The balance between memory and regulatory cell populations in kidney transplant recipients with operational tolerance.

Donor-reactive memory cells represent a barrier to long-term kidney graft survival. A better understanding of regulatory mechanisms that counterbalance alloreactive memory responses may help to identify patients with operational tolerance. This prospective study investigated the equilibrium between memory T-cell subsets and regulatory T or B cells (Tregs, Bregs) in peripheral blood of kidney transplant recipients with operational tolerance (N = 8), chronic rejection (N = 8), and different immunosuppressive treatment regimens (N = 81). Patients on hemodialysis and healthy individuals served as controls (N = 50). In addition, the expression of Treg- and Breg-associated molecule genes was analyzed. Patients with chronic rejection showed a disrupted memory T-cell composition with a significantly higher frequency of circulating CD8+ terminally differentiated effector memory (TEMRA) T cells than patients with operational tolerance, patients on hemodialysis, or healthy controls (P < 0.001). Low frequency of CD8+ TEMRA and high frequency of Tregs and transitional Bregs were found in operationally tolerant patients. Consequently, operationally tolerant patients showed, as compared to all other transplant recipients with different immunosuppressive regiments, the lowest ratios between CD8+ TEMRA T cells and Tregs or Bregs (for both P < 0.001). Moreover, a specific peripheral blood transcription pattern was found in operationally tolerant patients with an increased expression of Breg- and Treg-associated genes CD22 and FoxP3 and a decreased FcγRIIA/FcγRIIB transcript ratio (for all P < 0.001). In conclusion, monitoring the balance between circulating CD8+ TEMRA T cells and regulatory cell subsets and their transcripts may help to distinguish transplant recipients with operational tolerance from recipients at risk of graft loss.

The Joint Vasculitis Registry in German-speaking countries (GeVas): subgroup analysis of 266 AAV patients.

OBJECTIVES: Prospective long-term observational data on the disease course of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) were missing in Germany to date. Therefore, the Joint Vasculitis Registry in German-speaking countries (GeVas) has been established to follow the course of patients with AAV. The aim of this study is to present baseline data of patients with newly diagnosed and relapsing AAV enrolled in the GeVas registry. METHODS: GeVas is a prospective, web-based, multicentre, clinician-driven registry for the documentation of organ manifestations, damage, long-term outcomes, and therapy regimens in various types of vasculitis. Recruitment started in June 2019. RESULTS: Between June 2019 and October 2022, 266 patients with AAV were included in the GeVas registry: 173 (65%) with new-onset and 93 (35%) with relapsing AAV. One hundred and sixty-two (61%) patients were classified as granulomatosis with polyangiitis (GPA), 66 (25%) as microscopic polyangiitis (MPA), 36 (13%) as eosinophilic granulomatosis with polyangiitis (EGPA), and 2 (1%) as renal limited AAV. The median age was 59 years (51-70 years, IQR), 130 (51%) patients were female. Most patients were ANCA positive (177; 67%) and affected by general symptoms, pulmonary, ear nose throat (ENT), renal and neurological involvement. For induction of remission, the majority of patients received glucocorticoids (247, 93%) in combination with either rituximab (118, 45%) or cyclophosphamide (112, 42%). CONCLUSIONS: Demographic characteristics are comparable to those in other European countries. Differences were found regarding ANCA status, frequencies of organ manifestations, and therapeutic regimens. The GeVas registry will allow longitudinal observations and prospective outcome measures in AAV.

The Joint Vasculitis Registry in German-speaking countries (GeVas): subgroup analysis of 195 GCA patients.

