropes, and diuretics with careful attention to avoiding systemic hypotension. The scleroderma pulmonary-renal syndrome and the scleroderma renal crisis are distinct syndromes with different clinical presentations, histopathologic manifestations, treatments, and outcomes. The scleroderma pulmonary renal syndrome is an autoimmune vasculitis of kidney and lung associated with normal blood pressure. Treatment is supportive, and prognosis is dismal. In contrast, scleroderma renal crisis is associated with systemic hypertension, onion skinning of afferent arterioles, and response to ACE inhibition and renal replacement therapy. Pericardial effusions are common but only occasionally lead to tamponade. Esophageal dysmotility is often associated with aspiration, leading to pulmonary fibrosis, pneumonia, or ARDS. Diffuse bowel involvement may result in pseudo-obstruction, bacterial overgrowth, or malabsorption. Prokinetic agents, antibiotics, and parenteral nutrition may be required.

Scleroderma and related disorders: therapeutic aspects

Improvements in management of systemic sclerosis have occurred through a growing understanding of pathogenic events accompanied by advances in diagnosis and assessment, as well as developments in organ-based therapeutics. Unfortunately, disease-modifying therapies of proven efficacy remain elusive and several agents in current use have been shown in well-controlled clinical trials to be of questionable benefit. More positively, there have been advances in the treatment of major visceral complications such as renal crisis, pulmonary fibrosis, pulmonary hypertension, gastrointestinal involvement and in the management of scleroderma-associated Raynaud's phenomenon. Current approaches are reviewed, evidence supporting or refuting the use of putative disease-modifying agents is discussed, and new strategies are described that are currently being considered for this fascinating but complex multisystem connective tissue disease.

Antithymocyte globulin treatment of orbital Wegener granulomatosis: a follow-up study

PURPOSE

To describe the follow-up of patients with orbital Wegener granulomatosis after antithymocyte globulin treatment.

METHODS

Patients with ocular/orbital Wegener granulomatosis refractory to standard treatment were selected for immunotherapy with rabbit antithymocyte globulin intravenously. The specific ocular/orbital symptoms were monitored in patients with a vision-threatening form of Wegener granulomatosis or a life-threatening form with ocular symptoms.

RESULTS

One patient had a complete remission, two patients had remissions but still needed additional treatment, and one patient remained refractory.

CONCLUSIONS

In selected patients, antithymocyte globulin immunotherapy may present an alternative when vision or life is threatened by orbital Wegener granulomatosis.

Management of systemic sclerosis: the art and science

There have been substantial strides in the therapy of systemic sclerosis (SSc) in recent years, particularly in the management of individual organ manifestations. Effective treatments are available for SSc renal crisis and many of the gastrointestinal manifestations of the disease. Raynaud's phenomenon, a nearly universal problem in SSc, also may be effectively managed. Treatment of the pulmonary complications, pulmonary hypertension and interstitial lung disease, remains difficult. Patients with early, diffuse SSc are the best candidates for experimental therapies intended to modify the overall disease process. Most disease-modifying agents have been directed at the fibrotic and inflammatory processes characteristic of SSc and have achieved little success. Future therapies may target mediators of vascular dysfunction in SSc. The success of future therapeutic trials will depend on collaborative efforts between treatment centers.