The thyroid hormone triiodothyronine controls macrophage maturation and functions: protective role during inflammation

Hyperthyroidism keeps immunoglobulin levels but reduces milk fat and CD11b/c+ cells on early lactation

Thyroid hormones influence mammary gland differentiation and lactation by binding to thyroid hormone receptors. Hyperthyroidism disrupts pregnancy and lactation, affecting offspring growth and milk production. Despite maternal milk is a vital source of bioactive compounds and nutrients for newborns, it is unclear whether hyperthyroidism alters its composition, mainly immune factors. Therefore, our work aimed to evaluate the influence of hyperthyroidism on milk quality and immunological parameters during early lactation. Twelve-week-old female Wistar rats received daily injections of 0,25 mg/kg T4 (HyperT, n = 20) or vehicle (control, n = 19) starting 8 days before mating and continuing throughout pregnancy. Rats were euthanized on day 2 of lactation for analyzing the impact of hyperthyroidism on mammary gland, serum and milk samples. HyperT pups exhibited reduced weight, length and head circumference with altered serum hormones, glucose and albumin levels. HyperT mammary gland analysis revealed structural changes, including decreased alveolar area, adipose tissue, increased connective tissue and reduced epithelial elongation, accompanied by decreased TRβ1 RNA expression. HyperT milk displayed lower caloric value and fat concentration. HyperT animals exhibited altered milk immune cell counts, displaying increased numbers of CD45+ and CD3+ cells and decreased CD11b/c+ cells without changes on milk and serum IgA, IgG and IgG2a levels. In summary, we have demonstrated that hyperthyroidism affects mammary gland morphology, disrupts pup development and alters biochemical and immunological parameters. Our findings highlight the impact of maternal hyperthyroidism on offspring early development and milk immune composition, underscoring the importance of thyroid function in maternal and neonatal immune health.

Autoimmune Disorders Associated With Surgical Remission of Cushing's Disease : A Cohort Study

BACKGROUND

Glucocorticoids suppress inflammation. Autoimmune disease may occur after remission of Cushing's disease (CD). However, the development of autoimmune disease in this context is not well described.

OBJECTIVE

To determine 1) the incidence of autoimmune disease in patients with CD after surgical remission compared with patients with nonfunctioning pituitary adenomas (NFPAs) and 2) the clinical presentation of and risk factors for development of autoimmune disease in CD after remission.

DESIGN

Retrospective matched cohort analysis.

SETTING

Academic medical center/pituitary center.

PATIENTS

Patients with CD with surgical remission and surgically treated NFPA.

MEASUREMENTS

Cumulative incidence of new-onset autoimmune disease at 3 years after surgery. Assessment for hypercortisolemia included late-night salivary cortisol levels, 24-hour urine free cortisol (UFC) ratio (UFC value divided by the upper limit of the normal range for the assay), and dexamethasone suppression tests.

RESULTS

Cumulative incidence of new-onset autoimmune disease at 3 years after surgery was higher in patients with CD (10.4% [95% CI, 5.7% to 15.1%]) than in those with NFPAs (1.6% [CI, 0% to 4.6%]) (hazard ratio, 7.80 [CI, 2.88 to 21.10]). Patients with CD showed higher prevalence of postoperative adrenal insufficiency (93.8% vs. 16.5%) and lower postoperative nadir serum cortisol levels (63.8 vs. 282.3 nmol/L) than patients with NFPAs. Compared with patients with CD without autoimmune disease, those who developed autoimmune disease had a lower preoperative 24-hour UFC ratio (2.7 vs. 6.3) and a higher prevalence of family history of autoimmune disease (41.2% vs. 20.9%).

LIMITATION

The small sample of patients with autoimmune disease limited identification of independent risk factors.

CONCLUSION

Patients achieving surgical remission of CD have higher incidence of autoimmune disease than age- and sex-matched patients with NFPAs. Family history of autoimmune disease is a potential risk factor. Adrenal insufficiency may be a trigger.

PRIMARY FUNDING SOURCE

Recordati Rare Diseases Inc.