OBJECTIVES: Giant cell arteritis (GCA) is one of the most common forms of vasculitis. There is an abundance of studies which are conducted in a randomised controlled trial setting but limited with respect to cohort size and follow-up time. GeVas is the first large-scale registry for vasculitides in German-speaking countries that enables to evaluate this rare disease. Herein we focus on the subgroup of GCA patients including follow-up data up to one year. METHODS: GeVas is a prospective, web-based, multicentre registry for the documentation of organ manifestations, outcomes, and therapy regimens in vasculitides. Recruitment started in June 2019. By April 2023, 15 centres were initiated and have started to enrol patients. RESULTS: After 4 years, 195 GCA-patients were included in the registry, of which 64% were female and 36% were male. The average age was 76 years at the time of recruitment (IQR=69-82). Seventy-nine percent were included in the registry because of a newly diagnosed GCA and 21% because of a relapse. At the first assessment most of the patients (89%) described general symptoms. Thirty-one percent stated ocular symptoms. Cranial symptoms were documented in 78% of the cases. All patients were documented with immunosuppressive treatment at start, of whom 95% received prednisolone, 16% cyclophosphamide, 20% methotrexate, and 48% tocilizumab. After three months 62% and after one year 91% of the patients achieved remission. CONCLUSIONS: Regarding demographics, clinical manifestations and diagnostics, our study showed a similar composition compared to other studies. However, our data differed in terms of treatment regimens.

Induction of Long-Lasting Regulatory B Lymphocytes by Modified Immune Cells in Kidney Transplant Recipients.

BACKGROUND: We recently demonstrated that donor-derived modified immune cells (MICs)-PBMCs that acquire immunosuppressive properties after a brief treatment-induced specific immunosuppression against the allogeneic donor when administered before kidney transplantation. We found up to a 68-fold increase in CD19 + CD24 hi CD38 hi transitional B lymphocytes compared with transplanted controls. METHODS: Ten patients from a phase 1 clinical trial who had received MIC infusions before kidney transplantation were followed to post-transplant day 1080. RESULTS: Patients treated with MICs had a favorable clinical course, showing no donor-specific human leukocyte antigen antibodies or acute rejections. The four patients who had received the highest dose of MICs 7 days before surgery and were on reduced immunosuppressive therapy showed an absence of in vitro lymphocyte reactivity against stimulatory donor blood cells, whereas reactivity against third party cells was preserved. In these patients, numbers of transitional B lymphocytes were 75-fold and seven-fold higher than in 12 long-term survivors on minimal immunosuppression and four operationally tolerant patients, respectively ( P <0.001 for both). In addition, we found significantly higher numbers of other regulatory B lymphocyte subsets and a gene expression signature suggestive of operational tolerance in three of four patients. In MIC-treated patients, in vitro lymphocyte reactivity against donor blood cells was restored after B lymphocyte depletion, suggesting a direct pathophysiologic role of regulatory B lymphocytes in donor-specific unresponsiveness. CONCLUSIONS: These results indicate that donor-specific immunosuppression after MIC infusion is long-lasting and associated with a striking increase in regulatory B lymphocytes. Donor-derived MICs appear to be an immunoregulatory cell population that when administered to recipients before transplantation, may exert a beneficial effect on kidney transplants. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: MIC Cell Therapy for Individualized Immunosuppression in Living Donor Kidney Transplant Recipients (TOL-1), NCT02560220.

Live-virus serum neutralization after bivalent SARS-CoV-2 mRNA vaccination in hemodialysis patients.

The development of bivalent booster vaccines addresses the ongoing evolution of the emerging B.1.1.529 (omicron) variant subtypes that are known to escape vaccine-induced neutralizing antibody response. Little is known about the immunogenicity and reactogenicity of bivalent mRNA vaccines in hemodialysis patients with impaired vaccine response. In this prospective, observational cohort study, we analyzed SARS-CoV-2 anti-S1 IgG, surrogate neutralizing antibodies (SNA), and live-virus neutralization against the SARS-CoV-2 wildtype and the BA.5 variant in 42 hemodialysis patients with and without prior SARS-CoV-2 infection before and after an additional fifth bivalent vaccine dose. Anti-S1 IgG and SNA were significantly higher in hemodialysis patients with prior infection than in patients without infection (p < 0.001 and p < 0.01, respectively). In patients without prior infection, both antibody levels increased, and live-virus neutralizing antibodies against the wildtype and the BA.5 variant were correspondingly significantly higher after bivalent booster vaccination (p < 0.001 for both). Conversely, in patients with prior infection, anti-S1 IgG and SNA did not alter significantly, and bivalent booster vaccination did not induce additional humoral immune response against the SARS-CoV-2 wildtype and the BA.5 variant. Thus, bivalent mRNA vaccines might increase humoral responses in hemodialysis patients without prior infection. Larger clinical trials are needed to help guide vaccination strategies in these immunocompromised individuals.

