Tolerant Immune System Research Articles

Chapter 5 - Immune cell reconstitution following autologous hematopoietic stem cell transplantation in multiple sclerosis

Hematopoietic stem cell transplantation (HSCT) is a multistep procedure aimed at eradicating the immune system and replacing it with a new one reconstituted from hematopoietic stem cells which in autologous HSCT (AHSCT) have previously been harvested from the same individual. Over the last two decades, AHSCT has been developed as a treatment option for people affected by aggressive multiple sclerosis (MS), and it exerts a long-standing effect on new inflammation-driven disease activity. The rationale for the use of AHSCT in MS will be discussed, starting from the first observations on experimental models. The mechanisms and kinetics of repopulation (i.e., quantitative recovery) and reconstitution (i.e., qualitative changes) of the immune cell populations will be explored, focusing on immune reconstitution of the T and B cells compartments and briefly covering changes in the innate immune system. Finally, potential immunologic markers of response to treatment will be reviewed. Insights into the supposed mechanism(s) of action of AHSCT will be provided, discussing the leading hypothesis of the "rebuilding" of a newly tolerant immune system, and examining the apparent paradox of the long-standing control of disease activity despite a relatively short-term immunosuppressive effect of the procedure.

Unique Characteristics of Neonatal T Cells

Birth causes complex changes in the individual physiology and organ systems and certainly poses a big immune challenge. The sudden encounter with an antigen full world, with the exposure to food antigens, and the colonization of the skin and mucosa with microbiota, require a tolerant immune system. Nevertheless, neonates must also be able to deal with pathogens, which makes their immune system unique. T lymphocytes are responsible for the coordination of the adaptive immune system response, the elimination of infected cells and the type of immune response and memory. It has been shown that neonatal cells have intrinsic differences with adult cells, biased towards an innate response and a tolerant phenotype. In the perinatal period, the immune system changes from basal signaling and innate like responses, towards stimulus-specific signals, which increase with gestational age. After birth the cells of the immune system continue to change both in composition and function. In this review, we present the intrinsic differences of neonatal CD4+ and CD8+ T cells, as compared with adult naïve cells. A specific transcriptome profile is present in both CD4+ and CD8+ neonatal T cells, with overexpression of homeobox transcription factors. These cells also present differences in cell signaling and metabolic characteristics, which result in unique functional capabilities. Neonatal CD4+ T cells respond differently from adult cells, with a high production of IL-8, a prevalent Th2 over Th1 profile, and an innate inflammatory response. The neonatal period is one of the most vulnerable periods of life, with a high morbidity and mortality rate, approaching on average 17 deaths per 1000 live births worldwide. A better understanding of the neonatal immune system will help to ensure a better care of this vulnerable population.

Mass cytometry reveals cladribine-induced resets among innate lymphoid cells in multiple sclerosis

Here we present a comprehensive mass cytometry analysis of peripheral innate lymphoid cell (ILC) subsets in relapsing/remitting MS (RRMS) patients prior to and after onset of cladribine tablets (CladT). ILC analysis was conducted on CyTOF data from peripheral blood mononuclear cells (PBMC) of MS patients before, 2 and 6 months after onset of CladT, and non-MS controls. Dimensionality reduction was used for immunophenotyping ILC subsets. CladT reduced all ILC subsets, except for CD56bright NK cells and ILC2. Furthermore, CD38+ NK cell and CCR6+ ILC3 were excluded from CladT-induced immune cell reductions. Post-CladT replenishment by immature ILC was noted by increased CD5+ ILC1 proportions at 2 months, and boosted CD38−CD56bright NK cell numbers at 6 months. CladT induce immune cell depletion among ILC but exclude CD56bright NK cells and ILC2 subsets, as well as CD38+ NK cell and CCR6+ ILC3 immunophenotypes. Post-CladT ILC expansions indicate ILC reconstitution towards a more tolerant immune system phenotype.

Protein ubiquitination in T cell development.

