Mitochondrial reactive oxygen species control T cell activation by regulating IL-2 and IL-4 expression: mechanism of ciprofloxacin-mediated immunosuppression

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.

Mitigative Effects of Topical Norfloxacin on an Imiquimod-Induced Murine Model of Psoriasis

Psoriasis is a chronic, inflammatory dermatosis characterized by thickened, reddened, and scaly skin lesions. Norfloxacin is a fluoroquinolone antibiotic with enhanced antioxidant, anti-inflammatory, and immunomodulatory bioactivities. The aim of this study was to figure out the possible impact of topical norfloxacin on an imiquimod-induced model of psoriasis in mice. Thirty albino-type mice were split into five distinct groups of six animals each. The control group included healthy mice that had not received any treatment. The induction group was given the vehicle 2 h after the topical imiquimod, once daily for 8 days. Two hours after receiving topical imiquimod, the treatment groups including calcipotriol, norfloxacin 2.5%, and norfloxacin 5% were given topical ointments containing calcipotriol 0.005%, norfloxacin 2.5%, and norfloxacin 5%, for 8 days. Topical norfloxacin ointment significantly reduced the severity of imiquimod-exacerbated psoriatic lesions including erythema, shiny-white scaling, and acanthosis and fixed histological abnormalities. Furthermore, imiquimod-subjected mice treated with a higher concentration of norfloxacin ointment exhibited dramatically lower skin levels of inflammation-related biomarkers like IFN-γ, TNF-α, IL-6, IL-17A, IL-23, and TGF-β but higher levels of IL-10. They also demonstrated a notable decrease in angiogenesis parameters such as VEGF and IL-8, a substantial reduction in oxidative indicators like MDA and MPO, and a considerable rise in antioxidant enzymes like SOD and CAT. This study offers novel evidence that norfloxacin may assist in controlling inflammatory dermatoses like psoriasis by minimizing the severity of psoriatic plaques, correcting histological alterations, and diminishing the production of inflammatory, oxidative, and angiogenetic parameters.

Inherent metabolic preferences differentially regulate the sensitivity of Th1 and Th2 cells to ribosome-inhibiting antibiotics

Mitochondrial translation is essential to maintain mitochondrial function and energy production. Mutations in genes associated with mitochondrial translation cause several developmental disorders, and immune dysfunction is observed in many such patients. Besides genetic mutations, several antibiotics targeting bacterial ribosomes are well-established to inhibit mitochondrial translation. However, the effect of such antibiotics on different immune cells is not fully understood. Here, we addressed the differential effect of mitochondrial translation inhibition on different subsets of helper T cells (Th) of mice and humans. Inhibition of mitochondrial translation reduced the levels of mitochondrially encoded electron transport chain subunits without affecting their nuclear-encoded counterparts. As a result, mitochondrial oxygen consumption reduced dramatically, but mitochondrial mass was unaffected. Most importantly, we show that inhibition of mitochondrial translation induced apoptosis, specifically in Th2 cells. This increase in apoptosis was associated with higher expression of Bim and Puma, two activators of the intrinsic pathway of apoptosis. We propose that this difference in the sensitivity of Th1 and Th2 cells to mitochondrial translation inhibition reflects the intrinsic metabolic demands of these subtypes. Though Th1 and Th2 cells exhibit similar levels of oxidative phosphorylation, Th1 cells exhibit higher levels of aerobic glycolysis than Th2 cells. Moreover, Th1 cells are more sensitive to the inhibition of glycolysis, while higher concentrations of glycolysis inhibitor 2-deoxyglucose are required to induce cell death in the Th2 lineage. These observations reveal that selection of metabolic pathways for substrate utilization during differentiation of Th1 and Th2 lineages is a fundamental process conserved across species.

Exploring the Thioredoxin System as a Therapeutic Target in Cancer: Mechanisms and Implications

Cells constantly face the challenge of managing oxidants. In aerobic organisms, oxygen (O2) is used for energy production, generating reactive oxygen species (ROS) as byproducts of enzymatic reactions. To protect against oxidative damage, cells possess an intricate system of redox scavengers and antioxidant enzymes, collectively forming the antioxidant defense system. This system maintains the redox equilibrium and enables the generation of localized oxidative signals that regulate essential cellular functions. One key component of this defense is the thioredoxin (Trx) system, which includes Trx, thioredoxin reductase (TrxR), and NADPH. The Trx system reverses oxidation of macromolecules and indirectly neutralizes ROS via peroxiredoxin (Prx). This dual function protects cells from damage accumulation and supports physiological cell signaling. However, the Trx system also shields tumors from oxidative damage, aiding their survival. Due to elevated ROS levels from their metabolism, tumors often rely on the Trx system. In addition, the Trx system regulates critical pathways such as proliferation and neoangiogenesis, which tumors exploit to enhance growth and optimize nutrient and oxygen supply. Consequently, the Trx system is a potential target for cancer therapy. The challenge lies in selectively targeting malignant cells without disrupting the redox equilibrium in healthy cells. The aim of this review article is threefold: first, to elucidate the function of the Trx system; second, to discuss the Trx system as a potential target for cancer therapies; and third, to present the possibilities for inhibiting key components of the Trx system, along with an overview of the latest clinical studies on these inhibitors.

Mitochondrial control of lymphocyte homeostasis

Mitochondria play a multitude of essential roles within mammalian cells, and understanding how they control immunity is an emerging area of study. Lymphocytes, as integral cellular components of the adaptive immune system, rely on mitochondria for their function, and mitochondria can dynamically instruct their differentiation and activation by undergoing rapid and profound remodelling. Energy homeostasis and ATP production are often considered the primary functions of mitochondria in immune cells; however, their importance extends across a spectrum of other molecular processes, including regulation of redox balance, signalling pathways, and biosynthesis. In this review, we explore the dynamic landscape of mitochondrial homeostasis in T and B cells, and discuss how mitochondrial disorders compromise adaptive immunity.

Autocrine VEGF-B signaling maintains lipid synthesis and mitochondrial fitness to support T cell immune responses

T cells rewire their metabolic activities to meet the demand of immune responses, but how to coordinate the immune response by metabolic regulators in activated T cells is unknown. Here, we identified autocrine VEGF-B as a metabolic regulator to control lipid synthesis and maintain the integrity of the mitochondrial inner membrane for the survival of activated T cells. Disruption of autocrine VEGF-B signaling in T cells reduced cardiolipin mass, resulting in mitochondrial damage, with increased apoptosis and reduced memory development. The addition of cardiolipin or modulating VEGF-B signaling improved T cell mitochondrial fitness and survival. Autocrine VEGF-B signaling through GA-binding protein α (GABPα) induced sentrin/SUMO-specific protease 2 (SENP2) expression, which further de-SUMOylated PPARγ and enhanced phospholipid synthesis, leading to a cardiolipin increase in activated T cells. These data suggest that autocrine VEGF-B mediates a signal to coordinate lipid synthesis and mitochondrial fitness with T cell activation for survival and immune response. Moreover, autocrine VEGF-B signaling in T cells provides a therapeutic target against infection and tumors as well as an avenue for the treatment of autoimmune diseases.

Deficiency in the mitophagy mediator Parkin accelerates murine skin allograft rejection

Alterations in mitochondrial function and associated quality control programs, including mitochondrial-specific autophagy, termed mitophagy, are gaining increasing recognition in the context of disease. However, the role of mitophagy in organ transplant rejection remains poorly understood. Using mice deficient in Parkin, a ubiquitin ligase that tags damaged or dysfunctional mitochondria for autophagic clearance, we assessed the impact of Parkin-dependent mitophagy on skin-graft rejection. We observed accelerated graft loss in Parkin-deficient mice across multiple skin graft models. Immune cell distributions posttransplant were largely unperturbed compared to wild-type; however, the CD8+ T cells of Parkin-deficient mice expressed more T-bet, IFNγ, and Ki67, indicating greater priming toward effector function. This was accompanied by increased circulating levels of IL-12p70 in Parkin-deficient mice. Using a mixed leukocyte reaction, we demonstrated that naïve Parkin-deficient CD4+ and CD8+ T cells exhibit enhanced activation marker expression and proliferative responses to alloantigen, which were attenuated with administration of a pharmacological mitophagy inducer (p62-mediated mitophagy inducer), known to increase mitophagy in the absence of a functional PINK1-Parkin pathway. These findings indicate a role for Parkin-dependent mitophagy in curtailing skin-graft rejection.

