Rapamycin improves Graves' orbitopathy by suppressing CD4+ cytotoxic T lymphocytes

Thyroid eye disease (Graves' orbitopathy): clinical presentation, epidemiology, pathogenesis, and management

Thyroid eye disease (TED; also known as Graves' orbitopathy), causes swollen extraocular muscles and orbital fat. Mechanistically, TED involves lid retraction, oedema and redness of the eyelids and conjunctiva, proptosis, diplopia, and optic neuropathy. Investigation of TED involves assessment of disease activity (inflammation) and disease severity. TED is predominantly mild in 77% of cases, moderate-to-severe in 22%, and rarely sight-threatening in 1% of patients. While most patients with TED have Graves' hyperthyroidism, up to 5% are euthyroid or even hypothyroid. Risk factors include male sex, older age, smoking, diabetes, hypercholesterolaemia, duration of hyperthyroidism, radioactive iodine therapy, and the presence of thyrotropin receptor (TSHR) antibodies (detectable in more than 95% of patients and directly related to TED activity and severity). Genetic immunisation of mice with TSHR, but not with insulin-like growth factor-1 receptor (IGF-1R), provides a reliable animal model of TED, demonstrating that TSHR is the primary autoantigen in the disease. Crosstalk between TSHR and IGF-1R occurs via a β-arrestin scaffold. Teprotumumab, a human monoclonal antibody that blocks IGF-1R without binding to TSHR, has been shown to significantly improve outcomes in moderate-to-severe TED, including greater proptosis reduction compared with intravenous methylprednisolone. However, its disadvantages include side effects (eg, hearing loss in 30% of patients), a high cost, and a high relapse rate. Therefore, intravenous steroids remain the treatment of choice in many parts of the world. Tocilizumab, which blocks the interleukin-6 receptor, is an effective treatment option for patients with TED who are steroid-resistant. This Review further discusses alternative medications, surgical treatments, local measures, and the importance of quality-of-life assessments and multidisciplinary care.

Negative association between serum calcium and glucocorticoid-induced hypertension in thyroid-associated ophthalmopathy patients treated with methylprednisolone

Background

Hypertension is a common adverse event after systemic glucocorticoid therapy. Previous studies have suggested that blood pressure (BP) regulation is related to serum calcium. However, whether serum calcium affects the risk of glucocorticoid-induced hypertension remains understudied.

Methods

We used data from thyroid-associated ophthalmopathy (TAO) patients who completed a course of intravenous methylprednisolone (IVMP). Patients with high BP at baseline, a history of hypertension, and missing data were excluded. Glucocorticoid-induced hypertension was defined as systolic BP (SBP) ≥ 140 mmHg or diastolic BP (DBP) ≥ 90 mmHg during follow-up. Multivariate logistic regression and generalized additive models were used to investigate the associations between serum calcium and glucocorticoid-induced hypertension. Bar charts were used to compare the SBP and DBP fluctuations between patients with and without hypocalcemia. After accounting for missing data, all analyses were repeated in the imputed cohort.

Results

Serum calcium was negatively correlated with glucocorticoid-induced hypertension after adjusting for covariates with p-value < 0.1 (including age, body mass index, SBP, and DBP). For each 0.1 mmol/L increase in serum calcium, the OR (95% CI) was 0.61 (0.39, 0.95). Furthermore, a nonlinear relationship was observed, with an inflection point at 2.10 mmol/L. After the serum calcium level was converted into a categorical variable, hypocalcemia was positively associated with glucocorticoid-induced hypertension (OR = 3.26, 95% CI = 1.11-9.53). Patients with hypocalcemia exhibited significantly greater SBP fluctuations than patients without hypocalcemia (p < 0.05). These results were stable when adjusting for confounders and in the analyses of the imputed cohort.

Conclusions

Hypocalcemia was associated with glucocorticoid-induced hypertension in TAO patients. Further research is needed to confirm these findings in larger populations and to investigate whether calcium supplementation before glucocorticoid therapy may reduce such risk.

Targeted immunotherapies for Graves' thyroidal & orbital diseases

Background

Graves' hyperthyroidism and its associated Graves' orbitopathy are common autoimmune disorders associated with significant adverse health impact. Current standard treatments have limitations regarding efficacy and safety, and most do not specifically target the pathogenic mechanisms. We aim to review the latest development of targeted immunotherapies in these two closely related disorders.