Neutralizing antibody response against the B.1.617.2 (delta) and the B.1.1.529 (omicron) variants after a third mRNA SARS-CoV-2 vaccine dose in kidney transplant recipients.

Seroconversion after COVID-19 vaccination is impaired in kidney transplant recipients. Emerging variants of concern such as the B.1.617.2 (delta) and the B.1.1.529 (omicron) variants pose an increasing threat to these patients. In this observational cohort study, we measured anti-S1 IgG, surrogate neutralizing, and anti-receptor-binding domain antibodies three weeks after a third mRNA vaccine dose in 49 kidney transplant recipients and compared results to 25 age-matched healthy controls. In addition, vaccine-induced neutralization of SARS-CoV-2 wild-type, the B.1.617.2 (delta), and the B.1.1.529 (omicron) variants was assessed using a live-virus assay. After a third vaccine dose, anti-S1 IgG, surrogate neutralizing, and anti-receptor-binding domain antibodies were significantly lower in kidney transplant recipients compared to healthy controls. Only 29/49 (59%) sera of kidney transplant recipients contained neutralizing antibodies against the SARS-CoV-2 wild-type or the B.1.617.2 (delta) variant and neutralization titers were significantly reduced compared to healthy controls (p < 0.001). Vaccine-induced cross-neutralization of the B.1.1.529 (omicron) variants was detectable in 15/35 (43%) kidney transplant recipients with seropositivity for anti-S1 IgG, surrogate neutralizing, and/or anti-RBD antibodies. Neutralization of the B.1.1.529 (omicron) variants was significantly reduced compared to neutralization of SARS-CoV-2 wild-type or the B.1.617.2 (delta) variant for both, kidney transplant recipients and healthy controls (p < .001 for all).

The onset of active disease in systemic lupus erythematosus patients is characterised by excessive regulatory CD4+-T-cell differentiation.

OBJECTIVES: An imbalance between CD4+-regulatory T-cells (Tregs) and CD4+-responder T-cells (Tresps) correlates with active disease flares in systemic lupus erythematosus (SLE) patients. Both cell subsets consist of highly proliferating Tregs/Tresps expressing inducible T-cell co-stimulatory molecule (ICOS) and less proliferating ICOS--Tregs/Tresps. METHODS: Six-colour-flow-cytometric analysis was used to examine the effect of ICOS+- and ICOS--Treg/Tresp cell differentiation on the composition of the total CD4+-T-helper cell pool with ICOS+- and ICOS--Tregs/Tresps. Functionality of Tregs was examined using suppression assays. RESULTS: In 83 healthy volunteers, the ratio of ICOS+-Tregs/ICOS+-Tresps increased significantly with age, while that of ICOS--Tregs/ICOS--Tresps did not change. In 86 SLE patients (SLEDAI <7), disease activity was associated with an age-independently increased ratio of both ICOS+-Tregs/ICOS+-Tresps and ICOS--Tregs/ICOS--Tresps. In these patients, the functional activity of ICOS+-Tregs, but not of ICOS--Tregs, was preserved. In 13 markedly active disease patients (SLEDAI >7), the percentage of both ICOS+-Tregs and ICOS+-Tresps, was strongly increased within total CD4+-T-helper cells. However, the increased ratio of ICOS+-Tregs/ICOS+-Tresps was not maintained in these patients, due to terminal differentiation and accumulation of naïve cells within total ICOS+-Tregs. Despite increased differentiation of both ICOS--Tregs and ICOS--Tresps, the percentage of ICOS--Tregs increased within CD4+-T-helper cells, while that of ICOS--Tresps decreased, resulting in a significantly increased ratio of ICOS--Tregs/ICOS--Tresps independent of age. CONCLUSIONS: Our data reveal a crucial role of Treg immune senescence for the occurrence of disease flares in SLE patients, with ICOS+-Treg cells being most affected.

Glucocorticoid maintenance therapy and severe infectious complications in ANCA-associated vasculitis: a retrospective analysis.