The Differential Effect of a Shortage of Thyroid Hormone Compared with Knockout of Thyroid Hormone Transporters Mct8 and Mct10 on Murine Macrophage Polarization

Innate immune cells, including macrophages, are functionally affected by thyroid hormone (TH). Macrophages can undergo phenotypical alterations, shifting between proinflammatory (M1) and immunomodulatory (M2) profiles. Cellular TH concentrations are, among others, determined by TH transporters. To study the effect of TH and TH transporters on macrophage polarization, specific proinflammatory and immunomodulatory markers were analyzed in bone marrow-derived macrophages (BMDMs) depleted of triiodothyronine (T3) and BMDMs with a knockout (KO) of Mct8 and Mct10 and a double KO (dKO) of Mct10/Mct8. Our findings show that T3 is important for M1 polarization, while a lack of T3 stimulates M2 polarization. Mct8 KO BMDMs are unaffected in their T3 responsiveness, but exhibit slight alterations in M2 polarization, while Mct10 KO BMDMs show reduced T3 responsiveness, but unaltered polarization markers. KO of both the Mct8 and Mct10 transporters decreased T3 availability and, contrary to the T3-depleted BMDMs, showed partially increased M1 markers and unaltered M2 markers. These data suggest a role for TH transporters besides transport of TH in BMDMs. This study highlights the complex role of TH transporters in macrophages and provides a new angle on the interaction between the endocrine and immune systems.

Association between the Systemic Immune-Inflammation Index and Thyroid Function in U.S. Adults

Background

The systemic immune-inflammation index (SII) is used as an indicator of prognosis for a wide range of diseases. Thyroid function has been found to be strongly associated with inflammation. The purpose of this investigation was to analyze the correlation between SII and various thyroid functions.

Methods

This study utilized data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012. The association between SII and thyroid function was analyzed using weighted univariate and multivariate linear regression analyses. Subgroup analyses, interaction tests, and weighted restricted cubic spline (RCS) regression analyses were also employed to test this correlation.

Results

Of the 6,875 participants (age ≥ 20 years), the mean age was 46.87 ± 0.40 years. The adjusted model showed that lnSII was negatively correlated with FT3 (β = -0.0559, 95% CI -0.1060 to -0.0059,) and FT3/FT4 (β = -0.0920, 95% CI -0.1667 to -0.0173,). There was a positive correlation between lnSII and TT4 (β = 0.1499, 95% CI 0.0722-0.2276,). In subgroup analyses, lnSII still independently affected a wide range of thyroid functions. Weighted RCS analysis showed a nonlinear relationship between FT3 and lnSII.

Conclusion

Close relationships exist between SII and a variety of thyroid functions. SII can be used as an indicator to predict thyroid dysfunction. Control of inflammatory activity may be a protective measure against thyroid dysfunction. More large-scale prospective studies are necessary to further explore the correlation between SII and thyroid function and the role of obesity in this.

The effect of hyperthyroidism on cognitive function, neuroinflammation, and necroptosis in APP/PS1 mice

BACKGROUND

Increasing evidence has linked the thyroid dysfunction to the pathogenesis of dementia. Evidence from clinical studies has demonstrated that hypothyroidism is related to an increased risk of dementia. But the association of hyperthyroidism with dementia is largely unknown.

METHODS

We used the adenovirus containing thyrotropin receptor (TSHR) amino acid residues 1-289 (Ad-TSHR289)-induced Graves' disease (GD) phenotype in Alzheimer's disease (AD) model mice (APP/PS1 mice) to evaluate the effect of hyperthyroidism on the cognitive function and β-amyloid (Aβ) accumulation.

RESULTS

GD mice exhibited a stable long-term hyperthyroidism and cognitive deficits. Single Cell RNA-sequencing analysis indicated that microglia function played a critical role in the pathophysiological processes in GD mice. Neuroinflammation and polarization of microglia (M1/M2 phenotype) and activated receptor-interacting serine/threonine protein kinase 3 (RIPK3)/mixed lineage kinase domain-like pseudo-kinase (MLKL)-mediated necroptosis contributed to the pathological process, including Aβ deposition and neuronal loss. RIPK3 inhibitor could inhibit GD-mediated Aβ accumulation and neuronal loss.

CONCLUSIONS

Our findings reveal that GD hyperthyroidism aggravates cognitive deficits in AD mice and induces Aβ deposition and neuronal loss by inducing neuroinflammation and RIPK3/MLKL-mediated necroptosis.