Summary

Targeted immunotherapies of Graves' hyperthyroidism have recently demonstrated clinical efficacy in early phase clinical studies. They include rituximab, an anti-CD20 monoclonal antibody which causes rapid B cell depletion; ATX-GD-59, an antigen specific immunotherapy which restores immune tolerance to thyrotropin receptor; iscalimab, an anti-CD40 monoclonal antibody which blocks the CD40-CD154 co-stimulatory pathway in B-T cell interaction; and K1-70, a thyrotropin receptor blocking monoclonal antibody. Furthermore, there have been major therapeutic advances in the management of Graves' orbitopathy. Mycophenolate has a dual mechanism of action both inhibiting the proliferation of activated B & T cells as well as the mammalian target of rapamycin growth intracellular pathway. Rituximab appears to be effective in active disease of recent onset without impending dysthyroid optic neuropathy. Both tocilizumab (anti-interleukin 6 receptor monoclonal antibody) and sirolimus (mammalian target of rapamycin inhibitor) showed promise in glucocorticoid resistant active disease. Teprotumumab, an anti-insulin-like growth factor-1 receptor monoclonal antibody, demonstrated remarkable all-round efficacy across a wide disease spectrum. Linsitinib, a dual small molecule inhibitor of insulin-like growth factor-1 receptor and insulin receptor, displayed significant proptosis reduction in its phase 2b/3 study. Finally, Batoclimab, an anti-neonatal fragment crystallizable receptor monoclonal antibody, which blocks recycling of pathogenic thyrotropin receptor antibody, showed promising signals for significant proptosis reduction, disease inactivation, overall response, and improvement of quality of life.

Conclusion

Therapeutic advances will continue to optimize our management of Graves' hyperthyroidism and its associated orbitopathy in an effective and safe manner.

Single-cell RNA sequencing in autoimmune diseases: New insights and challenges

Autoimmune diseases involve a variety of cell types, yet the intricacies of their individual roles within molecular mechanisms and therapeutic strategies remain poorly understood. Single-cell RNA sequencing (scRNA-seq) offers detailed insights into transcriptional diversity at the single-cell level, significantly advancing research in autoimmune diseases. This article explores how scRNA-seq enhances the understanding of cellular heterogeneity and its potential applications in the etiology, diagnosis, treatment, and prognosis of autoimmune diseases. By revealing a comprehensive cellular landscape, scRNA-seq illuminates the functional regulation of different cell subtypes during disease progression. It aids in identifying diagnostic and prognostic markers, and analyzing cell communication networks to uncover potential therapeutic targets. Despite its valuable contributions, addressing the limitations of scRNA-seq is essential for making further advancements.

The role of autophagy in Graves disease: knowns and unknowns

Graves disease (GD), an autoimmune disease affects the thyroid gland, results in hyperthyroidisms and goiter. The main cause of GD is not clearly defined; however, stimulating autoantibodies for thyroid stimulating hormone receptor (TSHR) known as thyroid-stimulating immunoglobulins (TSIs) are the primary proposed mechanism. The TSI activation of TSHRs of thyroid gland results in excessive release of thyroid hormones with the subsequent development of hyperthyroidism and goiter. The cellular process of macroautophagy/autophagy is implicated in the pathogenesis of GD and other thyroid diseases. Autophagy plays a critical role in many thyroid diseases and in different stages of the same disease through modulation of immunity and the inflammatory response. In addition, autophagy is also implicated in the pathogenesis of thyroid-associated ophthalmopathy (TAO). However, the exact role of autophagy in GD is not well explained. Therefore, this review discusses how autophagy is intricately involved in the pathogenesis of GD regarding its protective and harmful effects.

Zotarolimus alleviates post-trabeculectomy fibrosis via dual functions of anti-inflammation and regulating AMPK/mTOR axis

OBJECTIVE

Postoperative scar formation is the primary cause of uncontrolled intraocular pressure following trabeculectomy failure. This study aimed to evaluate the efficacy of zotarolimus as an adjuvant anti-scarring agent in the experimental trabeculectomy.

