The role of immune reconstitution in relapse after allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Leukemia relapse following stem cell transplantation remains a significant barrier to long-term remission. Timely and balanced immune recovery after transplantation is crucial for preventing leukemia relapse.

AREAS COVERED

After an extensive literature search of PubMed and Web of Science through October 2023, we provide an overview of the dynamics of immune reconstitution and its role in controlling leukemia relapse. We also discuss strategies to promote immune reconstitution and reduce disease recurrence following allogeneic hematopoietic stem cell transplantation.

EXPERT OPINION

Immune reconstitution after transplantation has substantial potential to prevent relapse and might predict disease recurrence and prognosis. High dimensional cytometry, multi-omics, and T cell repertoire analysis allow for a more comprehensive and detailed understanding of the immune system's dynamics post-transplantation, and contribute to the identification of rare immune cell subsets or potential biomarkers associated with successful immune reconstitution or increased risk of complications. Strategies to enhance the immune system, such as adoptive immunotherapy and cytokine-based therapy, have great potential for reducing leukemia relapse after transplantation. Future research directions should focus on refining patient selection for these therapies, implementing appropriate and timely treatment, investigating combination approaches to maximize therapeutic outcomes, and achieving a robust graft-versus-leukemia (GVL) effect while minimizing graft-versus-host disease (GVHD) for optimal results.

Long-Term Clinical Outcomes and B Cell Immune Reconstitution Following Allo-HCT With Prophylactic, Post-Transplant Rituximab

Chronic graft-versus-host disease (cGVHD) remains a significant source of morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). Post-transplant, prophylactic rituximab has successfully decreased cGHVD rates in clinical trials, but the durability of this strategy is uncertain. The long-terms effect of post-HCT B cell depletion on immune reconstitution, B cell function, and infectious complications are also unknown. In this study, we provide 10 yr follow-up and correlative analyses on patients given post-HCT, prophylactic rituximab. The objective of the study is to examine the durability of cGVHD protection as well as the long-term effect of rituximab prophylaxis on protective immune reconstitution, B cell function, and alloantibody formation. We analyzed 35 patients given prophylactic rituximab on phase II clinical trial. Clinical outcomes included cGVHD development, relapse and survival outcomes, and infectious outcomes. Correlative analyses included B cell subset analysis, development of antibodies to infectious antigens, and, for male patients receiving female donor grafts, development of antibodies to HY antigens. To further investigate the effect of rituximab on immune reconstitution and function, we also analyzed 43 similarly transplanted patients who did not receive post- or peri-HCT rituximab as a comparator group. For patients who received rituximab, the 8-yr cumulative incidence of cGHVD and freedom from immunosuppression were 20.0% and 76.2%, respectively. Importantly, no late incidences of cGVHD developed beyond 14 mo post-HCT. Relative to patients who did not receive rituximab, post-HCT rituximab was associated with increased B cell aplasia at 1 yr post-HCT (42.9% versus 11% of patients, P = .037); by 3 yr post-HCT, this aplasia resolved. Patients who received rituximab also had a significantly lower proportion of IgD+/CD38+ transitional B cells at 3 yr post-HCT (78.8% versus 89.9%, P = .039); at 10 yr post-HCT, this percentage remained markedly decreased at 50.7%. Rituximab prophylaxis altered B cell function. In male patients receiving female donor grafts, fewer patients developed HY antibodies at 3 yr post-HCT (20% versus 78%, P = .04). At 10 yr post-HCT, HY antibody production remained decreased at 33%. Rituximab prophylaxis was also associated with significantly lower antibody response to tetanus and EBV infectious antigens as well as lower IgG levels. Despite these changes, post-HCT was not associated with increased infections, although patients who received rituximab required intravenous immunoglobulin (IVIG) supplementation more frequently than those who did not (62.9% versus 32.6% of patients, P = .01). Prior data on the efficacy and feasibility of rituximab prophylaxis are durable, with persistent reduction in cGVHD. Rituximab prophylaxis also results in lasting B cell immunologic changes, with altered B cell subset composition and decreased alloantibody formation. Associated infectious risks were not increased, perhaps mitigated by high IVIG use.

Treatment with Elapegademase Restores Immunity in Infants with Adenosine Deaminase Deficient Severe Combined Immunodeficiency

PURPOSE

Patients with adenosine deaminase 1 deficient severe combined immunodeficiency (ADA-SCID) are initially treated with enzyme replacement therapy (ERT) with polyethylene glycol-modified (PEGylated) ADA while awaiting definitive treatment with hematopoietic stem cell transplant (HSCT) or gene therapy. Beginning in 1990, ERT was performed with PEGylated bovine intestinal ADA (ADAGEN®). In 2019, a PEGylated recombinant bovine ADA (Revcovi®) replaced ADAGEN following studies in older patients previously treated with ADAGEN for many years. There are limited longitudinal data on ERT-naïve newborns treated with Revcovi.

METHODS

We report our clinical experience with Revcovi as initial bridge therapy in three newly diagnosed infants with ADA-SCID, along with comprehensive biochemical and immunologic data.

RESULTS

Revcovi was initiated at twice weekly dosing (0.2 mg/kg intramuscularly), and monitored by following plasma ADA activity and the concentration of total deoxyadenosine nucleotides (dAXP) in erythrocytes. All patients rapidly achieved a biochemically effective level of plasma ADA activity, and red cell dAXP were eliminated within 2-3 months. Two patients reconstituted B-cells and NK-cells within the first month of ERT, followed by naive T-cells one month later. The third patient reconstituted all lymphocyte subsets within the first month of ERT. One patient experienced declining lymphocyte counts with improvement following Revcovi dose escalation. Two patients developed early, self-resolving thrombocytosis, but no thromboembolic events occurred.

CONCLUSION

Revcovi was safe and effective as initial therapy to restore immune function in these newly diagnosed infants with ADA-SCID, however, time course and degree of reconstitution varied. Revcovi dose may need to be optimized based on immune reconstitution, clinical status, and biochemical data.

[Immune reconstitution and influencing factors in HIV infected men who have sex with men with access to antiviral therapy in Guangxi Zhuang Autonomous Region from 2005 to 2021]

Objective: To analyze immune reconstitution and influencing factors in HIV infected men who have sex with men (MSM) with access to antiviral therapy (ART) in Guangxi Zhuang Autonomous Region (Guangxi) during 2005-2021. Methods: The data were collected from Chinese Disease Prevention and Control Information System. The study subjects were HIV infected MSM with access to the initial ART for ≥24 weeks in Guangxi from 2005 to 2021 and HIV RNA lower than the detection limit within 24 months. The proportion of infected MSM who had immune reconstitution after ART was calculated. Cox proportional hazard regression model was used to analyze the influencing factors of immune reconstitution. Software SPSS 24.0 was used for statistical analysis. Results: A total of 3 200 HIV infected MSM were enrolled, in whom 15.56 % (498/3 200) had no immune reconstitution, 14.78% (473/3 200) had moderate immune reconstitution, and the rate of complete immune reconstitution was 69.66% (2 229/3 200). The M (Q1, Q3) of ART time for immune reconstitution was 12 (5, 27) months. Multivariate Cox proportional risk regression model analysis results showed that compared with those with initial ART at age ≥30 years, WHO clinical stage Ⅲ/Ⅳ illness, baseline BMI <18.50 kg/m2 and baseline CD4+T lymphocyte (CD4) counts <200 cells/µl, HIV infected MSM with initial ART at age <30 years, WHO clinical stageⅠ/Ⅱ illness, baseline BMI≥24.00 kg/m2 and baseline CD4 counts ≥200 cells/µl were more likely to have complete immune reconstitution. Conclusions: In the HIV infected MSM in Guangxi, failures to achieve moderate and complete immune reconstitution were observed. Surveillance and ART regimen should be improved for key populations, such as those with older age and low baseline CD4 counts.

The Expression Levels of TREX1 and IFN-α Are Associated with Immune Reconstitution in HIV-1-Infected Individuals

TREX1 acts in the initial prevention of an autoimmune response, but it may contribute to the permissiveness of retrovirus infections. This study investigated the association between the levels of TREX1 gene expression with the polymorphisms TREX1 rs3135941 (T/C) and TREX1 rs3135945 (G/A), and the presence of antinuclear antibodies (ANA) in antiretroviral therapy (ART)-naïve individuals and after 1 year of treatment. Blood samples from 119 individuals with HIV-1 were subjected to genotyping of polymorphisms and quantification of TREX1 gene expression and HIV-1 viral load by qPCR. The concentration of IFN-α and the number of CD4+/CD8+ T lymphocytes were determined by ELISA and flow cytometry, respectively; ANA was investigated by immunofluorescence. A control group of 167 seronegative individuals was used for the comparison of genotypic frequencies. The frequency of the polymorphisms were not associated with HIV infection or with variations in the expression of TREX1 and IFN-α (p > 0.05). ART-naïve individuals exhibited higher TREX1 expression and lower IFN-α expression. After 1 year of ART, TREX1 levels were reduced, while IFN-α and CD4+ T lymphocytes were elevated (p < 0.05). Some individuals on ART presented ANA. These results suggest that ART-mediated restoration of immune competence is associated with a reduction in TREX1 expression, which may induce the development of ANA, regardless of the polymorphism investigated.