As an important form of posttranslational modification, protein ubiquitination regulates a wide variety of biological processes, including different aspects of T cell development and differentiation. During T cell development, thymic seeding progenitor cells (TSPs) in the thymus undergo multistep maturation programs and checkpoints, which are critical to build a functional and tolerant immune system. Currently, a tremendous amount of research has focused on the transcriptional regulation of thymocyte development. However, in the past few years, compelling evidence has revealed that the ubiquitination system also plays a crucial role in the regulation of thymocyte developmental programs. In this review, we summarize recent findings on the molecular mechanisms and cellular pathways that regulate thymocyte ubiquitination and discuss the roles of E3 ligases and deubiquitinating enzymes (DUBs) involved in these processes. Understanding how T cell development is regulated by ubiquitination and deubiquitination will not only enhance our understanding of cell fate determination via gene regulatory networks but also provide potential novel therapeutic strategies for treating autoimmune diseases and cancer.

Design and development of an IoT based intelligent multi parameter screening system

The SARS-CoV-2 or shortly COVID-19, is a viral disease which causes serious lung fever and hugely impacts different body parts from mild to critical depending on tolerant immune system. As the virus multiplies through human-to-human contact, it has affected our lives in a devastating way, including the vigorous pressure on the public health system, the world economy, education sector, workplaces, and shopping malls. Viral spreading of this virus can only be prevented by early detection of positive cases and to treat infected patients as quickly as possible. As many businesses, banks, gymnasiums, and stores etc., are using temperature screening as the primary step to assess for possible COVID-19 infection. Moreover, the proper hand sanitization is the very effective method to limit the outspread of this virus. This paper proposes the design and development of a fully automated low-cost portable electronic system in the form of a robot named CovBot that can be installed in the above-mentioned places by incorporating the mechanisms to automatically detect the body temperature, store the details directly to cloud so as to get the data latter by the authorities, to control/restrict the entry, a hand sanitization dispenser unit, auto alert to refill the sanitizer, a mobile display unit etc. Whole system can be managed by a mobile application. The system is controlled using an Arduino-Uno development board. The mobile and the microcontroller system is wirelessly communicated and that to cloud is done by IoT facility. Once this system is implemented, the primary concern and the initial screening associated to COVID-19 can be fully resolved. Comparing to other systems CovBot is cost effective and can be easily installed and operated.

The role of innate immune cells in systemic sclerosis in the context of autologous hematopoietic stem cell transplantation.

SummarySystemic sclerosis (SSc) is a complex, heterogeneous autoimmune connective tissue disease. Autologous hematopoietic stem‐cell transplantation (AHSCT) has emerged as a valuable treatment option for rapidly progressive diffuse cutaneous SSc (dcSSc) patients, and thus far is the only treatment that has been shown to have a long‐term clinical benefit. AHSCT is thought to reintroduce immune homeostasis through elimination of pathogenic self‐reactive immune cells and reconstitution of a new, tolerant immune system. However, the mechanism of action underlying this reset to tolerance remains largely unknown. In this study we review the immune mechanisms underlying AHSCT for SSc, with a focus on the role of the innate immune cells, including monocytes and natural killer (NK) cells, in restoring immune balance after AHSCT.

The tolerant immune system: Biological significance and clinical implications of T cell tolerance

The tolerant immune system: Biological significance and clinical implications of T cell tolerance

The role of autologous haemopoietic stem cell transplantation in the treatment of autoimmune disorders.

Autologous haemopoietic stem cell transplantation (HSCT) has been used for over 30 years for malignant haematological diseases, such as myeloma and lymphoma, with considerable success. More recently this procedure has been adopted as a form of high dose immunosuppression in selected patients with autoimmune diseases that are resistant to conventional therapies. Animal models have previously outlined the rationale and validity of HSCT in patients with these non-malignant, but in many cases, life-threatening conditions. Recent data have that deletion of putative autoreactive immune clones with reconstitution of a thymic driven, tolerant immune system occurs in HSCT for auto-immune patients. Two randomised control trials have confirmed that HSCT is superior to monthly cyclophosphamide in systemic sclerosis with a highly significant disease free and overall survival benefit demonstrated in the Autologous Stem cell Transplantation International Scleroderma trial. Over 2000 patients worldwide with autoimmune conditions have been treated with HSCT - the commonest indications being multiple sclerosis (MS) and systemic sclerosis. Encouraging relapse free survival of 70-80% at 4 years, in heavily pre-treated MS patients, has been demonstrated in Phase II trials. A Phase III trial in MS patients who have failed interferon is currently accruing patients. Future challenges include improvements in safety of HSCT, particularly in cardiac assessment of systemic sclerosis patients, cost-benefit analyses of HSCT compared to standard therapy and establishment of centres of excellence to continue to enhance the safety and benefit of this exciting new therapy.

