Patients With Autoimmune Thyroiditis Show Diminished Levels and Defective Suppressive Function of Tr1 Regulatory Lymphocytes

Association of Myasthenia Gravis With Autoimmune Thyroid Disease: A Bidirectional Mendelian Randomization Study

BACKGROUND AND PURPOSE

Observational studies have indicated a high occurrence of coexistence between myasthenia gravis (MG) and autoimmune thyroid disease (AITD) in clinical settings, but the causal relationship between the two conditions remains ambiguous. Therefore, this study endeavors to investigate the causal links between MG, along with its subgroups, and AITD through a Mendelian randomization (MR) approach.

METHODS

Genetic instrumental variables associated with MG and AITD were selected from three major publicly available GWAS databases for MR analysis. The primary method for evaluating causal effects was the inverse variance weighted (IVW) method. Supplementary methods included MR-Egger regression and weighted median. The reliability and stability of the results were ensured through tests for heterogeneity, assessment of pleiotropy, and sensitivity analysis using the leave-one-out approach.

RESULTS

The investigation revealed reciprocal causal associations between MG and both Graves' disease and autoimmune hypothyroidism. Genetic predisposition to MG was linked to an increased likelihood of developing Hashimoto's thyroiditis (OR = 1.242(1.073-1.437, P = 0.0036)), and early-onset MG also exhibited an association with an elevated risk of HT (OR = 1.157(1.073-1.246), P = 1.269×10-4). No statistically significant relationships were found for the other conditions.

CONCLUSION

This extensive MR analysis provides evidence suggesting a potential association between MG and AITD, particularly with Graves' disease and Hashimoto's thyroiditis. Consequently, proactive treatment strategies targeting either MG or autoimmune thyroid disorders may help mitigate the risk of comorbidities in affected patients.

Analysis of T follicular and T peripheral helper lymphocytes in autoimmune thyroid disease

PURPOSE

Peripheral helper T (Tph) cells have an important role in the induction of humoral immune responses and autoantibody production. Accordingly, it is feasible that this lymphocyte subset has a relevant role in the pathogenesis of autoimmune thyroid diseases (AITD). In this study we aim to analyze the levels and function of Tph cells in blood samples from patients with AITD.

METHODS

We performed an observational study with cases and controls. Blood samples were obtained from nineteen patients with Hashimoto's thyroiditis (HT), twenty-four with Graves' disease (GD), and fifteen healthy controls. In addition, the levels of follicular T helper (Tfh) cells and Tph cells, the release of interleukin-21 (IL-21) by these lymphocytes and the number of plasmablasts were analyzed by multi-parametric flow cytometry analyses.

RESULTS

Increased percentages of Tfh and Tph lymphocytes were detected in patients with HT and GD. Furthermore, an enhanced synthesis of the cytokine IL-21 by these cells was observed. Accordingly, we detected significant higher percentages of plasmablasts in patients with GD, and these values tended to be also higher in HT patients. Moreover, significant positive associations were observed between the levels of Tfh or Tph and the number of plasmablast or anti-TSHR Ab titers in patients with AITD.

CONCLUSION

Our data suggest that Tph lymphocytes may have a relevant role in the pathogenesis of AITD.

Biological function of type 1 regulatory cells and their role in type 1 diabetes

The collapse of immune homeostasis induces type 1 diabetes (T1D). In T1D, uncontrolled immune attacks against islet β cells reduce insulin secretion, resulting in hyperglycaemia and various complications. Type 1 regulatory (Tr1) cell therapy is a promising approach for the treatment of T1D. Tr1 cells are a subset of regulatory T (Treg) cells that are characterised by high interleukin-10 secretion and forkhead box protein P3 non-expression. Tr1 cells are reduced and have impaired function in patients with T1D. Immunotherapy is used to treat various diseases, and Treg cells have been applied to treat T1D in animal models and clinical trials. However, the safety and efficacy of Tr1 cells in treating diabetes and other diseases remain unclear. In this review, we aim to investigate the identification and biological function of Tr1 cells and related studies on immune diseases; additionally, we discuss the feasibility, limitations, and possible solutions of Tr1 cell therapy in T1D. This review shows that T1D is caused by an immune imbalance where defective Tr1 cells fail to control effector T cells, leading to the destruction of islet β cells. However, Tr1 cell therapy is safe and effective for other immune diseases, suggesting its potential for treating T1D.