The relationship of redox signaling with the risk for atherosclerosis

Oxidative balance plays a pivotal role in physiological homeostasis, and many diseases, particularly age-related conditions, are closely associated with oxidative imbalance. While the strategic role of oxidative regulation in various diseases is well-established, the specific involvement of oxidative stress in atherosclerosis remains elusive. Atherosclerosis is a chronic inflammatory disorder characterized by plaque formation within the arteries. Alterations in the oxidative status of vascular tissues are linked to the onset, progression, and outcome of atherosclerosis. This review examines the role of redox signaling in atherosclerosis, including its impact on risk factors such as dyslipidemia, hyperglycemia, inflammation, and unhealthy lifestyle, along with dysregulation, vascular homeostasis, immune system interaction, and therapeutic considerations. Understanding redox signal transduction and the regulation of redox signaling will offer valuable insights into the pathogenesis of atherosclerosis and guide the development of novel therapeutic strategies.

Ablation of Atp5if1 impairs metabolic reprogramming and proliferation of T lymphocytes and compromises mouse survival

T cells experience metabolic reprogramming to an enhanced glycolysis upon activation. Herein, we have investigated whether ATPase Inhibitory Factor 1 (IF1), the physiological inhibitor of mitochondrial ATP synthase, participates in rewiring T cells to a particular metabolic phenotype. We show that the activation of naive CD4+ T lymphocytes both in vitro and in vivo is accompanied by a sharp upregulation of IF1, which is expressed only in Th1 effector cells. T lymphocytes of conditional CD4+-IF1-knockout mice display impaired glucose uptake and flux through glycolysis, reducing the biogenesis of mitochondria and cellular proliferation after activation. Consequently, mice devoid of IF1 in T lymphocytes cannot mount an effective Th1 response against bacterial infection compromising their survival. Overall, we show that the inhibition of a fraction of ATP synthase by IF1 regulates metabolic reprogramming and functionality of T cells, highlighting the essential role of IF1 in adaptive immune responses.

Role of antioxidants in modulating anti-tumor T cell immune resposne

It has been well established that in addition to oxygen's vital in cellular respiration, a disruption of oxygen balance can lead to increased stress and oxidative injury. Similarly, reduced oxygen during tumor proliferation and invasion generates a hypoxic tumor microenvironment, resulting in dysfunction of immune cells and providing a conducive milieu for tumors to adapt and grow. Strategies to improve the persistence tumor reactive T cells in the highly oxidative tumor environment are being pursued for enhancing immunotherapy outcomes. To this end, we have focused on various strategies that can help increase or maintain the antioxidant capacity of T cells, thus reducing their susceptibility to oxidative stress/damage. Herein we lay out an overview on the role of oxygen in T cell signaling and how pathways regulating oxidative stress or antioxidant signaling can be targeted to enhance immunotherapeutic approaches for cancer treatment.

Unraveling the Role of Reactive Oxygen Species in T Lymphocyte Signaling

Reactive oxygen species (ROS) are central to inter- and intracellular signaling. Their localized and transient effects are due to their short half-life, especially when generated in controlled amounts. Upon T cell receptor (TCR) activation, regulated ROS signaling is primarily initiated by complexes I and III of the electron transport chain (ETC). Subsequent ROS production triggers the activation of nicotinamide adenine dinucleotide phosphate oxidase 2 (NADPH oxidase 2), prolonging the oxidative signal. This signal then engages kinase signaling cascades such as the mitogen-activated protein kinase (MAPK) pathway and increases the activity of REDOX-sensitive transcription factors such as nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1). To limit ROS overproduction and prevent oxidative stress, nuclear factor erythroid 2-related factor 2 (Nrf2) and antioxidant proteins such as superoxide dismutases (SODs) finely regulate signal intensity and are capable of terminating the oxidative signal when needed. Thus, oxidative signals, such as T cell activation, are well-controlled and critical for cellular communication.

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.

Antibiotics, Sedatives, and Catecholamines Further Compromise Sepsis-Induced Immune Suppression in Peripheral Blood Mononuclear Cells

OBJECTIVES

We hypothesized that the immunosuppressive effects associated with antibiotics, sedatives, and catecholamines amplify sepsis-associated immune suppression through mitochondrial dysfunction, and there is a cumulative effect when used in combination. We thus sought to determine the impact of the exemplar drugs ciprofloxacin, propofol, and norepinephrine, used alone and in combination, at clinically relevant concentrations, on the ex vivo functionality of peripheral blood mononuclear cells (PBMCs) drawn from healthy, infected, and septic individuals.

DESIGN

In vitro/ex vivo investigation.

SETTING

University laboratory.

SUBJECTS

Healthy volunteers, infected (nonseptic) patients in the emergency department, and septic ICU patients.

INTERVENTIONS

PBMCs were isolated from these subjects and treated with ciprofloxacin (100 µg/mL), propofol (50 µg/mL), norepinephrine (10 µg/mL), or all three drugs combined, with and without lipopolysaccharide (100 ng/mL) for 6 or 24 hours. Comparison was made between study groups and against untreated cells. Measurements were made of cell viability, cytokine production, phagocytosis, human leukocyte antigen-DR (HLA-DR) status, mitochondrial membrane potential, mitochondrial reactive oxygen species production, and oxygen consumption. Gene expression in immune and metabolic pathways was investigated in PBMCs sampled from healthy volunteers coincubated with septic serum.

MEASUREMENTS AND RESULTS

Coincubation with each of the drugs reduced cytokine production and phagocytosis in PBMCs isolated from septic patients, and healthy volunteers coincubated with septic serum. No effect was seen on HLA-DR surface expression. No cumulative effects were seen with the drug combination. Sepsis-induced changes in gene expression and mitochondrial functionality were not further affected by addition of any of the drugs.

CONCLUSION

Drugs commonly used in critical care lead to significant immune dysfunction ex vivo and enhance sepsis-associated immunosuppression. Further studies are required to identify underlying mechanisms and potential impact on patient outcomes.

Immunomodulatory Effects of Fluoroquinolones in Community-Acquired Pneumonia-Associated Acute Respiratory Distress Syndrome

Community-acquired pneumonia is reported as one of the infectious diseases that leads to the development of acute respiratory distress syndrome. The innate immune system is the first line of defence against microbial invasion; however, its dysregulation during infection, resulting in an increased pathogen load, stimulates the over-secretion of chemokines and pro-inflammatory cytokines. This phenomenon causes damage to the epithelial-endothelial barrier of the pulmonary alveoli and the leakage of the intravascular protein into the alveolar lumen. Fluoroquinolones are synthetic antimicrobial agents with immunomodulatory properties that can inhibit bacterial proliferation as well as exhibit anti-inflammatory activities. It has been demonstrated that the structure of fluoroquinolones, particularly those with a cyclopropyl group, exerts immunomodulatory effects. Its capability to inhibit phosphodiesterase activity leads to the accumulation of intracellular cAMP, which subsequently enhances PKA activity, resulting in the inhibition of transcriptional factor NF-κB and the activation of CREB. Another mechanism reported is the inhibition of TLR and ERK signalling pathways. Although the sequence of events has not been completely understood, significant progress has been made in comprehending the specific mechanisms underlying the immunomodulatory effects of fluoroquinolones. Here, we review the indirect immunomodulatory effects of FQs as an alternative to empirical therapy in patients diagnosed with community-acquired pneumonia.

