Comparing the Effects of the mTOR Inhibitors Azithromycin and Rapamycin on In Vitro Expanded Regulatory T Cells

Host immunomodulation strategies to combat pandemic-associated antimicrobial-resistant secondary bacterial infections

The incidence of secondary bacterial infections has increased in recent decades owing to various viral pandemics. These infections further increase the morbidity and mortality rates associated with viral infections and remain a significant challenge in clinical practice. Intensive antibiotic therapy has mitigated the threat of such infections; however, overuse and misuse of antibiotics have resulted in poor outcomes, such as inducing the emergence of bacterial populations with antimicrobial resistance (AMR) and reducing the therapeutic options for this crisis. Several antibiotic substitutes have been suggested and employed; however, they have certain limitations and novel alternatives are urgently required. This review highlights host immunomodulation as a promising strategy against secondary bacterial infections to overcome AMR. The definition and risk factors of secondary bacterial infections, features and limitations of currently available therapeutic strategies, host immune responses, and future perspectives for treating such infections are discussed.

CD4+ Foxp3+ Regulatory T-cells in Modulating Inflammatory Microenvironment in Chronic Rhinosinusitis with Nasal Polyps: Progress and Future Prospect

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a subtype of chronic rhinosinusitis (CRS) characterized by the presence of nasal polyps (NP) in the paranasal mucosa. Despite the complex etiology, NP is believed to result from chronic inflammation. The long-term aftermath of the type 2 response is responsible for symptoms seen in NP patients, i.e. rhinorrhea, hyposmia, and nasal obstruction. Immune cellular tolerogenic mechanisms, particularly CD4 + Foxp3 + regulatory T cells (Tregs), are crucial to curtail inflammatory responses. Current evidence suggests impaired Treg activity is the main reason underlying the compromise of self-tolerance, contributing to the onset of CRSwNP. There is compelling evidence that tumor necrosis factor 2 (TNFR2) is preferentially expressed by Tregs, and TNFR2 is able to identify the most potent suppressive subset of Tregs. Tumor necrosis factor (TNF)-TNFR2 interaction plays a decisive role in the activation and expansion of Tregs. This review summarizes current understanding of Tregs biology, focusing on the discussion of the recent advances in the study of TNF-TNFR2 axis in the upregulation of Treg function as a negative feedback mechanism in the control of chronic inflammation. The role of dysregulation of Tregs in the immunopathogenesis of CRSwNP will be analyzed. The future perspective on the harnessing Tregs-mediated self-tolerant mechanism in the management of CRSwNP will be introduced.

Memory regulatory T cells in pregnancy

Pregnancy requires the process of maternal immune tolerance to semi-allogeneic embryos. In contrast, an overreactive maternal immune system to embryo-specific antigens is likely to result in the rejection of embryos while damaging the invading placenta, such that the likelihood of adverse pregnancy outcomes can be increased. Regulatory T cells (Tregs) are capable of suppressing excessive immune responses and regulating immune homeostasis. When stimulating Tregs, specific antigens will differentiate into memory Tregs with long-term survival and rapid and powerful immune regulatory ability. Immunomodulatory effects mediated by memory Tregs at the maternal-fetal interface take on critical significance in a successful pregnancy. The impaired function of memory Tregs shows a correlation with various pregnancy complications (e.g., preeclampsia, gestational diabetes mellitus, and recurrent pregnancy losses). However, the differentiation process and characteristics of memory Tregs, especially their role in pregnancy, remain unclear. In this study, a review is presented in terms of memory Tregs differentiation and activation, the characteristics of memory Tregs and their role in pregnancy, and the correlation between memory Tregs and pregnancy complications. Furthermore, several potential therapeutic methods are investigated to restore the function of memory Tregs in accordance with immunopathologies arising from memory Tregs abnormalities and provide novel targets for diagnosing and treating pregnancy-associated diseases.

Xin-Li formula attenuates heart failure induced by a combination of hyperlipidemia and myocardial infarction in rats via Treg immunomodulation and NLRP3 inflammasome inhibition

Background and aim

Heart failure (HF) is a complex clinical syndrome that represents the end result of several pathophysiologic processes. Despite a dramatic evolution in diagnosis and management of HF, most patients eventually become resistant to therapy. Xin-Li Formula (XLF) is a Chinese medicine formula which shows great potential in the treatment of HF according to our previous studies. The present study was designed to investigate the effects of XLF on HF induced by a combination of hyperlipidemia and myocardial infarction (MI) in rats and reveal the underlying mechanism.

Experimental procedure

A rat model of HF induced by hyperlipidemia and MI was established with intragastric administration of XLF and Perindopril. In vitro, CD4+ T cells from mouse spleen and LPS/ATP-stimulated THP-1 macrophages were employed.

