gp91phox, a Novel Biomarker Evaluating Oxidative Stress, Is Elevated in Subclinical Hypothyroidism

Low T3 syndrome is associated with 30-day mortality in adult patients with fulminant myocarditis

Background

Fulminant myocarditis (FM) is a critical disease with high early mortality. Low triiodothyronine syndrome (LT3S) was a strong predictor of poor prognosis of critical diseases. This study investigated whether LT3S was associated with 30-day mortality in FM patients.

Methods

Ninety-six FM patients were divided into LT3S (n=39, 40%) and normal free triiodothyronine (FT3) (n=57, 60%) groups based on serum FT3 level. Univariable and multivariable logistic regression analyses were performed to identify independent predictors of 30-day mortality. Kaplan-Meier curve was used to compare 30-day mortality between two groups. Receiver operating characteristic (ROC) curve and decision curve analysis (DCA) were used to assess the value of FT3 level for 30-day mortality prediction.

Results

Compared to normal FT3 group, LT3S group had higher incidence of ventricular arrhythmias, worse hemodynamics, worse cardiac function, more severe kidney impairment, and higher 30-day mortality (48.7% vs. 12.3%, P<0.001). In univariable analysis, LT3S (odds ratio [OR]:6.786, 95% confidence interval [CI]:2.472-18.629, P<0.001) and serum FT3 (OR:0.272, 95%CI:0.139-0.532, P<0.001) were significant strong predictors of 30-day mortality. After adjustment for confounders in multivariable analysis, LT3S (OR:3.409, 95%CI:1.019-11.413, P=0.047) and serum FT3 (OR:0.408, 95%CI:0.199-0.837, P=0.014) remained independent 30-day mortality predictors. The area under the ROC curve of FT3 level was 0.774 (cut-off: 3.58, sensitivity: 88.46%, specificity: 62.86%). In DCA, FT3 level showed good clinical-application value for 30-day mortality prediction.

Conclusion

In FM patients, LT3S could independently predict 30-day mortality. FT3 level was a strong 30-day mortality predictor and a potentially useful risk-stratification biomarker.

The role of thyroid hormone in the renal immune microenvironment

Thyroid hormones are essential for proper kidney growth and development. The kidney is not only the organ of thyroid hormone metabolism but also the target organ of thyroid hormone. Kidney disease is a common type of kidney damage, mainly including different types of acute kidney injury, chronic kidney disease, diabetic nephropathy, lupus nephritis, and renal cell carcinoma. The kidney is often damaged by an immune response directed against its antigens or a systemic immune response. A variety of immune cells in the innate and adaptive immune systems, including neutrophils, macrophages, dendritic cells, T lymphocytes, and B lymphocytes, is essential for maintaining immune homeostasis and preventing autoimmune kidney disease. Recent studies have found that thyroid hormone plays an indispensable role in the immune microenvironment of various kidney diseases. Thyroid hormones regulate the activity of neutrophils, and dendritic cells express triiodothyronine receptors. Compared to hypothyroidism, hyperthyroidism has a greater effect on neutrophils. Furthermore, in adaptive immune systems, thyroid hormone may activate T lymphocytes through several underlying mechanisms, such as mediating NF-κB, protein kinase C signalling pathways, and β-adrenergic receptors, leading to increased T lymphocyte activation. The present review discusses the effects of thyroid hormone metabolism regulation in the immune microenvironment on the function of various immune cells, especially neutrophils, macrophages, dendritic cells, T lymphocytes, and B lymphocytes. Although there are not enough data at this stage to conclude the clinical relevance of these findings, thyroid hormone metabolism may influence autoimmune kidney disease by regulating the renal immune microenvironment.