The hormonal physiology of immune components in breast milk and their impact on the infant immune response

During pregnancy, the maternal body undergoes a considerable transformation regarding the anatomy, metabolism, and immune profile that, after delivery, allows for protection and nourishment of the offspring via lactation. Pregnancy hormones are responsible for the development and functionality of the mammary gland for breast milk production, but little is known about how hormones control its immune properties. Breast milk composition is highly dynamic, adapting to the nutritional and immunological needs that the infant requires in the first months of life and is responsible for the main immune modeling of breastfed newborns. Therefore, alterations in the mechanisms that control the endocrinology of mammary gland adaptation for lactation could disturb the properties of breast milk that prepare the neonatal immune system to respond to the first immunologic challenges. In modern life, humans are chronically exposed to endocrine disruptors (EDs), which alter the endocrine physiology of mammals, affecting the composition of breast milk and hence the neonatal immune response. In this review, we provide a landscape of the possible role of hormones in the control of passive immunity transferred by breast milk and the possible effect of maternal exposure to EDs on lactation, as well as their impacts on the development of neonatal immunity.

Prognostic significance of thyroid hormone T3 in patients with septic shock: a retrospective cohort study

Background

The role of thyroid hormones is crucial in the response to stress and critical illness, which has been reported to be closely associated with a poor prognosis in patients admitted to the intensive care unit (ICU). This study aimed to explore the relationship between thyroid hormone and prognosis in septic shock patients.

Methods

A total of 186 patients with septic shock were enrolled in the analytical study between December 2014 and September 2022. The baseline variables and thyroid hormone were collected. The patients were divided into survivor group and non-survivor group according to whether they died during the ICU hospitalization. Among 186 patients with septic shock, 123 (66.13%) were in the survivor group and 63 (33.87%) were in the non-survivor group.

Results

There were significant differences in the indictors of free triiodothyronine (FT3) (p = 0.000), triiodothyronine (T3) (p = 0.000), T3/FT3 (p = 0.000), acute physiology and chronic health evaluation II score (APACHE II) (p = 0.000), sequential organ failure assessment score (SOFA) (p = 0.000), pulse rate (p = 0.020), creatinine (p = 0.008), PaO2/FiO2 (p = 0.000), length of stay (p = 0.000) and hospitalization expenses (p = 0.000) in ICU between the two groups. FT3 [odds ratio (OR): 1.062, 95% confidence interval(CI): (0.021, 0.447), p = 0.003], T3 (OR: 0.291, 95% CI: 0.172-0.975, p = 0.037) and T3/FT3 (OR: 0.985, 95% CI:0.974-0.996, p = 0.006) were independent risk factors of the short-term prognosis of septic shock patients after adjustment. The areas under the receiver operating characteristic curves for T3 was associated with ICU mortality (AUC = 0.796, p < 0.05) and was higher than that for FT3 (AUC = 0.670, p < 0.05) and T3/FT3 (AUC = 0.712, p < 0.05). A Kaplan-Meier curve showed that patients with T3 greater than 0.48 nmol/L had a significantly higher survival rate than the patients with T3 less than 0.48 nmol/L.

Conclusions

The decrease in serum level of T3 in patients with septic shock is associated with ICU mortality. Early detection of serum T3 level could help clinicians to identify septic shock patients at high risk of clinical deterioration.

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.

Dietary iodine attenuates allergic rhinitis by inducing ferroptosis in activated B cells

Iodine-containing formulations have been widely used to treat iodine deficiency and as antiseptics. Lecithin-bound iodine (LBI) has been approved to treat allergic diseases in Japan; however, its underlying mechanism remains unknown. In this study, we show that LBI ameliorated disease symptoms in an ovalbumin (OVA)-induced allergic rhinitis mouse model. LBI suppressed OVA-specific IgE production by attenuating germinal center (GC) reaction in the draining lymph nodes. The antiallergic effect of LBI is most likely attributed to increased serum iodine levels but not thyroid hormone levels. In vitro treatment of activated B cells with potassium iodide induced ferroptosis by increasing intracellular reactive oxygen species (ROS) and ferrous iron in a concentration-dependent manner. Accordingly, LBI diets increased ROS levels in GC B cells of the draining lymph nodes. This study suggests that iodine directly promotes ferroptosis in activated B cells and attenuates GC reactions, leading to the alleviation of allergic symptoms.