Abstract 5377: Low donor thymic output predicts increased incidence of extensive chronic GVHD and worse overall survival after TCD-matched sibling SCT

Abstract Low CD4+ T cell counts early post-SCT are associated with a greater risk of developing chronic GVHD (cGVHD). However, the factors affecting post graft CD4+ T cell recovery are not known. Furthermore, the CD4 T cell subset correlating best with protection from cGvHD is not defined. We hypothesized that the donor immune repertoire determines CD4+ reconstitution after SCT. We studied 220 donor-recipient pairs undergoing a myeloablative matched-sibling T-cell depleted SCT for a variety of hematological malignancies including AML, ALL, CML, and MDS. Median donor and patient age was 36 years (range, 9 - 70). Median CD34+ cell dose was 5.56 x106/kg (range, 2.3-14.5), with a fixed T cell dose per protocol of 1-5 x104/kg. Ninety-four patients (43%) developed chronic GvHD (32 limited, 64 extensive). Prior to SCT a cryopreserved mononuclear fraction (PBMC) was obtained by leukopheresis on all donors. PBMC from 139 donors were stained with fluorescently conjugated antibodies and acquired on a custom-built LSR Fortessa (BD) flow cytometer. Regulatory T cells (Tregs) and Treg subsets were identified within the CD4+ T cell population using a combination of FOXP3 and Helios. The combination of FOXP3 with Helios has recently been shown to identify natural, thymus-derived Tregs (nTregs), whereas CD4+FOXP3+ T cells lacking Helios represent a pool of induced Tregs (Thornton et al., 2010, J Immunol. 184:3433-3441). Combined expression of CD31 and CD45RA in the CD4+ and nTreg populations was used to identify recent thymic emigrants (RTE). Absolute lymphocyte counts in 220 donors were 2.11/µl (range 0.89 - 4.12). A low absolute lymphocyte count was significantly correlated with a higher cumulative probability for time to incidence of extensive cGVHD (HR 2.38, p = 0.0008). This relationship between lymphocytes and cGVHD was retained in CD4+ T cell subsets: CD3+CD4+ (HR 2.48, p = 0.005); CD3+CD4+CD25+ < 30 cells/μL (HR 2.1, p = 0.02); nTregs < 8 cells/μL (HR 1.97, p = 0.043). RTE of total CD4 did not correlate with RTE nTregs, indicating that nTreg production varies among donors with similar levels of thymic activity. Furthermore recipients of donors with low RTE nTregs relative to overall thymic output had a significantly higher likelihood of developing extensive chronic GvHD (HR 2.78, p=0.0014). In multivariate analysis including patient age, acute GvHD (grade II - IV), graft direction (female donor to male recipient vs. other combinations), disease and status at transplant, and administration of post SCT donor lymphocyte infusion, only thymic output of nTregs (HR = 0.8, p = 0.037) and graft direction (HR = 2.1, p = 0.023) remained significant risk factors for extensive cGvHD. These data show that the thymic output of nTreg varies inherently among donors. Donors with low thymic output of nTreg may recreate a less tolerant immune system in the recipient leading to cGVHD of greater severity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5377. doi:1538-7445.AM2012-5377

Low Thymic Natural Regulatory T Cell Output in the Donor Is Associated with An Increased Incidence of Extensive Chronic GvHD After T Cell Depleted Matched Sibling Stem Cell Transplantation (SCT)

