Low CD25 on autoreactive Tregs impairs tolerance via low dose IL-2 and antigen delivery

Tolerogenic dendritic cells in type 1 diabetes: no longer a concept

Tolerogenic dendritic cells (tDC) arrest the progression of autoimmune-driven dysglycemia into clinical, insulin-requiring type 1 diabetes (T1D) and preserve a critical mass of β cells able to restore some degree of normoglycemia in new-onset clinical disease. The safety of tDC, generated ex vivo from peripheral blood leukocytes, has been demonstrated in phase I clinical studies. Accumulating evidence shows that tDC act via multiple layers of immune regulation arresting the action of pancreatic β cell-targeting effector lymphocytes. tDC share a number of phenotypes and mechanisms of action, independent of the method by which they are generated ex vivo. In the context of safety, this yields confidence that the time has come to test the best characterized tDC in phase II clinical trials in T1D, especially given that tDC are already being tested for other autoimmune conditions. The time is also now to refine purity markers and to "universalize" the methods by which tDC are generated. This review summarizes the current state of tDC therapy for T1D, presents points of intersection of the mechanisms of action that the different embodiments use to induce tolerance, and offers insights into outstanding matters to address as phase II studies are imminent. Finally, we present a proposal for co-administration and serially-alternating administration of tDC and T-regulatory cells (Tregs) as a synergistic and complementary approach to prevent and treat T1D.

Identification of an immune-related gene prognostic index for predicting prognosis, immunotherapeutic efficacy, and candidate drugs in amyotrophic lateral sclerosis

Rationale and objectives

Considering the great insufficiency in the survival prediction and therapy of amyotrophic lateral sclerosis (ALS), it is fundamental to determine an accurate survival prediction for both the clinical practices and the design of treatment trials. Therefore, there is a need for more accurate biomarkers that can be used to identify the subtype of ALS which carries a high risk of progression to guide further treatment.

Methods

The transcriptome profiles and clinical parameters of a total of 561 ALS patients in this study were analyzed retrospectively by analysis of four public microarray datasets. Based on the results from a series of analyses using bioinformatics and machine learning, immune signatures are able to be used to predict overall survival (OS) and immunotherapeutic response in ALS patients. Apart from other comprehensive analyses, the decision tree and the nomogram, based on the immune signatures, were applied to guide individual risk stratification. In addition, molecular docking methodology was employed to screen potential small molecular to which the immune signatures might response.

Results

Immune was determined as a major risk factor contributing to OS among various biomarkers of ALS patients. As compared with traditional clinical features, the immune-related gene prognostic index (IRGPI) had a significantly higher capacity for survival prediction. The determination of risk stratification and assessment was optimized by integrating the decision tree and the nomogram. Moreover, the IRGPI may be used to guide preventative immunotherapy for patients at high risks for mortality. The administration of 2MIU IL2 injection in the short-term was likely to be beneficial for the prolongment of survival time, whose dosage should be reduced to 1MIU if the long-term therapy was required. Besides, a useful clinical application for the IRGPI was to screen potential compounds by the structure-based molecular docking methodology.

Conclusion

Ultimately, the immune-derived signatures in ALS patients were favorable biomarkers for the prediction of survival probabilities and immunotherapeutic responses, and the promotion of drug development.

Post-COVID-19 Immune-Mediated Neurological Complications in Children: An Ambispective Study

BACKGROUND

The neurological manifestation following a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is varied, and till now, only a few studies have reported the same.

METHODS

We used retrospective data from May to July 2021 and prospective study data from August to September 2021, including that from children aged between one month and 18 years who presented to a tertiary care referral center with the neurological manifestation and had a history of coronavirus disease 2019 (COVID-19) infection or exposure and positive SARS-CoV-2 serology. The neuroradiological manifestations were further categorized as in a predesigned proforma.

RESULTS

Case records of the 18 children who fulfilled the criteria were included in the study; among them, seven (38.8%) were male and 11 (61.1%) were female. Predominant presentation in our study group was status epilepticus (six of 18) and Guillain-Barré syndrome (five of 18). Other manifestations included stroke (two of 18), demyelinating syndromes (three of 18), and autoimmune encephalitis (two of 18). Most of the children had favorable outcomes except for one mortality in our cohort.