METHODS

We performed differential gene and Gene Ontology enrichment analysis on rabbit follicular transcriptome sequencing data (GSE156781). New Zealand white Rabbits were randomly assigned into three groups: Surgery only, Surgery with mitomycin-C treatment, Surgery with zotarolimus treatment. Rabbits were euthanized 3 days or 28 days post-trabeculectomy. Pathological sections were analyzed using immunohistochemistry, immunofluorescence, and Masson staining. In vitro, primary human tenon's capsule fibroblasts (HTFs) were stimulated by transforming growth factor-β1 (TGF-β1) and treated with either mitomycin-C or zotarolimus. Cell proliferation and migration were evaluated using cell counting kit-8, cell cycle, and scratch assays. Mitochondrial membrane potential was detected with the JC-1 probe, and reactive oxygen species were detected using the DCFH-DA probe. RNA and protein expressions were quantified using RT-qPCR and immunofluorescence.

RESULTS

Transcriptome sequencing analysis revealed the involvement of complex immune factors and metabolic disorders in trabeculectomy outcomes. Zotarolimus effectively inhibited fibrosis, reduced proinflammatory factor release and immune cell infiltration, and improved the surgical outcomes of trabeculectomy. In TGF-β1-induced HTFs, zotarolimus reduced fibrosis, proliferation, and migration without cytotoxicity via the dual regulation of the TGF-β1/Smad2/3 and AMPK/AKT/mTOR pathways.

CONCLUSION

Our study demonstrates that zotarolimus mitigates fibrosis by reducing immune infiltration and correcting metabolic imbalances, offering a potential treatment for improving trabeculectomy surgical outcomes.

Dynamic transition of Tregs to cytotoxic phenotype amid systemic inflammation in Graves' ophthalmopathy

Graves' disease (GD) is an autoimmune condition that can progress to Graves' ophthalmopathy (GO), leading to irreversible damage to orbital tissues and potential blindness. The pathogenic mechanism is not fully understood. In this study, we conducted single-cell multi-omics analyses on healthy individuals, patients with GD without GO, newly diagnosed patients with GO, and treated patients with GO. Our findings revealed gradual systemic inflammation during GO progression, marked by overactivation of cytotoxic effector T cell subsets, and expansion of specific T cell receptor clones. Importantly, we observed a decline in the immunosuppressive function of activated Treg (aTreg) accompanied by a cytotoxic phenotypic transition. In vitro experiments revealed that dysfunction and transition of GO-autoreactive Treg were regulated by the yin yang 1 (YY1) upon secondary stimulation of thyroid stimulating hormone receptor (TSHR) under inflammatory conditions. Furthermore, adoptive transfer experiments of the GO mouse model confirmed infiltration of these cytotoxic Treg into the orbital lesion tissues. Notably, these cells were found to upregulate inflammation and promote pathogenic fibrosis of orbital fibroblasts (OFs). Our results reveal the dynamic changes in immune landscape during GO progression and provide direct insights into the instability and phenotypic transition of Treg, offering potential targets for therapeutic intervention and prevention of autoimmune diseases.

Chimeric antigen receptor T-cell therapy in autoimmune diseases

The administration of T cells that have been modified to carry chimeric antigen receptors (CARs) aimed at B cells has been an effective strategy in treating B cell malignancies. This breakthrough has spurred the creation of CAR T cells intended to specifically reduce or alter the faulty immune responses associated with autoimmune disorders. Early positive outcomes from clinical trials involving CAR T cells that target the B cell protein CD19 in patients suffering from autoimmune diseases driven by B cells have been reported. Additional strategies are being developed to broaden the use of CAR T cell therapy and enhance its safety in autoimmune conditions. These include employing chimeric autoantireceptors (CAAR) to specifically eliminate B cells that are reactive to autoantigens, and using regulatory T cells (Tregs) engineered to carry antigen-specific CARs for precise immune modulation. This discussion emphasizes key factors such as choosing the right target cell groups, designing CAR constructs, defining tolerable side effects, and achieving a lasting immune modification, all of which are critical for safely integrating CAR T cell therapy in treating autoimmune diseases.