Single-cell RNA sequencing reveals unique monocyte-derived interstitial macrophage subsets during lipopolysaccharide-induced acute lung inflammation

Interstitial macrophages (IMs) reside in the lung tissue surrounding key structures including airways, vessels, and alveoli. Recent work has described IM heterogeneity during homeostasis, however, there are limited data on IMs during inflammation. We sought to characterize IM origin, subsets, and transcriptomic profiles during homeostasis and lipopolysaccharide (LPS) induced acute lung inflammation. During homeostasis, we used three complementary methods, spectral flow cytometry, single-cell RNA-sequencing, and gene regulatory network enrichment, to demonstrate that IMs can be divided into two core subsets distinguished by surface and transcriptional expression of folate receptor β (Folr2/FRβ). These subsets inhabited distinct niches within the lung interstitium. Within FRβ+ IMs we identified a subpopulation marked by coexpression of LYVE1. During acute LPS-induced inflammation, lung IM numbers expand. Lineage tracing revealed IM expansion was due to recruitment of monocyte-derived IMs. At the peak of inflammation, recruited IMs were comprised two unique subsets defined by expression of genes associated with interferon signaling and glycolytic pathways. As recruited IMs matured, they adopted the overall transcriptional state of FRβ- resident IMs but retained expression in several origin-specific genes, such as IL-1β. FRβ+ IMs were of near-pure resident origin. Taken together our data show that during LPS-induced inflammation, there are distinct populations of IMs that likely have unique functions. FRΒ+ IMs comprise a stable, resident population, whereas FRβ- ΙΜs represent a mixed population of resident and recruited IMs.

Chemotherapy, hypothyroidism and oral dysbiosis as a novel risk factor of cardiovascular pathology development

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in the population, as well as the economic burden of the health care system. Currently, CVDs account for more than 17.6 million deaths a year and are projected to exceed 23.6 million by 2030. Unstable atheroma, and its rupture, underlies the pathology of most cardiovascular complications, particularly acute coronary syndrome, mortality from which, compared with other CV events, remains the leading one. Despite numerous efforts by WHO, national health systems, and medical authorities, the incidence and mortality from cardiovascular events remain critically high. Thus, the search for new risk factors for the development of CV pathology looks very relevant. Our working group decided to amalgamate our research data, which reflects the study of modern risk factors from the Armenian, Russian, Georgian, and Iranian medical schools. In particular, the aspects of cardiotoxic effects of chemotherapy, hypothyroidism, and oral dysbiosis are discussed.

Thyroid hormone receptor knockout prevents the loss of Xenopus tail regeneration capacity at metamorphic climax

BACKGROUND

Animal regeneration is the natural process of replacing or restoring damaged or missing cells, tissues, organs, and even entire body to full function. Studies in mammals have revealed that many organs lose regenerative ability soon after birth when thyroid hormone (T3) level is high. This suggests that T3 play an important role in organ regeneration. Intriguingly, plasma T3 level peaks during amphibian metamorphosis, which is very similar to postembryonic development in humans. In addition, many organs, such as heart and tail, also lose their regenerative ability during metamorphosis. These make frogs as a good model to address how the organs gradually lose their regenerative ability during development and what roles T3 may play in this. Early tail regeneration studies have been done mainly in the tetraploid Xenopus laevis (X. laevis), which is difficult for gene knockout studies. Here we use the highly related but diploid anuran X. tropicalis to investigate the role of T3 signaling in tail regeneration with gene knockout approaches.

RESULTS

We discovered that X. tropicalis tadpoles could regenerate their tail from premetamorphic stages up to the climax stage 59 then lose regenerative capacity as tail resorption begins, just like what observed for X. laevis. To test the hypothesis that T3-induced metamorphic program inhibits tail regeneration, we used TR double knockout (TRDKO) tadpoles lacking both TRα and TRβ, the only two receptor genes in vertebrates, for tail regeneration studies. Our results showed that TRs were not necessary for tail regeneration at all stages. However, unlike wild type tadpoles, TRDKO tadpoles retained regenerative capacity at the climax stages 60/61, likely in part by increasing apoptosis at the early regenerative period and enhancing subsequent cell proliferation. In addition, TRDKO animals had higher levels of amputation-induced expression of many genes implicated to be important for tail regeneration, compared to the non-regenerative wild type tadpoles at stage 61. Finally, the high level of apoptosis in the remaining uncut portion of the tail as wild type tadpoles undergo tail resorption after stage 61 appeared to also contribute to the loss of regenerative ability.