CONCLUSIONS

Delayed complications following SARS-CoV-2 infection are seen in children. A temporal correlation was noted between the COVID-19 infection and the increasing number of neurological cases after the second wave. Steroids could be beneficial while treating such patients, especially in the presence of high inflammatory markers. Testing for SARS-CoV-2 serology during the pandemic can give a clue to the underlying etiology. Further multicentric studies are required to understand the varied neurological manifestations following SARS-CoV-2 infection in children.

Potential Utility of Natural Products against Oxidative Stress in Animal Models of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune-mediated degenerative disease of the central nervous system (CNS) characterized by immune cell infiltration, demyelination and axonal injury. Oxidative stress-induced inflammatory response, especially the destructive effect of immune cell-derived free radicals on neurons and oligodendrocytes, is crucial in the onset and progression of MS. Therefore, targeting oxidative stress-related processes may be a promising preventive and therapeutic strategy for MS. Animal models, especially rodent models, can be used to explore the in vivo molecular mechanisms of MS considering their similarity to the pathological processes and clinical signs of MS in humans and the significant oxidative damage observed within their CNS. Consequently, these models have been used widely in pre-clinical studies of oxidative stress in MS. To date, many natural products have been shown to exert antioxidant effects to attenuate the CNS damage in animal models of MS. This review summarized several common rodent models of MS and their association with oxidative stress. In addition, this review provides a comprehensive and concise overview of previously reported natural antioxidant products in inhibiting the progression of MS.

Vascular alterations impede fragile tolerance to pregnancy in type 1 diabetes

OBJECTIVE

To determine the impact of autoimmunity in the absence of glycemic alterations on pregnancy in type 1 diabetes (T1D).

DESIGN

Because nonobese diabetic (NOD) mice experience autoimmunity before the onset of hyperglycemia, we studied pregnancy outcomes in prediabetic NOD mice using flow cytometry and enzyme-linked immunosorbent assays. Once we determined that adverse events in pregnancy occurred in euglycemic mice, we performed an exploratory study using electronic health records to better understand pregnancy complications in humans with T1D and normal hemoglobin A1c levels.

SETTING

University Medical Center.

PATIENT(S)/ANIMAL(S)

Nonobese diabetic mice and electronic health records from Vanderbilt University Medical Center.

INTERVENTION(S)

Nonobese diabetic mice were administered 200 μg of an anti-interleukin 6 (IL-6) antibody every other day starting on day 5 of gestation.

MAIN OUTCOME MEASURE(S)

Changes in the number of abnormal and reabsorbed pups in NOD mice and odds of vascular complications in pregnancy in T1D in relation to A1c.

RESULT(S)

Prediabetic NOD mice had increased adverse pregnancy outcomes compared with nonautoimmune mice; blockade of IL-6, which was secreted by endothelial cells, decreased the number of reabsorbed and abnormal fetuses. Similarly, vascular complications were increased in pregnant patients with T1D across all A1c values.

CONCLUSION(S)

The vascular secretion of IL-6 drives adverse pregnancy outcomes in prediabetic NOD mice. Pregnant patients with T1D have increased vascular complications even with normal hemoglobin A1cs, indicating a potential effect of autoimmunity on the placental vasculature.

Interleukin-2 expands neuroprotective regulatory T cells in Parkinson's disease

Background

Pharmacological approaches that boost neuroprotective regulatory T cell (Treg) number and function lead to neuroprotective activities in neurodegenerative disorders.

Objectives

We investigated whether low-dose interleukin 2 (IL-2) expands Treg populations and protects nigrostriatal dopaminergic neurons in a model of Parkinson's disease (PD).

Methods

IL-2 at 2.5 × 104 IU/dose/mouse was administered for 5 days. Lymphocytes were isolated and phenotype determined by flow cytometric analyses. To 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxicated mice, 0.5 × 106 of enriched IL-2-induced Tregs were adoptively transferred to assess the effects on nigrostriatal neuron survival.

Results

IL-2 increased frequencies of CD4+CD25+CD127lowFoxP3+ Tregs that express ICOS and CD39 in blood and spleen. Adoptive transfer of IL-2-induced Tregs to MPTP-treated recipients increased tyrosine hydroxylase (TH)+ nigral dopaminergic neuronal bodies by 51% and TH+ striatal termini by 52% compared to control MPTP-treated animal controls.

Conclusions

IL-2 expands numbers of neuroprotective Tregs providing a vehicle for neuroprotection of nigrostriatal dopaminergic neurons in a pre-clinical PD model.

