Mycophenolate mofetil (MMF) is part of the standard immunosuppressive treatment after transplantation and usually given as "one-dose-fits-all" together with a calcineurin inhibitor (CNI). Although... Show moreMycophenolate mofetil (MMF) is part of the standard immunosuppressive treatment after transplantation and usually given as "one-dose-fits-all" together with a calcineurin inhibitor (CNI). Although drug concentrations are frequently monitored, there is still a group of patients who experience side effects related to excessive or insufficient immune suppression. We therefore aimed to identify biomarkers that reflect the overall immune status of the patient and might support individualized dosing. We previously studied immune biomarkers for CNIs and aimed to investigate whether these are also suitable to monitor MMF activity. Healthy volunteers received a single dose of MMF or placebo, after which IMPDH enzymatic activity, T cell proliferation, and cytokine production were measured and compared to MPA (MMF's active metabolite) concentration in three different matrices (plasma, peripheral blood mononuclear cells, and T cells). MPA concentrations in T cells exceeded those in PBMCs, but all intracellular concentrations correlated strongly with plasma concentrations. At clinically relevant MPA concentrations, IL-2 and IFN-& gamma; production was mildly suppressed, while MPA T cell proliferation was strongly inhibited. Based on these data, it is expected that monitoring of T cell proliferation in MMF-treated transplantation patients may be a valid strategy to avoid excessive immune suppression. Show less
Veld, A.E.I. 't; Jansen, M.A.A.; Huisman, B.W.; Schoonakker, M.; Kam, M.L. de; Moes, D.J.A.R.; ... ; Moerland, M. 2022
Therapeutic drug monitoring (TDM) of calcineurin inhibitors (i.e., tacrolimus and cyclosporin A) is standard of care after solid organ transplantation. Although the incidence of acute rejection has... Show moreTherapeutic drug monitoring (TDM) of calcineurin inhibitors (i.e., tacrolimus and cyclosporin A) is standard of care after solid organ transplantation. Although the incidence of acute rejection has strongly decreased, there are still many patients who experience severe side effects or rejection after long-term treatment. In this healthy volunteer study we therefore aimed to identify biomarkers to move from a pharmacokinetic-based towards a pharmacodynamic-based monitoring approach for calcineurin inhibitor treatment. Healthy volunteers received a single dose of cyclosporine A (CsA) or placebo, after which whole blood samples were stimulated to measure ex vivo T cell functionality, including proliferation, cytokine production, and activation marker expression. The highest whole blood concentration of CsA was found at 2 h post-dose, which resulted in a strong inhibition of interferon gamma (IFNy) and interleukin-2 (IL-2) production and expression of CD154 and CD71 on T cells. Moreover, the in vitro effect of CsA was studied by incubation of pre-dose whole blood samples with a concentration range of CsA. The average in vitro and ex vivo CsA activity overlapped, making the in vitro dose-effect relationship an interesting method for prediction of post-dose drug effect. The clinical relevance of the results is to be explored in transplantation patients on calcineurin inhibitor treatment. Show less
Background. The primary challenge of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patient care is the early detection of relapses to prevent organ damage and increase... Show moreBackground. The primary challenge of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patient care is the early detection of relapses to prevent organ damage and increase survival. Potential biomarkers for relapses are ANCA and B cells, but their predictive value is a matter of debate. Therefore this study investigated how ANCA and B-cell status related to relapses in AAV patients treated with rituximab (RTX) as remission induction (RI).Methods. This single-centre cohort study identified 110 ANCA-positive AAV patients treated with RTX between 2006 and 2018. Serial ANCA, CD19(+) B-cell status and relapses were assessed >2years.Results. Patients (31/110) relapsed within 2years after RTX RI treatment. Patients who achieved and maintained PR3-ANCA negativity (n=29) had few relapses (3%), while persistent proteinase 3 (PR3)-ANCA positivity (n=49) and reappearance of PR3-ANCAs (n=10) associated significantly with more relapses (37%, P=0.002 and 50%, P=0.002). Patients with incomplete B-cell depletion (n=11) had significantly more relapses (54%) as compared with patients with B-cell depletion [n=76 (26%), P=0.02]. Also, patients with repopulation of B cells (n=58) had significantly more relapses (41%) as compared with patients without B-cell repopulation [n=27 (15%), P=0.03]. Overall, the absence of PR3- or myeloperoxidase (MPO)-ANCA positivity was highly predictive for remaining relapse-free. In PR3-ANCA-positive patients, 96% of the relapses occurred with persistent or reappearance of PR3-ANCAs and 81% with B-cell repopulation. In MPO-ANCA-positive patients, all relapses were restricted to patients with persistent MPO-ANCAs and B-cell repopulation.Conclusions. Upon RI treatment with RTX in AAV patients, ANCA and B-cell status were predictive of the majority of relapses and specifically their absence strongly predicted a relapse-free status. Therefore the implementation of ANCA and B-cell monitoring could guide therapeutic decision-making to prevent relapses in AAV patients treated with RTX. Show less
BackgroundB-cell depletion with rituximab (RTX) is an effective treatment for anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) patients. Nevertheless, relapses are frequent... Show moreBackgroundB-cell depletion with rituximab (RTX) is an effective treatment for anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) patients. Nevertheless, relapses are frequent after RTX, often preceded by B-cell repopulation suggesting that residual autoreactive B-cells persist despite therapy. Therefore, this study aimed to identify minimal residual autoimmunity (MRA) in the B-cell compartment of AAV patients treated with RTX.MethodsEuroFlow-based highly-sensitive flow cytometry (HSFC) was employed to study B-cell and plasma cell (PC) subsets in-depth in AAV patients before and after RTX treatment. Additionally, peripheral blood mononuclear cells (PBMCs) of these RTX-treated AAV patients were cultured and in vitro stimulated with CpG, IL-2, and IL-21 to induce antibody-secreting cells (ASC). (ANCA)-IgG was measured in these supernatants by ELISA.ResultsBy employing EuroFlow-based HSFC, we detected circulating CD19(+) B-cells at all timepoints after RTX treatment, in contrast to conventional low-sensitive flow cytometry. Pre-germinal center (Pre-GC) B-cells, memory B-cells and CD20(+)CD138(-) plasmablasts (PBs) were rapidly and strongly reduced, while CD20(-)CD138(-) PrePC and CD20(-)CD138(+) mature (m)PCs were reduced slower and remained detectable. Both memory B-cells and CD20(-) PCs remained detectable after RTX. Serum ANCA-IgG decreased significantly upon RTX. Changes in ANCA levels strongly correlated with changes in naive, switched CD27(+) and CD27(-) (double-negative) memory B-cells, but not with plasma cells. Lastly, we demonstrated in vitro ANCA production by AAV PBMCs, 24 and 48 weeks after RTX treatment reflecting MRA in the memory compartment of AAV patients.ConclusionWe demonstrated that RTX induced strong reductions in circulating B-cells, but never resulted in complete B-cell depletion. Despite strongly reduced B-cell numbers after RTX, ANCA-specific memory B-cells were still detectable in AAV patients. Thus, MRA is identifiable in AAV and can provide a potential novel approach in personalizing RTX treatment in AAV patients. Show less
Veld, A.E.I.; Grievink, H.W.; Saghari, M.; Stuurman, F.E.; Kam, M.L. de; Vries, A.P.J. de; ... ; Moerland, M. 2019