Actives from the Micro-Immunotherapy Medicine 2LMIREG® Reduce the Expression of Cytokines and Immune-Related Markers Including Interleukin-2 and HLA-II While Modulating Oxidative Stress and Mitochondrial Function

Introduction

Micro-immunotherapy (MI) is a therapeutic option employing low doses (LD) and ultra-low doses (ULD) of cytokines and immune factors to help the organism at modulating the immune responses. In an overpowering inflammatory context, this strategy may support the restoration of the body's homeostasis, as the active ingredients of MI medicines' (MIM) could boost or slow down the physiological functions of the immune cells. The aim of the study is to evaluate for the first time the in vitro anti-inflammatory properties of some actives employed by the MIM of interest in several human immune cell models.

Methods

In the first part of the study, the effects of the actives from the MIM of interest were assessed from a molecular standpoint: the expression of HLA-II, interleukin (IL)-2, and the secretion of several other cytokines were evaluated. In addition, as mitochondrial metabolism is also involved in the inflammatory processes, the second part of the study aimed at assessing the effects of these actives on the mitochondrial reactive oxygen species (ROS) production and on the mitochondrial membrane potential.

Results

We showed that the tested actives decreased the expression of HLA-DR and HLA-DP in IFN-γ-stimulated endothelial cells and in LPS-treated-M1-macrophages. The tested MIM slightly reduced the intracellular expression of IL-2 in CD4+ and CD8+ T-cells isolated from PMA/Iono-stimulated human PBMCs. Additionally, while the secretion of IL-2, IL-10, and IFN-γ was diminished, the treatment increased IL-6, IL-9, and IL-17A, which may correspond to a "Th17-like" secretory pattern. Interestingly, in PMA/Iono-treated PBMCs, we reported that the treatment reduced the ROS production in B-cells. Finally, in PMA/Iono-treated human macrophages, we showed that the treatment slightly protected the cells from early cell death/apoptosis.

Discussion

Overall, these results provide data about the molecular and functional anti-inflammatory effects of several actives contained in the tested MIM in immune-related cells, and their impact on two mitochondria-related processes.

Extracellular Delivery of Functional Mitochondria Rescues the Dysfunction of CD4+ T Cells in Aging

Mitochondrial dysfunction alters cellular metabolism, increases tissue oxidative stress, and may be principal to the dysregulated signaling and function of CD4+ T lymphocytes in the elderly. In this proof of principle study, it is investigated whether the transfer of functional mitochondria into CD4+ T cells that are isolated from old mice (aged CD4+ T cells), can abrogate aging-associated mitochondrial dysfunction, and improve the aged CD4+ T cell functionality. The results show that the delivery of exogenous mitochondria to aged non-activated CD4+ T cells led to significant mitochondrial proteome alterations highlighted by improved aerobic metabolism and decreased cellular mitoROS. Additionally, mito-transferred aged CD4+ T cells showed improvements in activation-induced TCR-signaling kinetics displaying markers of activation (CD25), increased IL-2 production, enhanced proliferation ex vivo. Importantly, immune deficient mouse models (RAG-KO) showed that adoptive transfer of mito-transferred naive aged CD4+ T cells, protected recipient mice from influenza A and Mycobacterium tuberculosis infections. These findings support mitochondria as targets of therapeutic intervention in aging.

Immune Escape Strategies in Head and Neck Cancer: Evade, Resist, Inhibit, Recruit

Head and neck cancers (HNCs) arise from the mucosal lining of the aerodigestive tract and are often associated with alcohol use, tobacco use, and/or human papillomavirus (HPV) infection. Over 600,000 new cases of HNC are diagnosed each year, making it the sixth most common cancer worldwide. Historically, treatments have included surgery, radiation, and chemotherapy, and while these treatments are still the backbone of current therapy, several immunotherapies have recently been approved by the Food and Drug Administration (FDA) for use in HNC. The role of the immune system in tumorigenesis and cancer progression has been explored since the early 20th century, eventually coalescing into the current three-phase model of cancer immunoediting. During each of the three phases-elimination, equilibrium, and escape-cancer cells develop and utilize multiple strategies to either reach or remain in the final phase, escape, at which point the tumor is able to grow and metastasize with little to no detrimental interference from the immune system. In this review, we summarize the many strategies used by HNC to escape the immune system, which include ways to evade immune detection, resist immune cell attacks, inhibit immune cell functions, and recruit pro-tumor immune cells.

The ameliorative effects of topical gemifloxacin alone or in combination with clobetasol propionate on imiquimod-induced model of psoriasis in mice

Psoriasis is a lifelong immune-driven skin condition characterized by excessive epidermal overgrowth and inflammatory cell infiltration. Gemifloxacin is a fourth-generation fluoroquinolone with improved immunomodulatory and anti-inflammatory properties that are believed to possess an attractive role in psoriasis via suppressing the production of cytokines, chemokines, and eosinophil and neutrophil chemotaxis. The aim of this research is to investigate the ameliorative effects of prolonged topical gemifloxacin (GMF) alone and combined with clobetasol propionate (CLO) on an imiquimod (IMQ)-induced mouse model of psoriasis. Forty-eight Swiss albino mice were divided into six groups of eight. All groups except the negative controls got 62.5 mg of IMQ 5% topically for 8 days. Mice in the control group (controls) got Vaseline instead. Following the induction in the IMQ 5% group, mice in treatment groups CLO 0.05, GMF 1%, GMF 3%, and CLO + GMF obtained clobetasol propionate 0.05%, GMF 1% and 3%, and a combination of both, respectively, for an additional 8 days, rendering the experiment 16 days long. Our results revealed that gemifloxacin alleviated erythematous, thickened, and scaly psoriatic lesions and inhibited the tissue level of inflammatory cytokines, including interleukin (IL)-8, IL-17A, IL-23, tumor necrosis factor-α (TNF-α), and transforming growth factor-β1 (TGF-β1). The anti-inflammatory effect also occurred by hindering nuclear factor-kappa B (NF-κB) signaling and reversing histopathological problems. Gemifloxacin acts effectively in mitigating psoriasis-associated lesions and restricting NF-κB-mediated inflammation, recommending gemifloxacin as a promising adjuvant candidate for additional studies on the long-term treatment of autoimmune and autoinflammatory dermatoses like psoriasis.

Oxidative stress in pituitary neuroendocrine tumors: Affecting the tumor microenvironment and becoming a new target for pituitary neuroendocrine tumor therapy

Pituitary adenomas (PAs), or pituitary neuroendocrine tumors (PitNETs), are commonly found in the anterior pituitary gland. Although the majority of PitNETs are benign and stable, several tumors have malignant characteristics. The tumor microenvironment (TME) plays an important role in the process of tumorigenesis and is composed of several types of cells. Various cells in the TME are significantly affected by oxidative stress. It has been reported that immunotherapeutic strategies have good effects in several cancers. However, the clinical potential of immunotherapies in PitNETs has not yet been fully discussed. Oxidative stress can regulate PitNET cells and immune cells in the TME, thus affecting the immune status of the TME of PitNETs. Therefore, modulation of oxidative stress-regulated immune cells using a combination of several agents and the immune system to suppress PitNETs is a promising therapeutic direction. In this review, we systematically analyzed the oxidative stress process within PitNET cells and various immune cells to elucidate the potential value of immunotherapy.

Antigen receptor stimulation induces purifying selection against pathogenic mitochondrial tRNA mutations

Pathogenic mutations in mitochondrial (mt) tRNA genes that compromise oxidative phosphorylation (OXPHOS) exhibit heteroplasmy and cause a range of multisyndromic conditions. Although mitochondrial disease patients are known to suffer from abnormal immune responses, how heteroplasmic mtDNA mutations affect the immune system at the molecular level is largely unknown. Here, in mice carrying pathogenic C5024T in mt-tRNAAla and in patients with mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes (MELAS) syndrome carrying A3243G in mt-tRNALeu, we found memory T and B cells to have lower pathogenic mtDNA mutation burdens than their antigen-inexperienced naive counterparts, including after vaccination. Pathogenic burden reduction was less pronounced in myeloid compared with lymphoid lineages, despite C5024T compromising macrophage OXPHOS capacity. Rapid dilution of the C5024T mutation in T and B cell cultures could be induced by antigen receptor-triggered proliferation and was accelerated by metabolic stress conditions. Furthermore, we found C5024T to dysregulate CD8+ T cell metabolic remodeling and IFN-γ production after activation. Together, our data illustrate that the generation of memory lymphocytes shapes the mtDNA landscape, wherein pathogenic variants dysregulate the immune response.

