B Cell Function in the Tumor Microenvironment.

The tumor microenvironment (TME) is a heterogeneous, complex organization composed of tumor, stroma, and endothelial cells that is characterized by cross talk between tumor and innate and adaptive immune cells. Over the last decade, it has become increasingly clear that the immune cells in the TME play a critical role in controlling or promoting tumor growth. The function of T lymphocytes in this process has been well characterized. On the other hand, the function of B lymphocytes is less clear, although recent data from our group and others have strongly indicated a critical role for B cells in antitumor immunity. There are, however, a multitude of populations of B cells found within the TME, ranging from naive B cells all the way to terminally differentiated plasma cells and memory B cells. Here, we characterize the role of B cells in the TME in both animal models and patients, with an emphasis on dissecting how B cell heterogeneity contributes to the immune response to cancer.

Management of Velopharyngeal Insufficiency in Cleft Patients With and Without Multidisciplinary Team Care.

OBJECTIVE: To evaluate the effect of an American Cleft Palate-Craniofacial Association (ACPA)-approved multidisciplinary team on velopharyngeal insufficiency (VPI) diagnosis and treatment. DESIGN: Retrospective cohort setting; tertiary children's hospital patients; children with cleft palate repair identified through procedure codes. MAIN OUTCOME MEASURES: Velopharyngeal insufficiency diagnosis was assigned based on surgeon or team assessment. Age at diagnosis and surgery was recorded. Difference in age and rate of VPI diagnosis and surgery was analyzed with t test. Multivariate linear and logistic regression adjusted for confounding variables. RESULTS: Nine hundred forty patients were included with 71.5% cared for by an ACPA-approved multidisciplinary team. More (38.8% ) team care patients were found to have a diagnosis of VPI in comparison to 10% in independent care (P < .001). Team care was associated with an almost 6-fold increase in VPI diagnosis (P < .001). Team care was associated with a higher proportion of speech surgery (21% vs 10%, P < .001). Among children receiving team care, each visit was associated with 25% increased odds of being diagnosed with VPI (P < .001) and 20% increased odds of receiving speech surgery (P < .001). Age at VPI diagnosis and speech surgery were similar between groups (P = .55 and .29). DISCUSSION: Team care was associated with more accurate detection of VPI, resulting in more VPI speech therapy visits and surgical management. A higher number of team visits were similarly associated. CONCLUSION: Further studies of the clinical implication of timely and accurate VPI diagnosis, including quality of life assessments, are recommended to provide stronger guidance on team visit and evaluation planning.

Discovery and characterization of small molecules that target the GTPase Ral.

The Ras-like GTPases RalA and RalB are important drivers of tumour growth and metastasis. Chemicals that block Ral function would be valuable as research tools and for cancer therapeutics. Here we used protein structure analysis and virtual screening to identify drug-like molecules that bind to a site on the GDP-bound form of Ral. The compounds RBC6, RBC8 and RBC10 inhibited the binding of Ral to its effector RALBP1, as well as inhibiting Ral-mediated cell spreading of murine embryonic fibroblasts and anchorage-independent growth of human cancer cell lines. The binding of the RBC8 derivative BQU57 to RalB was confirmed by isothermal titration calorimetry, surface plasmon resonance and (1)H-(15)N transverse relaxation-optimized spectroscopy (TROSY) NMR spectroscopy. RBC8 and BQU57 show selectivity for Ral relative to the GTPases Ras and RhoA and inhibit tumour xenograft growth to a similar extent to the depletion of Ral using RNA interference. Our results show the utility of structure-based discovery for the development of therapeutics for Ral-dependent cancers.

Increased Risk of Velopharyngeal Insufficiency in Patients Undergoing Staged Palate Repair.

OBJECTIVE: To evaluate the association of 2-stage cleft palate (CP) surgery on velopharyngeal insufficiency (VPI) incidence, speech surgeries, and cleft-related surgical burden. DESIGN: Retrospective cohort with follow-up of 4 to 19 years. SETTING: Academic, tertiary children's hospital. PATIENTS: Patients who underwent CP surgery between 2000 and 2017. Exclusions included submucous CP or age at last contact under 3.9. INTERVENTIONS: Cleft palate surgery, completed in either a single-stage or 2-stage repair. MAIN OUTCOME MEASURE(S): Rates of VPI diagnosis and speech surgery and total cleft surgeries; t tests, tests of proportion, and linear and logistic regression were performed. Total cleft-related surgeries were examined in a subset (n = 418) of patients with chart reviews. RESULTS: A total of 1047 patients were included; 59.6% had 2-stage CP repair, 40.4% had single-stage repair. Approximately 32% of children with 2-stage CP repair were diagnosed with VPI, as opposed to 22% of single-stage patients (P < .001). Children with 2-stage CP repair were 1.8 times as likely to be diagnosed with VPI (P < .001). Speech surgery rates were similar across groups. Patients who had 2-stage repair received an average of 2.3 more cleft-related procedures, when excluding prosthesis management procedures. CONCLUSION: Our data show an increased risk of VPI diagnosis and increased surgical burden among patients receiving 2-stage CP repair.