Evaluation of 99Tcm-DTPA orbit SPECT/CT combined with thyroid function test in the treatment of radioactive iodine I-131 in patients with thyroid-associated ophthalmopathy-hyperthyroidism

Background

Thyroid-associated ophthalmopathy (TAO) is an autoimmune response to inflammation of the thyroid and orbital tissue. This research evaluated the efficacy of 99Tcm-DTPA orbital SPECT/CT combined with thyroid function test in radioactive iodine I-131 (RAI) treatment of TAO-hyperthyroidism.

Methods

We retrospectively studied clinical activity score (CAS), blood thyrotropine (TSH), free triiodothyronine (FT3), free thyroxine (FT4), thickness of extra-ocular muscle (EOM), and uptake rate (UR) of 99Tcm-DTPA orbital SPECT/CT of 43 patients after 6 months of treatment with 20 mCi RAI. Parameters were compared before and after RAI in patients assessed as effectively treated (normal thyroid function or hypothyroidism), and correlations between blood FSH, FT3, FT4, thickness of EOM, and UR were analyzed after treatment.

Results

After RAI, 35 cases (70 eyes, 81.4%) had normal or hypothyroidism, and 8 cases (16 eyes, 18.6%) had hyperthyroidism. Compared with the patients who failed treatment, effectively treated patients had lower CAS, FT3, FT4, and UR and higher blood TSH. In patients with effective treatment, UR of the inferior rectus muscle was positively correlated with FT3 and FT4. Adverse RAI outcomes were associated with smoking and higher iodine-thyroid iodine uptake before treatment.

Conclusions

Combined with TSH, FT3, and FT4 levels, the reduction of 99Tcm-DTPA orbital SPECT/CT UR also indicates an improvement in the disease course of patients. The UR of the inferior rectus muscle can be an objective index to evaluate the curative effect of TAO patients.

Single-cell transcriptomics in thyroid eye disease

Thyroid eye disease (TED) is a poorly understood autoimmune condition affecting the retroorbital tissue. Tissue inflammation, expansion, and fibrosis can potentially lead to debilitating sequelae such as vision loss, painful eye movement, proptosis, and eyelid retraction. Current treatment modalities for TED include systemic glucocorticoids, thioamides, methimazole, teprotumumab, beta-blockers, and radioactive iodine; however, it has been reported that up to 10%-20% of TED patients relapse after treatment withdrawal and 20%-30% are unresponsive to mainstay therapy for reasons that have yet to be more clearly elucidated. In the past 4 years, vision researchers have harnessed high-throughput single-cell RNA sequencing to elucidate the diversity of cell types and molecular mechanisms driving the pathogenesis of TED at single-cell resolution. Such studies have provided unprecedented insight regarding novel biomarkers and therapeutic targets in TED. This timely review summarizes recent breakthroughs and emerging opportunities for using single-cell and single-nuclei transcriptomic data to characterize this highly complex disease state. We also provide an overview of current challenges and future applications of this technology to potentially improve patient quality of life and facilitate reversal of disease endpoints.

Remodeling of T-cell mitochondrial metabolism to treat autoimmune diseases

T cells are key drivers of the pathogenesis of autoimmune diseases by producing cytokines, stimulating the generation of autoantibodies, and mediating tissue and cell damage. Distinct mitochondrial metabolic pathways govern the direction of T-cell differentiation and function and rely on specific nutrients and metabolic enzymes. Metabolic substrate uptake and mitochondrial metabolism form the foundational elements for T-cell activation, proliferation, differentiation, and effector function, contributing to the dynamic interplay between immunological signals and mitochondrial metabolism in coordinating adaptive immunity. Perturbations in substrate availability and enzyme activity may impair T-cell immunosuppressive function, fostering autoreactive responses and disrupting immune homeostasis, ultimately contributing to autoimmune disease pathogenesis. A growing body of studies has explored how metabolic processes regulate the function of diverse T-cell subsets in autoimmune diseases such as systemic lupus erythematosus (SLE), multiple sclerosis (MS), autoimmune hepatitis (AIH), inflammatory bowel disease (IBD), and psoriasis. This review describes the coordination of T-cell biology by mitochondrial metabolism, including the electron transport chain (ETC), oxidative phosphorylation, amino acid metabolism, fatty acid metabolism, and one‑carbon metabolism. This study elucidated the intricate crosstalk between mitochondrial metabolic programs, signal transduction pathways, and transcription factors. This review summarizes potential therapeutic targets for T-cell mitochondrial metabolism and signaling in autoimmune diseases, providing insights for future studies.