Application of honeybee venom loaded nanoparticles for the treatment of chronic toxoplasmosis: parasitological, histopathological, and immunohistochemical studies

Toxoplasma gondii is an opportunistic intracellular protozoon which may cause severe disease in the immunocompromised patients. Unfortunately, the majority of treatments on the market work against tachyzoites in the acute infection but can't affect tissue cysts in the chronic phase. So, this study aimed to evaluate the effect of bee venom (BV) loaded metal organic frameworks (MOFs) nanoparticles (NPs) for the treatment of chronic murine toxoplasmosis. Ninety laboratory Swiss Albino mice were divided into 9 groups (10 mice each); GI (negative control), GII (infected control), GIII-GXI (infected with Me49 strain of Toxoplasma and treated); GIII (MOFs-NPs), GIV and GV (BV alone and loaded on MOFs-NPs), GVI and GVII (spiramycin alone and loaded on MOFs-NPs), GVIII and GIX (ciprofloxacin alone and loaded on MOFs-NPs). Parasitological examination of brain cyst count, histopathological study of brain, retina, liver, and kidney tissue sections and immunohistochemical (IHC) evaluation of liver was performed. Counting of Toxoplasma brain cysts showed high statistically significant difference between the infected treated groups and GII. GV showed the least count of brain cysts; mean ± SD (281 ± 29.5). Histopathological examination revealed a marked ameliorative effect of BV administration when used alone or loaded MOFs-NPs. It significantly reduced tissue inflammation, degeneration, and fibrosis. IHC examination of liver sections revealed high density CD8+ infiltration in GII, low density CD8+ infiltration in GIII, GVI, GVII, GVIII, and GIX while GIV and GV showed intermediate density CD8+ infiltration. BV is a promising Apitherapy against chronic toxoplasmosis. This effect is markedly enhanced by MOFs-NPs.

Graphical abstract

The tale of antibiotics beyond antimicrobials: Expanding horizons

Antibiotics had proved to be a godsend for mankind since their discovery. They were once the magical solution to the vexing problem of infection-related deaths. German scientist Paul Ehrlich had termed salvarsan as the silver bullet to treatsyphilis.As time passed, the magic of newly discovered silver bullets got tarnished with raging antibiotic resistance among bacteria and associated side-effects. Still, antibiotics remain the primary line of treatment for bacterial infections. Our understanding of their chemical and biological activities has increased immensely with advancement in the research field. Non-antibacterial effects of antibiotics are studied extensively to optimise their safer, broad-range use. These non-antibacterial effects could be both useful and harmful to us. Various researchers across the globe including our lab are studying the direct/indirect effects and molecular mechanisms behind these non-antibacterial effects of antibiotics. So, it is interesting for us to sum up the available literature. In this review, we have briefed the possible reason behind the non-antibacterial effects of antibiotics, owing to the endosymbiotic origin of host mitochondria. We further discuss the physiological and immunomodulatory effects of antibiotics. We then extend the review to discuss molecular mechanisms behind the plausible use of antibiotics as anticancer agents.

Mitochondria during T cell aging

Mitochondrial dysfunction is a hallmark of aging that contributes to inflammaging. It is characterized by alterations of the mitochondrial DNA, reduced respiratory capacity, decreased mitochondrial membrane potential and increased reactive oxygen species production. These primary alterations disrupt other interconnected and important mitochondrial-related processes such as metabolism, mitochondrial dynamics and biogenesis, mitophagy, calcium homeostasis or apoptosis. In this review, we gather the current knowledge about the different mitochondrial processes which are altered during aging, with special focus on their contribution to age-associated T cell dysfunction and inflammaging.

Anti-inflammatory, anti-apoptotic, and neuroprotective potentials of anethole in Parkinson's disease-like motor and non-motor symptoms induced by rotenone in rats

Parkinson's disease (PD) is a complex neurological disorder characterized by a combination of motor and non-motor symptoms (NMS). Antioxidant and anti-inflammatory compounds are considered a potential therapeutic strategy against PD. The present study examined the neuroprotective effects of anethole as a potent antioxidant and anti-inflammatory agent against motor and non-motor deficits induced by rotenone toxicity. Rats were treated with anethole (62.5, 125, and 250 mg/kg, i.g) concomitantly with rotenone (2 mg/kg, s.c) for 5 weeks. After the treatment, behavioral tests were performed to evaluate motor function and depression-/anxiety-like behaviors. After the behavioral tests, rats were decapitated and brains were removed for histological analysis. Striatum samples were also isolated for neurochemical, and molecular analysis. Our data showed that rotenone-induced motor deficit, anxiety-and depression-like behaviors were significantly improved in rats treated with anethole. Furthermore, anethole treatment reduced inflammatory cytokines tumor necrosis factor α (TNFα) and Interleukin 6 (IL-6), and increased anti-inflammatory cytokine IL-4 in the striatum of rotenone-induced PD rats. Western blot analysis showed that treatment with anethole markedly suppressed caspase-3 activation induced by rotenone. Moreover, histological examination of striatum showed an increase in the number of surviving neurons after treatment with anethole. Anethole also significantly enhanced the striatal levels of dopamine in rotenone-induced PD rats. In addition, treatment with L-Dopa as a positive control group had effects similar to those of anethole on histological, neurochemical, and molecular parameters in rotenone-induced parkinsonian rats. Our results suggested the neuroprotective effects of anethole through anti-inflammatory, anti-apoptotic, and antioxidant mechanisms against rotenone-induced toxicity in rats.

Unlocking the power of NOX2: A comprehensive review on its role in immune regulation

Reactive oxygen species (ROS) are a family of highly reactive molecules with numerous, often pleiotropic functions within the cell and the organism. Due to their potential to destroy biological structures such as membranes, enzymes and organelles, ROS have long been recognized as harmful yet unavoidable by-products of cellular metabolism leading to "oxidative stress" unless counterbalanced by cellular anti-oxidative defense mechanisms. Phagocytes utilize this destructive potential of ROS released in high amounts to defend against invading pathogens. In contrast, a regulated and fine-tuned release of "signaling ROS" (sROS) provides essential intracellular second messengers to modulate central aspects of immunity, including antigen presentation, activation of antigen presenting cells (APC) as well as the APC:T cell interaction during T cell activation. This regulated release of sROS is foremost attributed to the specialized enzyme NADPH-oxidase (NOX) 2 expressed mainly in myeloid cells such as neutrophils, macrophages and dendritic cells (DC). NOX-2-derived sROS are primarily involved in immune regulation and mediate protection against autoimmunity as well as maintenance of self-tolerance. Consequently, deficiencies in NOX2 not only result in primary immune-deficiencies such as Chronic Granulomatous Disease (CGD) but also lead to auto-inflammatory diseases and autoimmunity. A comprehensive understanding of NOX2 activation and regulation will be key for successful pharmaceutical interventions of such ROS-related diseases in the future. In this review, we summarize recent progress regarding immune regulation by NOX2-derived ROS and the consequences of its deregulation on the development of immune disorders.

Mating modifies the expression of crucial oxidative-reductive transcripts in the pig oviductal sperm reservoir: is the female ensuring sperm survival?

Background

Mating induces large changes in the female genital tract, warranting female homeostasis and immune preparation for pregnancy, including the preservation of crucial oxidative status among its pathways. Being highly susceptible to oxidative stress, sperm survival and preserved function depend on the seminal plasma, a protection that is removed during sperm handling but also after mating when spermatozoa enter the oviduct. Therefore, it is pertinent to consider that the female sperm reservoir takes up this protection, providing a suitable environment for sperm viability. These aspects have not been explored despite the increasing strategies in modulating the female status through diet control and nutritional supplementation.