Results and conclusion

XLF was shown to have markedly protective effects on MI-induced HF with hyperlipidemia in rats, including improvement of left ventricular function, reduction of left ventricular fibrosis and infarct size. Moreover, XLF administration significantly increased the number of Foxp3+ Tregs, and inhibited mTOR phosphorylation and NLRP3 signaling pathway. In vitro, we found that XLF had induced Treg activation via the inhibition of mTOR phosphorylation in CD4+ T cells. Additionally, XLF inhibited NLRP3 inflammasome activation in LPS/ATP-stimulated THP-1 macrophages. Taken together, this study raises the exciting possibility that Xin-Li Formula may benefit HF patients due to its immunomodulatory and anti-inflammatory effects via Treg activation and NLRP3 inflammasome inhibition.

Urinary antibiotic exposure and low grip strength risk in community-dwelling elderly Chinese by gender and age

Emerging studies have shown that environmental contaminants were related to decreased handgrip strength. Nevertheless, no prior research has investigated the relationship of exposure to environmental antibiotics with grip strength. Thus, we explored the relationship between urinary antibiotic burden and grip strength among the elderly in China. This study consisted of 451 men and 539 women from the baseline survey of a cohort study. Commonly used antibiotics for humans and animals were detected in 990 urine samples through a biomonitoring method. Grip strength was measured by an electronic dynamometer. We examined the associations of antibiotic exposure with low grip strength (LGS), grip strength, and grip strength index, respectively. Results suggested that 34.9% of participants developed LGS, and 93.0% of individuals were exposed to 1-10 antibiotics. Among women, oxytetracycline (Quartile 2: odds ratio: 2.97, 95% confidence interval: 1.36-6.50), florfenicol (Quartile 3: 2.60 [1.28-5.27]), fluoroquinolones (Quartile 4: 1.88 [1.07-3.30]), and chloramphenicols (Quartile 3: 2.73 [1.35-5.51]) could enhance LGS risk. Among men, ofloxacin (Quartile 2: 3.32 [1.45-7.59]) increased LGS risk, whereas tetracycline (Quartile 2: 0.31 [0.11-0.88]) was implicated in reduced LGS risk. In participants < 70 years, ofloxacin (Quartile 2: 3.00 [1.40-6.42]) could increase LGS risk. For participants who were 70 years of age or older, veterinary antibiotics (Quartile 3: 1.73 [1.02-2.94]) were linked to a 73% increased risk of LGS. Our findings suggested that antibiotics mainly pertained to LGS, and there were gender and age disparities in associations between antibiotic exposure and muscle strength indicators in the elderly Chinese population.

Effect of Mammalian Target of Rapamycin Inhibition on Activated Regulatory T-Cell Expansion in Kidney Transplantation

BACKGROUND

The mammalian target of rapamycin (mTOR) plays a critical role in the host immune response in organ transplantation. This study evaluates the regulatory benefits of mTOR inhibitors in kidney transplant recipients (KTRs).

METHODS

The mTOR-dependent immune-regulating effects in KTRs were evaluated by examining T-cell subsets among peripheral blood mononuclear cells from 79 KTRs. Recipients included an early introduction of everolimus (EVR) and reduced-exposure tacrolimus group (n = 46) and a standard tacrolimus-based without EVR (non-EVR) group (n = 33).

RESULTS

Trough concentrations of tacrolimus at 3 months and 1 year were significantly lower in the EVR group than the non-EVR group (both P < .001). In addition, the respective proportions of patients without estimated glomerular filtration rate < 20% in the EVR and non-EVR groups were 100% and 93.3% at 1 year, 96.3% and 89.7% at 2 years, and 96.3% and 89.7% at 3 years after blood collection, respectively (P = .079). The frequencies of CD3⁺ T cells and CD4⁺ T cells among peripheral blood mononuclear cells were comparable between groups. Total CD25^highCD127^-CD4⁺ regulatory T (Treg) cells were similar in the EVR and non-EVR groups. In contrast, circulating CD45RA^-CD25^highCD127^-CD4⁺ activated Treg cells were significantly higher in the EVR group (P= .008).

CONCLUSION

These results suggest that the early introduction of mTOR benefits long-term kidney graft function and circulating activated Treg-cell expansion in KTRs.

