Treatment with the phosphodiesterase type-4 inhibitor rolipram fails to inhibit blood--brain barrier disruption in multiple sclerosis

Abstract

Rolipram, a prototypic phosphodiesterase-4 inhibitor, is highly effective in suppressing Th1 autoimmunity in multiple animal models, including experimental autoimmune encephalomyelitis. In addition, rolipram has been extensively studied as a potential neuroprotective agent. Based on its anti-inflammatory activity, we tested the efficacy of rolipram in suppressing inflammatory disease activity in multiple sclerosis in a proof-of-principle phase I/II open-label clinical trial. Enrolled MS patients were evaluated by monthly MRI and clinical examinations during 3 months (four MRIs) of pretreatment baseline and 8 months of rolipram therapy. The primary outcome was a change in contrast-enhanced lesions between baseline and the last 4 months of rolipram therapy. Previously defined biomarkers of rolipram-mediated immunomodulation were evaluated during the study. The trial was stopped prematurely because the drug was poorly tolerated and because of safety concerns: we observed an increase, rather than decrease, in the brain inflammatory activity measured by contrast-enhanced lesions on brain MRI. At the administered doses rolipram was active in vivo as documented by immunological assays. We conclude that the reasons underlying the discrepancy between the therapeutic efficacy of rolipram in experimental autoimmune encephalomyelitis versus multiple sclerosis are at present not clear.

Conflict of interest statement

Conflict of interest: Dr. Claus-Steffen Stürzebecher was an employee of Schering, AG, Berlin, Germany at the time when the rolipram clinical trial was performed at the NINDS/NIH.

Figures

Figure 1. NIB rolipram trial design

A/ Schematic delineation of the rolipram trial design. Shaded areas represent predetermined comparison for the primary outcome measure. PK = pharmacokinetics. Triangle under “drug dosing” represents slow pre-determined titration of rolipram during the first month of rolipram therapy.

Figure 2. Effect of rolipram on brain MRI contrast-enhancing lesions (CELs): Primary outcome measure

Number of new (black circles) and total (open triangles) CELs in individual patients from A/ Stage I (low inflammatory MS) and B/ Stage II (high inflammatory MS) of the trial. C/ Cumulative number of contrast-enhancing lesions (CELs) per entire cohort per month. Duration of rolipram treatment is highlighted by gray shading. Pre-determined analysis compares the number of total and new CELs during four months of baseline (Months -3 to 0) and the last four months of treatment (Months 5–9; darker gray shading).

Figure 3. Effect of rolipram therapy on CD80 and CD86 expression on B cells and monocytes

A/ Prospective ex-vivo immunophenotyping of CD80 and CD86 surface expression on CD19+ B cells. For each subject, baseline data-point represents average of two baseline samples and therapy data-point represents the average of 2–3 therapy samples acquired prospectively, every other month. B/ From cryopreserved PBMC samples monocytes and B cells were activated with LPS. Surface expression of CD80 on CD19+ B cells and on CD14+ monocytes was evaluated before and 20h after activation by flow cytometry. C/ Changes in subpopulations of immune cells induced by rolipram therapy. For each subject, baseline data-point represents average of two baseline samples and therapy data-point represents the average of 2–3 therapy samples acquired prospectively, every other month.

Figure 4. Effect of rolipram therapy on T cell proliferation

Cryopreserved PBMC were thawed and analyzed in parallel for all tree time-points. PBMC were CFSE stained and polyclonally activated for 6–7 days. Number of mitoses was calculated independently for CD4+ and CD8+ T cells. Mo3 Th = month 3 on therapy, Mo8 Th = month 8 on therapy.