Ocular surface and meibomian gland evaluation in euthyroid Graves' ophthalmopathy

PURPOSE

Euthyroid Graves' ophthalmology (EGO) refers to the subgroup of thyroid eye disease patients with distinct clinical presentations. This study evaluated the ocular surface and meibomian gland changes in EGO patients.

METHODS

A cross-sectional study was conducted at The Chinese University of Hong Kong including 34 EGO patients and 34 age-and sex- matched healthy controls. Outcome measures include anterior segment examination, keratographic and meibographic imaging.

RESULTS

Between 34 EGO patients and 34 age and sex-matched healthy controls, EGO was associated with a higher ocular surface disease index (P < 0.01), higher severity of meibomian gland dropout (upper: P < 0.001, lower: P < 0.00001) and higher percentage of partial blinking (P = 0.0036). The worse affected eyes of the EGO patients were associated with corneal staining (P = 0.0019), eyelid telangiectasia (P = 0.0009), eyelid thickening (P = 0.0013), eyelid irregularity (P = 0.0054), meibomian gland plugging (P < 0.00001), expressibility (P < 0.00001), and meibum quality (P < 0.00001). When the two eyes of the same EGO patient were compared, the degree of meibomian gland dropout was higher among the worse affected eyes (upper: P < 0.00001, and lower: P < 0.00001). Tear meniscus height, lipid layer thickness, and noninvasive break-up time were comparable between the two eyes of EGO patients and also between EGO patients and healthy controls. TMH was positively correlated with the degree of exophthalmos (r = 0.383, P < 0.05).

CONCLUSION

EGO patients have more ocular surface complications and meibomian gland dropouts than healthy controls. Almost 60% of them had dry eye symptoms, but aqueous deficiency was not apparent. Further studies are warranted to clarify the mechanism of dry eye in EGO. (249 words).

Current Therapeutic Approaches for Graves' Orbitopathy - are Targeted Therapies the Future?

Graves' orbitopathy is an autoimmune disease of the orbit that most frequently occurs with Graves' hyperthyroidism. The occurrence of autoantibodies directed against the TSH receptor (TRAb) is of central importance for the diagnosis and pathogenesis. These autoantibodies are mostly stimulating, and induce uncontrolled hyperthyroidism and tissue remodelling in the orbit and more or less pronounced inflammation. Consequently, patients suffer to a variable extent from periocular swelling, exophthalmos, and fibrosis of the eye muscles and thus restrictive motility impairment with double vision. In recent decades, therapeutic approaches have mainly comprised immunosuppressive treatments and antithyroid drug therapy for hyperthyroidism to inhibit thyroid hormone production. With the recognition that TRAb also activates an important growth factor receptor, IGF1R (insulin-like growth factor 1 receptor), biological agents have been developed. Teprotumumab (an inhibitory IGF1R antibody) has already been approved in the USA and the therapeutic effects are enormous, especially with regard to the reduction of exophthalmos. Side effects are to be considered, especially hyperglycaemia and hearing loss. It is not yet clear whether the autoimmune reaction (development of the TRAb/attraction of immunocompetent cells) is also influenced by anti-IGF1R inhibiting agents. Recurrences after therapy show that the inhibition of antibody development must be included in the therapeutic concept, especially in severe cases.

