Mycophenolate mofetil interferes with interferon gamma production in T-cell activation models

Case Report: A Novel Pathogenic Missense Mutation in FAS: A Multi-Generational Case Series of Autoimmune Lymphoproliferative Syndrome

Autoimmune Lymphoproliferative Syndrome (ALPS), commonly caused by mutations in the FAS gene, is a disease with variable penetrance. Subjects may be asymptomatic, or they may present with lymphadenopathy, splenomegaly, cytopenias, or malignancy. Prompt recognition of ALPS is needed for optimal management. We describe a multi-generational cohort presenting with clinical manifestations of ALPS, and a previously unreported heterozygous missense variant of uncertain significance in FAS (c.758G >T, p.G253V), located in exon 9. Knowledge of the underlying genetic defect permitted prompt targeted therapy to treat acute episodes of cytopenia. This cohort underscores the importance of genetic testing in subjects with clinical features of ALPS and should facilitate the reclassification of this variant as pathogenic.

Oral mycophenolate mofetil as a stabilizing treatment for progressive non-segmental vitiligo: results from a prospective, randomized, investigator-blinded pilot study

Dexamethasone oral mini-pulse (OMP) is commonly used to halt progression of non-segmental vitiligo (NSV). There is an unmet need for non-phototherapy, non-corticosteroid therapeutic options for stabilizing actively spreading NSV. To assess the efficacy of oral mycophenolate mofetil in stabilizing active NSV in comparison to OMP. In this prospective, randomized, investigator-blinded study, 50 patients of active vitiligo [baseline vitiligo disease activity (VIDA) score 4] were randomized into two groups in 1:1 ratio. Group A received oral dexamethasone (2.5 mg on two successive days a week) and group B received mycophenolate mofetil (up to 2 g) for 180 days with a treatment-free follow-up period of 90 days. Assessment was done using VIDA, number of new lesions in past 30 days, and Vitiligo Area Scoring Index (VASI). Arrest of disease progression was defined as the absence of any new lesions in past 30 days. Twenty-five patients received OMP (group A, 11 males, 14 females), and 25 received mycophenolate (group B, 12 males, 13 females). In both groups, Kruskal-Wallis revealed a significant trend for reduction in VIDA and the number of new lesions in last 30 days, over the treatment and follow-up duration when compared to baseline (p < 0.001). The first significant reduction in VIDA was noticed on 90th day in groups A and B (p < 0.001). In both groups, VIDA reduced significantly at the 180th day compared to baseline (p < 0.001, WMP), only to increase significantly at the 270th day (p < 0.001, WMP). VIDA in group B was marginally higher at 270 days than group A (p 0.03; Mann-Whitney). Eighteen and 17 patients achieved VIDA 2 + on the 180th day in groups A and B, respectively. The mean number of new lesions in last 30 days reduced significantly in both groups at the 180th day (p < 0.001) and 270th day [p < 0.001; Wilcoxon matched pairs (WMP)] when compared to baseline; but increased significantly at the 270th day compared to the 180th day (p 0.006 WMP). Twenty patients in group A and 18 patients in group B had arrest of the disease activity with treatment. Mean duration to arrest disease progression was 47.2 ± 12.1 days in group A, and 52.5 ± 9.3 days in group B; p 0.21. The difference between VASI at baseline and VASI at the 180 and 270th days was non-significant in both groups (p 0.18 WMP). Five patients in each group failed the respective treatments. Acne (n = 3), weight gain (n = 3), headache, insomnia and menstrual irregularity (n = 1 each) were the important adverse effects noted with dexamethasone pulse; whereas nausea (n = 6) and diarrhea (n = 4) were the commonest adverse effects noted with mycophenolate. Two patients in group B discontinued treatment because of leucopenia (n = 1) and transaminitis (n = 1) that resolved after the discontinuation of mycophenolate. Both OMP and mycophenolate mofetil halt actively spreading vitiligo, and have distinct adverse effect profiles. These should be offered in progressive vitiligo, especially in circumstances precluding the use of phototherapy. Relapse occurred significantly earlier with mycophenolate, and relapse rate was higher (though non-significant) than dexamethasone OMP. The repigmentation potential is minimal for both therapies. This study was approved by Institute Ethics Committee, and retrospectively registered with clinical trial registry of India (CTRI/2018/02/011,664).