Aims

To test the hypothesis that mating modifies the expression of crucial oxidative-reductive transcripts across the entire pig female genital tract (cervix to infundibulum) and, particularly in the sperm reservoir at the utero-tubal junction, before ovulation, a period dominated by estrogen stimulation of ovarian as well as of seminal origin.

Methods

The differential expression of estrogen (ER) and progesterone (PR) receptors and of 59 oxidative-reductive transcripts were studied using a species-specific microarray platform, in specific segments of the peri-ovulatory sow reproductive tract in response to mating.

Results

Mating induced changes along the entire tract, with a conspicuous downregulation of both ER and PR and an upregulation of superoxide dismutase 1 (SOD1), glutaredoxin (GLRX3), and peroxiredoxin 1 and 3 (PRDX1, PRDX3), among other NADH Dehydrogenase Ubiquinone Flavoproteins, in the distal uterus segment. These changes perhaps helped prevent oxidative stress in the area adjacent to the sperm reservoir at the utero-tubal junction. Concomitantly, there were a downregulation of catalase (CAT) and NADH dehydrogenase (ubiquinone) oxidoreductases 1 beta subcomplex, subunit 1 (NDUFB1) in the utero-tubal junction alongside an overall downregulation of CAT, SOD1, and PRDX3 in the ampullar and infundibulum segments.

Conclusions

Natural mating is an inducer of changes in the expression of female genes commanding antioxidant enzymes relevant for sperm survival during sperm transport, under predominant estrogen influence through the bloodstream and semen. The findings could contribute to the design of new therapeutics for the female to improve oxidative-reductive balance.

Reactive oxygen species formation and its effect on CD4+ T cell-mediated inflammation

Reactive oxygen species (ROS) are produced both enzymatically and non-enzymatically in vivo. Physiological concentrations of ROS act as signaling molecules that participate in various physiological and pathophysiological activities and play an important role in basic metabolic functions. Diseases related to metabolic disorders may be affected by changes in redox balance. This review details the common generation pathways of intracellular ROS and discusses the damage to physiological functions when the ROS concentration is too high to reach an oxidative stress state. We also summarize the main features and energy metabolism of CD4+ T-cell activation and differentiation and the effects of ROS produced during the oxidative metabolism of CD4+ T cells. Because the current treatment for autoimmune diseases damages other immune responses and functional cells in the body, inhibiting the activation and differentiation of autoreactive T cells by targeting oxidative metabolism or ROS production without damaging systemic immune function is a promising treatment option. Therefore, exploring the relationship between T-cell energy metabolism and ROS and the T-cell differentiation process provides theoretical support for discovering effective treatments for T cell-mediated autoimmune diseases.

The PRAK-NRF2 axis promotes the differentiation of Th17 cells by mediating the redox homeostasis and glycolysis

Oxidative stress is a key feature in both chronic inflammation and cancer. P38 regulated/activated protein kinase (PRAK) deficiency can cause functional disorders in neutrophils and macrophages under high oxidative stress, but the precise mechanisms by which PRAK regulates reactive oxygen species (ROS) elimination and its potential impact on CD4+ T helper subset function are unclear. The present study reveals that the PRAK-NF-E2-related factor 2(NRF2) axis is essential for maintaining the intracellular redox homeostasis of T helper 17(Th17) cells, thereby promoting Th17 cell differentiation and antitumor effects. Through mechanistic analysis, we identify NRF2 as a novel protein substrate of PRAK and find that PRAK enhances the stability of the NRF2 protein through phosphorylation NRF2 Serine(S) 558 independent of protein ubiquitination. High accumulation of cellular ROS caused by loss of PRAK disrupts both glycolysis and PKM2-dependent phosphorylation of STAT3, which subsequently impairs the differentiation of Th17 cells. As a result, Prak knockout (KO) mice display significant resistance to experimental autoimmune encephalomyelitis (EAE) but impaired antitumor immunity in a MC38 tumor model. This work reveals that the PRAK-NRF2-mediated antioxidant pathway is a metabolic checkpoint that controls Th17-cell glycolysis and differentiation. Targeting PRAK is a promising strategy for maintaining an active ROS scavenging system and may lead to potent Th17 cell antitumor immunity.

The Influence of Gut Microbiota on Oxidative Stress and the Immune System

The human gastrointestinal tract is home to a complex microbial community that plays an important role in the general well-being of the entire organism. The gut microbiota generates a variety of metabolites and thereby regulates many biological processes, such as the regulation of the immune system. In the gut, bacteria are in direct contact with the host. The major challenge here is to prevent unwanted inflammatory reactions on one hand and on the other hand to ensure that the immune system can be activated when pathogens invade. Here the REDOX equilibrium is of utmost importance. This REDOX equilibrium is controlled by the microbiota either directly or indirectly via bacterial-derived metabolites. A balanced microbiome sorts for a stable REDOX balance, whereas dysbiosis destabilizes this equilibrium. An imbalanced REDOX status directly affects the immune system by disrupting intracellular signaling and promoting inflammatory responses. Here we (i) focus on the most common reactive oxygen species (ROS) and (ii) define the transition from a balanced REDOX state to oxidative stress. Further, we (iii) describe the role of ROS in regulating the immune system and inflammatory responses. Thereafter, we (iv) examine the influence of microbiota on REDOX homeostasis and how shifts in pro- and anti-oxidative cellular conditions can suppress or promote immune responses or inflammation.

ROS fine-tunes the function and fate of immune cells

The redox state is essential to the process of cell life, which determines cell fate. As an important signaling molecule of the redox state, reactive oxygen species (ROS) are crucial for the homeostasis of immune cells and participate in the pathological processes of different diseases. We discuss the underlying mechanisms and possible signaling pathways of ROS to fine-tune the proliferation, differentiation, polarization and function of immune cells, including T cells, B cells, neutrophils, macrophages, myeloid-derived inhibitory cells (MDSCs) and dendritic cells (DCs). We further emphasize how excessive ROS lead to programmed immune cell death such as apoptosis, ferroptosis, pyroptosis, NETosis and necroptosis, providing valuable insights for future therapeutic strategies in human diseases.

Treatment with Exogenously Added Catalase Alters CD8 T Cell Memory Differentiation and Function

Cell-based immunotherapy is a promising approach to cancer treatment. However, the metabolically hostile tumor microenvironment (TME) poses a major barrier to this therapeutic approach. Metabolic reprogramming may enhance T cell effector function and support longevity and persistence within the TME. Metabolic processes lead reactive oxygen species (ROS) production, which are mandatory mediators of signaling and immune cell functions, but detrimental when present in excess. Catalase (CAT) is an intracellular antioxidant enzyme that scavenges hydrogen peroxide (H2 O2 ), a central ROS member with a plethora of biological effects. H2 O2 is produced intracellularly and extracellularly, diffusing freely between the two compartments. In this study, it is found that scavenging extracellular H2 O2 by CAT supplementation has a major impact on the cell redox state, decreased intracellular ROS, but enhanced activation and altered memory differentiation. Under in vitro chronic activation conditions, CAT treatment favors CD8 T cells with less exhausted phenotype, increased activation and memory markers, and high bioenergetic capacity. Under in vitro acute activation conditions, CAT treatment selectively prevents differentiation transition from the stem cell memory/naive (TSCM /TN )- to the central memory (TCM )-like phenotype, while enhancing activation and polyfunctionality. The study highlights the critical role of H2 O2 as a "hidden player" in T cell fitness and memory differentiation.

P2RX7 signaling drives the differentiation of Th1 cells through metabolic reprogramming for aerobic glycolysis

Introduction

This study provides evidence of how Th1 cell metabolism is modulated by the purinergic receptor P2X7 (P2RX7), a cation cannel activated by high extracellular concentrations of adenosine triphosphate (ATP).

Methods

In vivo analysis was performed in the Plasmodium chabaudi model of malaria in view of the great relevance of this infectious disease for human health, as well as the availability of data concerning Th1/Tfh differentiation.