Echinacoside Improves Cognitive Impairment by Inhibiting Aβ Deposition Through the PI3K/AKT/Nrf2/PPARγ Signaling Pathways in APP/PS1 Mice

Echinacoside (ECH), a phenylethanoid glycoside, has protective activity in neurodegenerative disease, including anti-inflammation and antioxidation. However, the effects of ECH in Alzheimer's disease (AD) are not very clear. This present study investigates the role and mechanism of ECH in the pathological process of AD. APP/PS1 mice treated with ECH in 50 mg/kg/day for 3 months. Morris water maze, nesting test, and immunofluorescence staining used to observe whether ECH could improve AD pathology. Western blot used to study the mechanism of ECH improving AD pathology. The results showed that ECH alleviated the memory impairment of APP/PS1 mice by reducing the time of escape latency as well as increasing the times of crossing the platform and rescued the impaired ability to construct nests. In addition, ECH significantly reduced the deposition of senile plaques in the brain and decreased the expression of BACE1 in APP/PS1 mice through activating PI3K/AKT/Nrf2/PPARγ pathway. Furthermore, ECH decreased ROS formation, GP91 and 8-OHdG expression, upregulated the expression of SOD1 and SOD2 as well as activating the PI3K/AKT/Nrf2 signaling pathway. Moreover, ECH inhibited glia cells activation, pro-inflammatory cytokine IL-1β and TNF-α release, NLRP3 inflammasome formation through TXNIP/Trx-1 signaling pathway. In conclusion, this paper reported that ECH improved cognitive function, inhibited oxidative stress, and inflammatory response in AD. Therefore, we suggest that ECH may considered as a potential drug for AD treatment.

The interplay of thyroid hormones and the immune system - where we stand and why we need to know about it

Over the past few years, growing evidence suggests direct crosstalk between thyroid hormones (THs) and the immune system. Components of the immune system were proposed to interfere with the central regulation of systemic TH levels. Conversely, THs regulate innate and adaptive immune responses as immune cells are direct target cells of THs. Accordingly, they express different components of local TH action, such as TH transporters or receptors, but our picture of the interplay between THs and the immune system is still incomplete. This review provides a critical overview of current knowledge regarding the interaction of THs and the immune system with the main focus on local TH action within major innate and adaptive immune cell subsets. Thereby, this review aims to highlight open issues which might help to infer the clinical relevance of THs in host defence in the context of different types of diseases such as infection, ischemic organ injury or cancer.

Hyperbaric oxygen influences chronic wound healing – a cellular level review

Chronic wound is a serious medical issue due to its high prevalence and complications; hyperbaric oxygen therapy (HBOT) is also considered in comprehensive treatment. Clinical trials, including large meta-analyses bring inconsistent results about HBOT efficacy. This review is summarizing the possible effect of HBOT on the healing of chronic wound models at the cellular level. HBOT undoubtedly escalates the production of reactive oxygen and nitrogen radicals (ROS and RNS), which underlie both the therapeutic and toxic effects of HBOT on certain tissues. HBOT paradoxically elevates the concentration of Hypoxia inducible factor (HIF) 1 by diverting the HIF-1 degradation to pathways that are independent of the oxygen concentration. Elevated HIF-1 stimulates the production of different growth factors, boosting the healing process. HBOT supports synthesis of Heat shock proteins (HSP), which are serving as chaperones of HIF-1. HBOT has antimicrobial effect, increases the effectiveness of some antibiotics, stimulates fibroblasts growth, collagen synthesis and suppresses the activity of proteolytic enzymes like matrix metalloproteinases. All effects of HBOT were investigated on cell cultures and animal models, the limitation of their translation is discussed at the end of this revie

Myeloid-derived suppressor cells: Important communicators in systemic lupus erythematosus pathogenesis and its potential therapeutic significance

Systemic lupus erythematosus (SLE) is a recognized chronic condition associated with immune system disorders that affect women nine times more commonly than men. SLE is characterized by over-secretion and release of autoantibodies in response to different cellular compartments and self-tolerance breaks to its own antigens. The detailed immunological dysregulation as an associated event that elicits the onset of clinical manifestations of SLE has not been clarified yet. Though, research using several animal models in the last two decades has indicated the role of the immune system in the pathogenesis of this disease. Myeloid-derived suppressor cells (MDSCs) as heterogeneous myeloid cells, are responsible for severe pathological conditions, including infection, autoimmunity, and cancer, by exerting considerable immunosuppressive effects on T-cells responses. It has been reported that these cells are involved in the regulation process of the immune response in several autoimmune diseases, particularly SLE. The function of MDSC is deleterious in infection and cancer diseases, though their role is more complicated in autoimmune diseases. In this review, we summarized the role and function of MDSCs in the pathogenesis and progression of SLE and its possible therapeutic approach.