To study the impact of glucocorticoid maintenance dose and treatment duration on outcomes in patients with AAV (ANCA-associated vasculitis) with emphasis on infectious complications. A total of 130 AAV patients from two German vasculitis centers diagnosed between August 2004 and January 2019 treated with cyclophosphamide and glucocorticoids for induction therapy and glucocorticoids for maintenance therapy were retrospectively enrolled. We investigated the influence of glucocorticoid maintenance therapy on patient survival, time to relapse, kidney function, infectious complications and irreversible physical damage. The patients were divided into the following groups: patients treated according to the predefined reduction scheme (< 7.5 mg) or patients treated with glucocorticoids ≥ 7.5 mg after 6 months. Compared to patients receiving < 7.5 mg glucocorticoids after 6 months, patients receiving [Formula: see text] 7.5 mg had an increased rate of infectious episodes per patient (1.7 vs. 0.6; p < 0.001), including urinary tract infection (p = 0.007), pneumonia (p = 0.003), opportunistic pneumonia (p = 0.022) and sepsis (p = 0.008). Especially pneumonia during the first 24 months after disease onset [hazard ratio, 3.0 (95% CI 1.5 - 6.1)] led to more deaths from infection (p = 0.034). Glucocorticoid maintenance therapy after 6 months had no impact on relapse rate or patient survival and decline in kidney function was comparable. Glucocorticoid maintenance therapy with [Formula: see text] 7.5 mg after 6 months is associated with more severe infectious complications leading to an increased frequency of deaths from infection. Glucocorticoid maintenance therapy has no effect on time to relapse or patient survival and should therefore be critically revised throughout the aftercare of AAV patients.

Impaired Differentiation of Highly Proliferative ICOS+-Tregs Is Involved in the Transition from Low to High Disease Activity in Systemic Lupus Erythematosus (SLE) Patients.

Dysregulations in the differentiation of CD4+-regulatory-T-cells (Tregs) and CD4+-responder-T-cells (Tresps) are involved in the development of active systemic lupus erythematosus (SLE). Three differentiation pathways of highly proliferative inducible costimulatory molecule (ICOS)+- and less proliferative ICOS--CD45RA+CD31+-recent-thymic-emigrant (RTE)-Tregs/Tresps via CD45RA-CD31+-memory-Tregs/Tresps (CD31+-memory-Tregs/Tresps), their direct proliferation via CD45RA+CD31--mature naïve (MN)-Tregs/Tresps, and the production and differentiation of resting MN-Tregs/Tresp into CD45RA-CD31--memory-Tregs/Tresps (CD31--memory-Tregs/Tresps) were examined in 115 healthy controls, 96 SLE remission patients, and 20 active disease patients using six color flow cytometric analysis. In healthy controls an appropriate sequence of these pathways ensured regular age-dependent differentiation. In SLE patients, an age-independently exaggerated differentiation was observed for all Treg/Tresp subsets, where the increased conversion of resting MN-Tregs/Tresps particularly guaranteed the significantly increased ratios of ICOS+-Tregs/ICOS+-Tresps and ICOS--Tregs/ICOS--Tresps during remission. Changes in the differentiation of resting ICOS+-MN-Tresps and ICOS--MN-Tregs from conversion to proliferation caused a significant shift in the ratio of ICOS+-Tregs/ICOS+-Tresps in favor of ICOS+-Tresps and a further increase in the ratio of ICOS--Tregs/ICOS--Tresps with active disease. The differentiation of ICOS+-RTE-Tregs/Tresps seems to be crucial for keeping patients in remission, where their limited production of proliferating resting MN-Tregs may be responsible for the occurrence of active disease flares.

Outcomes and complications following ABO-incompatible kidney transplantation performed after desensitization by semi-selective immunoadsorption - a retrospective study.