Mycophenolate mofetil and animal models

Mycophenolate mofetil (MMF), is the morpholinoethyl ester of mycophenolic acid (MPA). Though initially developed as an anti-rejection treatment, MMF is beginning to find application in more common immune-mediated diseases. MMF has been shown to be effective against transplant-associated vascular disease, lupus and other inflammatory diseases via multiple mechanisms in several animal models. MMF treatment blocks the proliferation of T cells and B cells, attenuates the production of autoreactive IgG and IgM, diminishes complement deposition, and reduces the production of multiple proinflammatory cytokines including TNF-α, IFN-γ, IL-2, IL-3, IL-4, IL-5, IL-6 and IL-12. It also increases production of the anti-inflammatory mediator IL-10. In addition, MMF reduces the infiltration of immune cells into sites of inflammation by interfering with the expression of cell-surface molecules critical for this process, including MHC class II, CD40, CD80, CD86, I-A, and ICAM-1. Additional mechanisms involving mannosylation and N-linked glycosylation of cell-surface molecules are only beginning to be investigated. This article will focus on the contribution of animal models of disease as investigational tools in the development of MMF as an immunomodulatory drug. The use of mice, rats, rabbits, monkeys, baboons and interspecific xenografts will be discussed.

In Vitro Influence of Mycophenolic Acid on Selected Parameters of Stimulated Peripheral Canine Lymphocytes

Mycophenolic acid (MPA) is an active metabolite of mycophenolate mofetil, a new immunosuppressive drug effective in the treatment of canine autoimmune diseases. The impact of MPA on immunity is ambiguous and its influence on the canine immune system is unknown. The aim of the study was to determine markers of changes in stimulated peripheral canine lymphocytes after treatment with MPA in vitro. Twenty nine healthy dogs were studied. Phenotypic and functional analysis of lymphocytes was performed on peripheral blood mononuclear cells cultured with mitogens and different MPA concentrations– 1 μM (10⁻³ mol/m³), 10 μM or 100 μM. Apoptotic cells were detected by Annexin V and 7-aminoactinomycin D (7-AAD). The expression of antigens (CD3, CD4, CD8, CD21, CD25, forkhead box P3 [FoxP3] and proliferating cell nuclear antigen [PCNA]) was assessed with monoclonal antibodies. The proliferation indices were analyzed in carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled cells. All analyses were performed using flow cytometry. The influence of MPA on apoptosis was dependent on the mechanism of cell activation and MPA concentration. MPA caused a decrease in the expression of lymphocyte surface antigens, CD3, CD8 and CD25. Its impact on the expression of CD4 and CD21 was negligible. Its negative influence on the expression of FoxP3 was dependent on cell stimulation. MPA inhibited lymphocyte proliferation. In conclusion, MPA inhibited the activity of stimulated canine lymphocytes by blocking lymphocyte activation and proliferation. The influence of MPA on the development of immune tolerance–expansion of Treg cells and lymphocyte apoptosis–was ambiguous and was dependent on the mechanism of cellular activation. The concentration that MPA reaches in the blood may lead to inhibition of the functions of the canine immune system. The applied panel of markers can be used for evaluation of the effects of immunosuppressive compounds in the dog.

New advances in the diagnosis and treatment of autoimmune lymphoproliferative syndrome

PURPOSE OF REVIEW

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of disrupted lymphocyte homeostasis, resulting from mutations in the Fas apoptotic pathway. Clinical manifestations include lymphadenopathy, splenomegaly, and autoimmune cytopenias. A number of new insights have improved the understanding of the genetics and biology of ALPS. These will be discussed in this review.

RECENT FINDINGS

A number of key observations have been made recently that better define the pathophysiology of ALPS, including the characterization of somatic FAS variant ALPS, the identification of haploinsufficiency as a mechanism of decreased Fas expression, and the description of multiple genetic hits in FAS in some families that may explain the variable penetrance of the disease. In addition, ALPS has been shown to be a more common condition, as patients diagnosed with other disorders, including Evans syndrome and common variable immune deficiency, have been found to have ALPS. Finally, the treatment of the disease has changed as splenectomy and rituximab have been shown to have unexpected ALPS-specific toxicities, and mycophenolate mofetil and sirolimus have been demonstrated to have marked activity against the disease.

SUMMARY

On the basis of novel advances, the diagnostic algorithm and recommended treatment for ALPS have changed significantly, improving quality of life for many patients.