The relationship between migraine and Hashimoto's thyroiditis: a single center experience

Introduction

Hashimoto's thyroiditis (HT) is nowadays the leading cause of hypothyroidism with high and still growing prevalence in general population, but there are lack of data regarding migraine and HT connection.

Methods

The aim of this study was to analyze the prevalence of HT in migraine and to check if the presence of HT influence migraine severity. This retrospective observational cohort study involved consecutive migraine patients consulted at our Headache Center with diagnosis of migraine. Electronic charts of patients were collected, including data on migraine type, presence of cranial autonomic symptoms (CAS), monthly migraine days (MMD), medication overuse headache (MOH), and the presence of comorbidities including HT.

Results

We found 928 eligible migraine patients, 88.7% were women. The mean age was 36.09 years. 592 (63.8%) were diagnosed with episodic migraine (EM), the rest with chronic migraine (CM). MOH was additionally diagnosed in 258 (27.8%) patients. The duration of migraine was 15.99 years. 106 (11.4%) was diagnosed with HT, 148 (15.9%) with hypothyroidisms, while 84 (9.05%) had both diagnosis. Migraine patients with HT were significantly older (p < 0.001), were more frequently women (p = 0.0017), had longer duration of migraine (p < 0.001), had CAS more frequently (<0.001), developed CM (p = 0.0169) and depression more frequently (p = 0.0047) and had more MMD (p = 0.0195) as compared with individuals without HT. According to our multivariate logistic model, the presence CM was positively associated with HT (OR 1.76, p = 0.045), MOH and duration of migraine, while negatively associated with aura.

Conclusion

HT is very prevalent in migraine patients. This is the first study considering migraine and HT to be comorbid and suggesting that HT may influence the course of migraine causing its chronification.

Yiqi Jiedu Xiaoying Decoction Improves Experimental Autoimmune Thyroiditis in Rats by Regulating Th17/Treg Cell Balance

BACKGROUND

Experimental autoimmune thyroiditis (EAT) is a widely used animal model to study the pathogenesis and treatment of autoimmune thyroid diseases. Yiqi Jiedu Xiaoying Decoction (YJXD) is a traditional Chinese medicine formula with potential immunomodulatory effects. In this study, we investigated the therapeutic effects of YJXD on EAT in rats and explored its underlying mechanisms.

METHODS

Female Wistar rats were induced to develop EAT by immunization with thyroglobulin (Tg) and taken sodium iodide water (0.05%) and then treated with YJXD or sodium selenite. HE staining was used to observe the pathological changes of thyroid tissue in EAT rats. Th17 and Treg cell frequencies were analyzed by flow cytometry, and the expression levels of Th17- and Treg-related cytokines and thyroid autoantibody were determined by enzyme-linked immunosorbent assay (ELISA). The expression of Th17- and Treg-related transcriptional factors was detected by real-time polymerase chain reaction (RT-PCR) and Immunohistochemistry (IHC).

RESULTS

Our results demonstrated that treatment with YJXD significantly attenuated the severity of EAT, as evidenced by reduced thyroid gland inflammatory infiltration and decreased serum thyroglobulin autoantibody levels. Importantly, YJXD treatment effectively modulated the Th17/Treg cell balance by suppressing Th17 cell differentiation and promoting Treg cell expansion. Moreover, YJXD was also found to regulate the expression levels of Th17- and Treg-related cytokines and transcriptional factors, further supporting its immunomodulatory effects in EAT.

CONCLUSION

YJXD exerted therapeutic effects on EAT by regulating the Th17/Treg cell balance, modulating the production of Th17- and Treg-related cytokines and the expression of transcriptional factors.

Th17 cytokines and factors modulating their activity in patients with pernicious anemia

The effects of specific cytokines produced by T cell subsets (such as Th1, Th2, and newly discovered Th17, Treg, Tfh, or Th22) are diverse, depending on interactions with other cytokines, distinct signaling pathways, phase of the disease, or etiological factor. The immunity equilibrium of the immune cells, such as the Th1/Th2, the Th17/Treg, and the Th17/Th1 balance is necessary for the maintenance of the immune homeostasis. If the balance of the T cells subsets is damaged, the autoimmune response becomes enhanced which leads to autoimmune diseases. Indeed, both the Th1/Th2 and the Th17/Treg dichotomies are involved in the pathomechanism of autoimmune diseases. The aim of the study was to determine the cytokines of Th17 lymphocytes as well as the factors modulating their activity in patients with pernicious anemia. The magnetic bead-based immunoassays used (Bio-Plex) allow simultaneous detection of multiple immune mediators from one serum sample. In our study, we showed that patients suffering from pernicious anemia develop the Th1/Th2 imbalance with a quantitative advantage of cytokines participating in Th1-related immune response, the Th17/Treg imbalance with a quantitative advantage of cytokines participating in Treg-related response, as well as the Th17/Th1 imbalance with a quantitative predominance of cytokines participating in Th1-related immune response. Our study results indicate that T lymphocytes and their specific cytokines play an role in the course of pernicious anemia. The observed changes may indicate the immune response to pernicious anemia or be an element of the pernicious anemia pathomechanism.

