Peripheral blood lymphocyte subsets change after steroid withdrawal in renal allograft recipients: a prospective study

Microvascular inflammation in the absence of human leukocyte antigen-donor-specific antibody and C4d: An orphan category in Banff classification with cytotoxic T and natural killer cell infiltration

Isolated microvascular inflammation (iMVI) without HLA donor-specific antibodies or C4d deposition in peritubular capillaries remains an enigmatic phenotype that cannot be categorized as antibody-mediated rejection (ABMR) in recent Banff classifications. We included 221 kidney transplant recipients with biopsies with ABMR (n = 73), iMVI (n = 32), and normal (n = 116) diagnoses. We compared peripheral blood leukocyte distribution by flow cytometry and inflammatory infiltrates in kidney transplant biopsies among groups. Flow cytometry showed fewer lymphocytes and total, CD4+, and CD8+ peripheral T cells in iMVI compared with ABMR and normal cases. ABMR and iMVI had fewer total natural Killer (NK) cells but more NKG2A+ NK cells. Immunohistochemistry indicated that ABMR and iMVI had greater CD3+ and CD68+ glomerular infiltration than normal biopsies, whereas CD8+ and TIA1+ cells showed only increased iMVI, suggesting they are cytotoxic T cells. Peritubular capillaries displayed more CD3+, CD56+, TIA1+, and CD68+ cells in both ABMR and iMVI. In contrast, iMVI had less plasma cell infiltration in peritubular capillaries and interstitial aggregates than ABMR. iMVI displayed decreased circulating T and NK cells mirrored by T cell and NK cell infiltration in the renal allograft, similar to ABMR. However, the lesser plasma cell infiltration in iMVI may suggest an antibody-independent underlying stimulus.

Long-term glucocorticoid exposure persistently impairs CD4+ T cell biology by epigenetically modulating the mTORC1 pathway

Conventional glucocorticoid (GC) treatment has a long-term influence on T-cell immunity, resulting in an increased risk of opportunistic infection after drug withdrawal. The underlying mechanisms remain ambiguous. This study demonstrated that long-term GC treatment induced persistent lymphopenia in patients with primary glomerular disease. GCs continuously suppressed the proportion of CD4+ T cells even after the daily dose was tapered down to the physiologic equivalences, leading to a significant decline of the CD4/CD8 ratio. Meanwhile, GCs impaired CD4+ T cell biology, leading to enhanced apoptotic cell death, reduced proliferative capacity, downregulated pro-inflammatory genes, and upregulated immunoregulatory genes. Specifically, GCs altered FOXP3 expression pattern in CD4+ T cells and favored their acquisition of an active T regulatory (Treg) cell phenotype with enhanced IL-10 production upon stimulation. Mechanistically, GCs tampered with the transcriptional regulation of mechanistic target of rapamycin complex 1 (mTORC1) pathway, resulting in an inhibitory impact on the signaling activity. Targeting mTORC1 signaling by siRNAs could sufficiently modify the viability of GC-exposed CD4+ T cells. By high-throughput sequencing of genome-wide DNA methylation and mRNA, we further uncovered a causal relationship between the altered DNA methylation level and transcription activity in a subset of mTORC1 pathway genes in long-term GC exposure. Taken together, this study reveals a novel regulation of mTORC1 signaling, which might dominate the long-term influence of GC on CD4+ T cell biology in a dose-independent manner.

Alloimmune risk assessment for antibody-mediated rejection in kidney transplantation: A practical proposal

Kidney transplantation is the treatment of choice for patients with end-stage renal disease. Although an improvement in graft survival has been observed in the last decades with the use of different immunosuppressive drugs, this is still limited in time with antibody-mediated rejection being a main cause of graft-loss. Immune monitoring and risk assessment of antibody-mediated rejection before and after kidney transplantation with useful biomarkers is key to tailoring treatments to achieve the best outcomes. Here, we provide a review of the rationale and several accessible tools for immune monitoring, from the most classic to the modern ones. Finally, we end up discussing a practical proposal for alloimmune risk assessment in kidney transplantation, including histocompatibility leukocyte antigen (HLA) and non-HLA antibodies, HLA molecular mismatch analysis and characterization of peripheral blood immune cells.