CONCLUSIONS

Our findings for the first time revealed an evolutionary conservation in the loss of tail regeneration capacity at metamorphic climax between X. laevis and X. tropicalis. Our studies with molecular and genetic approaches demonstrated that TR-mediated, T3-induced gene regulation program is responsible not only for tail resorption but also for the loss of tail regeneration capacity. Further studies by using the model should uncover how T3 modulates the regenerative outcome and offer potential new avenues for regenerative medicines toward human patients.

Epigenetic developmental programming and intergenerational effects of thyroid hormones

Mounting evidence is showing that altered signaling through the nuclear hormone receptor superfamily can cause abnormal, long-term epigenetic changes which translate into pathological modifications and susceptibility to disease. These effects seem to be more prominent if the exposure occurs early in life, when transcriptomic profiles are rapidly changing. At this time, the coordination of the complex coordinated processes of cell proliferation and differentiation that characterize mammalian development. Such exposures may also alter the epigenetic information of the germ line, potentially leading to developmental changes and abnormal outcomes in subsequent generations. Thyroid hormone (TH) signaling is mediated by specific nuclear receptors, which have the ability to markedly change chromatin structure and gene transcription, and can also regulate other determinants of epigenetic marks. TH exhibits pleiotropic effects in mammals, and during development, its action is regulated in a highly dynamic manner to suit the rapidly evolving needs of multiple tissues. Their molecular mechanisms of action, timely developmental regulation and broad biological effects place THs in a central position to play a role in the developmental epigenetic programming of adult pathophysiology and, through effects on the germ line, in inter- and trans-generational epigenetic phenomena. These areas of epigenetic research are in their infancy, and studies regarding THs are limited. In the context of their characteristics as epigenetic modifiers and their finely tuned developmental action, here we review some of the observations underscoring the role that altered TH action may play in the developmental programming of adult traits and in the phenotypes of subsequent generations via germ line transmission of altered epigenetic information. Considering the relatively high prevalence of thyroid disease and the ability of some environmental chemicals to disrupt TH action, the epigenetic effects of abnormal levels of TH action may be important contributors to the non-genetic etiology of human disease.

Induced Overexpression of B Cell-Activating Factor by Triiodothyronine Results in Abnormal B Cell Differentiation in Mice

Breakdown of tolerance and abnormal activation in B cells is an important mechanism in the pathogenesis of Graves' disease (GD) and high levels of thyroid hormones (THs) can drive the progression of GD. However, the interactions between THs and abnormal activation of B cells in the context of GD are not well understood. The aim of this study was to investigate B cell-activating factor (BAFF) mediating the cross talk between THs and B cells and the possible underlying mechanisms. A high-level triiodothyronine (T3) mouse model was used to verify T3-mediated induction of overexpression of BAFF and B cell abnormal differentiation. The possible promotion of BAFF overexpression in the mice spleen macrophages during polarization to M1 by T3 was also studied. We showed that high levels of T3 can induce BAFF overexpression and lead to abnormal differentiation of B cells in the mice. While the overexpression of BAFF was observed across many tissue types in the mice, high levels of T3 could induce M1 macrophages polarization by IFN (interferon-gamma)-γ in the spleen of the mice, which in turn generated BAFF overexpression. Our findings provide a novel insight into the interactions between the endocrine and immune systems, as well as provide insight into the role of TH in the pathogenesis of GD.

Hashimoto's thyroiditis increases the risk of new-onset systemic lupus erythematosus: a nationwide population-based cohort study

BACKGROUND

Previous studies have shown systemic lupus erythematosus (SLE) patients had a significantly higher prevalence of thyroid diseases and hypothyroidism than matched controls, and some case reports showed SLE may occur after Hashimoto's thyroiditis (HT).

OBJECTIVE

This study aimed to investigate the subsequent risk of SLE in patients with HT.

METHODS

In this retrospective cohort study done by the Taiwan National Health Insurance Research Database, the HT group (exposure group) and the non-HT group (comparator group) were propensity score matched at a ratio of 1:2 by demographic data, comorbidities, medications, and the index date. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Several sensitivity analyses were done for cross-validation of our findings.

RESULTS

We identified 15,512 HT patients and matched 31,024 individuals. The incidence rate ratio of SLE was 3.58 (95% CI, 2.43-5.28; p < 0.01). Several sensitivity analyses show adjusted hazard ratio (aHR) (CIs) of 4.35 (3.28-5.76), 4.39 (3.31-5.82), 5.11 (3.75-6.98), and 4.70 (3.46-6.38), consistent with the results of the main model.