From bench to bedside: targeting lymphocyte activation gene 3 as a therapeutic strategy for autoimmune diseases

BACKGROUND

Immune checkpoints negatively regulate immune response, thereby playing an important role in maintaining immune homeostasis. Substantial studies have confirmed that blockade or deficiency of immune checkpoint pathways contributes to the deterioration of autoimmune diseases. In this context, focusing on immune checkpoints might provide alternative strategies for the treatment of autoimmunity. Lymphocyte activation gene 3 (LAG3), as a member of immune checkpoint, is critical in regulating immune responses as manifested in multiple preclinical studies and clinical trials. Recent success of dual-blockade of LAG3 and programmed death-1 in melanoma also supports the notion that LAG3 is a crucial regulator in immune tolerance.

METHODS

We wrote this review article by searching the PubMed, Web of Science and Google Scholar databases.

CONCLUSION

In this review, we summarize the molecular structure and the action mechanisms of LAG3. Additionally, we highlight its roles in diverse autoimmune diseases and discuss how the manipulation of the LAG3 pathway can serve as a promising therapeutic strategy as well as its specific mechanism with the aim of filling the gaps from bench to bedside.

Autoimmunity and Carcinogenesis: Their Relationship under the Umbrella of Autophagy

The immune system and autophagy share a functional relationship. Both innate and adaptive immune responses involve autophagy and, depending on the disease's origin and pathophysiology, it may have a detrimental or positive role on autoimmune disorders. As a "double-edged sword" in tumors, autophagy can either facilitate or impede tumor growth. The autophagy regulatory network that influences tumor progression and treatment resistance is dependent on cell and tissue types and tumor stages. The connection between autoimmunity and carcinogenesis has not been sufficiently explored in past studies. As a crucial mechanism between the two phenomena, autophagy may play a substantial role, though the specifics remain unclear. Several autophagy modifiers have demonstrated beneficial effects in models of autoimmune disease, emphasizing their therapeutic potential as treatments for autoimmune disorders. The function of autophagy in the tumor microenvironment and immune cells is the subject of intensive study. The objective of this review is to investigate the role of autophagy in the simultaneous genesis of autoimmunity and malignancy, shedding light on both sides of the issue. We believe our work will assist in the organization of current understanding in the field and promote additional research on this urgent and crucial topic.

MicroRNAs in autoimmune thyroid diseases and their role as biomarkers

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at the posttranscriptional level. They are emerging as potential biomarkers and as therapeutic targets for several diseases including autoimmune thyroid diseases (AITD). They control a wide range of biological phenomena, including immune activation, apoptosis, differentiation and development, proliferation and metabolism. This function makes miRNAs attractive as disease biomarker candidates or even as therapeutic agents. Because of their stability and reproducibility circulating miRNAs have been an interesting area of research in many diseases, and studies describing their role in the immune response and in autoimmune diseases have progressively developed. The mechanisms underlying AITD remain elusive. AITD pathogenesis is characterized by a multifactorial interplay based on the synergy between susceptibility genes and environmental stimulation, together with epigenetic modulation. Understanding the regulatory role of miRNAs could lead to identify potential susceptibility pathways, diagnostic biomarkers and therapeutic targets for this disease. Herein we update our present knowledge on the role of microRNAs in AITD and discuss on their importance as possible diagnostic and prognostic biomarkers in the most prevalent AITDs: Hashimoto's thyroiditis (HT), Graves' disease (GD) and Graves' Ophthalmopathy (GO). This review provides an overview of the state of the art in the pathological roles of microRNAs as well as in possible novel miRNA-based therapeutic approaches in AITD.