Current and promising therapies based on the pathogenesis of Graves' ophthalmopathy

Graves' ophthalmopathy (GO) is a hyperthyroidism-related and immune-mediated disease that poses a significant threat to human health. The pathogenesis of GO primarily involves T cells, B cells, and fibroblasts, suggesting a pivotal role for the thyrotropin-antibody-immunocyte-fibroblast axis. Traditional treatment approaches for Graves' disease (GD) or GO encompass antithyroid drugs (ATDs), radioactive iodine, and beta-blockers. However, despite decades of treatment, there has been limited improvement in the global incidence of GO. In recent years, promising therapies, including immunotherapy, have emerged as leading contenders, demonstrating substantial benefits in clinical trials by inhibiting the activation of immune cells like Th1 and B cells. Furthermore, the impact of diet, gut microbiota, and metabolites on GO regulation has been recognized, suggesting the potential of non-pharmaceutical interventions. Moreover, as traditional Chinese medicine (TCM) components have been extensively explored and have shown effective results in treating autoimmune diseases, remarkable progress has been achieved in managing GO with TCM. In this review, we elucidate the pathogenesis of GO, summarize current and prospective therapies for GO, and delve into the mechanisms and prospects of TCM in its treatment.

Defective LAT signalosome pathology in mice mimics human IgG4-related disease at single-cell level

Mice with a loss-of-function mutation in the LAT adaptor (LatY136F) develop an autoimmune and type 2 inflammatory disorder called defective LAT signalosome pathology (DLSP). We analyzed via single-cell omics the trajectory leading to LatY136F DLSP and the underlying CD4+ T cell diversification. T follicular helper cells, CD4+ cytotoxic T cells, activated B cells, and plasma cells were found in LatY136F spleen and lung. Such cell constellation entailed all the cell types causative of human IgG4-related disease (IgG4-RD), an autoimmune and inflammatory condition with LatY136F DLSP-like histopathological manifestations. Most previously described T cell-mediated autoimmune manifestations require persistent TCR input. In contrast, following their first engagement by self-antigens, the autoreactive TCR expressed by LatY136F CD4+ T cells hand over their central role in T cell activation to CD28 costimulatory molecules. As a result, all subsequent LatY136F DLSP manifestations, including the production of autoantibodies, solely rely on CD28 engagement. Our findings elucidate the etiology of the LatY136F DLSP and qualify it as a model of IgG4-RD.

Graves' Orbitopathy Models: Valuable Tools for Exploring Pathogenesis and Treatment

Graves' orbitopathy (GO) is the most common extrathyroidal complication of Graves' disease (GD) and severely affects quality of life. However, its pathogenesis is still poorly understood, and therapeutic options are limited. Animal models are important tools for preclinical research. The animals in some previous models only exhibited symptoms of hyperthyroidism without ocular lesions. With the improvements achieved in modeling methods, some progressive animal models have been established. Immunization of mice with A subunit of the human thyroid stimulating hormone receptor (TSHR) by either adenovirus or plasmid (with electroporation) is widely used and convincing. These models are successful to identify that the gut microbiota influences the occurrence and severity of GD and GO, and sex-related risk factors may be key contributors to the female bias in the occurrence of GO rather than sex itself. Some data provide insight that macrophages and CD8+ T cells may play an important pathogenic role in the early stage of GO. Our team also replicated the time window from GD onset to GO onset and identified a group of CD4+ cytotoxic T cells. In therapeutic exploration, TSHR derived peptides, fingolimod, and rapamycin offer new potential options. Further clinical trials are needed to investigate these drugs. With the increasing use of these animal models and more in-depth studies of the new findings, scientists will gain a clearer understanding of the pathogenesis of GO and identify more treatments for patients.

Targeting hnRNPC suppresses thyroid follicular epithelial cell apoptosis and necroptosis through m6A-modified ATF4 in autoimmune thyroid disease

Both environmental and genetic factors contribute to the etiology of autoimmune thyroid disease (AITD) including Graves' disease (GD) and Hashimoto's thyroiditis (HT). However, the exact pathogenesis and interactions that occur between environmental factors and genes remain unclear, and therapeutic targets require further investigation due to limited therapeutic options. To solve such problems, this study utilized single-cell transcriptome, whole transcriptome, full-length transcriptome (Oxford nanopore technology), and metabolome sequencing to examine thyroid lesion tissues from 2 HT patients and 2 GD patients as well as healthy thyroid tissue from 1 control subject. HT patients had increased ATF4-positive thyroid follicular epithelial (ThyFoEp) cells, which significantly increased endoplasmic reticulum stress. The enhanced sustained stress resulted in cell death mainly including apoptosis and necroptosis. The ATF4-based global gene regulatory network and experimental validation revealed that N6-methyladenosine (m6A) reader hnRNPC promoted the transcriptional activity, synthesis, and translation of ATF4 through mediating m6A modification of ATF4. Increased ATF4 expression initiated endoplasmic reticulum stress signaling, which when sustained, caused apoptosis and necroptosis in ThyFoEp cells, and mediated HT development. Targeting hnRNPC and ATF4 notably decreased ThyFoEp cell death, thus ameliorating disease progression. Collectively, this study reveals the mechanisms by which microenvironmental cells in HT and GD patients trigger and amplify the thyroid autoimmune cascade response. Furthermore, we identify new therapeutic targets for the treatment of autoimmune thyroid disease, hoping to provide a potential way for targeted therapy.