Pleiotropic effects of antibiotics on T cell metabolism and T cell-mediated immunity

T cells orchestrate adaptive and innate immune responses against pathogens and transformed cells. However, T cells are also the main adaptive effector cells that mediate allergic and autoimmune reactions. Within the last few years, it has become abundantly clear that activation, differentiation, effector function, and environmental adaptation of T cells is closely linked to their energy metabolism. Beyond the provision of energy equivalents, metabolic pathways in T cells generate building blocks required for clonal expansion. Furthermore, metabolic intermediates directly serve as a source for epigenetic gene regulation by histone and DNA modification mechanisms. To date, several antibiotics were demonstrated to modulate the metabolism of T cells especially by altering mitochondrial function. Here, we set out to systematically review current evidence about how beta-lactam antibiotics, macrolides, fluoroquinolones, tetracyclines, oxazolidinones, nitroimidazoles, and amphenicols alter the metabolism and effector functions of CD4+ T helper cell populations and CD8+ T cells in vitro and in vivo. Based on this evidence, we have developed an overview on how the use of these antibiotics may be beneficial or detrimental in T cell-mediated physiological and pathogenic immune responses, such as allergic and autoimmune diseases, by altering the metabolism of different T cell populations.

Emerging translational strategies and challenges for enhancing regulatory T cell therapy for graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapy for many types of cancer. Genetic disparities between donor and host can result in immune-mediated attack of host tissues, known as graft versus host disease (GVHD), a major cause of morbidity and mortality following HSCT. Regulatory CD4+ T cells (Tregs) are a rare cell type crucial for immune system homeostasis, limiting the activation and differentiation of effector T cells (Teff) that are self-reactive or stimulated by foreign antigen exposure. Adoptive cell therapy (ACT) with Treg has demonstrated, first in murine models and now in patients, that prophylactic Treg infusion can also suppress GVHD. While clinical trials have demonstrated Treg reduce severe GVHD occurrence, several impediments remain, including Treg variability and practical need for individualized Treg production for each patient. Additionally, there are challenges in the use of in vitro expansion techniques and in achieving in vivo Treg persistence in context of both immune suppressive drugs and in lymphoreplete patients being treated for GVHD. This review will focus on 3 main translational approaches taken to improve the efficacy of tTreg ACT in GVHD prophylaxis and development of treatment options, following HSCT: genetic modification, manipulating TCR and cytokine signaling, and Treg production protocols. In vitro expansion for Treg ACT presents a multitude of approaches for gene modification to improve efficacy, including: antigen specificity, tissue targeting, deletion of negative regulators/exhaustion markers, resistance to immunosuppressive drugs common in GVHD treatment. Such expansion is particularly important in patients without significant lymphopenia that can drive Treg expansion, enabling a favorable Treg:Teff ratio in vivo. Several potential therapeutics have also been identified that enhance tTreg stability or persistence/expansion following ACT that target specific pathways, including: DNA/histone methylation status, TCR/co-stimulation signaling, and IL-2/STAT5 signaling. Finally, this review will discuss improvements in Treg production related to tissue source, Treg subsets, therapeutic approaches to increase Treg suppression and stability during tTreg expansion, and potential for storing large numbers of Treg from a single production run to be used as an off-the-shelf infusion product capable of treating multiple recipients.

Effective Disease Control After Combinatorial Treatment with a PD-1 Antibody and an mTOR Inhibitor for Recurrent Ovarian Clear Cell Carcinomas: A Case Report and Literature Review

Ovarian clear cell carcinoma (OCCC) is a rare type of epithelial ovarian cancer characterized by a chemoresistant phenotype and high-grade tumor. Conventional therapies for OCCC include surgery and chemotherapy. However, these OCCC treatment approaches are characterized by a high risk of relapse and drug resistance resulting in poor prognosis. Therefore, alternative therapeutic approaches are required to achieve better outcomes. In this study, a PIK3CA p.R88Q mutation and PD-L1 expression with a tumor proportion score of 10% was explored in a patient who presented with rapid recurrence after surgery and unsuccessful postoperative chemotherapy. Based on the clinical condition and the patient preference, she was administered a novel combinatorial therapy comprising mTOR inhibitor everolimus, which is a well-known and potent inhibitor of the PI3K/AKT signaling pathway, and the anti-PD-1 antibody toripalimab. Treatment with this combinatorial therapy showed good prognosis, with more than eight months of disease control, and no severe adverse events were observed. The findings of this study provide a novel and effective strategy for OCCC patients. To the best of our knowledge, this is the first study to report a new combination regimen of immunotherapy (everolimus plus toripalimab) for solid tumors. Everolimus is not only an antitumor targeted drug but also an immunosuppressant; it’s combination with immunotherapy is controversial. This is the first report to demonstrate that it has a synergistic effect.