Comorbidity of Myasthenia gravis and Graves' disease as immune reconstitution-associated autoimmune disease in HIV infection: A case report and literature review

BACKGROUND

Comorbidity of Myasthenia gravis (MG) and Graves' disease (GD) in treated HIV-infected individuals has rarely been described and little study has been done on the link between HIV-related immune reconstitution and autoimmune diseases occurring post antiretroviral therapy.

CASE PRESENTATION

Here we report on a 33-year-old Chinese man with HIV infection who had been virologically suppressed since 2018. The patient was diagnosed with GD and was treated in 2020. Early in 2022, he developed fluctuating weakness and fatigue involving the bilateral extraocular muscles and limbs. With a positive neostigmine test, he was considered to have MG, but showed a poor response to oral medication. After multiple failed medication attempts, a thymectomy was finally performed to resolve his symptoms. The consecutive onset of immunological events may have partially resulted from immune reconstitution after viral control.

CONCLUSIONS

This is a rare case of HIV-related immune reconstitution-associated autoimmune disease (IRAD) with comorbidity of MG and GD which was reported initially. Cooperation with multidisciplinary teams is essential to avoid misdiagnosis and to promote the overall health of HIV-infected patients.

Modulation of cytomegalovirus immune evasion identifies direct antigen presentation as the predominant mode of CD8 T-cell priming during immune reconstitution after hematopoietic cell transplantation

Cytomegalovirus (CMV) infection is the most critical infectious complication in recipients of hematopoietic cell transplantation (HCT) in the period between a therapeutic hematoablative treatment and the hematopoietic reconstitution of the immune system. Clinical investigation as well as the mouse model of experimental HCT have consistently shown that timely reconstitution of antiviral CD8 T cells is critical for preventing CMV disease in HCT recipients. Reconstitution of cells of the T-cell lineage generates naïve CD8 T cells with random specificities among which CMV-specific cells need to be primed by presentation of viral antigen for antigen-specific clonal expansion and generation of protective antiviral effector CD8 T cells. For CD8 T-cell priming two pathways are discussed: "direct antigen presentation" by infected professional antigen-presenting cells (pAPCs) and "antigen cross-presentation" by uninfected pAPCs that take up antigenic material derived from infected tissue cells. Current view in CMV immunology favors the cross-priming hypothesis with the argument that viral immune evasion proteins, known to interfere with the MHC class-I pathway of direct antigen presentation by infected cells, would inhibit the CD8 T-cell response. While the mode of antigen presentation in the mouse model of CMV infection has been studied in the immunocompetent host under genetic or experimental conditions excluding either pathway of antigen presentation, we are not aware of any study addressing the medically relevant question of how newly generated naïve CD8 T cells become primed in the phase of lympho-hematopoietic reconstitution after HCT. Here we used the well-established mouse model of experimental HCT and infection with murine CMV (mCMV) and pursued the recently described approach of up- or down-modulating direct antigen presentation by using recombinant viruses lacking or overexpressing the central immune evasion protein m152 of mCMV, respectively. Our data reveal that the magnitude of the CD8 T-cell response directly reflects the level of direct antigen presentation.

[Immune Reconstitution after BTKi Treatment in Chronic Lymphocytic Leukemia]

OBJECTIVE

To analyze the immune reconstitution after BTKi treatment in patients with chronic lymphocytic leukemia (CLL).

METHODS

The clinical and laboratorial data of 59 CLL patients admitted from January 2017 to March 2022 in Fujian Medical University Union Hospital were collected and analyzed retrospectively.

RESULTS

The median age of 59 CLL patients was 60.5(36-78). After one year of BTKi treatment, the CLL clones (CD5 +/CD19 +) of 51 cases (86.4%) were significantly reduced, in which the number of cloned-B cells decreased significantly from (46±6.1)×109/L to (2.3±0.4)×109/L (P =0.0013). But there was no significant change in the number of non-cloned B cells (CD19 + minus CD5 +/CD19 +). After BTKi treatment, IgA increased significantly from (0.75±0.09)g/L to (1.31±0.1)g/L (P <0.001), while IgG and IgM decreased from (8.1±0.2)g/L and (0.52±0.6)g/L to (7.1±0.1)g/L and (0.47±0.1)g/L, respectively (P <0.001, P =0.002). BTKi treatment resulted in a significant change in T cell subpopulation of CLL patients, which manifested as both a decrease in total number of T cells from (2.1±0.1)×109/L to (1.6±0.4)×109/L and NK/T cells from (0.11±0.1)×109/L to (0.07±0.01)×109/L (P =0.042, P =0.038), both an increase in number of CD4 + cells from (0.15±6.1)×109/L to (0.19±0.4)×109/L and CD8 + cells from (0.27±0.01)×109/L to (0.41±0.08)×109/L (both P <0.001). BTKi treatment also up-regulated the expression of interleukin (IL)-2 while down-regulated IL-4 and interferon (IFN)-γ. However, the expression of IL-6, IL-10, and tumor necrosis factor (TNF)-α did not change significantly. BTKi treatment could also restored the diversity of TCR and BCR in CLL patients, especially obviously in those patients with complete remission (CR) than those with partial remission (PR). Before and after BTKi treatment, Shannon index of TCR in patients with CR was 0.02±0.008 and 0.14±0.001 (P <0.001), while in patients with PR was 0.01±0.03 and 0.05±0.02 (P >0.05), respectively. Shannon index of BCR in patients with CR was 0.19±0.003 and 0.33±0.15 (P <0.001), while in patients with PR was 0.15±0.009 and 0.23±0.18 (P <0.05), respectively.

CONCLUSIONS

BTKi treatment can shrink the clone size in CLL patients, promote the expression of IgA, increase the number of functional T cells, and regulate the secretion of cytokines such as IL-2, IL-4, and IFN-γ. BTKi also promote the recovery of diversity of TCR and BCR. BTKi treatment contributes to the reconstitution of immune function in CLL patients.

Development and Evaluation of a Nomogram for Predicting the Outcome of Immune Reconstitution Among HIV/AIDS Patients Receiving Antiretroviral Therapy in China

This study aims to develop and evaluate a model to predict the immune reconstitution among HIV/AIDS patients after antiretroviral therapy (ART). A total of 502 HIV/AIDS patients are randomized to the training cohort and evaluation cohort. Least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression analysis are performed to identify the indicators and establish the nomogram for predicting the immune reconstitution. Decision curve analysis (DCA) and clinical impact curve (CIC) are used to evaluate the clinical effectiveness of the nomogram. Predictive factors included white blood cells (WBC), baseline CD4+ T-cell counts (baseline CD4), ratio of effector regulatory T cells to resting regulatory T cells (eTreg/rTreg) and low-density lipoprotein cholesterol (LDL-C) and are incorporated into the nomogram. The area under the curve (AUC) is 0.812 (95% CI, 0.767∼0.851) and 0.794 (95%CI, 0.719∼0.857) in the training cohort and evaluation cohort, respectively. The calibration curve shows a high consistency between the predicted and actual observations. Moreover, DCA and CIC indicate that the nomogram has a superior net benefit in predicting poor immune reconstitution. A simple-to-use nomogram containing four routinely collected variables is developed and internally evaluated and can be used to predict the poor immune reconstitution in HIV/AIDS patients after ART.

Plasma Cytokine Expression and Immune Reconstitution in Early and Delayed Anti-HIV 96-Weeks Treatment: A Retrospective Study

HIV is an immunodeficiency disease with emergence of inadequate corresponding reconstruction therapies. Pyroptosis of CD4+T cell is mainly caused by immune activation and inflammation that cannot be reduced by successful antiretroviral therapy (ART) alone. Coinfections because of CD4+T cell reconstitution failure can occur. Anti-inflammatory treatment determines the success of immune reconstitution. In our experiment, only a few cytokines could recover to normal level following a 2-year antiretroviral treatment in early ART initiation, which is consistent with current findings about adjuvant HIV anti-inflammatory therapy. Early infection is often accompanied by a more severe inflammatory response. Innate immunity cytokines like granulocyte macrophage-colony stimulating factor, IFN-γ induced protein 10 kDa, and tumor necrosis factor-α exhibited the most elevated levels among all kinds of inflammatory cytokines. The correlation analysis showed at least eight cytokines contributing to the changes of CD4/CD8 ratio.