Because of the current organ shortage, ABO-incompatible (ABOi) transplantations have been increasingly performed in recent years. The results seem comparable to those of compatible transplantations, but there have also been reports of increased side effects possibly because of the desensitization therapy. To address an increase in severe infectious complications, we compared the outcomes of 48 ABOi transplant recipients to outcomes of 96 matched ABO-compatible (ABOc) controls transplanted at Heidelberg University Hospital from August 2005 to April 2018. Over a follow-up period of 8 years, ABOi transplant recipients had comparable graft and patient survival as well as graft function compared with ABOc patients. T-cell-mediated and antibody-mediated rejections were not different between groups. In ABOi transplant recipients, urosepsis (22.9% vs. 8.5%; P = 0.019) and pneumonia with opportunistic pathogens (8.3% vs. 1.0%, P = 0.025) appeared more frequently. As a consequence, a significantly higher number of deaths from infection have been observed after ABOi transplantations (6.3% vs. 0%, P = 0.010). High-titer recipients (isoagglutinin titer of ≥1:256) showed a higher incidence of BK virus replication and postoperative bleeding complications. ABO-incompatible transplantations can be performed with results that are not different from results after ABOc transplantations. However, an increased rate of serious infectious complications must be taken into account.

End-stage renal disease, dialysis, kidney transplantation and their impact on CD4+ T-cell differentiation.

Premature aging of both CD4+ regulatory T (Treg) and CD4+ responder-T (Tresp) cells in patients with end-stage renal disease (ESRD) is expected to affect the success of later kidney transplantation. Both T-cell populations are released from the thymus as inducible T-cell co-stimulator-positive (ICOS+ ) and ICOS- recent thymic emigrant (RTE) Treg/Tresp cells, which differ primarily in their proliferative capacities. In this study, we analysed the effect of ESRD and subsequent renal replacement therapies on the differentiation of ICOS+ and ICOS- RTE Treg/Tresp cells into ICOS+  CD31- or ICOS-  CD31- memory Treg/Tresp cells and examined whether diverging pathways affected the suppressive activity of ICOS+ and ICOS- Treg cells in co-culture with autologous Tresp cells. Compared with healthy controls, we found an increased differentiation of ICOS+ RTE Treg/Tresp cells and ICOS- RTE Treg cells through CD31+ memory Treg/Tresp cells into CD31- memory Treg/Tresp cells in ESRD and dialysis patients. In contrast, ICOS- RTE Tresp cells showed an increased differentiation via ICOS- mature naive (MN) Tresp cells into CD31- memory Tresp cells. Thereby, the ratio of ICOS+ Treg/ICOS+ Tresp cells was not changed, whereas that of ICOS- Treg/ICOS- Tresp cells was significantly increased. This differentiation preserved the suppressive activity of both Treg populations in ESRD and partly in dialysis patients. After transplantation, the increased differentiation of ICOS+ and ICOS- RTE Tresp cells proceeded, whereas that of ICOS+ RTE Treg cells ceased and that of ICOS- RTE Treg cells switched to an increased differentiation via ICOS- MN Treg cells. Consequently, the ratios of ICOS+ Treg/ICOS+ Tresp cells and of ICOS- Treg/ICOS- Tresp cells decreased significantly, reducing the suppressive activity of Treg cells markedly. Our data reveal that an increased tolerance-inducing differentiation of ICOS+ and ICOS- Treg cells preserves the functional activity of Treg cells in ESRD patients, but this cannot be maintained during long-term renal replacement therapy.

Cell therapeutic approaches to immunosuppression after clinical kidney transplantation.

Refinement of immunosuppressive strategies has led to further improvement of kidney graft survival in recent years. Currently, the main limitations to long-term graft survival are life-threatening side effects of immunosuppression and chronic allograft injury, emphasizing the need for innovative immunosuppressive regimens that resolve this therapeutic dilemma. Several cell therapeutic approaches to immunosuppression and donor-specific unresponsiveness have been tested in early phase I and phase II clinical trials in kidney transplantation. The aim of this overview is to summarize current cell therapeutic approaches to immunosuppression in clinical kidney transplantation with a focus on myeloid suppressor cell therapy by mitomycin C-induced cells (MICs). MICs show great promise as a therapeutic agent to achieve the rapid and durable establishment of donor-unresponsiveness in living-donor kidney transplantation. Cell-based therapeutic approaches may eventually revolutionize immunosuppression in kidney transplantation in the near future.

Randomized Trial of C5a Receptor Inhibitor Avacopan in ANCA-Associated Vasculitis.