Effect of Si-Miao-Yong-An decoction on the differentiation of monocytes, macrophages, and regulatory T cells in ApoE-/- mice

ETHNOPHARMACOLOGICAL RELEVANCE

Si-Miao-Yong-An decoction (SMYAD) is a renowned traditional Chinese medicinal formula. SMYAD was originally recorded in the "Shi Shi Mi Lu", which was edited by medical scientist Chen Shi'duo during the Qing Dynasty. SMYAD has been traditionally used to treat thromboangiitis obliterans. At present, it is mainly used in clinical applications and research of cardiovascular diseases.

AIM OF THE STUDY

To explore the effects of SMYAD on the pathological changes of atherosclerosis (AS) and the differentiation of monocytes, macrophages, and regulatory T (Treg) cells in apolipoprotein E knockout (ApoE-/-) mice.

MATERIALS AND METHODS

Eight C57BL/6J mice, which were fed with normal diet for 16 weeks, were used as control group. Forty ApoE-/- mice were randomly divided into model group, atorvastatin group, SMYAD low-dose (SMYAD-LD) group, SMYAD medium-dose (SMYAD-MD) group, and SMYAD high-dose (SMYAD-HD) group. ApoE-/- mice were fed with western diet (WD) for 8 weeks, and the drugs were continuously administered for 8 weeks. The levels of serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were measured by the esterase method. Morphological changes of the aortic sinus in mice were observed by hematoxylin-eosin (HE) staining, the lipid infiltration of the aorta and aortic sinus were observed by oil red O staining, and the spleen index was calculated. The proportion of Ly6Chigh and Ly6Clow monocyte subsets, macrophages, and their M1 phenotype, as well as Treg cells in spleen were measured by flow cytometry. The expressions of cluster of differentiation 36 (CD36), scavenger receptor A1 (SRA1), lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), F4/80, and fork head frame protein 3 (FOXP3) in aortic sinus were assessed by immunohistochemical staining. The serum levels of oxidized low density lipoprotein (ox-LDL), interleukin-1β (IL-1β), IL-18, transforming growth factor-β (TGF-β), and IL-10 were measured by enzyme-linked immunosorbent assays (ELISA).

RESULTS

Compared with the model group, the level of serum TC and LDL-C decreased in the SMYAD group, the pathological changes of aortic sinus decreased, and lipid infiltration of aorta and aortic sinus also decreased. These decreases were accompanied by a significant downregulation of CD36, SRA1, and LOX-1. Furthermore, the proportions of Ly6Chigh pro-inflammatory monocyte subsets, macrophages, and their M1 phenotypes in spleen decreased significantly, while the proportion of Treg cells increased. In addition, while the expression of F4/80 decreased, the expression of FOXP3 increased in the aorta sinus. The levels of serum pro-inflammatory factors IL-1β and IL-18 decreased.

CONCLUSIONS

SMYAD can improve the pathological changes associated with AS and can inhibit lipid deposition in ApoE-/- mice induced by WD diet. The likely mechanism is the inhibition of the differentiation and recruitment of monocytes and macrophages, the promotion of the differentiation and recruitment of Treg cells, as well as the reduction of the secretion of pro-inflammatory factors.

Auto-antigen and Immunomodulatory Agent-Based Approaches for Antigen-Specific Tolerance in NOD Mice

PURPOSE OF REVIEW

Type 1 diabetes (T1D) can be managed by insulin replacement, but it is still associated with an increased risk of microvascular/cardiovascular complications. There is considerable interest in antigen-specific approaches for treating T1D due to their potential for a favorable risk-benefit ratio relative to non-specific immune-based treatments. Here we review recent antigen-specific tolerance approaches using auto-antigen and/or immunomodulatory agents in NOD mice and provide insight into seemingly contradictory findings.

RECENT FINDINGS

Although delivery of auto-antigen alone can prevent T1D in NOD mice, this approach may be prone to inconsistent results and has not demonstrated an ability to reverse established T1D. Conversely, several approaches that promote presentation of auto-antigen in a tolerogenic context through cell/tissue targeting, delivery system properties, or the delivery of immunomodulatory agents have had success in reversing recent-onset T1D in NOD mice. While initial auto-antigen based approaches were unable to substantially influence T1D progression clinically, recent antigen-specific approaches have promising potential.