[DNAM-1 regulates the proliferation and function of T regulatory type 1 cells via the IL-2/STAT5 pathway]

OBJECTIVE

To explore the role of DNAM-1 in the activation, proliferation and function of type Ⅰ regulatory T cells (Tr1 cells).

METHODS

Anti-CD3/CD28 antibodies were used to stimulate mouse T cells derived from the spleen of wild-type (WT) mice, and the expression level of DNAM-1 in resting and activated Tr1 cells was evaluated with flow cytometry. Na?ve CD4⁺ T cells isolated by magnetic cell sorting from the spleens of WT mice and DNAM-1 knockout (KO) mice were cultured in Tr1 polarizing conditions for 3 days, after which CD25 and CD69 expressions were measured using flow cytometry. The induced Tr1 cells were labelled with CFSE and cultured in the presence of anti-CD/CD28 antibodies for 3 days, and their proliferative activity was analyzed. The expressions of IL-10 and p-STAT5 in DNAM-1-deficient Tr1 cells were detected before and after IL-2 stimulation.

RESULTS

The expression level of DNAM-1 was significantly upregulated in CD4⁺ T cells and Tr1 cells after stimulation with anti-CD3/CD28 antibodies (P < 0.05). DNAM-1 knockout did not cause significant changes in the number or proportion of Tr1 cells, but but significantly increased the expression levels of the activation markers CD69 and CD25 (P < 0.05). Compared with WT Tr1 cells, DNAM-1-deficient Tr1 cells exhibited reduced proliferative activity in vitro (P < 0.05) with downregulated IL-10 production (P < 0.05) and decreased expressions of Il-10 and Gzmb mRNA (P < 0.05). In DNAM-1-deficient Tr1 cells, IL-2 stimulation significantly reduced IL-10 secretion level and the expression of p-STAT5 as compared with WT Tr1 cells.

CONCLUSION

DNAM-1 participate in the activation and proliferation of Tr1 cells and affect the biological functions of Tr1 cells through the IL-2/STAT5 pathway.

Autoimmunity and Cancer-Two Sides of the Same Coin

Autoimmune disease results from the immune response against self-antigens, while cancer develops when the immune system does not respond to malignant cells. Thus, for years, autoimmunity and cancer have been considered as two separate fields of research that do not have a lot in common. However, the discovery of immune checkpoints and the development of anti-cancer drugs targeting PD-1 (programmed cell death receptor 1) and CTLA-4 (cytotoxic T lymphocyte antigen 4) pathways proved that studying autoimmune diseases can be extremely helpful in the development of novel anti-cancer drugs. Therefore, autoimmunity and cancer seem to be just two sides of the same coin. In the current review, we broadly discuss how various regulatory cell populations, effector molecules, genetic predisposition, and environmental factors contribute to the loss of self-tolerance in autoimmunity or tolerance induction to cancer. With the current paper, we also aim to convince the readers that the pathways involved in cancer and autoimmune disease development consist of similar molecular players working in opposite directions. Therefore, a deep understanding of the two sides of immune tolerance is crucial for the proper designing of novel and selective immunotherapies.

Lymphocyte activation gene-3 (LAG-3) regulatory T cells: An evolving biomarker for treatment response in autoimmune diseases

Regulatory T cells (Tregs) comprise a CD4⁺CD25⁺Foxp3⁺ T cell subset for maintaining immune tolerance, and their deficits and/or dysfunction are observed in autoimmune diseases. The lymphocyte activation gene 3 (LAG-3, also known as CD223), which is an immunoglobulin superfamily member expressed on peripheral immune cells, is recognized as an inhibitory regulator of Tregs. LAG-3⁺ T cells represent a novel protective Tregs subset that produces interleukin-10. Alterations in LAG-3⁺ Tregs have been reported in several autoimmune diseases, suggesting their potential pathogenic role. Recent studies have indicated that LAG-3⁺ Tregs may be associated not only with immunopathology but also with response to therapy in several autoimmune and autoinflammatory diseases, such as rheumatoid arthritis, psoriasis, psoriatic arthritis and others. We present a review of Tregs phenotypes and functions, with a focus on LAG-3⁺ Tregs, and discuss their potential role as biomarkers for treatment response in autoimmune diseases.

Analysis of Expression of Different Histone Deacetylases in Autoimmune Thyroid Disease

CONTEXT

Histone deacetylases (HDACs) and histone acetyltransferases (HAT) have an important role in the regulation of gene transcription as well as in the development and function of CD4+Foxp3+ T regulatory (Treg) cells. Our group and others have reported that patients with autoimmune thyroid disease (AITD) show abnormalities in the levels and function of different Treg cell subsets.