Hematopoiesis and immune reconstitution after CD19 directed chimeric antigen receptor T-cells (CAR-T): A comprehensive review on incidence, risk factors and current management

Impaired function of hematopoiesis after treatment with chimeric antigen T-cells (CAR-T) is a frequent finding and can interest a wide range of patients, regardless of age and underlying disease. Trilinear cytopenias, as well as hypogammaglobulinemia, B-cell aplasia, and T-cell impairment, can severely affect the infectious risk of CAR-T recipients, as well as their quality of life. In this review, we provide an overview of defects in hematopoiesis after CAR-T, starting with a summary of different definitions and thresholds. We then move to summarize the main pathogenetic mechanisms of cytopenias, and we offer insight into cytomorphological aspects, the role of clonal hematopoiesis, and the risk of secondary myeloid malignancies. Subsequently, we expose the major findings and reports on T-cell and B-cell quantitative and functional impairment after CAR-T. Finally, we provide an overview of current recommendations and leading experiences regarding the management of cytopenias and defective B- and T-cell function.

Inhibition of RIP1 improves immune reconstitution and reduces GVHD mortality while preserving graft-versus-leukemia effects

Graft-versus-host disease (GVHD) remains the major cause of morbidity and nonrelapse mortality (NRM) after hematopoietic cell transplantation (HCT). Inflammatory cytokines mediate damage to key GVHD targets such as intestinal stem cells (ISCs) and also activate receptor interacting protein kinase 1 (RIP1; RIPK1), a critical regulator of apoptosis and necroptosis. We therefore investigated the role of RIP1 in acute GVHD using samples from HCT patients, modeling GVHD damage in vitro with both human and mouse gastrointestinal (GI) organoids, and blocking RIP1 activation in vivo using several well-characterized mouse HCT models. Increased phospho-RIP1 expression in GI biopsies from patients with acute GVHD correlated with tissue damage and predicted NRM. Both the genetic inactivation of RIP1 and the RIP1 inhibitor GNE684 prevented GVHD-induced apoptosis of ISCs in vivo and in vitro. Daily administration of GNE684 for 14 days reduced inflammatory infiltrates in three GVHD target organs (intestine, liver, and spleen) in mice. Unexpectedly, GNE684 administration also reversed the marked loss of regulatory T cells in the intestines and liver during GVHD and reduced splenic T cell exhaustion, thus improving immune reconstitution. Pharmacological and genetic inhibition of RIP1 improved long-term survival without compromising the graft-versus-leukemia (GVL) effect in lymphocytic and myeloid leukemia mouse models. Thus, RIP1inhibition may represent a nonimmunosuppressive treatment for GVHD.

Gender and the length of time since autologous hematopoietic stem cell transplantation-What is their influence on the immune reconstitution in multiple myeloma patients?

INTRODUCTION

In the literature there is lack of information on the influence of gender and time since autologous hematopoietic stem cell transplantation (HSCT) on the immune reconstitution in multiple myeloma (MM) patients.

OBJECTIVE

The aim of this study was to assess the diversity of the immune reconstitution according to gender in MM patients after autologous HSCT on the day of the clinic discharge and on the 29th day after discharge, as well as to investigate the changes in the immune system in females and males after staying at home for 28 days.

METHOD

The studied population comprised 13 females and 13 males after autologous HSCT. On the day of the clinic discharge and on the 29th day after discharge blood samples were taken to analyse 22 immunological parameters. Statistical analysis was performed using STATISTICA 10 StatSoft Poland. For multiple comparisons, the Bonferroni correction was used.

RESULTS

No statistically significant differences were observed in the analysed immunological parameters between the studied females and males with MM on the day of the clinic discharge and on the 29th day after discharge. However, on the 29th day after the clinic discharge compared to the day of the clinic discharge, statistically significant differences were found in 8 immunological parameters among females and 6 immunological parameters among males.

CONCLUSION AND RECOMMENDATION

Our results indicate that the immune reconstitution is similar but not the same in patients of both genders. Statistically significant differences in the immune response in the studied females and males imply that gender may play a role in the immune reconstitution and that the results obtained in MM patients should be analysed separately in females and males. In order to explain the observed changes in the immune system according to gender, further research should be carried out on a larger population. This would most probably make it possible to find their clinical application.

[Effect of HCMV infection on immune reconstitution of CD8+T cells in children with allogeneic hematopoietic stem cell transplantation]

Objective: To investigate the risk factors for human cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation in children and the impact of human cytomegalovirus infection on post-transplant immune reconstitution. Methods: A Retrospective Co-Hort study design was used to include 81 children treated with allo-HSCT from January 2020 to March 2022 at the Department of Hematology, Capital Institute of Pediatrics, Beijing, China, and followed up for 1 year. Real-time quantitative PCR was used to detect positive detection of HCMV in children after allo-HSCT, multifactorial logistic regression modeling was used to analyze the risk factors leading to HCMV infection, and generalized estimating equation modeling was used to analyze the effect of HCMV infection on the T-cells of the children who received allo-HSCT. Results: The age M(Q1, Q3) of 81 children was 5.1 years (10 months, 13.8 years), and 50 (61.7%) were male. By the endpoint of follow-up, a total of 50 HCMV-positive cases were detected, with an HCMV detection rate of 61.7%; The results of multifactorial logistic regression modeling showed that children with grade 2-4 aGVHD had a higher risk of HCMV infection compared with grade 0-1 after transplantation [OR (95%CI) value: 2.735 (1.027-7.286)]. The results of generalized estimating equation modeling analysis showed that the number of CD3+T cells in HCMV-positive children after transplantation was higher than that in the HCMV-negative group [RR (95%CI) value: 1.34 (1.008-1.795)]; the ratio of CD4+T/CD8+T cells was smaller than that in the HCMV-negative group [RR (95%CI) value: 0.377 (0.202-0.704)]; the number of CD8+T cells was higher than that in the HCMV-negative group [RR (95%CI) value: 1.435 (1.025-2.061)]; the number of effector memory CD8+T cells was higher than that in the HCMV-negative group [RR (95%CI) value: 1.877 (1.089-3.236)]. Conclusion: Acute graft-versus-host disease may be a risk factor for HCMV infection in children after allo-HSCT; post-transplant HCMV infection promotes proliferation of memory CD8+T-cell populations and affects immune cell reconstitution.

CD70-induced differentiation of proinflammatory Th1/17/22/GM lymphocytes associated with disease progression and immune reconstitution during HIV infection

Immune overactivation is a hallmark of chronic HIV infection, which is critical to HIV pathogenesis and disease progression. The imbalance of helper T cell (Th) differentiation and subsequent cytokine dysregulation are generally considered to be the major drivers of excessive activation and inflammatory disorders in HIV infection. However, the accurate factors driving HIV-associated Th changes remained to be established. CD70, which was a costimulatory molecule, was found to increase on CD4+ T cells during HIV infection. Overexpression of CD70 on CD4+ T cells was recently reported to associate with highly pathogenic proinflammatory Th1/Th17 polarization in multiple sclerosis. Thus, the role of CD70 in the imbalance of Th polarization and immune overactivation during HIV infection needs to be investigated. Here, we found that the elevated frequency of CD70 + CD4+ T cells was negatively correlated with CD4 count and positively associated with immune activation in treatment-naïve people living with HIV (PLWH). More importantly, CD70 expression defined a population of proinflammatory Th1/17/22/GM subsets in PLWH. Blocking CD70 decreased the mRNA expression of subset-specific markers during Th1/17/22/GM polarization. Furthermore, we demonstrated that CD70 influenced the differentiation of these Th cells through STAT pathway. Finally, it was revealed that patients with a high baseline level of CD70 on CD4+ T cells exhibited a greater risk of poor immune reconstitution after antiretroviral therapy (ART) than those with low CD70. In general, our data highlighted the role of CD70 in Th1/17/22/GM differentiation during HIV infection and provided evidence for CD70 as a potential biomarker for predicting immune recovery.

Cryopreservation of mouse thymus depletes thymocytes but supports immune reconstitution on transplantation

Cryopreservation of mouse thymus depletes donor thymocytes but preserves thymus function when transplanted after thawing into athymic mice. No differences in immune reconstitution were observed between fresh and frozen/thawed transplants suggesting that donor thymocyte depletion does not affect outcome. Thus, cryopreservation of thymus may improve outcomes in thymus transplant patients.

Dominant CD4+ T cell receptors remain stable throughout antiretroviral therapy-mediated immune restoration in people with HIV

In people with HIV (PWH), the post-antiretroviral therapy (ART) window is critical for immune restoration and HIV reservoir stabilization. We employ deep immune profiling and T cell receptor (TCR) sequencing and examine proliferation to assess how ART impacts T cell homeostasis. In PWH on long-term ART, lymphocyte frequencies and phenotypes are mostly stable. By contrast, broad phenotypic changes in natural killer (NK) cells, γδ T cells, B cells, and CD4+ and CD8+ T cells are observed in the post-ART window. Whereas CD8+ T cells mostly restore, memory CD4+ T subsets and cytolytic NK cells show incomplete restoration 1.4 years post ART. Surprisingly, the hierarchies and frequencies of dominant CD4 TCR clonotypes (0.1%-11% of all CD4+ T cells) remain stable post ART, suggesting that clonal homeostasis can be independent of homeostatic processes regulating CD4+ T cell absolute number, phenotypes, and function. The slow restoration of host immunity post ART also has implications for the design of ART interruption studies.