Results

We show that P2RX7 induces T-bet expression and aerobic glycolysis in splenic CD4+ T cells that respond to malaria, at a time prior to Th1/Tfh polarization. Cell-intrinsic P2RX7 signaling sustains the glycolytic pathway and causes bioenergetic mitochondrial stress in activated CD4+ T cells. We also show in vitro the phenotypic similarities of Th1-conditioned CD4+ T cells that do not express P2RX7 and those in which the glycolytic pathway is pharmacologically inhibited. In addition, in vitro ATP synthase blockade and the consequent inhibition of oxidative phosphorylation, which drives cellular metabolism for aerobic glycolysis, is sufficient to promote rapid CD4+ T cell proliferation and polarization to the Th1 profile in the absence of P2RX7.

Conclusion

These data demonstrate that P2RX7-mediated metabolic reprograming for aerobic glycolysis is a key event for Th1 differentiation and suggest that ATP synthase inhibition is a downstream effect of P2RX7 signaling that potentiates the Th1 response.

Mitochondria-Related Transcriptome Characterization Associated with the Immune Microenvironment, Therapeutic Response and Survival Prediction in Pancreatic Cancer

(1) Background: Pancreatic cancer (PC) is one of the most lethal tumors. Mitochondrial dysfunction has been reported to be involved in cancer development; however, its role in PC has remained unclear. (2) Methods: The differentially expressed NMGs were selected between PC and normal pancreatic tissue. The NMG-related prognostic signature was established by LASSO regression. A nomogram was developed based on the 12-gene signature combined with other significant pathological features. An extensive analysis of the 12 critical NMGs was performed in multiple dimensions. The expression of some key genes was verified in our external cohort. (3) Results: Mitochondria-related transcriptome features was obviously altered in PC compared with normal pancreas tissue. The 12-NMG signature showed good performance in predicting prognosis in various cohorts. The high- and low-risk groups exhibited notable diversity in gene mutation characteristics, biological characteristics, chemotherapy response, and the tumor immune microenvironment. Critical gene expression was demonstrated in our cohort at the mRNA and protein levels and in organelle localization. (4) Conclusions: Our study analyzed the mitochondrial molecular characterization of PC, proving the crucial role of NMGs in PC development. The established NMG signature helps classify patient subtypes in terms of prognosis prediction, treatment response, immunological features, and biological function, providing a potential therapeutic strategy targeting mitochondrial transcriptome characterization.

Modulation of redox homeostasis: A strategy to overcome cancer drug resistance

Cancer treatment is hampered by resistance to conventional therapeutic strategies, including chemotherapy, immunotherapy, and targeted therapy. Redox homeostasis manipulation is one of the most effective innovative treatment techniques for overcoming drug resistance. Reactive oxygen species (ROS), previously considered intracellular byproducts of aerobic metabolism, are now known to regulate multiple signaling pathways as second messengers. Cancer cells cope with elevated amounts of ROS during therapy by upregulating the antioxidant system, enabling tumor therapeutic resistance via a variety of mechanisms. In this review, we aim to shed light on redox modification and signaling pathways that may contribute to therapeutic resistance. We summarized the molecular mechanisms by which redox signaling-regulated drug resistance, including altered drug efflux, action targets and metabolism, enhanced DNA damage repair, maintained stemness, and reshaped tumor microenvironment. A comprehensive understanding of these interrelationships should improve treatment efficacy from a fundamental and clinical research point of view.

Mitochondria Drive Immune Responses in Critical Disease

Mitochondria engage in multiple cellular and extracellular signaling pathways ranging from metabolic control, antiviral and antibacterial host defense to the modulation of inflammatory responses following cellular damage and stress. The remarkable contributions of these organelles to innate and adaptive immunity, shape cell phenotype and modulate their functions during infection, after trauma and in the setting of inflammatory disease. We review the latest knowledge of mitochondrial biology and then discuss how these organelles may impact immune cells to drive aberrant immune responses in critical disease.

Receptor-Mediated Redox Imbalance: An Emerging Clinical Avenue against Aggressive Cancers

Cancer cells are more vulnerable to abnormal redox fluctuations due to their imbalanced antioxidant system, where cell surface receptors sense stress and trigger intracellular signal relay. As canonical targets of many targeted therapies, cell receptors sensitize the cells to specific drugs. On the other hand, cell target mutations are commonly associated with drug resistance. Thus, exploring effective therapeutics targeting diverse cell receptors may open new clinical avenues against aggressive cancers. This paper uses focused case studies to reveal the intrinsic relationship between the cell receptors of different categories and the primary cancer hallmarks that are associated with the responses to external or internal redox perturbations. Cold atmospheric plasma (CAP) is examined as a promising redox modulation medium and highly selective anti-cancer therapeutic modality featuring dynamically varying receptor targets and minimized drug resistance against aggressive cancers.

Impaired migratory phenotype of CD4+ T cells in Parkinson's disease

Dysfunctions in the immune system appear implicated in both disease onset and progression of Parkinson's disease (PD). Neurodegeneration observed in the brain of PD patients has been associated with neuroinflammation that is linked to alterations in peripheral adaptive immunity, where CD4⁺ T cells are key players. In the present study, we elucidated the immunological aspect of PD by employing a wide range of cellular assays, immunocytochemistry and flow cytometry to examine CD4⁺ T cells. We particularly investigated the role of CD4⁺ T cell migration in the proper functioning of the adaptive immune system. Our data reveal the altered migration potential of CD4⁺ T cells derived from PD patients, along with impaired mitochondrial positioning within the cell and reduced mitochondrial functionality. In addition, a cross-sectional study of p11 levels in CD4⁺ T cell subsets showed a differentially increased level of p11 in Th1, Th2 and Th17 populations. Taken together, these results demonstrate major impairments in the functionality of peripheral CD4⁺ T cells in PD.

Energy substrate metabolism and oxidative stress in metabolic cardiomyopathy

Metabolic cardiomyopathy is an emerging cause of heart failure in patients with obesity, insulin resistance, and diabetes. It is characterized by impaired myocardial metabolic flexibility, intramyocardial triglyceride accumulation, and lipotoxic damage in association with structural and functional alterations of the heart, unrelated to hypertension, coronary artery disease, and other cardiovascular diseases. Oxidative stress plays an important role in the development and progression of metabolic cardiomyopathy. Mitochondria are the most significant sources of reactive oxygen species (ROS) in cardiomyocytes. Disturbances in myocardial substrate metabolism induce mitochondrial adaptation and dysfunction, manifested as a mismatch between mitochondrial fatty acid oxidation and the electron transport chain (ETC) activity, which facilitates ROS production within the ETC components. In addition, non-ETC sources of mitochondrial ROS, such as β-oxidation of fatty acids, may also produce a considerable quantity of ROS in metabolic cardiomyopathy. Augmented ROS production in cardiomyocytes can induce a variety of effects, including the programming of myocardial energy substrate metabolism, modulation of metabolic inflammation, redox modification of ion channels and transporters, and cardiomyocyte apoptosis, ultimately leading to the structural and functional alterations of the heart. Based on the above mechanistic views, the present review summarizes the current understanding of the mechanisms underlying metabolic cardiomyopathy, focusing on the role of oxidative stress.

Elucidating the mitochondrial function of murine lymphocyte subsets and the heterogeneity of the mitophagy pathway inherited from hematopoietic stem cells

BACKGROUND

Mitochondria are mainly involved in ATP production to meet the energy demands of cells. Researchers are increasingly recognizing the important role of mitochondria in the differentiation and activation of hematopoietic cells, but research on how mitochondrial metabolism influence different subsets of lymphocyte at different stages of differentiation and activation are yet to be carried out. In this work, the mitochondrial functions of lymphocytes were compared at different differentiation and activation stages and included CD8+ T lymphocytes, CD4+ T lymphocytes, B lymphocytes, NK cells as well as their subsets. For this purpose, a complete set of methods was used to comprehensively analyze mitophagy levels, mitochondrial reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and the mitochondrial mass (MM) of subsets of lymphocytes. It is expected that this will provide a complete set of standards, and drawing the mitochondrial metabolic map of lymphocyte subsets at different stages of differentiation and activation.