An inhibitory and beneficial effect of chlorpromazine and promethazine (C + P) on hyperglycolysis through HIF-1α regulation in ischemic stroke

BACKGROUND

After ischemic stroke, the increased catabolism of glucose (hyperglycolysis) results in the production of reactive oxygen species (ROS) via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). A depressive or hibernation-like effect of C + P on brain activity was reported to induce neuroprotection. The current study assesses the effect of C + P on hyperglycolysis and NOX activation.

METHODS

Adult male Sprague-Dawley rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) followed by 6 or 24 h of reperfusion. At the onset of reperfusion, rats received C + P with or without temperature control, or phloretin [glucose transporter (GLUT)-1 inhibitor], or cytochalasin B (GLUT-3 inhibitor). We detected brain ROS, apoptotic cell death, and ATP levels along with HIF-1α expression. Cerebral hyperglycolysis was measured by glucose, protein expression of GLUT-1/3, and phosphofructokinase-1 (PFK-1), as well as lactate and lactate dehydrogenase (LDH) at 6 and 24 h of reperfusion. The enzymatic activity of NOX and protein expression of its subunits (gp91^phox) were detected. Neural SHSY5Y cells were placed under 2 h of oxygen-glucose deprivation (OGD) followed by reoxygenation for 6 and 24 h with C + P treatment. Cell viability and protein levels of HIF-1α, GLUT-1/3, PFK-1, LDH, and gp91^phox were measured. A HIF-1α overexpression vector was transfected into the cells, and then protein levels of HIF-1α, GLUT-1/3, PFK-1, and LDH were quantitated. In sham-operated rats and control cells, the protein levels of HIF-1α, GLUT-1/3, PFK-1, LDH, and gp91^phox were measured at 6 and 24 h after C + P administration.

RESULTS

C + P reduced the protein elevations after stroke in HIF-1α, glycolytic enzymes, as well as in ROS, cell death, glucose and lactate, but raised ATP levels in the brain. In ischemic rats exposed to GLUT-1/3 inhibitors, ROS, cell death, glucose, and lactate were all decreased, as well as GLUT-1, GLUT-3, LDH, and PFK-1 protein levels. C + P decreased ischemia-induced NOX activation by reducing the enzymatic activity and protein expression of the NOX subunit gp91^phox, as was observed in the presence of GLUT-1/3 inhibitors. These markers were significantly decreased following C + P administration with the induced hypothermia, while C + P administration with temperature control at 37 °C induced lesser protection after ischemia stroke. In the OGD/reoxygenation model, C + P treatment increased cell viability and diminished protein levels of HIF-1α, GLUT-1, GLUT-3, PFK-1, LDH, and gp91^phox. However, in OGD with HIF-1α overexpression, C + P was unable to effectively reduce the upregulated GLUT-1, GLUT-3, and LDH. In normal conditions, C + P reduced HIF-1α and the levels of key glycolytic enzymes depending on its pharmacological effect.

CONCLUSION

C + P, partially depending on hypothermia, attenuates hyperglycolysis and NOX activation through HIF-1α regulation.

Thyroid Hormone and Deiodination in Innate Immune Cells

Thyroid hormone has recently been recognized as an important determinant of innate immune cell function. Highly specialized cells of the innate immune system, including neutrophils, monocytes/macrophages, and dendritic cells, are capable of identifying pathogens and initiating an inflammatory response. They can either phagocytose and kill microbes, or recruit other innate or adaptive immune cells to the site of inflammation. Innate immune cells derive from the hematopoietic lineage and are generated in the bone marrow, from where they can be recruited into the blood and tissues in the case of infection. The link between the immune and endocrine systems is increasingly well established, and recent studies have shown that innate immune cells can be seen as important thyroid hormone target cells. Tight regulation of cellular thyroid hormone availability and action is performed by thyroid hormone transporters, receptors, and the deiodinase enzymes. Innate immune cells express all these molecular elements of intracellular thyroid hormone metabolism. Interestingly, there is recent evidence for a causal relationship between cellular thyroid hormone status and innate immune cell function. This review describes the effects of modulation of intracellular thyroid hormone metabolism on innate immune cell function, specifically neutrophils, macrophages, and dendritic cells, with a special focus on the deiodinase enzymes. Although there are insufficient data at this stage for conclusions on the clinical relevance of these findings, thyroid hormone metabolism may partially determine the innate immune response and, by inference, the clinical susceptibility to infections.