Abstract 328Low CD4+ T cell counts early post-SCT are associated with a greater risk of developing chronic GVHD (cGVHD). However, the factors affecting post graft CD4+ T cell recovery are not known. Furthermore, the CD4 T cell subset correlating best with protection from cGvHD is not defined. We hypothesized that the donor immune repertoire determines CD4+ reconstitution after SCT. We studied 220 donor-recipient pairs undergoing a myeloablative matched-sibling T-cell depleted SCT for a variety of hematological malignancies including AML, ALL, CML, and MDS. Median donor and patient age was 36 years (range, 9 – 70). Median CD34+ cell dose was 5.56 ×106/kg (range, 2.3–14.5), with a fixed T cell dose per protocol of 1–5 ×104/kg. Ninety-four patients (43%) developed chronic GvHD (32 limited, 64 extensive). Prior to SCT a cryopreserved mononuclear fraction (PBMC) was obtained by leukopheresis on all donors. PBMC from 139 donors were stained with fluorescently conjugated antibodies against CD3, CD4, CD8, CD27, CD45RA, CD31, CD25, CD14, CD19, FOXP3, and Helios and acquired on a custom-built LSR Fortessa (BD) flow cytometer. The following T cell subsets were examined: naive, CD27+CD45RA+; central memory, CD27+CD45RA-; effector memory, CD27-CD45RA-; and effector T cells, CD27-CD45RA+. Regulatory T cells (Tregs) and Treg subsets were identified within the CD4+ T cell population using a combination of FOXP3 and Helios The combination of FOXP3 with Helios has recently been shown to identify natural, thymus-derived Tregs (nTregs), whereas CD4+FOXP3+ T cells lacking Helios represent a pool of induced Tregs (Thornton et al., 2010, J Immunol. 184:3433–3441). Combined expression of CD31 and CD45RA in the CD4+ and nTreg populations was used to identify recent thymic emigrants (RTE). Data were analyzed by FlowJo (Treestar, Ashland, OH, version 8.6.6), and both univariate and multivariate analysis analyses using the Cox regression models with right censored time-to-event variables were performed on the readouts (SPSS 15.0, S-Plus 8 and Prism 4 Software). All p-values were computed based on the log-rank test statistics. Absolute lymphocyte counts in 220 donors were 2.11/μl (range 0.89 – 4.12). A low absolute lymphocyte count was significantly correlated with a higher cumulative probability for time to incidence of extensive cGVHD (HR 2.38, p = 0.0008). This relationship between lymphocytes and cGVHD was retained in CD4+ T cell subsets: CD3+CD4+ (HR 2.48, p = 0.005); CD3+CD4+CD25+ < 30 cells/μL (HR 2.1, p = 0.02); nTregs < 8 cells/μL (HR 1.97, p = 0.043). RTE of total CD4 did not correlate with RTE nTregs, indicating that nTreg production varies among donors with similar levels of thymic activity. Furthermore recipients of donors with low RTE nTregs relative to overall thymic output had a significantly higher likelihood of developing extensive chronic GvHD (HR 2.78, p=0.0014). In multivariate analysis including patient age, acute GvHD (grade II – IV), graft direction (female donor to male recipient vs. other combinations), disease and status at transplant, and administration of post SCT donor lymphocyte infusion, only thymic output of nTregs (HR = 0.8, p = 0.037) and graft direction (HR = 2.1, p = 0.023) remained significant risk factors for extensive cGvHD. These data show that the thymic output of nTreg varies inherently among donors. Donors with low thymic output of nTreg may recreate a less tolerant immune system in the recipient leading to cGVHD of greater severity.(ZAM and JJM contributed equally to this work). [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Hematopoietic SCT for the treatment of multiple sclerosis