RESULTS AND DISCUSSION

Of all lymphocytes, B cells had a relatively high mitochondrial metabolic activity which was evident from the higher levels of mitophagy, ROS, MMP and MM, and this reflected the highly heterogeneous nature of the mitochondrial metabolism in lymphocytes. Among the B cell subsets, pro-B cells had relatively higher levels of MM and MMP, while the mitochondrial metabolism level of mature B cells was relatively low. Similarly, among the subsets of CD4+ T cell, a relatively higher level of mitochondrial metabolism was noted for naive CD4+ T cells. Finally, from the CD8+ T cell subsets, CD8+ Tcm had relatively high levels of MM and MMP but relatively low ones for mitophagy, with effector T cells displaying the opposite characteristics. Meanwhile, the autophagy-related genes of lymphoid hematopoietic cells including hematopoietic stem cells, hematopoietic progenitor cells and lymphocyte subsets were analyzed, which preliminarily showed that these cells were heterogeneous in the selection of mitophagy related Pink1/Park2, BNIP3/NIX and FUNDC1 pathways. The results showed that compared with CD4+ T, CD8+ T and NK cells, B cells were more similar to long-term hematopoietic stem cell (LT-HSC) and short-term hematopoietic stem cell (ST-HSC) in terms of their participation in the Pink1/Park2 pathway, as well as the degree to which the characteristics of autophagy pathway were inherited from HSC. Compared with CLP and B cells, HSC are less involved in BNIP3/NIX pathway. Among the B cell subsets, pro-B cells inherited the least characteristics of HSC in participating in Pink1/Park2 pathway compared with pre-B, immature B and immature B cells. Among CD4+ T cell subsets, nTreg cells inherited the least characteristics of HSC in participating in Pink1/Park2 pathway compared with naive CD4+ T and memory CD4+ T cells. Among the CD8+ T cell subsets, compared with CLP and effector CD8+ T cells, CD8+ Tcm inherit the least characteristics of HSC in participating in Pink1/Park2 pathway. Meanwhile, CLP, naive CD4+ T and effector CD8+ T were more involved in BNIP3/NIX pathway than other lymphoid hematopoietic cells.

CONCLUSION

This study is expected to provide a complete set of methods and basic reference values for future studies on the mitochondrial functions of lymphocyte subsets at different stages of differentiation and activation in physiological state, and also provides a standard and reference for the study of infection and immunity based on mitochondrial metabolism.

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.

Dual near-infrared II laser modulates the cellular redox state of T cells and augments the efficacy of cancer immunotherapy

Immunotherapy, including immune checkpoint inhibitors, has revolutionized cancer treatment, but only a minor fraction of patients shows durable responses. A new approach to overcome this limitation is yet to be identified. Recently, we have shown that photobiomodulation (PBM) with near-infrared (NIR) light in the NIR-II window reduces oxidative stress and supports the proliferation of CD8+ T cells, suggesting that PBM with NIR-II light could augment anti-cancer immunity. Here, we report a novel approach to support tumor-infiltrating CD8+ T cells upon PBM with NIR-II laser with high tissue penetration depth. Brief treatments of a murine model of breast cancer with dual 1064 and 1270 nm lasers reduced the expression of the programmed cell death protein 1 (PD-1) in CD8+ T cells in a syngeneic mouse model of breast cancer. The direct effect of the NIR-II laser treatment on T cells was confirmed by the enhanced tumor growth delay by the adoptive transfer of laser-treated CD8+ T cells ex vivo against a model tumor antigen. We further demonstrated that specific NIR-II laser parameters augmented the effect of the immune checkpoint inhibitor on tumor growth. PBM with NIR-II light augments the efficacy of cancer immunotherapy by supporting CD8+ T cells. Unlike the current immunotherapy with risks of undesirable drug-drug interactions and severe adverse events, the laser is safe and low-cost. It can be broadly combined with other therapy without modification to achieve clinical significance. In addition, our study established a path to develop a novel laser-based therapy to treat cancer effectively.

The emerging role of microbiota-derived short-chain fatty acids in immunometabolism

The accumulating evidence revealed that microbiota plays a significant function in training, function, and the induction of host immunity. Once this interaction (immune system-microbiota) works correctly, it enables the production of protective responses against pathogens and keeps the regulatory pathways essential for maintaining tolerance to innocent antigens. This concept of immunity and metabolic activity redefines the realm of immunometabolism, paving the way for innovative therapeutic interventions to modulate immune cells through immune metabolic alterations. A body of evidence suggests that microbiota-derived metabolites, including short-chain fatty acids (SCFAs) such as butyrate, acetate, and propionate, play a key role in immune balance. SCFAs act on many cell types to regulate various vital biological processes, including host metabolism, intestinal function, and the immune system. Such SCFAs generated by gut bacteria also impact immunity, cellular function, and immune cell fate. This is a new concept of immune metabolism, and better knowledge about how lifestyle affects intestinal immunometabolism is crucial for preventing and treating disease. In this review article, we explicitly focus on the function of SCFAs in the metabolism of immune cells, especially macrophages, neutrophils, dendritic cells (DCs), B cells, T (Th) helper cells, and cytotoxic T cells (CTLs).

P2 Receptors: Novel Disease Markers and Metabolic Checkpoints in Immune Cells

Extracellular ATP (eATP) and P2 receptors are novel emerging regulators of T-lymphocyte responses. Cellular ATP is released via multiple pathways and accumulates at sites of tissue damage and inflammation. P2 receptor expression and function are affected by numerous single nucleotide polymorphisms (SNPs) associated with diverse disease conditions. Stimulation by released nucleotides (purinergic signalling) modulates several T-lymphocyte functions, among which energy metabolism. Energy metabolism, whether oxidative or glycolytic, in turn deeply affects T-cell activation, differentiation and effector responses. Specific P2R subtypes, among which the P2X7 receptor (P2X7R), are either up- or down-regulated during T-cell activation and differentiation; thus, they can be considered indexes of activation/quiescence, reporters of T-cell metabolic status and, in principle, markers of immune-mediated disease conditions.

Mitochondrial reactive oxygen is critical for IL-12/IL-18-induced IFN-γ production by CD4+ T cells and is regulated by Fas/FasL signaling

Mitochondrial activation and the production of mitochondrial reactive oxygen species (mROS) are crucial for CD4⁺ T cell responses and have a role in naïve cell signaling after TCR activation. However, little is known about mROS role in TCR-independent signaling and in recall responses. Here, we found that mROS are required for IL-12 plus IL-18-driven production of IFN-γ, an essential cytokine for inflammatory and autoimmune disease development. Compared to TCR stimulation, which induced similar levels of mROS in naïve and memory-like cells, IL-12/IL-18 showed faster and augmented mROS production in memory-like cells. mROS inhibition significantly downregulated IFN-γ and CD44 expression, suggesting a direct mROS effect on memory-like T cell function. The mechanism that promotes IFN-γ production after IL-12/IL-18 challenge depended on the effect of mROS on optimal activation of downstream signaling pathways, leading to STAT4 and NF-κB activation. To relate our findings to IFN-γ-driven lupus-like disease, we used Fas-deficient memory-like CD4⁺ T cells from lpr mice. Importantly, we found significantly increased IFN-γ and mROS production in lpr compared with parental cells. Treatment of WT cells with FasL significantly reduced mROS production and the activation of signaling events leading to IFN-γ. Moreover, Fas deficiency was associated with increased mitochondrial levels of cytochrome C and caspase-3 compared with WT memory-like cells. mROS inhibition significantly reduced the population of disease-associated lpr CD44^hiCD62L^loCD4⁺ T cells and their IFN-γ production. Overall, these findings uncovered a previously unidentified role of Fas/FasL interaction in regulating mROS production by memory-like T cells. This apoptosis-independent Fas activity might contribute to the accumulation of CD44^hiCD62L^loCD4⁺ T cells that produce increased IFN-γ levels in lpr mice. Overall, our findings pinpoint mROS as central regulators of TCR-independent signaling, and support mROS pharmacological targeting to control aberrant immune responses in autoimmune-like disease.