Thymus aging and immune reconstitution, progresses and challenges

Thymus is a primary lymphoid organ essential for the development of T lymphocytes. Age-related thymic involution is a prominent feature of immune senescence. The thymus undergoes rapid growth during fetal and neonatal development, peaks in size before puberty and then begins to undergo a decrease in cellularity with age. Dramatic changes occur with age-associated thymic involution. The most prominent features of thymic involution include: (i) epithelial structure disruption, (ii) adipogenesis, and (iii) thymocyte development arrest. There is a sex disparity in thymus aging. It is a multifactorial process controlled and regulated by a series of molecules, including the transcription factor FOXN1, fibroblast and keratinocyte growth factors (FGF and KGF, respectively), sex steroids, Notch signaling, WNT signaling, and microRNAs. Nevertheless, there is still no satisfactory evolutionary or physiological explanation for age-associated thymic involution, and understanding the precise mechanism(s) for thymus aging remains challenging. Sustained thymic regeneration has yet to be achieved by sex steroid ablation. Recent preclinical studies indicate that long-term thymic reconstitution can be achieved via adoptive transfer of in vitro-generated progenitor T (proT) cells, and improvements in the methods for the generation of human proT cells make this an attractive approach. Future clinical applications may rely on new applications integrating proT cells, cytokine support and sex-steroid inhibition treatments.

The role of pyroptosis in incomplete immune reconstitution among people living with HIV：Potential therapeutic targets

Globally, HIV infection causes significant morbidity and mortality, and is a major public health problem. Despite the fact that widespread use of antiretroviral therapy (ART) has substantially altered the natural history of HIV infection from originally being a universally lethal disease to now being a chronic medical condition for those taking appropriate treatment, approximately 10-40% of people living with HIV (PLWH) who take effective ART and maintain long-term viral suppression fail to achieve normalization of CD4 + T-cell counts. This phenomenon is referred to as incomplete immune reconstitution or immunological non-response. Although the precise mechanisms underlying this outcome have not been elucidated, recent evidence indicates that excessive pyroptosis may play a crucial role in the development of incomplete immune reconstitution. Pyroptosis is characterized by the formation of pores in the cell membrane, cell rupture, and secretion of intracellular contents and pro-inflammatory cytokines, including IL-1β and IL-18. This excessive inflammation-induced programmed cell death leads to a massive loss of CD4 + T-cells, and inflammatory consequences that may promote and sustain incomplete immune reconstitution. Herein, we review the possible pathways activated in HIV infection by inflammasomes that act as switches of pyroptosis, and the role of pyroptosis in HIV, as well as the relevance of CD4 + T-cells in incomplete immune reconstitution. We also highlight the possible mechanisms of pyroptosis involved in incomplete immune reconstitution, thus paving the way for the development of potential targets for the treatment of incomplete immune reconstitution.

Abnormal blood microbiota profiles are associated with inflammation and immune restoration in HIV/AIDS individuals

IMPORTANCE

The characteristics of blood microbiota in HIV-infected individuals and their relevance to disease progression are still unknown, despite alterations in gut microbiota diversity and composition in HIV-infected individuals. Here, we present evidence of increased blood microbiota diversity in HIV-infected individuals, which may result from gut microbiota translocation. Also, we identify a group of microbes, Porphyromonas gingivalis, Prevotella sp. CAG:5226, Eubacterium sp. CAG:251, Phascolarctobacterium succinatutens, Anaerobutyricum hallii, Prevotella sp. AM34-19LB, and Phocaeicola plebeius, which are linked to poor immunological recovery. This work provides a scientific foundation toward therapeutic strategies targeting blood microbiota for immune recovery of HIV infection.

Current knowledge of the immune reconstitution inflammatory syndrome in Whipple disease: a review

Immune reconstitution inflammatory syndrome (IRIS) is characterized by exaggerated and dysregulated inflammatory responses that occur as a result of reconstitution of adaptive or innate immunity. A wide range of microorganisms have been found to be associated with IRIS, such as human immunodeficiency virus (HIV), Mycobacterium and actinobacteria. Whipple disease (WD) is an infectious disorder caused by the Gram-positive bacterium Tropheryma whipplei (T. whipplei) and IRIS also serves as a complication during its treament. Although many of these pathological mechanisms are shared with related inflammatory disorders, IRIS in WD exhibits distinct features and is poorly described in the medical literature. Novel investigations of the intestinal mucosal immune system have provided new insights into the pathogenesis of IRIS, elucidating the interplay between systemic and local immune responses. These insights may be used to identify monitoring tools for disease prevention and to develop treatment strategies. Therefore, this review synthesizes these new concepts in WD IRIS to approach the feasibility of manipulating host immunity and immune reconstitution of inflammatory syndromes from a newer, more comprehensive perspective and study hypothetical options for the management of WD IRIS.

Diffuse retinal dysfunction following immune reconstitution uveitis in patients with prior cytomegalovirus retinitis: a novel observation

PURPOSE

To report continuing diffuse retinal dysfunction following resolution of immune reconstitution uveitis (IRU) in patients with cytomegalovirus retinitis (CMVR).

METHODS

Retrospective case series describing two patients with IRU following CMVR who underwent serial fundus photography and macular optical coherence tomography. One patient had serial electrophysiology.

RESULTS

Both patients had CMVR successfully treated with antiviral medication. The affected eyes later developed IRU that resolved with steroids. However, following resolution, chronic retinal damage was evidenced by ellipsoid line loss in one case and gradual optic disc cupping in the other. Electrophysiology in both cases revealed generalized retinal dysfunction worse in the eye with more severe IRU and demonstrated objectively the efficacy of treatment intervention in the patient with serial recordings.

CONCLUSIONS

Patients with IRU following CMV retinitis may have continuing diffuse retinal dysfunction despite apparent recovery and normal visual acuity. An aggressive approach to inflammation control may be warranted in such patients.

Cytomegalovirus Immune reconstitution in cord blood transplant recipients on letermovir prophylaxis

INTRODUCTION

Cytomegalovirus (CMV) can cause significant morbidity and mortality in cord blood transplant (CBT) recipients. Development of CMV-specific cell-mediated immunity (CMV-CMI) has been associated with protection against CMV clinically significant reactivation (CsCMV). In this study, we evaluated CMV-CMI reconstitution during letermovir prophylactic therapy, which prevents CsCMV without complete suppression of CMV reactivation.

METHODS

We measured CMV-CMI in CMV-seropositive CBT recipients pre-transplant after Day+90 of letermovir prophylaxis and at Days +180, and +360- post-transplant using a dual color CMV-specific IFNγ/IL2 FLUOROSpot. CsCMV and nonCsCMV reactivations were abstracted from medical records. CsCMV was defined as CMV viral load ≥5,000 IU/ml using a whole blood assay.

RESULTS

Among 70 CBT recipients, 31 developed CMV-CMI by Day+90 and an additional eight and five participants by Days +180 and +360, respectively. Thirty-eight participants developed CMV reactivation, including nine with CsCMV. Most reactivations (33 of 38) occurred before Day+180. Early CMV-CMI was present in six out of nine participants with CsCMV, indicating a lack of protection against CsCMV. Moreover, the magnitude of CMV-CMI at Day+90 did not differ between participants with CsCMV and nonCsCMV.

CONCLUSION

Approximately 50% of CBT recipients reconstituted CMV-CMI during letermovir prophylactic therapy. However, CMV-CMI did not reach levels protective against CsCMV. Extension of CMV prophylaxis beyond Day+90 may be considered in CMV-seropositive CBT recipients.

Immune restoration with ibrutinib plus venetoclax in first-line chronic lymphocytic leukemia: the phase 2 CAPTIVATE study

We evaluated immune cell subsets in patients with chronic lymphocytic leukemia (CLL) who received first-line therapy with 3 cycles of ibrutinib then 13 cycles of ibrutinib plus venetoclax in the minimal residual disease (MRD) cohort of the CAPTIVATE study (NCT02910583). Patients with Confirmed undetectable MRD (uMRD) were randomly assigned to placebo or ibrutinib groups; patients without Confirmed uMRD were randomly assigned to ibrutinib or ibrutinib plus venetoclax groups. We compared immune cell subsets in samples collected at 7 time points with age-matched healthy donors. CLL cells decreased within 3 cycles after venetoclax initiation; from cycle 16 onward, levels were similar to healthy donor levels (HDL; ≤0.8 cells per μL) in patients with Confirmed uMRD and slightly above HDL in patients without Confirmed uMRD. By 4 months after cycle 16, normal B cells had recovered to HDL in patients randomly assigned to placebo. Regardless of randomized treatment, abnormal counts of T cells, classical monocytes, and conventional dendritic cells recovered to HDL within 6 months (median change from baseline -49%, +101%, and +91%, respectively); plasmacytoid dendritic cells recovered by cycle 20 (+598%). Infections generally decreased over time regardless of randomized treatment and were numerically lowest in patients randomly assigned to placebo within 12 months after cycle 16. Sustained elimination of CLL cells and recovery of normal B cells were confirmed in samples from patients treated with fixed-duration ibrutinib plus venetoclax in the GLOW study (NCT03462719). These results demonstrate promising evidence of restoration of normal blood immune composition with ibrutinib plus venetoclax.