CONCLUSION

Our study showed an increased risk of SLE in the HT group after adjustment for baseline characteristics, comorbidities, and medical confounders compared with the reference group.

Low serum thyroid-stimulating hormone levels may be an early predictor of sepsis

OBJECTIVE

This study aimed to explore whether thyroid-stimulating hormone (TSH) plays an early warning role in detecting progression of bacterial infection to sepsis and can serve as a novel marker for the diagnosis of sepsis.

METHOD

This was a prospective study of patients treated for 'bacterial infection' in the emergency department of Beijing Chaoyang Hospital from 1 January 2021 to 31 August 2021. Subjects were divided into a sepsis group (SG) and a non-SG (NSG), according to whether their condition had progressed to sepsis within 72 hours of admission. Routine blood test results as well as biochemical and thyroid function indices (T4, FT4, T3, FT3) were recorded at the time of admission. TSH, Acute Physiology and Chronic Health Evaluation II scores and Sequential Organ Failure Assessment scores were likewise documented.

RESULTS

A total of 62 patients were enrolled, the SG and the NSG showed significant differences in their levels of TSH. The results indicate that TSH is an early warning marker for sepsis.

CONCLUSIONS

TSH plays an early warning role in the diagnosis of bacterial infection progressing to sepsis, having a strong predictive value.

Refining personalized diagnosis, treatment and exploitation of hypothyroidism related to solid nonthyroid cancer

Hypothyroidism in the setting of cancer is a puzzling entity due to the dual role of the thyroid hormones (TH) in cancer – promoting versus inhibitory – and the complexity of the hypothyroidism itself. The present review provides a comprehensive overview of the personalized approach to hypothyroidism in patients with solid nonthyroid cancer, focusing on current challenges, unmet needs and future perspectives. Major electronic databases were searched from January 2011 until March 2022. The milestones of the refinement of such a personalized approach are prompt diagnosis, proper TH replacement and development of interventions and/or pharmaceutical agents to exploit hypothyroidism or, on the contrary, TH replacement as an anticancer strategy. Further elucidation of the dual role of TH in cancer – especially of the interference of TH signaling with the hallmarks of cancer – is anticipated to inform decision-making and optimize patient selection.

Role of thyroid hormone in an experimental model of atherosclerosis: the potential mediating role of immune response and autophagy

Accumulating evidence has revealed that several conditions related to abnormal thyroid hormone status, such as dyslipidemia, hypertension, or hypercoagulable state, can exacerbate atherosclerotic vascular disease. Thyroid hormone effects on vascular smooth muscle cells and endothelial cells have also been studied extensively. However, only limited information is available on thyroid hormone-mediated immune response in current review articles on the pathophysiology of atherosclerosis. This report thus presents an overview of the recent advances in the understanding of the dynamic interactions taking place between thyroid hormone status and immune response in the pathogenesis of atherosclerosis. In particular, we focus on macrophages and T-lymphocytes, which have been recognized as important determinants for the initiation and development of atherosclerosis. Numerous studies have revealed the role of autophagy in immune cells produced in atherosclerosis. In addition, thyroid hormones induce autophagy in several cells and tissues, such as liver, skeletal muscles, lungs, and brown adipose tissue. Our research group, among others, have reported different targets of thyroid hormone-mediated autophagy, including lipid droplets (lipophagy), mitochondria (mitophagy), and aggregated proteins (aggrephagy). Based on these findings, thyroid hormone-mediated autophagy could serve as a novel therapeutic approach for atherosclerosis. We also consider the limitations of the current murine models for studies on atherosclerosis, especially in relation to low-density lipoprotein-cholesterol driven atherosclerotic plaque.

Thyroid hormones act as modulators of inflammation through their nuclear receptors

Reciprocal crosstalk between endocrine and immune systems has been well-documented both in physiological and pathological conditions, although the connection between the immune system and thyroid hormones (THs) remains largely unclear. Inflammation and infection are two important processes modulated by the immune system, which have profound effects on both central and peripheral THs metabolism. Conversely, optimal levels of THs are necessary for the maintenance of immune function and response. Although some effects of THs are mediated by their binding to cell membrane integrin receptors, triggering a non-genomic response, most of the actions of these hormones involve their binding to specific nuclear thyroid receptors (TRs), which generate a genomic response by modulating the activity of a great variety of transcription factors. In this special review on THs role in health and disease, we highlight the relevance of these hormones in the molecular mechanisms linked to inflammation upon their binding to specific nuclear receptors. In particular, we focus on THs effects on different signaling pathways involved in the inflammation associated with various infectious and/or pathological processes, emphasizing those mediated by NF-kB, p38MAPK and JAK/STAT. The findings showed in this review suggest new opportunities to improve current therapeutic strategies for the treatment of inflammation associated with several infections and/or diseases, such as cancer, sepsis or Covid-19 infection.