OBJECTIVE

We aimed to analyze the levels of expression of several HDACs and the Tip60 HAT in the thyroid gland and immune cells from patients with AITD.

METHODS

The expression of HDAC1-11 and the Tip60 HAT, at RNA and protein levels, were determined in thyroid tissue from 20 patients with AITD and 10 healthy controls and these findings were correlated with clinical data. HDAC9 and Tip60 levels were also analyzed in thyroid cell cultures, stimulated or not with proinflammatory cytokines, as well as in different cell subsets from peripheral blood mononuclear cells.

RESULTS

Altered expression of different HDACs was observed in thyroid tissue from AITD patients, including a significant increase in HDAC9, at RNA and protein levels. Likewise, HDAC9 expression was increased in peripheral blood mononuclear cells particularly in Treg cells in patients with AITD. In contrast, Tip60 expression was reduced in thyroid gland samples from patients with Hashimoto thyroiditis.

CONCLUSION

Our results indicate that HDAC expression is dysregulated in thyroid gland and immune cells from patients with AITD, suggesting involvement in the pathogenesis of this condition.

An update on the pathogenesis of Hashimoto's thyroiditis

It is 70 years since Noel Rose embarked on his pioneering studies that lead to the discovery of autoimmune thyroiditis and the elucidation of Hashimoto's thyroiditis. This short review to honour his passing focuses on the developments in our understanding of the causes and pathogenesis of HT over the last five years. Recent genetic studies have reported heritability estimates for HT and associated diseases for the first time, and emphasised the complexity of the genetic factors involved, including monogenic forms of HT. Environmental factors continue to be elucidated, especially as a side effect of drugs which modulate the immune system therapeutically. Regarding pathogenetic mechanisms, multiple cytokine networks have been identified which involve the thyroid cells in a circuit of escalating proinflammatory effects, such as the expression of inflammasome components, and an array of different defects in T regulatory cells may underlie the loss of self-tolerance to thyroid autoantigens. Finally, a number of studies have revealed fresh insights into disease associations with HT which may have both pathological and clinical significance, the most intriguing of which is a possible direct role of the autoimmune process itself in causing some of the persistent symptoms reported by a minority of patients with levothyroxine-treated HT.

Clinical relevance of T lymphocyte subsets in pediatric Graves' disease

Objectives Graves' disease (GD) is an autoimmune disease involving intimate response of both T cells and B cells. Immunophenotyping of peripheral blood lymphocyte subsets in GD children with different clinical characteristics can provide further information of the pathogenesis of GD. Methods We studied the lymphocyte subsets in peripheral blood of 141 children with GD. We repeatedly divided the patients into two groups in accordance with different clinical characteristics (abnormal or normal alanine aminotransferase (ALT) levels, the presence or absence of Graves' orbitopathy (GO), and the presence or absence of hematuria. Then we compared the lymphocyte subsets measurements between two paired groups. Results We found that serum ALT levels correlated positively with CD3+CD8+ T cell percentages in children with GD. Moreover, we detected higher percentages of CD3-CD19+ cells and higher ratio of CD4/CD8 in patients with GO. However, no correlation was found between GO status and lymphocyte subsets after excluding confounding effect of TRAb. No difference of lymphocyte subset percentages was found between groups with or without hematuria. Conclusions Serum ALT levels correlate positively with cytotoxic T cell percentages in the peripheral blood of children with GD. The cytotoxic T cell may play a role in the pathogenesis of hepatic dysfunction in children with GD.

The proportion of peripheral blood Tregs among the CD4+ T cells of autoimmune thyroid disease patients: a meta-analysis