Advances in the management and understanding of autoimmune lymphoproliferative syndrome (ALPS)

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of T cell dysregulation caused by defective Fas-mediated apoptosis. Patients with ALPS can develop a myriad of clinical manifestations including lymphadenopathy, hepatosplenomegaly, autoimmunity and increased rates of malignancy. ALPS may be more common that originally thought, and testing for ALPS should be considered in patients with unexplained lymphadenopathy, hepatosplenomegaly, and/or autoimmunity. As the pathophysiology of ALPS is better characterized, a number of targeted therapies are in preclinical development and clinical trials with promising early results. This review describes the clinical and laboratory manifestations found in ALPS patients, as well as the molecular basis for the disease and new advances in treatment.

Mycophenolate Mofetil and Atherosclerosis: Results of Animal and Human Studies

The immunosuppressive agent mycophenolate mofetil (MMF) has beneficial effects in cardiac transplant patients beyond the suppression of tissue rejection. Patients with regimens containing MMF experience diminished intimal thickening and cardiac allograft vasculopathy compared to patients treated with azathioprine. Studies have shown that diet-induced atherosclerosis (a related vasculopathy) is a chronic inflammatory process, and so MMF has also been used to reduce atherosclerosis in a rabbit model of hyperlipidemia. These data hold out the intriguing possibility that MMF might be a viable primary or secondary preventive agent in people at significant risk for atherosclerosis.

Rapamycin improves lymphoproliferative disease in murine autoimmune lymphoproliferative syndrome (ALPS)

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of abnormal lymphocyte survival caused by defective Fas-mediated apoptosis, leading to lymphadenopathy, hepatosplenomegaly, and an increased number of double-negative T cells (DNTs). Treatment options for patients with ALPS are limited. Rapamycin has been shown to induce apoptosis in normal and malignant lymphocytes. Since ALPS is caused by defective lymphocyte apoptosis, we hypothesized that rapamycin would be effective in treating ALPS. We tested this hypothesis using rapamycin in murine models of ALPS. We followed treatment response with serial assessment of DNTs by flow cytometry in blood and lymphoid tissue, by serial monitoring of lymph node and spleen size with ultrasonography, and by enzyme-linked immunosorbent assay (ELISA) for anti-double-stranded DNA (dsDNA) antibodies. Three-dimensional ultrasound measurements in the mice correlated to actual tissue measurements at death (r = .9648). We found a dramatic and statistically significant decrease in DNTs, lymphadenopathy, splenomegaly, and autoantibodies after only 4 weeks when comparing rapamycin-treated mice with controls. Rapamycin induced apoptosis through the intrinsic mitochondrial pathway. We compared rapamycin to mycophenolate mofetil, a second-line agent used to treat ALPS, and found rapamycin's control of lymphoproliferation was superior. We conclude that rapamycin is an effective treatment for murine ALPS and should be explored as treatment for affected humans.

Short communication: No detrimental immunological effects of mycophenolate mofetil and HAART in treatment-naive acute and chronic HIV-1-infected patients

Mycophenolate mofetil has been proposed for HIV-1 therapy because of its guanine-depleting effect, which is expected to interfere with HIV-1 replication directly by hampering reverse transcription and indirectly via inhibition of CD4+ T cell proliferation. However, treatment with mycophenolate mofetil might also compromise lymphocyte reconstitution and HIV-specific immunity. Therefore we longitudinally studied the effects of mycophenolate mofetil in combination with HAART on T cell proliferation, lymphocyte reconstitution, and HIV-specific CD4+ and CD8+ T cell responses in six therapy-naive, acute or chronic HIV-1-infected patients, as compared to eight patients treated with HAART alone. T cell proliferation in whole blood cultures of patients treated with mycophenolate mofetil was inhibited. Strikingly, ex vivo Ki67 expression within T cells was not influenced by treatment with mycophenolate mofetil. In vitro studies showed that Ki67 expression occurs at an early step of the cell cycle and was not inhibited by guanine depletion. When treatment with mycophenolate mofetil was stopped a transient increase in apoptosis and Ki67-expressing T cells was detected. This observation together with near complete inhibition of T cell proliferation in whole blood cultures during treatment with mycophenolate mofetil indicated that T cell proliferation was inhibited in patients treated with mycophenolate mofetil. Still, there was no evidence for detrimental effects of treatment with mycophenolate mofetil in addition to HAART on CD4+ T cell reconstitution or HIV-specific immunity.