Alternative C activation is involved in the pathogenesis of ANCA-associated vasculitis. However, glucocorticoids used as treatment contribute to the morbidity and mortality of vasculitis. We determined whether avacopan (CCX168), an orally administered, selective C5a receptor inhibitor, could replace oral glucocorticoids without compromising efficacy. In this randomized, placebo-controlled trial, adults with newly diagnosed or relapsing vasculitis received placebo plus prednisone starting at 60 mg daily (control group), avacopan (30 mg, twice daily) plus reduced-dose prednisone (20 mg daily), or avacopan (30 mg, twice daily) without prednisone. All patients received cyclophosphamide or rituximab. The primary efficacy measure was the proportion of patients achieving a ≥50% reduction in Birmingham Vasculitis Activity Score by week 12 and no worsening in any body system. We enrolled 67 patients, 23 in the control and 22 in each of the avacopan groups. Clinical response at week 12 was achieved in 14 of 20 (70.0%) control patients, 19 of 22 (86.4%) patients in the avacopan plus reduced-dose prednisone group (difference from control 16.4%; two-sided 90% confidence limit, -4.3% to 37.1%; P=0.002 for noninferiority), and 17 of 21 (81.0%) patients in the avacopan without prednisone group (difference from control 11.0%; two-sided 90% confidence limit, -11.0% to 32.9%; P=0.01 for noninferiority). Adverse events occurred in 21 of 23 (91%) control patients, 19 of 22 (86%) patients in the avacopan plus reduced-dose prednisone group, and 21 of 22 (96%) patients in the avacopan without prednisone group. In conclusion, C5a receptor inhibition with avacopan was effective in replacing high-dose glucocorticoids in treating vasculitis.

The role of age-related T-cell differentiation in patients with renal replacement therapy.

Dialysis patients have deficiencies regarding the generation of immune responses and show an increased susceptibility for infections. Persisting uremic conditions are made responsible for the increased aging of their immune system. In this study, we analyzed whether age-related differences in the differentiation of both recent-thymic-emigrant-(RTE)-regulatory (Tregs) and RTE-responder T cells (Tresps) into CD31--memory Tregs/Tresps led to differences in the suppressive activity of naive and memory Tregs on autologous Tresps between healthy volunteers and dialysis patients. We found that regardless of age, the differentiation of RTE-Treg/Tresps into CD31--memory-Treg/Tresps was significantly increased in dialysis patients. By analyzing the age-related differences in the differentiation of Tregs/Tresps, we saw that in healthy volunteers RTE-Tregs differentiate via CD31+-memory Tregs into CD31--memory Tregs, which may strengthen the suppressive activity of the total Treg pool. In contrast RTE-Tresps of healthy volunteers differentiate via mature naive (MN)-Tresps into CD31--memory-Tresps, which may weaken the reactivity of the total Tresp pool. Our data revealed that this normal differentiation via MN-Tresps was lost in dialysis patients, suggesting that their Tresps are less sensitive to Treg-mediated immunosuppression. Functional analysis of Tregs on autologous Tresps showed an increasing suppressive activity with age in healthy individuals, who therefore may have a lower risk of developing autoimmune diseases but owing to decreased reactivity of their Tresps are more likely to suffer from infections. In contrast, dialysis patients exhibited a decreasing suppressive activity with age, owing to strengthened Tresp reactivity, which could explain the higher prevalence of chronic inflammatory conditions in these patients.

Switch to an everolimus-facilitated cyclosporine A sparing immunosuppression improves glycemic control in selected kidney transplant recipients.

BACKGROUND: Mammalian target of rapamycin inhibitors (mToRi) allow calcineurin inhibitor (CNI) sparing therapy in renal transplant recipients with possible beneficial effects on the long-term allograft function and cardiovascular risk. The influence of mToRi on glucose metabolism is still under discussion. METHODS: In a retrospective analysis, renal allograft recipients switched from a cyclosporine A (CsA) to an everolimus (EVR)-based immunosuppression in the first year after transplantation were compared with patients on continued CsA treatment. At 6-month intervals, the prevalence of impaired fasting glucose (IFG) and new onset of diabetes after transplantation (NODAT) were assessed. RESULTS: A total of 146 renal transplant recipients were included. The cumulative prevalence of IFG and NODAT 30-months post-transplantation was significantly lower in patients switched to an immunosuppression with EVR compared to patients on continued CsA treatment (10% vs 22%, P=.049). However, patients switched to EVR showed a higher incidence of acute cellular rejections in the first 12 months (23% vs 11%, P=.048). CONCLUSION: EVR-based immunosuppression was associated with a similar or even improved glycemic control and improved renal function. However, due to higher rejection rates, patients switched to EVR should be carefully selected as rejection therapy with steroids counteracts the benefit in glycemic control.