Autoimmune thyroid disease (AITD) is characterized by a loss of self-tolerance to thyroid antigen. Tregs, whose proportions are controversial among CD4+ T cell from AITD patients (AITDs), are crucial in immune tolerance. Considering that drugs might affect Treg levels, we assumed that the differences originated from different treatment statuses. Thus, we performed a meta-analysis to explore proportions of Tregs in untreated and treated AITDs. PubMed, Embase and ISI Web of Knowledge were searched for relevant studies. Review Manager 5.3 and Stata 14.0 were used to conduct the meta-analysis. Subgroup analysis based on different diseases and cell surface markers was performed. Egger linear regression analysis was used to assess publication bias. Approximately 1,100 AITDs and healthy controls (HCs) from fourteen studies were included. Proportions of Tregs among CD4+ T cells of untreated AITDs were significantly lower than those in HCs (p = 0.002), but were not in treated patients (p = 0.40). Subgroup analysis revealed lower proportions of Tregs in untreated Graves' disease patients (GDs) (p = 0.001) but did not show obvious differences in untreated Hashimoto's thyroiditis patients (HTs) (p = 0.62). Furthermore, proportions of circulating FoxP3+ Tregs were reduced in untreated GDs (p < 0.00001) and HTs (p = 0.04). No publication bias was found. In this first meta-analysis exploring proportions of circulating Tregs among CD4+ T cells of AITDs with different treatment statuses, we found that Tregs potentially contribute to the pathogenesis of AITD but function differently in GD and HT. Remarkably, FoxP3+ Tregs, which were decreased in both diseases, might be promising targets for novel therapies.

Integrated miRNA and mRNA expression profiling identifies novel targets and pathological mechanisms in autoimmune thyroid diseases

Background

The mechanisms underlying autoimmune thyroid disease (AITD) remain elusive. Identification of such mechanisms would reveal novel and/or better therapeutic targets. Here, we use integrated analysis of miRNAs and mRNAs expression profiling to identify potential therapeutic targets involved in the mechanisms underlying AITD.

Methods

miRNA and mRNA from twenty fresh-frozen thyroid tissues (15 from AITD patients and 5 from healthy controls) were subjected to next-generation sequencing. An anti-correlated method revealed potential pathways and disease targets, including proteins involved in the formation of primary cilia. Thus, we examined the distribution and length of primary cilia in thyroid tissues from AITD and controls using immunofluorescence and scanning electron microscopy, and parsed cilia formation in thyroid cell lines in response to inflammatory stimuli in the presence of miRNA mimics.

Findings

We found that the expression of miR-21-5p, miR-146b-3p, miR-5571-3p and miR-6503-3p was anti-correlated with Enolase 4 (ENO4), in-turned planar cell polarity protein (INTU), kinesin family member 27 (KIF27), parkin co-regulated (PACRG) and serine/threonine kinase 36 (STK36) genes. Functional classification of these miRNA/mRNAs revealed that their differential expression was associated with cilia organization. We demonstrated that the number and length of primary cilia in thyroid tissues was significantly lower in AITD than in control (frequency of follicular ciliated cells in controls = 67.54% vs a mean of 22.74% and 21.61% in HT and GD respectively p = 0.0001, by one-way ANOVA test). In addition, pro-inflammatory cytokines (IFNγ and TNFα) and specific miRNA mimics for the newly identified target genes affected cilia appearance in thyroid cell lines.

Interpretation

Integrated miRNA/gene expression analysis has identified abnormal ciliogenesis as a novel susceptibility pathway that is involved in the pathogenesis of AITD. These results reflect that ciliogenesis plays a relevant role in AITD, and opens research pathways to design therapeutic targets in AITD.

Funding

Instituto de Salud Carlos III, Comunidad de Madrid, Grupo Español de Tumores Neuroendocrinos y Endocrinos, Ministerio de Economía y Empresa and FEDER.

Decreased number and impaired function of type 1 regulatory T cells in autoimmune diseases

Type 1 regulatory T (Tr1) cell is a special type of T regulatory cells with surface molecular markers such as lymphocyte-activation gene 3 and CD49b. A key property of Tr1 cells is the capability to produce high-level interleukin 10 (IL-10) upon activation, in a FOXP3-independent manner. The immunosuppressive function of IL-10 producing Tr1 cells has been extensively studied for many years. Autoimmune diseases (AIDs) are conditions in which the immune system breaks down and starts to attack the body. AIDs include inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis (MS), type 1 diabetes mellitus, Greaves' disease, and so forth. In recent years, more and more studies have documented that the number of Tr1 cells is decreased and the function is inhibited in a variety of AIDs, among which MS is the most widely studied. The protocol for engineering Tr1 cell therapy has been established and is gradually being used in clinical practice in recent years. Tr1 cell therapy has been proven to be safe and effective, but it is mainly involved in myeloid leukemia, graft versus host disease currently. Its therapeutic role in AIDs still needs to be further explored. In this study, we will summarize the research advances of Tr1 cells in AIDs, which will provide useful information for treating AIDs through Tr1 cell therapy in the future.