mTOR signaling in hair follicle and hair diseases: recent progress

Mammalian target of rapamycin (mTOR) signaling pathway is a major regulator of cell proliferation and metabolism, playing significant roles in proliferation, apoptosis, inflammation, and illness. More and more evidences showed that the mTOR signaling pathway affects hair follicle circulation and maintains the stability of hair follicle stem cells. mTOR signaling may be a critical cog in Vitamin D receptor (VDR) deficiency-mediated hair follicle damage and degeneration and related alopecia disorders. This review examines the function of mTOR signaling in hair follicles and hair diseases, and talks about the underlying molecular mechanisms that mTOR signaling regulates.

Rapamycin and Low-dose IL-2 Mediate an Immunosuppressive Microenvironment to Inhibit Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a condition that becomes more common with age and manifests itself primarily as the expansion of the prostate and surrounding tissues. However, to date, the etiology of BPH remains unclear. In this respect, we performed single-cell RNA sequencing of prostate transition zone tissues from elderly individuals with different prostate volumes to reveal their distinct tissue microenvironment. Ultimately, we demonstrated that a reduced Treg/CD4+ T-cell ratio in the large-volume prostate and a relatively activated immune microenvironment were present, characterized partially by increased expression levels of granzymes, which may promote vascular growth and profibrotic processes and further exacerbate BPH progression. Consistently, we observed that the prostate gland of patients taking immunosuppressive drugs usually remained at a smaller volume. Furthermore, in mouse models, we confirmed that both suppression of the immune system with rapamycin and induction of Treg proliferation with low doses of IL-2 therapy indeed prevented the progression of BPH. Taken together, our findings suggest that an activated immune microenvironment is necessary for prostate volume growth and that Tregs can reverse this immune activation state, thereby inhibiting the progression of BPH.

VEGF-A enhances the cytotoxic function of CD4+ cytotoxic T cells via the VEGF-receptor 1/VEGF-receptor 2/AKT/mTOR pathway

BACKGROUND

CD4⁺ cytotoxic T cells (CD4 CTLs) are CD4⁺ T cells with major histocompatibility complex-II-restricted cytotoxic function. Under pathologic conditions, CD4 CTLs hasten the development of autoimmune disease or viral infection by enhancing cytotoxicity. However, the regulators of the cytotoxicity of CD4 CTLs are not fully understood.

METHODS

To explore the potential regulators of the cytotoxicity of CD4 CTLs, bulk RNA and single-cell RNA sequencing (scRNA-seq), enzyme-linked immunosorbent assay, flow cytometry, quantitative PCR, and in-vitro stimulation and inhibition assays were performed.

RESULTS

In this study, we found that VEGF-A promoted the cytotoxicity of CD4 CTLs through scRNA-seq and flow cytometry. Regarding the specific VEGF receptor (R) involved, VEGF-R1/R2 signaling was activated in CD4 CTLs with increased cytotoxicity, and the VEGF-A effects were inhibited when anti-VEGF-R1/R2 neutralizing antibodies were applied. Mechanistically, VEGF-A treatment activated the AKT/mTOR pathway in CD4 CTLs, and the increases of cytotoxic molecules induced by VEGF-A were significantly reduced when the AKT/mTOR pathway was inhibited.

CONCLUSION

In conclusion, VEGF-A enhances the cytotoxicity of CD4 CTLs through the VEGF-R1/VEGF-R2/AKT/mTOR pathway, providing insights for the development of novel treatments for disorders associated with CD4 CTLs.