Metformin may be a viable adjunctive therapeutic option to potentially enhance immune reconstitution in HIV-positive immunological non-responders

ABSTRACT

Incomplete immune reconstitution remains a global challenge for human immunodeficiency virus (HIV) treatment in the present era of potent antiretroviral therapy (ART), especially for those individuals referred to as immunological non-responders (INRs), who exhibit dramatically low CD4 + T-cell counts despite the use of effective antiretroviral therapy, with long-term inhibition of viral replication. In this review, we provide a critical overview of the concept of ART-treated HIV-positive immunological non-response, and also explain the known mechanisms which could potentially account for the emergence of immunological non-response in some HIV-infected individuals treated with appropriate and effective ART. We found that immune cell exhaustion, combined with chronic inflammation and the HIV-associated dysbiosis syndrome, may represent strategic aspects of the immune response that may be fundamental to incomplete immune recovery. Interestingly, we noted from the literature that metformin exhibits properties and characteristics that may potentially be useful to specifically target immune cell exhaustion, chronic inflammation, and HIV-associated gut dysbiosis syndrome, mechanisms which are now recognized for their critically important complicity in HIV disease-related incomplete immune recovery. In light of evidence discussed in this review, it can be seen that metformin may be of particularly favorable use if utilized as adjunctive treatment in INRs to potentially enhance immune reconstitution. The approach described herein may represent a promising area of therapeutic intervention, aiding in significantly reducing the risk of HIV disease progression and mortality in a particularly vulnerable subgroup of HIV-positive individuals.

Longitudinal analysis of immune reconstitution and metabolic changes in women living with HIV: A real-world observational study

BACKGROUND

Women comprise more than half of people living with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) worldwide and incomplete immune recovery and metabolic abnormalities affect them deeply. Studies of HIV antiretroviral therapy (ART) have a low female representation in China. We aimed to investigate immune reconstitution and metabolic changes of female HIV-positive cohort in China longitudinally.

METHODS

HIV-positive women who initiated ART from January 2005 to June 2021 and were followed up regularly at least once a year were included in this study. Immunological indicators (cluster of differentiation 4 [CD4] counts and CD8 counts), viral load (VL), and metabolic indicators were collected at follow-up. All data were collected from the China Disease Prevention and Control Information System (CDPCIS). VL was tested half a year, 1 year after receiving ART, and every other year subsequently according to local policy. CD4/CD8 ratio normalization was considered as the primary outcome and defined as a value ≥1. Incidence rate and probability of CD4/CD8 ratio normalization were estimated through per 100 person-years follow-up (PYFU) and Kaplan-Meier curve, respectively. Multivariate Cox regression was used to identify independent risk factors associated with CD4/CD8 ratio normalization. We further studied the rate of dyslipidemia, hyperuricemia, diabetes, liver injury, and renal injury after ART initiation with the chi-squared tests or Fisher's exact probability tests, and a generalized estimating equation model was used to analyze factors of dyslipidemia and hyperuricemia.

RESULTS

A total of 494 female patients with HIV/AIDS started ART within 16 years from January 2005 to June 2021, out of which 301 women were enrolled with a median duration of ART for 4.1 years (interquartile range, 2.3-7.0 years). The overall incidence rate of CD4/CD8 ratio normalization was 8.9 (95% confidence interval [CI], 7.4-10.6) per 100 PYFU, and probabilities of CD4/CD8 normalization after initiating ART at 1 year, 2 years, 5 years, and 10 years follow-up were 11.7%, 23.2%, 44.0%, and 59.0%, respectively. Independent risk factors associated with CD4/CD8 normalization were baseline CD4 cell counts <200 cells/μL, CD8 counts >1000 cells/μL, and more than 6 months from the start of combined ART (cART) to first virological suppression. Longitudinally, the rate of hypercholesterolemia (total cholesterol [TC]) and high triglyceride (TG) showed an increasing trend, while the rate of low high-density lipoprotein cholesterol (HDL) showed a decreasing trend. The rate of hyperuricemia presented a downtrend at follow-up. Although liver and renal injury and diabetes persisted during ART, the rate was not statistically significant. Older age and protease inhibitors were independent risk factors for increase of TC and TG, and ART duration was an independent factor for elevation of TC and recovery of HDL-C.

CONCLUSIONS

This study showed that women were more likely to normalize CD4/CD8 ratio in comparison with findings reported in the literature even though immune reconstruction was incomplete.

Incomplete immune reconstitution and its predictors in people living with HIV in Wuhan, China

OBJECTIVE

This study aimed to build and validate a nomogram model to predict the risk of incomplete immune reconstitution in people living with HIV (PLWH).

METHODS

Totally 3783 individuals with a confirmed diagnosis of HIV/AIDS were included. A predictive model was developed based on a retrospective set (N = 2678) and was validated using the remaining cases (N = 1105). Univariate and multivariate logistic regression analyses were performed to determine valuable predictors among the collected clinical and laboratory variables. The predictive model is presented in the form of a nomogram, which is internally and externally validated with two independent datasets. The discrimination of nomograms was assessed by calculating the area under the curve (AUC). Besides, calibration curve and decision curve (DCA) analyses were performed in the training and validation sets.

RESULTS

The final model comprised 5 predictors, including baseline CD4, age at ART initiation, BMI, HZ and TBIL. The AUC of the nomogram model was 0.902, 0.926, 0.851 in the training cohort, internal validation and external cohorts. The calibration accuracy and diagnostic performance were satisfactory in both the training and validation sets.

CONCLUSIONS

This predictive model based on a retrospective study was externally validated using 5 readily available clinical indicators. It showed high performance in predicting the risk of incomplete immune reconstitution in people living with HIV.

Immune reconstitution following alemtuzumab therapy is characterized by exhausted T cells, increased regulatory control of proinflammatory T cells and reduced B cell control

Alemtuzumab is a monoclonal antibody targeting CD52 on the surface of immune cells, approved for the treatment of active relapsing-remitting multiple sclerosis (RRMS). The purpose of this study was to analyze the repopulation of peripheral lymphocytes following alemtuzumab-induced lymphocyte depletion and investigate associations with disease activity and development of secondary autoimmunity. For this, blood samples were collected two years after initiation of alemtuzumab treatment and lymphocytes were subjected to a comprehensive flow cytometry analysis. Included in the study were 40 patients treated with alemtuzumab and 40 treatment-naïve patients with RRMS. Disease activity and development of secondary autoimmune disease was evaluated after three years of treatment. Our study confirms that alemtuzumab treatment profoundly alters the circulating lymphocyte phenotype and describes a reconstituted immune system characterized by T cell activation/exhaustion, an increased regulatory control of IL-17 producing effector T cells and CD20+ T cells, and a reduced control of B cells. There were no obvious associations between immune cell subsets and disease activity or development of secondary autoimmune disease during treatment with alemtuzumab. Our results indicate that the reconstituted immune response is skewed towards a more effective regulatory control of MS-associated proinflammatory T cell responses. Also, the enlarged pool of naïve B cells together with the apparent decrease in control of B cell activity may explain why alemtuzumab-treated patients retain the ability to mount a humoral immune response towards new antigens.

Early immune reconstitution as predictor for outcomes after allogeneic hematopoietic cell transplant; a tri-institutional analysis

BACKGROUND AIMS

CD4 immune reconstitution (IR) after allogeneic hematopoietic cell transplant (allo-HCT) correlates with lower non-relapse mortality (NRM), but its impact on leukemia relapse remains less clear, especially in children. We studied the correlation between IR of lymphocyte subsets and HCT outcomes in a large cohort of children/young adults with hematological malignancies.

METHODS

We retrospectively analyzed CD4, CD8, B-cell and natural killer (NK) cell reconstitution in patients after first allo-HCT for a hematological malignancy at three large academic institutions (n = 503; period 2008-2019). We used Cox proportional hazard and Fine-Gray competing risk models, martingale residual plots and maximally selected log-rank statistics to assess the impact of IR on outcomes.

RESULTS

Achieving CD4 >50 and/or B cells >25 cells/μL before day 100 after allo-HCT was a predictor of lower NRM (CD4 IR: hazard ratio [HR] 0.26, 95% confidence interval [CI] 0.11-0.62, P = 0.002; CD4 and B cell IR: HR 0.06, 95% CI 0.03-0.16, P < 0.001), acute graft-versus-host disease (GVHD) (CD4 and B cell IR: HR 0.02, 95% CI 0.01-0.04, P < 0.001) and chronic GVHD (CD4 and B cell IR: HR 0.16, 95% CI 0.05-0.49, P = 0.001) in the full cohort, and of lower risk of relapse (CD4 and B cell IR: HR 0.24, 95% CI 0.06-0.92, P = 0.038) in the acute myeloid leukemia subgroup. No correlation between CD8 and NK-cell IR and relapse or NRM was found.