Turn analysis and patient-centredness in paediatric otolaryngology surgical consultations.

OBJECTIVES: Physician and patient/parent communication is of utmost importance in consultations to improve the shared decision-making (SDM) processes. This study investigated SDM-related outcomes through turn analysis and an assessment of patient-centred dialogue. DESIGN: Multi-centre prospective cohort study analysing audio- and video-recorded patient/parent-physician interactions. SETTING: Two tertiary paediatric hospitals in Halifax, Nova Scotia and Salt Lake City, Utah. PARTICIPANTS: Paediatric otolaryngologists, patients and parents during consultation for adenotonsillectomy. MAIN OUTCOME MEASURES: Medical dialogue measures (turn analysis, patient-centredness scores via the Roter Interaction Analysis System) and SDM questionnaires (SDM-Q-9). RESULTS: Turn density was significantly higher for physicians than patients/parents (P < .001), as were total statements (P < .001), and total time talking (P < .001). The opening statement was completed by the physician in 91.5% of interactions and was significantly longer than family opening statements (P = .003). The mean number of informed consent elements addressed per interaction was 4.5 out of 6. The mean patient-centredness score was 0.2 (range 0-0.56). Significant negative correlations between patient-centredness score and physician turn density (r = -.390, P = .002), physician mean turn time (r = -.406, P = .001), total physician statements (r = -.426, P = .001) and total physician speaking time (r = -.313, P = .016) were noted. There were no correlations in SDM questionnaire scores with turn analysis variables, informed consent elements or patient-centredness scores. CONCLUSIONS: Surgeons dominated the consultation in terms of talking, mostly in a unidirectional manner. Neither patient-centredness nor turn analysis correlated with perceptions of SDM from the parents' perspective.

T Cell Repertoire Evolution after Allogeneic Bone Marrow Transplantation: An Organizational Perspective.

High-throughput sequencing (HTS) of human T cell receptors has revealed a high level of complexity in the T cell repertoire, which makes it difficult to correlate T cell reconstitution with clinical outcomes. The associations identified thus far are of a broadly statistical nature, precluding precise modeling of outcomes based on T cell repertoire development following bone marrow transplantation (BMT). Previous work has demonstrated an inherent, mathematically definable order observed in the T cells from a diverse group of donors, which is perturbed in recipients following BMT. In this study, T cell receptor (TCR)-ß sequences from HLA-matched related donor and recipient pairs are analyzed to further develop this methodology. TCR-ß sequencing from unsorted and sorted T cell subsets isolated from the peripheral blood samples of BMT donors and recipients show conservation and symmetry of VJ segment usage in the clonal frequencies, linked to the organization of the gene segments along the TCR locus. This TCR-ß VJ segment translational symmetry is preserved post-transplantation and even in cases of acute graft-versus-host disease (aGVHD), suggesting that GVHD occurrence represents a polyclonal donor T cell response to recipient antigens. The complexity of the repertoire is significantly diminished after BMT, and the T cell clonal hierarchy is altered post-transplantation. Low-frequency donor clones tended to take on a higher rank in the recipients following BMT, especially in patients with aGVHD. Over time, the repertoire evolves to a more donor-like state in the recipients who did not develop GVHD as opposed to those who did. The results presented here support new methods of quantifying and characterizing post-transplantation T cell repertoire reconstitution.

STAT3 suppresses Wnt/ß-catenin signaling during the induction phase of primary Myf5+ brown adipogenesis.