Azithromycin modulates Teff/Treg balance in retinal inflammation via the mTOR signaling pathway

Uveitis is one of the most common blindness-causing ocular disorders. Due to its complicated pathogenesis, the treatment of uveitis has been widely recognized as a challenge for ophthalmologists. Recently, the anti-inflammatory properties of the antibiotic Azithromycin (AZM) have been reported. However, the therapeutic effects of Azithromycin in experimental autoimmune uveitis (EAU), a representative model of human AU, have not been elucidated till date. We conducted this study to examine the therapeutic effects and potential mechanisms of Azithromycin in EAU. We observed that Azithromycin significantly attenuated retinal inflammation in EAU mice at day 14 after immunization along with a significantly decreased inflammatory cell infiltration and cytokine production in the retina. Furthermore, we observed that Azithromycin increased the number of regulatory T cells (Treg) and decreased the number of effector T cells (Teff) in both the draining lymph nodes and spleen of EAU mice. Additionally, Azithromycin suppressed the proliferation and activation of CD4 + T cells, and induced the apoptosis of CD4 + CD44 + memory T and CD4 + CXCR3 + Th1 cells. Mechanistically, we proved that Azithromycin could regulate Teff/Treg balance by inhibiting the phosphorylation of S6 ribosomal protein, a downstream target of mammalian target of rapamycin (mTOR). Together, our findings revealed that Azithromycin alleviated EAU by regulating the Teff/Treg balance through the mTOR signaling pathway, suggesting that Azithromycin could be a promising therapeutic candidate for AU.

The role of CD4+FoxP3+ regulatory T cells in the immunopathogenesis of COVID-19: implications for treatment

The severe cases of Coronavirus Disease 2019 (COVID-19) frequently exhibit excessive inflammatory responses, acute respiratory distress syndrome (ARDS), coagulopathy, and organ damage. The most striking immunopathology of advanced COVID-19 is cytokine release syndrome or "cytokine storm" that is attributable to the deficiencies in immune regulatory mechanisms. CD4+FoxP3+ regulatory T cells (Tregs) are central regulators of immune responses and play an indispensable role in the maintenance of immune homeostasis. Tregs are likely involved in the attenuation of antiviral defense at the early stage of infection and ameliorating inflammation-induced organ injury at the late stage of COVID-19. In this article, we review and summarize the current understanding of the change of Tregs in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and discuss the potential role of Tregs in the immunopathology of COVID-19. The emerging concept of Treg-targeted therapies, including both adoptive Treg transfer and low dose of IL-2 treatment, is introduced. Furthermore, the potential Treg-boosting effect of therapeutic agents used in the treatment of COVID-19, including dexamethasone, vitamin D, tocilizumab and sarilumab, chloroquine, hydroxychloroquine, azithromycin, adalimumab and tetrandrine, is discussed. The problems in the current study of Treg cells in COVID-19 and future perspectives are also addressed.

Analysis of 3702 patients with acne vulgaris and concomitant comorbidities in Turkey: a multi-centered, prospective, controlled study

BACKGROUND

Acne vulgaris is a chronic inflammatory skin disease that affects the pilosebaceous unit. Although it is considered to be a skin-limited disease, different clinical studies have recently been published in which the disease is accompanied by systemic symptoms. In this study, systemic comorbidities accompanying acne vulgaris and the relationship between existing comorbidities and disease severity are investigated.

METHODS

This prospective multicenter study was conducted by the Turkish Society of Dermatology Acne Study Group. Twelve dermatology clinics and 14 clinicians throughout Turkey participated in the study. A structured physician-administered questionnaire was used to collect patient demographics, clinical findings, and lifestyle data. Physicians recorded each participant's medical history, including current and past comorbidities, duration of any comorbidity, smoking, and drinking. Body mass index (BMI) was calculated.

RESULTS

There were 3022 patients in the adolescent acne group and 897 in the control group. The incidence of nonmigraine headache in adolescents with acne was significantly higher than in the nonacne group (P = 0.019). There were 680 patients in the postadolescent acne group and 545 in the control group. In the postadolescent group, incidence of metabolic disease was lower than the control group (P = 0.003). In the postadolescent group, premenstrual syndrome (P < 0.001) and PCOS (P = 0.007) were more common than the control group.

CONCLUSIONS

In this study, we observed that acne vulgaris does not cause systemic comorbidities. There is also a need for new studies involving a large number of patients to illuminate systemic diseases accompanying acne vulgaris.

Recent Progress in Treg Biology and Transplant Therapeutics

Purpose of Review

Regulatory T cell (Treg) biology continues to evolve at a rapid pace. The role of Tregs in solid organ transplantation offers a unique window into Treg ontogeny and function as well as limitless possibilities for clinical application. Here we review recent significant discoveries and key translational work.

Recent Findings

Advances in transplantation deepen understanding of Treg differentiation, expansion, transcription, co-stimulation, and signaling. T cell receptor (TCR) sequencing and single-cell analytics allow unprecedented insight into Treg repertoire diversity and phenotypic heterogeneity. Efforts to replace conventional immunosuppression with Treg adoptive immunotherapy are underway and coalescing around strategies to increase efficiency through development of donor-reactive Tregs.

Summary

Adoptive immunotherapy with Tregs is a leading tolerogenic strategy. Early clinical trials suggest that Treg infusion is safe and reports on efficacy will soon follow.