CONCLUSIONS

CD4 and B-cell IR was associated with clinically significant lower NRM, GVHD and, in patients with acute myeloid leukemia, disease relapse. CD8 and NK-cell IR was neither associated with relapse nor NRM. If confirmed in other cohorts, these results can be easily implemented for risk stratification and clinical decision making.

[Differences in biochemical indexes and AIDS-related complications at baseline in HIV- infected patients with different levels of immune reconstitution after antiretroviral therapy]

Objective: To observe the differences in biochemical indexes and AIDS-related complications at baseline in HIV-infected patients with different levels of immune reconstitution to antiretroviral therapy (ART). Methods: The subjects were treat-naïve adult HIV-infected patients who were followed up for more than 24 months in the Guangzhou Eighth People's Hospital affiliated infection clinic at Guangzhou Medical University from January 2010 to December 2017. CD4+ T lymphocyte count at baseline at <200, 200-350, and >350 cells/µl levels were divided into poor, partial, and good immune reconstitution groups. The Kruskal-Wallis H and chi-square tests were used to analyze the differences in baseline sociodemographic characteristics, biochemical indexes, and AIDS-related complications among different groups. The SPSS 20.0 software was used for statistical analysis. Results: Among the 3 900 HIV-infected individuals, 385 cases (9.9%), 1 206 cases (30.9%), and 2 309 cases (59.2%) were grouped into poor, partial and good immune reconstitution groups, respectively. The baseline biochemical indexes of leukocyte, platelet, hemoglobin, TG, TC, FPG, AST, ALT and total bilirubin in the poor immune reconstitution group were significantly different from those in the good immune reconstitution group (all P<0.05). The proportion of AIDS-related complications at baseline in the poor immune reconstitution group, such as tuberculosis, pneumocystis yeli pneumonia, disseminated mycosis, esophageal candidiasis, extrapulmonary tuberculosis, dermatitis, oral candidiasis, oral mucous leukoplakia, continuous diarrhea for more than 1 month and continuous or intermittent fever for more than 1 month, was significantly higher than that in the good immune reconstitution group (all P<0.05). Conclusions: The biochemical indexes and AIDS-related complications in HIV-infected patients with different levels of immune reconstitution were significantly different at baseline. Attention should be paid to monitoring abnormal biomedical indicators and AIDS-related complications at baseline.

Differential analysis of immune reconstitution after allogeneic hematopoietic stem cell transplantation in children with Wiskott-Aldrich syndrome and chronic granulomatous disease

Objective

To investigate similarities and differences in immune reconstitution after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children with Wiskott-Aldrich syndrome (WAS) and chronic granulomatous disease (CGD).

Method

We retrospectively analyzed the lymphocyte subpopulations and the serum level of various immune-related protein or peptide on Days 15, 30, 100, 180 and 360 post-transplantation in 70 children with WAS and 48 children with CGD who underwent allo-HSCT at the Transplantation Center of the Department of Hematology-Oncology, Children's Hospital of Chongqing Medical University from January 2007 to December 2020, and we analyzed the differences in the immune reconstitution process between the two groups.

Results

① The WAS group had higher lymphocyte subpopulation counts than the CGD group. ② Among children aged 1-3 years who underwent transplantation, the WAS group had higher lymphocyte subpopulation counts than the CGD group. ③ Further comparisons were performed between children with non-umbilical cord blood transplantation (non-UCBT) and children with umbilical cord blood transplantation (UCBT) in the WAS group. On Day 15 and 30 post-transplantation, the non-UCBT group had higher B-cell counts than the UCBT group. On the remaining time points post-transplantation, the UCBT group had higher lymphocyte subpopulation counts than the non-UCBT group. ④ Comparisons were performed between children with non-UCBT in the WAS group and in the CGD group, the lymphocyte subpopulation counts were higher in the WAS group compared to the CGD group. ⑤ On Day 100 post-transplantation, the CGD group had higher C3 levels than the WAS group. On Day 360 post-transplantation, the CGD group had higher IgA and C4 levels than the WAS group.

Conclusion

① The rate of immunity recovery was faster in children within the WAS group compared to those children within the CGD group, which may be attributed to the difference of percentage undergoing UCBT and primary diseases. ② In the WAS group, the non-UCBT group had higher B-cell counts than the UCBT group at Day 15 and 30 post-transplantation, however, the UCBT group had higher B-cell counts than the non-UCBT group at Day 100 and 180 post-transplantation, suggesting that cord blood has strong B-cell reconstitution potentiality after transplantation.

Long-Term Immune Reconstitution in ADA-Deficient Patients Treated With Elapegademase: A Real-World Experience

BACKGROUND

ADAGEN, a bovine-based enzyme replacement therapy (ERT), has been used to treat adenosine deaminase severe combined immunodeficiency (ADA-SCID). In 2018, ADAGEN was replaced by REVCOVI (elapegademase), a modified bovine recombinant protein.

OBJECTIVE

To determine the real-life long-term benefits of REVCOVI in ADA-SCID.

METHODS

Data on ERT, infectious and noninfectious complications, and metabolic and immune evaluations were collected from 17 patients with ADA-SCID treated for 6 months or more with REVCOVI.

RESULTS

Eleven patients had previously received ADAGEN for 16 to 324 months, whereas 6 patients were ERT-naive. REVCOVI was administered twice weekly at 0.4 mg/kg/wk in ERT-naive patients, whereas patients transitioning to REVCOVI from ADAGEN typically continued at the same frequency and equivalent dosing as ADAGEN, resulting in a significantly lower (P = .007) total REVCOVI dose in the transitioning group. REVCOVI treatment in the ERT-naive group led to the resolution of many clinical and laboratory complications of ADA deficiency, whereas there were no new adverse effects among the transitioning patients. REVCOVI treatment increased plasma ADA activity and decreased dAXP (which included deoxyadenosine mono-, di-, and tri phosphate) among most patients, effects that persisted throughout the 7- to 37-month treatment periods, except in 2 patients with incomplete adherence. Among some patients, after 0.5 to 6 months, injection frequency was reduced to once a week, while maintaining adequate metabolic profiles. All ERT-naive infants treated with REVCOVI demonstrated an increase in the number of CD4+ T and CD19+ B cells, although these counts remained stable but lower than normal in most transitioning patients.

CONCLUSIONS

REVCOVI is effective for the management of ADA-SCID.

Time series clustering of T cell subsets dissects heterogeneity in immune reconstitution and clinical outcomes among MUD-HCT patients receiving ATG or PTCy

Introduction

Anti-T-lymphocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy) prevent graft-versus-host disease (GVHD) after hematopoietic cell transplantation (HCT), yet individual patients benefit differentially.

Methods

Given the sparse comparative data on the impact of cellular immune reconstitution in this setting, we studied flow cytometry and clinical outcomes in 339 recipients of 10/10 matched-unrelated donor (MUD) HCT using either ATG (n=304) or PTCy (n=35) for in vivo T cell manipulation along with a haploidentical PTCy control cohort (n=45). Longitudinal cellular immune reconstitution data were analyzed conventionally and with a data science approach using clustering with dynamic time warping to determine the similarity between time-series of T cell subsets.

Results

Consistent with published studies, no significant differences in clinical outcomes were observed at the cohort level between MUD-ATG and MUD-PTCy. However, cellular reconstitution revealed preferences for distinct T cell subpopulations associating with GVHD protection in each setting. Starting early after HCT, MUD-PTCy patients had higher regulatory T cell levels after HCT (p &lt;0.0001), while MUD-ATG patients presented with higher levels of γδ T- or NKT cells (both p &lt;0.0001). Time-series clustering further dissected the patient population’s heterogeneity revealing distinct immune reconstitution clusters. Importantly, it identified phenotypes that reproducibly associated with impaired clinical outcomes within the same in vivo T cell manipulation platform. Exemplarily, patients with lower activated- and αβ T cell counts had significantly higher NRM (p=0.032) and relapse rates (p =0.01).

Discussion

The improved understanding of the heterogeneity of cellular reconstitution in MUD patients with T cell manipulation both at the cohort and individual level may support clinicians in managing HCT complications.

Alterations in circulating markers in HIV/AIDS patients with poor immune reconstitution: Novel insights from microbial translocation and innate immunity

After long-term anti-retroviral therapy (ART) treatment, most human immunodeficiency virus (HIV)/Acquired Immure Deficiency Syndrome (AIDS) patients can achieve virological suppression and gradual recovery of CD4⁺ T-lymphocyte (CD4⁺ T cell) counts. However, some patients still fail to attain normal CD4⁺ T cell counts; this group of patients are called immune non-responders (INRs), and these patients show severe immune dysfunction. The potential mechanism of poor immune reconstitution (PIR) remains unclear and the identification of uniform biomarkers to predict the occurrence of PIR is particularly vital. But limited information is available on the relationship between circulating markers of INRs and immune recovery. Hence, this review summarises alterations in the intestine microbiota and associated markers in the setting of PIR to better understand host-microbiota-metabolite interactions in HIV immune reconstitution and to identify biomarkers that can predict recovery of CD4⁺ T cell counts in INRs.