The role of ROS in tumour development and progression

Eukaryotic cells have developed complex systems to regulate the production and response to reactive oxygen species (ROS). Different ROS control diverse aspects of cell behaviour from signalling to death, and deregulation of ROS production and ROS limitation pathways are common features of cancer cells. ROS also function to modulate the tumour environment, affecting the various stromal cells that provide metabolic support, a blood supply and immune responses to the tumour. Although it is clear that ROS play important roles during tumorigenesis, it has been difficult to reliably predict the effect of ROS modulating therapies. We now understand that the responses to ROS are highly complex and dependent on multiple factors, including the types, levels, localization and persistence of ROS, as well as the origin, environment and stage of the tumours themselves. This increasing understanding of the complexity of ROS in malignancies will be key to unlocking the potential of ROS-targeting therapies for cancer treatment.

The SNPs of mitochondrial DNA displacement loop region and mitochondrial DNA copy number associated with risk of polymyositis and dermatomyositis

Oxidative damage-induced mitochondrial dysfunction may activate muscle catabolism and autophagy pathways to initiate muscle weakening in idiopathic inflammatory myopathies (IIMs). In this study, Single nucleotide polymorphisms (SNPs) in the mitochondrial displacement loop (D-loop) and mitochondrial DNA (mtDNA) copy number were assessed and their association with the risk of polymyositis and dermatomyositis (PM/DM) was evaluated. Excessive D-loop SNPs (8.779 ± 1.912 vs. 7.972 ± 1.903, p = 0.004) correlated positively with mtDNA copy number (0.602 ± 0.457 vs. 0.300 ± 0.118, p < 0.001). Compared with that of the controls, the mtDNA of PM/DM patients showed D-loop SNP accumulation. In addition, the distribution frequencies of 16304C (p = 0.047) and 16519C (p = 0.043) were significantly higher in the patients with PM/DM. Subsequent analysis showed that reactive oxygen species (ROS) generation was increased in PM/DM patients compared with that in the controls (18,477.756 ± 13,574.916 vs. 14,484.191 ± 5703.097, p = 0.012). Further analysis showed that the PM/DM risk-related allele 16304C was significantly associated with lower IL-4 levels (p = 0.021), while 16519C had a trend to be associated with higher IL-2 expression (p = 0.064). The allele 16519C was associated with a positive antinuclear antibody (ANA) status in PM/DM patients (p = 0.011). Our findings suggest that mitochondrial D-loop SNPs could be potential biomarkers for PM/DM risk and these SNPs associated with cytokine expression may be involved in the development of PM/DM. Further, mtDNA copy number-mediated mitochondrial dysfunction may precede the onset of PM/DM.

SENP7 senses oxidative stress to sustain metabolic fitness and antitumor functions of CD8+ T cells

The functional integrity of CD8⁺ T cells is tightly coupled to metabolic reprogramming, but how oxidative stress directs CD8⁺ T cell metabolic fitness in the tumor microenvironment (TME) remains elusive. Here, we report that SUMO-specific protease 7 (SENP7) senses oxidative stress to maintain the CD8⁺ T cell metabolic state and antitumor functions. SENP7-deficient CD8⁺ T cells exhibited decreased glycolysis and oxidative phosphorylation, resulting in attenuated proliferation in vitro and dampened antitumor functions in vivo. Mechanistically, CD8⁺ T cell–derived ROS triggered cytosolic SENP7–mediated PTEN deSUMOylation, thereby promoting PTEN degradation and preventing PTEN-dependent metabolic defects. Importantly, lowering T cell–intrinsic ROS restricted SENP7 cytosolic translocation and repressed CD8⁺ T cell metabolic and functional activity in human colorectal cancer samples. Our findings reveal that SENP7, as an oxidative stress sensor, sustains CD8⁺ T cell metabolic fitness and effector functions and unveil an oxidative stress–sensing machinery in tumor-infiltrating CD8⁺ T cells.

T cell metabolism and possible therapeutic targets in systemic lupus erythematosus: a narrative review

In the immunopathogenesis of systemic lupus erythematosus (SLE), there is a dysregulation of specific immune cells, including T cells. The metabolic reprogramming in T cells causes different effects. Metabolic programs are critical checkpoints in immune responses and are involved in the etiology of autoimmune disease. For instance, resting lymphocytes generate energy through oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO), whereas activated lymphocytes rapidly shift to the glycolytic pathway. Specifically, mitochondrial dysfunction, oxidative stress, abnormal metabolism (including glucose, lipid, and amino acid metabolism), and mTOR signaling are hallmarks of T lymphocyte metabolic dysfunction in SLE. Herein it is summarized how metabolic defects contribute to T cell responses in SLE, and some epigenetic alterations involved in the disease. Finally, it is shown how metabolic defects could be modified therapeutically.

Prescription Drugs and Mitochondrial Metabolism

Mitochondria are central to the physiology and survival of nearly all eukaryotic cells and house diverse metabolic processes including oxidative phosphorylation, reactive oxygen species buffering, metabolite synthesis/exchange, and Ca2+ sequestration. Mitochondria are phenotypically heterogeneous and this variation is essential to the complexity of physiological function among cells, tissues, and organ systems. As a consequence of mitochondrial integration with so many physiological processes, small molecules that modulate mitochondrial metabolism induce complex systemic effects. In the case of many common prescribed drugs, these interactions may contribute to drug therapeutic mechanisms, induce adverse drug reactions, or both. The purpose of this article is to review historical and recent advances in the understanding of the effects of prescription drugs on mitochondrial metabolism. Specific 'modes' of xenobiotic-mitochondria interactions are discussed to provide a set of qualitative models that aid in conceptualizing how the mitochondrial energy transduction system may be affected. Findings of recent in vitro high-throughput screening studies are reviewed, and a few candidate drug classes are chosen for additional brief discussion (i.e. antihyperglycemics, antidepressants, antibiotics, and antihyperlipidemics). Finally, recent improvements in pharmacokinetic models that aid in quantifying systemic effects of drug-mitochondria interactions are briefly considered.

Mitochondrial Displacement Loop Region SNPs Modify Sjögren’s Syndrome Development by Regulating Cytokines Expression in Female Patients

Mitochondrial dysfunction could induce innate immune response with cytokines releasing to initiate Sjögren’s syndrome (SS) onset. Single nucleotide polymorphisms (SNPs) in the mitochondrial displacement loop (D-loop) and mitochondrial DNA (mtDNA) copy number of female SS patients were evaluated for their association with SS in female patients. At the nucleotide site of 152, 16304, 16311 and 16362 in the D-loop, the frequencies for the minor alleles of 152C (p = 0.040, odds ratio [OR] = 0.504), 16304C (p = 0.045, OR = 0.406), 16311C (p = 0.045, OR = 0.406) and 16362C (p = 0.028, OR = 0.519) were significantly higher in the SS patients than those in the female controls, which indicated that 152,C, 16304C, 16311C, and 16362C allele in the D-loop of mtDNA were associated with the risk of SS. Meanwhile, the excessive SNPs were accumulated in D-loop region of SS patients (8.955 ± 2.028 versus 7.898 ± 1.987, p < 0.001, 95% confidence interval [CI]: 0.477–1.637) and mtDNA copy number increased in SS patients (1.509 ± 0.836 versus 1.221 ± 0.506, p = 0.006, 95% CI: 0.086–0.490) by a case-control analysis. The subsequent analysis showed that SS risk-related allele 16311C was associated with higher IL-2 levels (p = 0.010) at significantly statistical level whereas 152C associated with lower IL-10 levels (p = 0.058) at a borderline statistical levels. Our findings suggest that mitochondrial D-loop SNPs are predictors for SS risk, it might modify the SS development by regulating cytokine expression.