Thermogenic fat is a promising target for new therapies in diabetes and obesity. Understanding how thermogenic fat develops is important to develop rational strategies to treat obesity. Previously, we have shown that Tyk2 and STAT3, part of the JAK-STAT pathway, are necessary for proper development of classical brown fat. Using primary preadipocytes isolated from newborn mice we demonstrate that STAT3 is required for differentiation and robust expression of Uncoupling Protein 1 (UCP1). We also confirm that STAT3 is necessary during the early induction stage of differentiation and is dispensable during the later terminal differentiation stage. The inability of STAT3-/- preadipocytes to differentiate can be rescued using Wnt ligand secretion inhibitors when applied during the induction stage. Through chemical inhibition and RNAi, we show that it is the canonical ß-catenin pathway that is responsible for the block in differentiation; inhibition or knockdown of ß-catenin can fully rescue adipogenesis and UCP1 expression in the STAT3-/- adipocytes. During the induction stage, Wnts 1, 3a, and 10b have increased expression in the STAT3-/- adipocytes, potentially explaining the increased levels and activity of ß-catenin. Our results for the first time point towards an interaction between the JAK/STAT pathway and the Wnt/ß-catenin pathway during the early stages of in-vitro adipogenesis.

Toward a new STATe: the role of STATs in mitochondrial function.

Signal Transducers and Activators of Transcription (STATs) have been studied extensively and have been associated with virtually every biochemical pathway. Until recently, however, they were thought to exert these effects solely as a nuclear transcription factor. The finding that STAT3 localizes to the mitochondria and modulates respiration has opened up a new avenue through which STATs may regulate the cell. Recently, other members of the STAT family (STAT1, STAT2, STAT5, and STAT6) have also been shown to be present in the mitochondria. Coordinate regulation at the nucleus and mitochondria by these proteins places them in a unique position to drive cellular processes to achieve a specific response. This review summarizes recent findings that have led to our current understanding of how STATs influence mitochondrial function in health and disease.

Dynamical System Modeling to Simulate Donor T Cell Response to Whole Exome Sequencing-Derived Recipient Peptides Demonstrates Different Alloreactivity Potential in HLA-Matched and -Mismatched Donor-Recipient Pairs.

Immune reconstitution kinetics and subsequent clinical outcomes in HLA-matched recipients of allogeneic stem cell transplantation (SCT) are variable and difficult to predict. Considering SCT as a dynamical system may allow sequence differences across the exomes of the transplant donors and recipients to be used to simulate an alloreactive T cell response, which may allow better clinical outcome prediction. To accomplish this, whole exome sequencing was performed on 34 HLA-matched SCT donor-recipient pairs (DRPs) and the nucleotide sequence differences translated to peptides. The binding affinity of the peptides to the relevant HLA in each DRP was determined. The resulting array of peptide-HLA binding affinity values in each patient was considered as an operator modifying a hypothetical T cell repertoire vector, in which each T cell clone proliferates in accordance with the logistic equation of growth. Using an iterating system of matrices, each simulated T cell clone's growth was calculated with the steady-state population being proportional to the magnitude of the binding affinity of the driving HLA-peptide complex. Incorporating competition between T cell clones responding to different HLA-peptide complexes reproduces a number of features of clinically observed T cell clonal repertoire in the simulated repertoire, including sigmoidal growth kinetics of individual T cell clones and overall repertoire, Power Law clonal frequency distribution, increase in repertoire complexity over time with increasing clonal diversity, and alteration of clonal dominance when a different antigen array is encountered, such as in SCT. The simulated, alloreactive T cell repertoire was markedly different in HLA-matched DRPs. The patterns were differentiated by rate of growth and steady-state magnitude of the simulated T cell repertoire and demonstrate a possible correlation with survival. In conclusion, exome wide sequence differences in DRPs may allow simulation of donor alloreactive T cell response to recipient antigens and may provide a quantitative basis for refining donor selection and titration of immunosuppression after SCT.

Dynamical System Modeling of Immune Reconstitution after Allogeneic Stem Cell Transplantation Identifies Patients at Risk for Adverse Outcomes.

Systems that evolve over time and follow mathematical laws as they evolve are called dynamical systems. Lymphocyte recovery and clinical outcomes in 41 allograft recipients conditioned using antithymocyte globulin (ATG) and 4.5-Gy total body irradiation were studied to determine if immune reconstitution could be described as a dynamical system. Survival, relapse, and graft-versus-host disease (GVHD) were not significantly different in 2 cohorts of patients receiving different doses of ATG. However, donor-derived CD3(+) cell reconstitution was superior in the lower ATG dose cohort, and there were fewer instances of donor lymphocyte infusion (DLI). Lymphoid recovery was plotted in each individual over time and demonstrated 1 of 3 sigmoid growth patterns: Pattern A (n = 15) had rapid growth with high lymphocyte counts, pattern B (n = 14) had slower growth with intermediate recovery, and pattern C (n = 10) had poor lymphocyte reconstitution. There was a significant association between lymphocyte recovery patterns and both the rate of change of donor-derived CD3(+) at day 30 after stem cell transplantation (SCT) and clinical outcomes. GVHD was observed more frequently with pattern A, relapse and DLI more so with pattern C, with a consequent survival advantage in patients with patterns A and B. We conclude that evaluating immune reconstitution after SCT as a dynamical system may differentiate patients at risk of adverse outcomes and allow early intervention to modulate that risk.