The role of recent thymic emigrant-regulatory T-cell (RTE-Treg) differentiation during pregnancy.

During pregnancy, regulatory T cells (Tregs) have a key role in maternal immune tolerance to the semi-allogeneic fetus. Our previous results showed that the naive CD45RA(+)-Treg pool is functionally improved in pregnant women compared with non-pregnant women. Therefore, we examined the thymic output and differentiation of CD45RA(+)CD31(+) recent thymic emigrant (RTE)-Tregs during normal pregnancy and in the presence of preeclampsia. With the onset of pregnancy, the composition of the total CD4(+)CD127(low+/-)FoxP3(+)-Treg pool changed in the way that its percentage of RTE- and CD45RA(-)CD31(+)-memory Tregs decreased strongly, whereas that of the CD45RA(+)CD31(-)-mature naive (MN)-Tregs did not change and that of the CD45RA(-)CD31(-)-memory Tregs increased complementary. Thereby, the ratio of RTE-/MN-Tregs decreased from 1.0 to 0.7 leading to a significant increase in the suppressive activity of the naive CD45RA(+)-Treg pool. This effect was confirmed by re-assembling separated RTE- and MN-Tregs from non-pregnant women in the ratio of pregnant women. The suppressive activity of both separated naive Treg subsets was equally high in non-pregnant and pregnant women, but considerably reduced in preeclampsia patients, who showed significantly increased percentages of CD45RA(-)CD31(+)-memory Tregs, but decreased percentages of RTE- and MN-Tregs. Our results suggest a reduced thymic output of RTE-Tregs during pregnancy, which causes a decrease in the ratio of RTE-/MN-Tregs and thus an increase in the differentiation of RTE-Tregs towards CD45RA(-)CD31(-)-memory Tregs. Presumably, this differentiation of RTE-Tregs, which was impaired in preeclampsia patients, ensures the improved suppressive activity of the CD45RA(+)-naive Treg pool and thus retains the maintenance of pregnancy.

High interpatient variability in response to mycophenolic acid maintenance therapy in patients with ANCA-associated vasculitis.

BACKGROUND: Mycophenolic acid (MPA) is used in the maintenance therapy of antineutrophil cytoplasm antibody-associated systemic vasculitis (AASV). MPA exerts its immunosuppression by inhibiting inosine 5'-monophosphate dehydrogenase (IMPDH), depleting activated lymphocytes of guanine nucleotides and retarding their proliferation. The purpose of our study was to examine the correlation between clinical outcome and pharmacokinetic-pharmacodynamic (PD) relationships of MPA in patients with AASV. METHODS: We studied 358 Caucasian control patients without any MPA therapy to examine basal IMPDH activity. Thirty Caucasian patients with AASV under maintenance therapy with mycophenolate mofetil (MMF) underwent therapeutic drug monitoring. RESULTS: We observed a high interindividual variability with regard to basal IMPDH activity in patients without any MPA treatment (0.8-35 nmol/mg protein/h). Patients were followed for a mean (±SD) period of 22 ± 8 months. During the observation period, seven patients had a relapse with an elevated Birmingham Vasculitis Activity Score of 9.2 ± 6. The basal IMPDH activity (Abasal) in patients who subsequently relapsed was raised at baseline, before receiving their first dose of MMF, and further increased at the time of relapse, when compared with stable patients. Patients with a relapse during the maintenance therapy had significantly higher levels of IMPDH activity [IMPDH enzyme activity curve (AEC) (0-12)] than stable patients (P = 0.001), indicating inadequate IMPDH suppression. MPA-AUC (0-12) was significantly decreased in relapse patients, in contrast to stable patients (P < 0.05). CONCLUSIONS: Due to the highly variable response to maintenance therapy with MPA, PD drug monitoring is a new tool for detecting inadequate immunosuppression in AASV patients.