Effect of panel reactive antibodies on T cell immunity reinstatement following renal transplantation

BACKGROUND

Chronic kidney disease is associated with immunological disorders, presented as phenotypic alterations of T lymphocytes. These changes are expected to be restored after a successful renal transplantation; however, additional parameters may contribute to this process.

AIM

To evaluate the impact of positive panel reactive antibodies (PRAs) on the restoration of T cell phenotype, after renal transplantation.

METHODS

CD4CD28null, CD8CD28null, natural killer cells (NKs), and regulatory T cells (Tregs) were estimated by flow cytometry at T0, T3, and T6 which were the time of transplantation, and 3- and 6-mo follow-up, respectively. Changes were estimated regarding the presence or absence of PRAs.

RESULTS

Patients were classified in two groups: PRA(-) (n = 43) and PRA(+) (n = 28) groups. Lymphocyte and their subtypes were similar between the two groups at T0, whereas their percentage was increased at T3 in PRA(-) compared to PRA(+) [23 (10.9-47.9) vs 16.4 (7.5-36.8 μ/L, respectively; P = 0.03]. Lymphocyte changes in PRA(-) patients included a significant increase in CD4 cells (P < 0.0001), CD8 cells (P < 0.0001), and Tregs (P < 0.0001), and a reduction of NKs (P < 0.0001). PRA(+) patients showed an increase in CD4 (P = 0.008) and CD8 (P = 0.0001), and a reduction in NKs (P = 0.07). CD4CD28null and CD8CD28null cells, although initially reduced in both groups, were stabilized thereafter.

CONCLUSION

Our study described important differences in the immune response between PRA(+) and PRA(-) patients with changes in lymphocytes and lymphocyte subpopulations. PRA(+) patients seemed to have a worse immune profile after 6 mo follow-up, regardless of renal function.

Benefits of Switching Mycophenolic Acid to Sirolimus on Serological Response after a SARS-CoV-2 Booster Dose among Kidney Transplant Recipients: A Pilot Study

Kidney transplant recipients (KTRs) have a suboptimal immune response to COVID-19 vaccination due to the effects of immunosuppression, mostly mycophenolic acid (MPA). This study investigated the benefits of switching from the standard immunosuppressive regimen (tacrolimus (TAC), MPA, and prednisolone) to a regimen of mammalian target of rapamycin inhibitor (mTORi), TAC and prednisolone two weeks pre- and two weeks post-BNT162b2 booster vaccination. A single-center, opened-label pilot study was conducted in KTRs, who received two doses of ChAdOx-1 and a single dose of BNT162b2. The participants were randomly assigned to continue the standard regimen (control group, n = 14) or switched to a sirolimus (an mTORi), TAC, and prednisolone (switching group, n = 14) regimen two weeks before and two weeks after receiving a booster dose of BNT162b2. The anti-SARS-CoV-2 S antibody level after vaccination in the switching group was significantly greater than the control group (4051.0 [IQR 3142.0-6466.0] BAU/mL vs. 2081.0 [IQR 1077.0-3960.0] BAU/mL, respectively; p = 0.01). One participant who was initially seronegative in the control group remained seronegative after the booster dose. These findings suggest humoral immune response benefits of switching the standard immunosuppressive regimen to the regimen of mTORi, TAC, and prednisolone in KTRs during vaccination.

Changes in T and B cell subsets in end stage renal disease patients before and after kidney transplantation

BACKGROUND

The incidence of kidney transplantation performed in elderly patients has increased steadily recently. Higher risk of infection and mortality, but lower rate of rejection, are reported in older kidney transplant patients. This study aims to analyze the effect of transplantation on aging of T and B cells in kidney transplant patients, with the emphasis on age and Cytomegalovirus (CMV) latency.