Pediatric tracheostomy: timing of the first tube change.

OBJECTIVES: No consensus exists on appropriate timing for the first tracheostomy tube change. The purpose of this study is to evaluate the safety of early tracheostomy change in the pediatric population. METHODS: A case series of all children undergoing tracheostomy at a tertiary children's hospital between 2008-2013 was retrospectively reviewed. RESULTS: A total of 151 children undergoing tracheostomy were identified. The average age was 48.1±66 months and median age was 10 months. The initial tracheostomy tube change occurred on postoperative day 3 (POD 3) in 65 children (43.0%) safely without any complications. CONCLUSIONS: Early tracheostomy tube change was safely performed in a significant portion of this population. Routine tube change on POD 3 in many children could save resources by reducing the length of ICU and hospital stays.

Mitochondrial localized Stat3 promotes breast cancer growth via phosphorylation of serine 727.

Signal transducer and activator of transcription 3 (Stat3) is a key mediator in the development of many cancers. For 20 years, it has been assumed that Stat3 mediates its biological activities as a nuclear localized transcription factor activated by many cytokines. However, recent studies from this laboratory and others indicate that Stat3 has an independent function in the mitochondria (mitoStat3) where it controls the activity of the electron transport chain (ETC) and mediates Ras-induced transformation of mouse embryo fibroblasts. The actions of mitoStat3 in controlling respiration and Ras transformation are mediated by the phosphorylation state of serine 727. To address the role of mitoStat3 in the pathogenesis of cells that are transformed, we used 4T1 breast cancer cells, which form tumors that metastasize in immunocompetent mice. Substitution of Ser-727 for an alanine or aspartate in Stat3 that has a mitochondrial localization sequence, MLS-Stat3, has profound effects on tumor growth, complex I activity of the ETC, and accumulation of reactive oxygen species (ROS). Cells expressing MLS-Stat3(S727A) display slower tumor growth, decreased complex I activity of the ETC, and increased ROS accumulation under hypoxia compared with cells expressing MLS-Stat3. In contrast, cells expressing MLS-Stat3(S727D) show enhanced tumor growth and complex I activity and decreased production of ROS. These results highlight the importance of serine 727 of mitoStat3 in breast cancer and suggest a novel role for mitoStat3 in regulation of ROS concentrations through its action on the ETC.

Bronchial artery pseudoaneurysm as an unsuspected cause of hemoptysis in a pediatric patient.

OBJECTIVE: Hemoptysis in the pediatric population may be caused by foreign body aspiration, cystic fibrosis, bronchiectasis, or infection. Vascular causes are uncommon. We present a rare cause of hemoptysis related to a bronchial artery pseudoaneurysm. METHODS: We report the case of a child with a bronchial artery pseudoaneurysm causing hemoptysis and describe the clinical evaluation, treatment, and outcome. RESULTS: A 12-year-old girl presented to a tertiary children's hospital with a history of daily, intermittent, moderate-volume hemoptysis. Rigid bronchoscopy showed a fresh clot occluding the right bronchus intermedius. Computed tomography angiogram was concerning for mild external vascular compression of the right mainstem bronchus. A bronchial arteriogram showed a right mid-bronchial pseudoaneurysm, which was embolized without complication. On repeat bronchoscopy, thrombus was removed from the bronchus intermedius with no new active bleeding. The patient was discharged in stable condition and did not have any more episodes of hemoptysis. Additional medical work-up did not reveal another source of the patient's bleeding. CONCLUSION: Hemoptysis in the pediatric population can be inflammatory, infectious, or due to systemic disease. Although extremely rare, bronchial artery pseudoaneurysm should be considered in cases of moderate to severe intermittent hemoptysis without another identifiable cause. Bronchial angiography can be both diagnostic and therapeutic.

Evaluation and management of neck masses in children.