Gamma delta T-cell reconstitution after allogeneic HCT: A platform for cell therapy

Allogeneic Hematopoietic stem cell transplantation (allo-HCT) is a curative platform for several hematological diseases. Despite its therapeutic benefits, the profound immunodeficiency associated with the transplant procedure remains a major challenge that renders patients vulnerable to several complications. Today, It is well established that a rapid and efficient immune reconstitution, particularly of the T cell compartment is pivotal to both a short-term and a long-term favorable outcome. T cells expressing a TCR heterodimer comprised of gamma (γ) and delta (δ) chains have received particular attention in allo-HCT setting, as a large body of evidence has indicated that γδ T cells can exert favorable potent anti-tumor effects without inducing severe graft versus host disease (GVHD). However, despite their potential role in allo-HCT, studies investigating their detailed reconstitution in patients after allo-HCT are scarce. In this review we aim to shed lights on the current literature and understanding of γδ T cell reconstitution kinetics as well as the different transplant-related factors that may influence γδ reconstitution in allo-HCT. Furthermore, we will present data from available reports supporting a role of γδ cells and their subsets in patient outcome. Finally, we discuss the current and future strategies to develop γδ cell-based therapies to exploit the full immunotherapeutic potential of γδ cells in HCT setting.

Evolution of Graves' Disease during Immune Reconstitution following Nonmyeloablative Haploidentical Peripheral Blood Stem Cell Transplantation in a Boy Carrying Germline SAMD9L and FLT3 Variants

Graves’ disease, characterized by hyperthyroidism resulting from loss of immune tolerance to thyroid autoantigens, may be attributable to both genetic and environmental factors. Allogeneic hematopoietic stem cell transplantation (HSCT) represents a means to induce immunotolerance via an artificial immune environment. We present a male patient with severe aplastic anemia arising from a germline SAMD9L missense mutation who successfully underwent HSCT from his HLA-haploidentical SAMD9L non-mutated father together with nonmyeloablative conditioning and post-transplant cyclophosphamide at 8 years of age. He did not suffer graft-versus-host disease, but Graves’ disease evolved 10 months post-transplant when cyclosporine was discontinued for one month. Reconstitution of peripheral lymphocyte subsets was found to be transiently downregulated shortly after Graves’ disease onset but recovered upon antithyroid treatment. Our investigation revealed the presence of genetic factors associated with Graves’ disease, including HLA-B*46:01 and HLA-DRB1*09:01 haplotypes carried by the asymptomatic donor and germline FLT3 c.2500C>T mutation carried by both the patient and the donor. Given his current euthyroid state with normal hematopoiesis, the patient has returned to normal school life. This rare event of Graves’ disease in a young boy arising from special HSCT circumstances indicates that both the genetic background and the HSCT environment can prompt the evolution of Graves’ disease.

BCG lymphadenitis: a potential complication of immune reconstitution following haematopoietic stem cell transplant

An MHC class II deficient 2-year-old boy presented with fever and an enlarging left neck mass 100 days post allogeneic haematopoietic stem cell transplant (HSCT). Fever persisted despite treatment with broad-spectrum β-lactam antibiotics. His BCG vaccination site at presentation was quiescent. Ultrasound showed enlarged cervical lymph nodes. An incisional biopsy of the large nodal mass yielded acid-fast bacilli, identified as Mycobacterium bovis by genome sequencing. Treatment with rifampicin, isoniazid and pyridoxine was started. The mass suppurated (figure 1), before healing concurrently with T-lymphocyte reconstitution at approximately day 130 post-HSCT.

HSCT using carrier donors for CD40L deficiency results in excellent immune function and higher CD40L expression in cTfh

Data are limited regarding the immune status of CD40 ligand (CD40L)-deficient carriers and hematopoietic stem cell transplantation (HSCT) outcomes using them as donors for CD40L-deficient patients. Therefore, we studied the immune profiles of 7 carriers, 4 of whom were HSCT donors for family members with CD40L deficiency, and we characterized their HSCT outcomes. Immunoglobulin profiles, CD4, CD8, circulating T-follicular helper (cTfh) cells, and regulatory T cells (Tregs) in carriers were comparable to those in healthy controls. CD40L expression in carriers ranged from 37% to 78%. cTfh cells from carriers expressed higher CD40L compared with total CD4 cells or the memory CD4 compartment, suggesting a potential advantage to CD40L-expressing cTfh cells. Tregs had minimal CD40L expression in carriers and healthy controls. So we postulated that HSCT using donors who were CD40L carriers may result in excellent immune reconstitution without immune dysregulation. Four CD40L-deficient patients underwent HSCT from carriers who had CD40L expression from 37% to 63%. All patients engrafted, achieved excellent immune reconstitution with lack of opportunistic infections, graft-versus-host disease, and immune dysregulation; stable CD40L expression mimicked that of donors 1 to 5 years after HSCT. Immunoglobulin independence was achieved in 3 of the 4 patients. We demonstrated higher CD40L expression in the cTfh compartment of carriers and excellent immune reconstitution using donors who were CD40L carriers in CD40L-deficient patients.

Variation in blood microbial lipopolysaccharide (LPS) contributes to immune reconstitution in response to suppressive antiretroviral therapy in HIV

BACKGROUND

In HIV infection, even under long-term antiretroviral therapy (ART), up to 20% of HIV-infected individuals fail to restore CD4+ T cell counts to the levels similar to those of healthy controls. The mechanisms of poor CD4+ T cell reconstitution on suppressive ART are not fully understood.

METHODS

Here, we tested the hypothesis that lipopolysaccharide (LPS) from bacteria enriched in the plasma from immune non-responders (INRs) contributes to blunted CD4+ T cell recovery on suppressive ART in HIV. We characterized plasma microbiome in HIV INRs (aviremic, CD4+ T cell counts < 350 cells/μl), immune responders (IRs, CD4+ T cell counts > 500 cells/μl), and healthy controls. Next, we analyzed the structure of the lipid A domain of three bacterial species identified by mass spectrometry (MS) and evaluated the LPS function through LPS induced proinflammatory responses and CD4+ T cell apoptosis in PBMCs. In comparison, we also evaluated plasma levels of proinflammatory cytokine and chemokine patterns in these three groups. At last, to study the causality of microbiome-blunted CD4+ T cell recovery in HIV, B6 mice were intraperitoneally (i.p.) injected with heat-killed Burkholderia fungorum, Serratia marcescens, or Phyllobacterium myrsinacearum, twice per week for total of eight weeks.

FINDINGS

INRs exhibited elevated plasma levels of total microbial translocation compared to the IRs and healthy controls. The most enriched bacteria were Burkholderia and Serratia in INRs and were Phyllobacterium in IRs. Further, unlike P. myrsinacearum LPS, B. fungorum and S. marcescens LPS induced proinflammatory responses and CD4+ T cell apoptosis in PBMCs, and gene profiles of bacteria-mediated cell activation pathways in THP-1 cells in vitro. Notably, LPS structural analysis by mass spectrometry revealed that lipid A from P. myrsinacearum exhibited a divergent structure consistent with weak toll-like receptor (TLR) 4 agonism, similar to the biological profile of probiotic bacteria. In contrast, lipid A from B. fungorum and S. marcescens showed structures more consistent with canonical TLR4 agonists stemming from proinflammatory bacterial strains. Finally, intraperitoneal (i.p.) injection of inactivated B. fungorum and S. marcescens but not P. myrsinacearum resulted in cell apoptosis in mesenteric lymph nodes of C57BL/6 mice in vivo.

INTERPRETATION

These results suggest that the microbial products are causally associated with INR phenotype. In summary, variation in blood microbial LPS immunogenicity may contribute to immune reconstitution in response to suppressive ART. Collectively, this work is consistent with immunologically silencing microbiome being causal and targetable with therapy in HIV.