Multiple sclerosis (MS) is the leading autoimmune indication for autologous hematopoietic SCT (aHSCT). Patient selection criteria and transplant interventions have been refined through a series of cohort and registry studies. High- and low-intensity chemotherapy-based conditioning regimens have been used, creating trade-offs between toxicity and effectiveness. TBI has been associated with greater toxicity and poor outcomes. aHSCT stops MS relapses and lessens the disability in malignant MS, which otherwise rapidly incapacitates patients. Better responses occur in progressive MS earlier in the disease when it has a more inflammatory nature. aHSCT prevents further disability in many patients, but some actually recover from their infirmities. Current regimens and supportive care result in very low morbidity and mortality. MS patients experience unique complications in addition to the expected toxicities. Cytokines used alone for stem-cell mobilization may induce MS flares but are safe to be used in combination with steroids or cytotoxic agents. Urinary tract infections, herpes virus reactivation and an engraftment syndrome may occur early after aHSCT. Rarely secondary autoimmune diseases have been reported late after HSCT. Increasing experience in caring for patients with MS has reduced the frequency and severity of toxicity. Conceived as an opportunity to 'reboot' a tolerant immune system, aHSCT is successful in treating patients with MS that is refractory to conventional immunomodulatory drugs.

Identification of cellular markers predicting relapses after immunoablation and autologous haematopoietic stem cell transplantation (ASCT) for refractory systemic lupus erythematosus

We recently showed that clinical remissions in systemic lupus erythematosus (SLE) after immunoablation and autologous haematopoietic stem cell transplantation (ASCT) are associated with depletion of the autoreactive immunological memory and...

Depletion of autoreactive immunologic memory followed by autologous hematopoietic stem cell transplantation in patients with refractory SLE induces long-term remission through de novo generation of a juvenile and tolerant immune system

AbstractClinical trials have indicated that immunoablation followed by autologous hematopoietic stem cell transplantation (ASCT) has the potential to induce clinical remission in patients with refractory systemic lupus erythematosus (SLE), but the mechanisms have remained unclear. We now report the results of a single-center prospective study of long-term immune reconstitution after ASCT in 7 patients with SLE. The clinical remissions observed in these patients are accompanied by the depletion of autoreactive immunologic memory, reflected by the disappearance of pathogenic anti–double-stranded DNA (dsDNA) antibodies and protective antibodies in serum and a fundamental resetting of the adaptive immune system. The latter comprises recurrence of CD31+CD45RA+CD4+ T cells (recent thymic emigrants) with a doubling in absolute numbers compared with age-matched healthy controls at the 3-year follow-up (P = .016), the regeneration of thymic-derived FoxP3+ regulatory T cells, and normalization of peripheral T-cell receptor (TCR) repertoire usage. Likewise, responders exhibited normalization of the previously disturbed B-cell homeostasis with numeric recovery of the naive B-cell compartment within 1 year after ASCT. These data are the first to demonstrate that both depletion of the autoreactive immunologic memory and a profound resetting of the adaptive immune system are required to reestablish self-tolerance in SLE. This trial was registered at www.clinicaltrials.gov as #NCT00742300.

Emerging Therapies for Multiple Sclerosis

This review examines the mode of action, safety profile and clinical efficacy of some of the most promising new therapeutic strategies for multiple sclerosis. Autologous hematopoietic stem cell transplantation can regenerate a new and tolerant immune system and is a potentially effective rescue therapy in a subset of patients with aggressive forms of MS refractory to approved immunomodulatory and immunosuppressive agents. High-dose cyclophosphamide without stem cell support is suggested to induce prolonged remissions through similar immunological mechanisms with less toxicity. Fingolimod (FTY720) is a novel oral immunomodulating agent that acts through preventing lymphocyte recirculation from lymphoid organs. Monoclonal antibody therapy has provided scientists and clinicians the opportunity to rationally direct the therapeutic intervention against specific molecules. Targeting molecules of the immune system such as CD52 (alemtuzumab), CD25 (daclizumab), VLA-4 (natalizumab) and CD20 (rituximab) have resulted in potent immunomodulatory effects through sometimes unpredicted mechanisms. The potential of immunoglobulins to induce remyelination in the CNS is being investigated in an attempt to develop therapies promoting tissue repair and functional recovery. The evidence supporting the potential of these emerging immunotherapies suggests that strong progress is being made in the development of effective cures for multiple sclerosis.