Neck masses in children usually fall into one of three categories: developmental, inflammatory/reactive, or neoplastic. Common congenital developmental masses in the neck include thyroglossal duct cysts, branchial cleft cysts, dermoid cysts, vascular malformations, and hemangiomas. Inflammatory neck masses can be the result of reactive lymphadenopathy, infectious lymphadenitis (viral, staphylococcal, and mycobacterial infections; cat-scratch disease), or Kawasaki disease. Common benign neoplastic lesions include pilomatrixomas, lipomas, fibromas, neurofibromas, and salivary gland tumors. Although rare in children, malignant lesions occurring in the neck include lymphoma, rhabdomyosarcoma, thyroid carcinoma, and metastatic nasopharyngeal carcinoma. Workup for a neck mass may include a complete blood count; purified protein derivative test for tuberculosis; and measurement of titers for Epstein-Barr virus, cat-scratch disease, cytomegalovirus, human immunodeficiency virus, and toxoplasmosis if the history raises suspicion for any of these conditions. Ultrasonography is the preferred imaging study for a developmental or palpable mass. Computed tomography with intravenous contrast media is recommended for evaluating a malignancy or a suspected retropharyngeal or deep neck abscess. Congenital neck masses are excised to prevent potential growth and secondary infection of the lesion. Antibiotic therapy for suspected bacterial lymphadenitis should target Staphylococcus aureus and group A streptococcus. Lack of response to initial antibiotics should prompt consideration of intravenous antibiotic therapy, referral for possible incision and drainage, or further workup. If malignancy is suspected (accompanying type B symptoms; hard, firm, or rubbery consistency; fixed mass; supraclavicular mass; lymph node larger than 2 cm in diameter; persistent enlargement for more than two weeks; no decrease in size after four to six weeks; absence of inflammation; ulceration; failure to respond to antibiotic therapy; or a thyroid mass), the patient should be referred to a head and neck surgeon for urgent evaluation and possible biopsy.

Salivary gland disorders.

Salivary gland disorders include inflammatory, bacterial, viral, and neoplastic etiologies. The presentation can be acute, recurrent, or chronic. Acute suppurative sialadenitis presents as rapid-onset pain and swelling and is treated with antibiotics, salivary massage, hydration, and sialagogues such as lemon drops or vitamin C lozenges. Viral etiologies include mumps and human immunodeficiency virus, and treatment is directed at the underlying disease. Recurrent or chronic sialadenitis is more likely to be inflammatory than infectious; examples include recurrent parotitis of childhood and sialolithiasis. Inflammation is commonly caused by an obstruction such as a stone or duct stricture. Management is directed at relieving the obstruction. Benign and malignant tumors can occur in the salivary glands and usually present as a painless solitary neck mass. Diagnosis is made by imaging (e.g., ultrasonography, computed tomography, magnetic resonance imaging) and biopsy (initially with fine-needle aspiration). Overall, most salivary gland tumors are benign and can be treated with surgical excision.

The presence of fear: How subjective fear, not physiological changes, shapes the experience of presence.

When we become engrossed in novels, films, games, or even our own wandering thoughts, we can feel present in a reality distinct from the real world. Although this subjective sense of presence is, presumably, a ubiquitous aspect of conscious experience, the mechanisms that produce it are unknown. Correlational studies conducted in virtual reality have shown that we feel more present when we are afraid, motivating claims that physiological changes contribute to presence; however, such causal claims remain to be evaluated. Here, we report two experiments that test the causal role of subjective and physiological components of fear (i.e., activation of the sympathetic nervous system) in generating presence. In Study 1, we validated a virtual reality simulation capable of inducing fear. Participants rated their emotions while they crossed a wooden plank that appeared to be suspended above a city street; at the same time, we recorded heart rate and skin conductance levels. Height exposure increased ratings of fear, presence, and both measures of sympathetic activation. Although presence and fear ratings were correlated during height exposure, presence and sympathetic activation were unrelated. In Study 2, we manipulated whether the plank appeared at height or at ground level. We also captured participants' movements, which revealed that alongside increases in subjective fear, presence, and sympathetic activation, participants also moved more slowly at height relative to controls. Using a mediational approach, we found that the relationship between height exposure and presence on the plank was fully mediated by self-reported fear, and not by sympathetic activation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Acetyl-CoA carboxylase obstructs CD8+ T cell lipid utilization in the tumor microenvironment.