FUNDING

This work was supported by the National Institute of Allergy and Infectious Diseases (NIAID; R01 AI128864, Jiang) (NIAID; P30 AI027767, Saag/Health), the Medical Research Service at the Ralph H. Johnson VA Medical Center (merit grant VA CSRD MERIT I01 CX-002422, Jiang), and the National Institute of Aging (R21 AG074331, Scott). The SCOPE cohort was supported by the UCSF/Gladstone Institute of Virology & Immunology CFAR (P30 AI027763, Gandhi) and the CFAR Network of Integrated Clinical Systems (R24 AI067039, Saag). The National Center for Advancing Translational Sciences of the National Institutes of Health under Award Number UL1TR001450 (the pilot grant, Jiang). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Decreased CD73+ Double-Negative T Cells and Elevated Level of Soluble CD73 Correlated With and Predicted Poor Immune Reconstitution in HIV-Infected Patients After Antiretroviral Therapy

Although extensive use of antiretroviral therapy (ART) has made great progress in controlling HIV replication and improving CD4+ T cell recovery, the immune reconstitution remained insufficient in some patients, who were defined as poor immunological responders (PIRs). These PIRs were at a high risk of AIDS-related and non-AIDS complications, resulting in higher morbidity and mortality rate. Thus, it is a major challenge and urgently needed to distinguish PIRs early and improve their immune function in time. Immune activation is a key factor that leads to impaired immune reconstitution in people living with HIV (PLWH) who are receiving effective ART. Double negative T cells (DNT) were reported to associate with the control of immune activation during HIV infection. However, the precise mechanisms by which DNT cells exerted their suppressive capacity during HIV infection remained puzzled. CD73, both a soluble and a membrane-bound form, display immunosuppressive effects through producing adenosine (ADO). Thus, whether DNT cells expressed CD73 and mediated immune suppression through CD73-ADO pathway needs to be investigated. Here, we found a significant downregulation of CD73 expression on DNT cells in treatment-naïve PLWH (TNs) compared to healthy controls, accompanied with increased concentration of sCD73 in plasma. Both the frequency of CD73+ DNT cells and the level of plasma sCD73 recovered after ART treatment. However, PIRs showed decreased percentage of CD73+ DNT cells compared to immunological responders (IRs). The frequency of CD73+ DNT cells was positively correlated with CD4+ T cell count and CD4/CD8 ratio, and negatively correlated with immune activation in PLWH. The level of sCD73 also showed a negative correlation to CD4+ T cell count and CD4/CD8 ratio. More importantly, in the present cohort, a higher level of sCD73 at the time of initiating ART could predict poor immune reconstitution in PLWH after long-term ART. Our findings highlighted the importance of CD73+ DNT cells and sCD73 in the disease progression and immune reconstitution of PLWH, and provided evidences for sCD73 as a potential biomarker of predicting immune recovery.

An ISCT Stem Cell Engineering Committee Position Statement on Immune Reconstitution: the importance of predictable and modifiable milestones of immune reconstitution to transplant outcomes

Allogeneic stem cell transplantation is a potentially curative therapy for some malignant and non-malignant disease. There have been substantial advances since the approaches first introduced in the 1970s, and the development of approaches to transplant with HLA incompatible or alternative donors has improved access to transplant for those without a fully matched donor. However, success is still limited by morbidity and mortality from toxicity and imperfect disease control. Here we review our emerging understanding of how reconstitution of effective immunity after allogeneic transplant can protect from these events and improve outcomes. We provide perspective on milestones of immune reconstitution that are easily measured and modifiable.

Tendon Immune Regeneration: Insights on the Synergetic Role of Stem and Immune Cells during Tendon Regeneration

Tendon disorders represent a very common pathology in today’s population, and tendinopathies that account 30% of tendon-related injuries, affect yearly millions of people which in turn cause huge socioeconomic and health repercussions worldwide. Inflammation plays a prominent role in the development of tendon pathologies, and advances in understanding the underlying mechanisms during the inflammatory state have provided additional insights into its potential role in tendon disorders. Different cell compartments, in combination with secreted immune modulators, have shown to control and modulate the inflammatory response during tendinopathies. Stromal compartment represented by tenocytes has shown to display an important role in orchestrating the inflammatory response during tendon injuries due to the interplay they exhibit with the immune-sensing and infiltrating compartments, which belong to resident and recruited immune cells. The use of stem cells or their derived secretomes within the regenerative medicine field might represent synergic new therapeutical approaches that can be used to tune the reaction of immune cells within the damaged tissues. To this end, promising opportunities are headed to the stimulation of macrophages polarization towards anti-inflammatory phenotype together with the recruitment of stem cells, that possess immunomodulatory properties, able to infiltrate within the damaged tissues and improve tendinopathies resolution. Indeed, the comprehension of the interactions between tenocytes or stem cells with the immune cells might considerably modulate the immune reaction solving hence the inflammatory response and preventing fibrotic tissue formation. The purpose of this review is to compare the roles of distinct cell compartments during tendon homeostasis and injury. Furthermore, the role of immune cells in this field, as well as their interactions with stem cells and tenocytes during tendon regeneration, will be discussed to gain insights into new ways for dealing with tendinopathies.

Signatures of GVHD and relapse after posttransplant cyclophosphamide revealed by immune profiling and machine learning

The key immunologic signatures associated with clinical outcomes after posttransplant cyclophosphamide (PTCy)-based HLA-haploidentical (haplo) and HLA-matched bone marrow transplantation (BMT) are largely unknown. To address this gap in knowledge, we used machine learning to decipher clinically relevant signatures from immunophenotypic, proteomic, and clinical data and then examined transcriptome changes in the lymphocyte subsets that predicted major posttransplant outcomes. Kinetics of immune subset reconstitution after day 28 were similar for 70 patients undergoing haplo and 75 patients undergoing HLA-matched BMT. Machine learning based on 35 candidate factors (10 clinical, 18 cellular, and 7 proteomic) revealed that combined elevations in effector CD4+ conventional T cells (Tconv) and CXCL9 at day 28 predicted acute graft-versus-host disease (aGVHD). Furthermore, higher NK cell counts predicted improved overall survival (OS) due to a reduction in both nonrelapse mortality and relapse. Transcriptional and flow-cytometric analyses of recovering lymphocytes in patients with aGVHD identified preserved hallmarks of functional CD4+ regulatory T cells (Tregs) while highlighting a Tconv-driven inflammatory and metabolic axis distinct from that seen with conventional GVHD prophylaxis. Patients developing early relapse displayed a loss of inflammatory gene signatures in NK cells and a transcriptional exhaustion phenotype in CD8+ T cells. Using a multimodality approach, we highlight the utility of systems biology in BMT biomarker discovery and offer a novel understanding of how PTCy influences alloimmune responses. Our work charts future directions for novel therapeutic interventions after these increasingly used GVHD prophylaxis platforms. Specimens collected on NCT0079656226 and NCT0080927627 https://clinicaltrials.gov/.

Primary chest wall Burkitt lymphoma in a case of HIV infection with immune reconstitution

Burkitt lymphoma (BL) develops at an increased frequency in patients with HIV irrespective of the CD4 count. Lymph nodes and gastrointestinal tract are common sites of involvement by BL; however, primary chest wall BL is rare. A 52-year-old man on highly active antiretroviral therapy (HAART) for HIV with a CD4 count of 0.204 x 109 cells/L presented with a 3-month history of enlarging chest wall mass. PET-CT scan imaging showed a bulky mass involving the musculoskeletal planes of left chest wall with the involvement of underlying pleura. Biopsy with immunohistochemistry confirmed BL. Patient received EPOCH-R (infusional etoposide, vincristine, and doxorubicin with prednisone, cyclophosphamide and rituximab) regime for six cycles along with HAART, attained complete remission (CR) and remains free of BL at 5 years. BL should be considered in the differential diagnosis of soft tissue masses in HIV-infected patients irrespective of their CD4 count.

IgG4-related autoimmune manifestations in Alemtuzumab-treated multiple sclerosis patients

We aimed to determine whether Alemtuzumab-induced immune reconstitution affects immunoglobulin and complement levels in the serum of Relapsing-Remitting Multiple Sclerosis (RRMS) patients. IgG4-levels were increased 24-months after treatment initiation compared to baseline levels in twenty-nine patients. Alemtuzumab-treated patients with the highest IgG4-levels were more prone to thyroid-related autoimmune manifestations and specific autoimmune adverse events such as Crohn's disease, Graves' disease, and hemolytic anemia. Compared to baseline, total IgG-levels showed a trend towards reduced levels following two-courses of Alemtuzumab, but no significant change of C3 and/or C4-levels was observed. In conclusion, monitoring of IgG4-levels can serve as a marker for secondary autoimmunity risk in multiple sclerosis patients treated with Alemtuzumab.

Lymphoid and myeloid immune cell reconstitution after nicotinamide-expanded cord blood transplantation

Omidubicel (nicotinamide-expanded cord blood) is a potential alternative source for allogeneic hematopoietic cell transplantation (HCT) when an HLA-identical donor is lacking. A phase I/II trial with standalone omidubicel HCT showed rapid and robust neutrophil and platelet engraftment. In this study, we evaluated the immune reconstitution (IR) of patients receiving omidubicel grafts during the first 6 months post-transplant, as IR is critical for favorable outcomes of the procedure. Data was collected from the omidubicel phase I-II international, multicenter trial. The primary endpoint was the probability of achieving adequate CD4+ T-cell IR (CD4IR: > 50 × 106/L within 100 days). Secondary endpoints were the recovery of T-cells, natural killer (NK)-cells, B-cells, dendritic cells (DC), and monocytes as determined with multicolor flow cytometry. LOESS-regression curves and cumulative incidence plots were used for data description. Thirty-six omidubicel recipients (median 44; 13-63 years) were included, and IR data was available from 28 recipients. Of these patients, 90% achieved adequate CD4IR. Overall, IR was complete and consisted of T-cell, monocyte, DC, and notably fast NK- and B-cell reconstitution, compared to conventional grafts. Our data show that transplantation of adolescent and adult patients with omidubicel results in full and broad IR, which is comparable with IR after HCT with conventional graft sources.