The Antigen Presenting Potential of CD21low B Cells

Human CD21^low B cells are expanded in autoimmune (AI) diseases and display a unique phenotype with high expression of co-stimulatory molecules, compatible with a potential role as antigen-presenting cells (APCs). Thus, we addressed the co-stimulatory capacity of naïve-like, IgM-memory, switched memory and CD27^negIgD^neg memory CD21^low B cells in allogenic co-cultures with CD4 T cells. CD21^low B cells of patients with AI disorders expressed high levels of not only CD86, CD80, and HLA-DR (memory B cells) but also PD-L1 ex vivo and efficiently co-stimulated CD4 T cells of healthy donors (HD), as measured by upregulation of CD25, CD69, inducible co-stimulator (ICOS), and programmed cell death protein 1 (PD-1) and induction of cytokines. While the co-stimulatory capacity of the different CD21^low B-cell populations was over all comparable to CD21^pos counterparts of patients and HD, especially switched memory CD21^low B cells lacked the increased capacity of CD21^pos switched memory B-cells to induce high expression of ICOS, IL-2, IL-10, and IFN-γ. Acknowledging the limitation of the in vitro setting, CD21^low B cells do not seem to preferentially support a specific T_h effector response. In summary, our data implies that CD21^low B cells of patients with AI diseases can become competent APCs and may, when enriched for autoreactive B-cell receptors (BCR), potentially contribute to AI reactions as cognate interaction partners of autoreactive T cells at sites of inflammation.

Tolerogenic vaccines: Targeting the antigenic and cytokine niches of FOXP3+ regulatory T cells

FOXP3+ regulatory T cells (Tregs) constitute a critical barrier that enforces tolerance to both the self-peptidome and the extended-self peptidome to ensure tissue-specific resistance to autoimmune, allergic, and other inflammatory disorders. Here, we review intuitive models regarding how T cell antigen receptor (TCR) specificity and antigen recognition efficiency shape the Treg and conventional T cell (Tcon) repertoires to adaptively regulate T cell maintenance, tissue-residency, phenotypic stability, and immune function in peripheral tissues. Three zones of TCR recognition efficiency are considered, including Tcon recognition of specific low-efficiency self MHC-ligands, Treg recognition of intermediate-efficiency agonistic self MHC-ligands, and Tcon recognition of cross-reactive high-efficiency agonistic foreign MHC-ligands. These respective zones of TCR recognition efficiency are key to understanding how tissue-resident immune networks integrate the antigenic complexity of local environments to provide adaptive decisions setting the balance of suppressive and immunogenic responses. Importantly, deficiencies in the Treg repertoire appear to be an important cause of chronic inflammatory disease. Deficiencies may include global deficiencies in Treg numbers or function, subtle 'holes in the Treg repertoire' in tissue-resident Treg populations, or simply Treg insufficiencies that are unable to counter an overwhelming molecular mimicry stimulus. Tolerogenic vaccination and Treg-based immunotherapy are two therapeutic modalities meant to restore dominance of Treg networks to reverse chronic inflammatory disease. Studies of these therapeutic modalities in a preclinical setting have provided insight into the Treg niche, including the concept that intermediate-efficiency TCR signaling, high IFN-β concentrations, and low IL-2 concentrations favor Treg responses and active dominant mechanisms of immune tolerance. Overall, the purpose here is to assimilate new and established concepts regarding how cognate TCR specificity of the Treg repertoire and the contingent cytokine networks provide a foundation for understanding Treg suppressive strategy.

Post-infectious neurological disorders

A multitude of environmental factors can result in breakdown of immune tolerance in susceptible hosts. Infectious pathogens are among the most important environmental triggers in the pathogenesis of autoimmunity. Certain autoimmune disorders have a strong association with specific infections. Several neurological autoimmune disorders are thought to occur through post-infectious mechanisms. In this review, we discuss the proposed mechanisms underlying pathogen-induced autoimmunity, and highlight the clinical presentation and treatment of several post-infectious autoimmune neurological disorders. We also highlight post-infectious neurological disorders in the setting of recent outbreaks.