The solid tumor microenvironment (TME) imprints a compromised metabolic state in tumor-infiltrating T cells (TILs), hallmarked by the inability to maintain effective energy synthesis for antitumor function and survival. T cells in the TME must catabolize lipids via mitochondrial fatty acid oxidation (FAO) to supply energy in nutrient stress, and it is established that T cells enriched in FAO are adept at cancer control. However, endogenous TILs and unmodified cellular therapy products fail to sustain bioenergetics in tumors. We reveal that the solid TME imposes perpetual acetyl-coenzyme A (CoA) carboxylase (ACC) activity, invoking lipid biogenesis and storage in TILs that opposes FAO. Using metabolic, lipidomic, and confocal imaging strategies, we find that restricting ACC rewires T cell metabolism, enabling energy maintenance in TME stress. Limiting ACC activity potentiates a gene and phenotypic program indicative of T cell longevity, engendering T cells with increased survival and polyfunctionality, which sustains cancer control.

Fractal organization of the human T cell repertoire in health and after stem cell transplantation.

T cell repertoire diversity is generated in part by recombination of variable (V), diversity (D), and joining (J) segments in the T cell receptor ß (TCR) locus. T cell clonal frequency distribution determined by high-throughput sequencing of TCR ß in 10 stem cell transplantation (SCT) donors revealed a fractal, self-similar frequency distribution of unique TCR bearing clones with respect to V, D, and J segment usage in the T cell repertoire of these individuals. Further, ranking of T cell clones by frequency of gene segment usage in the observed sequences revealed an ordered distribution of dominant clones conforming to a power law, with a fractal dimension of 1.6 and 1.8 in TCR ß DJ and VDJ containing clones in healthy stem cell donors. This self-similar distribution was perturbed in the recipients after SCT, with patients demonstrating a lower level of complexity in their TCR repertoire at day 100 followed by a modest improvement by 1 year post-SCT. A large shift was observed in the frequency distribution of the dominant T cell clones compared to the donor, with fewer than one third of the VDJ-containing clones shared in the top 4 ranks. In conclusion, the normal T cell repertoire is highly ordered with a TCR gene segment usage that results in a fractal self-similar motif of pattern repetition across levels of organization. Fractal analysis of high-throughput TCR ß sequencing data provides a comprehensive measure of immune reconstitution after SCT.

Endoscopic fluorescence lifetime imaging for in vivo intraoperative diagnosis of oral carcinoma.

A clinically compatible fluorescence lifetime imaging microscopy (FLIM) system was developed. The system was applied to intraoperative in vivo imaging of head and neck squamous cell carcinoma (HNSCC). The endoscopic FLIM prototype integrates a gated (down to 0.2 ns) intensifier imaging system and a fiber-bundle endoscope (0.5-mm-diameter, 10,000 fibers with a gradient index lens objective 0.5 NA, 4-mm field of view), which provides intraoperative access to the surgical field. Tissue autofluorescence was induced by a pulsed laser (337 nm, 700 ps pulse width) and collected in the 460 ± 25 nm spectral band. FLIM experiments were conducted at 26 anatomic sites in ten patients during head and neck cancer surgery. HNSCC exhibited a weaker florescence intensity (~50% less) when compared with healthy tissue and a shorter average lifetime (τ(HNSCC) = 1.21 ± 0.04 ns) than the surrounding normal tissue (τN = 1.49 ± 0.06 ns). This work demonstrates the potential of FLIM for label-free head and neck tumor demarcation during intraoperative surgical procedures.

Melatonin protects against cadmium-induced oxidative stress via mitochondrial STAT3 signaling in human prostate stromal cells.

Melatonin protects against Cadmium (Cd)-induced toxicity, a ubiquitous environmental toxicant that causes adverse health effects by increasing reactive oxygen species (ROS) production and mitochondrial dysfunction. However, the underlying mechanism remains unclear. Here, we demonstrate that Cd exposure reduces the levels of mitochondrially-localized signal transducer and activator of transcription 3 (mitoSTAT3) using human prostate stromal cells and mouse embryonic fibroblasts. Melatonin enhances mitoSTAT3 abundance following Cd exposure, which is required to attenuate ROS damage, mitochondrial dysfunction, and cell death caused by Cd exposure. Moreover, melatonin increases mitochondrial levels of GRIM-19, an electron transport chain component that mediates STAT3 import into mitochondria, which are downregulated by Cd. In vivo, melatonin reverses the reduced size of mouse prostate tissue and levels of mitoSTAT3 and GRIM-19 induced by Cd exposure. Together, these data suggest that melatonin regulates mitoSTAT3 function to prevent Cd-induced cytotoxicity and could preserve mitochondrial function during Cd-induced stress.