RESULTS

We included 36 patients before and after (median 2.7 years) kidney transplantation and 27 age- and sex-matched healthy controls (HC). T and B cell subsets were measured by flow cytometry, with a focus on aged T cells (CD28-), and age associated B cells (ABCs, CD19 + CD21-CD11c+). Three years after transplantation a significant increase of total T cells among the lymphocytes was found compared to pre-transplantation and HC. Among the T cells CD4+ cells were decreased, especially naïve CD4+ cells and regulatory T cells. Total CD8+ cell proportions were increased, and proportions of naïve CD8+ cells were significantly decreased after transplantation, while CD8+ effector memory T cells re-expressing CD45RA were increased. CD28- T cells were significantly higher compared to HC after transplantation, especially in CMV seropositive patients. B cells were significantly decreased, while among B cells memory B cells and especially ABCs were increased after transplantation.

CONCLUSIONS

After transplantation T and B cell subsets change towards more terminally differentiated memory cells compared to age-matched HC. Proportions of aged T cells and ABCs were associated with CMV serostatus.

The development of autoverification system of lymphocyte subset assays on the flow cytometry platform

OBJECTIVES

Peripheral blood lymphocyte subsets are important parameters for monitoring immune status; however, lymphocyte subset detection is time-consuming and error-prone. This study aimed to explore a highly efficient and clinically useful autoverification system for lymphocyte subset assays performed on the flow cytometry platform.

METHODS

A total of 94,402 lymphocyte subset test results were collected. To establish the limited-range rules, 80,427 results were first used (69,135 T lymphocyte subset tests and 11,292 NK, B, T lymphocyte tests), of which 15,000 T lymphocyte subset tests from human immunodeficiency virus (HIV) infected patients were used to set customized limited-range rules for HIV infected patients. Subsequently, 13,975 results were used for historical data validation and online test validation.

RESULTS

Three key autoverification rules were established, including limited-range, delta-check, and logical rules. Guidelines for addressing the issues that trigger these rules were summarized. The historical data during the validation phase showed that the total autoverification passing rate of lymphocyte subset assays was 69.65% (6,941/9,966), with a 67.93% (5,268/7,755) passing rate for T lymphocyte subset tests and 75.67% (1,673/2,211) for NK, B, T lymphocyte tests. For online test validation, the total autoverification passing rate was 75.26% (3,017/4,009), with 73.23% (2,191/2,992) for the T lymphocyte subset test and 81.22% (826/1,017) for the NK, B, T lymphocyte test. The turnaround time (TAT) was reduced from 228 to 167 min using the autoverification system.

CONCLUSIONS

The autoverification system based on the laboratory information system for lymphocyte subset assays reduced TAT and the number of error reports and helped in the identification of abnormal cell populations that may offer clues for clinical interventions.

Long-Term Redistribution of Peripheral Lymphocyte Subpopulations after Switching from Calcineurin to mTOR Inhibitors in Kidney Transplant Recipients

Classical immunosuppression based on steroids, calcineurin inhibitors, and mycophenolate results in several unwanted effects and unsatisfactory long-term outcomes in kidney transplantation (KT). New immunosuppressors search for fewer adverse events and increased graft survival but may have a distinct impact on graft function and immunological biomarkers according to their mechanism of action. This prospective study evaluates the immunological effect of tacrolimus to serine/threonine protein kinase mechanistic target of rapamycin inhibitors (mTORi) conversion in 29 KT recipients compared with 16 controls maintained on tacrolimus. We evaluated renal function, human leukocyte antigen (HLA) antibodies and peripheral blood lymphocyte subsets at inclusion and at 3, 12, and 24 months later. Twenty immunophenotyped healthy subjects served as reference. Renal function remained stable in both groups with no significant change in proteinuria. Two patients in the mTORi group developed HLA donor-specific antibodies and none in the control group (7% vs. 0%, p = 0.53). Both groups showed a progressive increase in regulatory T cells, more prominent in patients converted to mTORi within the first 18 months post-KT (p < 0.001). All patients showed a decrease in naïve B cells (p < 0.001), excepting those converted to mTORi without receiving steroids (p = 0.31). Transitional B cells significantly decreased in mTORi patients (p < 0.001), independently of concomitant steroid treatment. Finally, CD56^bright and CD94/NK group 2 member A receptor positive (NKG2A⁺) Natural Killer (NK) cell subsets increased in mTORi- compared to tacrolimus-treated patients (both p < 0.001). Patients switched to mTORi displayed a significant redistribution of peripheral blood lymphocyte subpopulations proposed to be associated with graft outcomes. The administration of steroids modified some of these changes.