Bystander activation and autoimmunity

The interaction over time of genetic, epigenetic and environmental factors (i.e., autoimmune ecology) increases or decreases the liability an individual would have to develop an autoimmune disease (AD) depending on the misbalance between risk and protective effects. Pathogens have been the most common antecedent events studied, but multiple other environmental factors including xenobiotic chemicals, drugs, vaccines, and nutritional factors have been implicated into the development of ADs. Three main mechanisms have been offered to explain the development of autoimmunity: molecular mimicry, epitope spreading, and bystander activation. The latter is characterized by auto-reactive B and T cells that undergo activation in an antigen-independent manner, influencing the development and course of autoimmunity. Activation occurs due to a combination of an inflammatory milieu, co-signaling ligands, and interactions with neighboring cells. In this review, we will discuss the studies performed seeking to define the role of bystander activation in systemic and organ-specific ADs. In all cases, we are cognizant of individual differences between hosts and the variable latency time for clinical expression of disease, all of which have made our understanding of the etiology of loss of immune tolerance difficult and enigmatic.

Combining anti-IL-7Rα antibodies with autoantigen-specific immunotherapy enhances non-specific cytokine production but fails to prevent Type 1 Diabetes

Autoantigen-specific methods to prevent and treat Type 1 Diabetes (T1D) carry high hopes to permanently cure this disease, but have largely failed in clinical trials. One suggested approach to increase the efficacy of islet antigen-specific vaccination is to combine it with a modulator of the T cell response, with the goal of reducing effector differentiation and promoting regulatory T cells (Tregs). Here we asked if addition of antibodies that block the IL-7/IL-7Rα pathway altered the T cell response to islet antigen vaccination and prevented T1D in non-obese diabetic (NOD) mice. Anti-IL-7Rα monoclonal antibodies (mAbs) reduced the numbers of islet antigen-specific T cells generated after vaccination with islet peptides and alum. However, addition of anti-IL-7Rα antibodies to peptide/alum vaccination unexpectedly increased non-specific IFN-γ, IL-2 and IL-10 cytokine production and did not result in improved prevention of T1D onset. In a second approach, we used a conjugate vaccine to deliver islet autoantigens, using Keyhole Limpet Hemocyanin (KLH) as a carrier. Islet antigen-KLH vaccination led to a significant expansion of antigen-specific Tregs and delayed diabetes onset in NOD mice. These outcomes were not further improved by addition of anti-IL-7Rα antibodies. To the contrary, blocking IL-7Rα during vaccination led to non-specific cytokine production and reduced the efficacy of a KLH-conjugated vaccine to prevent T1D. Our study thus revealed that adding anti-IL-7Rα antibodies during autoantigen immunization did not improve the efficacy of such vaccinations to prevent T1D, despite altering some aspects of the T cell response in a potentially advantageous way. Further refinement of this approach will be required to separate the beneficial from the adverse effects of anti-IL-7Rα antibodies to treat autoimmune disease.

Tolerogenic Dendritic Cells and T-Regulatory Cells at the Clinical Trials Crossroad for the Treatment of Autoimmune Disease; Emphasis on Type 1 Diabetes Therapy

Tolerogenic dendritic cells and T-regulatory cells are two immune cell populations with the potential to prevent the onset of clinical stage type 1 diabetes, and manage the beginning of underlying autoimmunity, at the time-at-onset and onwards. Initial phase I trials demonstrated that the administration of a number of these cell populations, generated ex vivo from peripheral blood leukocytes, was safe. Outcomes of some of these trials also suggested some level of autoimmunity regulation, by the increase in the numbers of regulatory cells at different points in a network of immune regulation in vivo. As these cell populations come to the cusp of pivotal phase II efficacy trials, a number of questions still need to be addressed. At least one mechanism of action needs to be verified as operational, and through this mechanism biomarkers predictive of the underlying autoimmunity need to be identified. Efficacy in the regulation of the underlying autoimmunity also need to be monitored. At the same time, the absence of a common phenotype core among the different dendritic cell and T-regulatory cell populations, that have completed phase I and early phase II trials, necessitates a better understanding of what makes these cells tolerogenic, especially if a uniform phenotypic core cannot be identified. Finally, the inter-relationship of tolerogenic dendritic cells and T-regulatory cells for survival, induction, and maintenance of a tolerogenic state that manages the underlying diabetes autoimmunity, raises the possibility to co-administer, or even to serially-administer tolerogenic dendritic cells together with T-regulatory cells as a cellular co-therapy, enabling the best possible outcome. This is currently a knowledge gap that this review aims to address.