Regulation of metabolic and transcriptional responses by the thyroid hormone in cellular models of murine macrophages

Oncogene-immortalized bone marrow-derived macrophages are considered to be a good model for the study of immune cell functions, but the factors required for their survival and proliferation are still unknown. Although the effect of the thyroid hormones on global metabolic and transcriptional responses in macrophages has not yet been examined, there is increasing evidence that they could modulate macrophage functions. We show here that the thyroid hormone T3 is an absolute requirement for the growth of immortal macrophages. The hormone regulates the activity of the main signaling pathways required for proliferation and anabolic processes, including the phosphorylation of ERK and p38 MAPKs, AKT, ribosomal S6 protein, AMPK and Sirtuin-1. T3 also alters the levels of metabolites controlling transcriptional and post-transcriptional actions in macrophages, and causes widespread transcriptomic changes, up-regulating genes needed for protein synthesis and cell proliferation, while down-regulating genes involved in immune responses and endocytosis, among others. This is not observed in primary bone marrow-derived macrophages, where only p38 and AMPK activation is regulated by T3 and in which the metabolic and transcriptomic effects of the hormone are much weaker. However, the response to IFN-γ is reduced by T3 similarly in immortalized macrophages and in the primary cells, confirming previous results showing that the thyroid hormones can antagonize JAK/STAT-mediated signaling. These results provide new perspectives on the relevant pathways involved in proliferation and survival of macrophage cell culture models and on the crosstalk between the thyroid hormones and the immune system.

Bidirectional Relationship Between Tuberculosis and Hypothyroidism: An 18-Year Nationwide Population-Based Longitudinal Cohort Study

Some antituberculosis agents may cause hypothyroidism, and thyroid hormones play a vital role in Mycobacterium tuberculosis infection. However, the relationship between tuberculosis (TB) and hypothyroidism has not been clearly established. Therefore, this retrospective, longitudinal cohort study aimed to investigate the association between these two diseases using the 2000–2017 data from the Taiwan's National Health Insurance Research Database. The hypothyroidism and TB cohorts were matched with the control group in a 1:4 ratio. Adjusted hazard ratios (aHRs) were assessed using Cox proportional hazards regression analysis in each cohort. In total, 3,976 individuals with hypothyroidism and 35 120 individuals with TB were included in this study. The risk of developing TB in patients with hypothyroidism was 2.91 times higher than that in those without hypothyroidism (95% confidence interval [CI], 1.50–3.65). The subgroup of thyroxine replacement therapy (TRT) had a 2.40 times higher risk (95% CI, 1.26–3.01), whereas the subgroup of non-TRT had a 3.62 times higher risk of developing TB than those without hypothyroidism (95% CI, 2.19–4.84). On the other hand, the risk of developing hypothyroidism in patients with TB was 2.01 times higher than that in those without TB (95% CI, 1.41–2.38). Our findings provide evidence that TB and hypothyroidism are interrelated. Thus, clinicians and public health authorities should monitor the association between these two diseases to reduce the relevant disease burden.

The continuum of care of anticancer treatment-induced hypothyroidism in patients with solid non thyroid tumors: time for an intimate collaboration between oncologists and endocrinologists

INTRODUCTION

Hypothyroidism is a common adverse event of various anticancer treatment modalities, constituting a notable paradigm of the integration of the endocrine perspective into precision oncology.

AREAS COVERED

The present narrative review provides a comprehensive and updated overview of anticancer treatment-induced hypothyroidism in patients with solid non-thyroid tumors. A study search was conducted on the following electronic databases: PubMed, Google Scholar, Scopus.com, ClinicalTrials.gov, and European Union Clinical Trials Register from 2011 until August 2021.

EXPERT OPINION

In patients with solid non-thyroid tumors, hypothyroidism is a common adverse event of radiotherapy, high dose interleukin 2 (HD IL-2), interferon alpha (IFN-α), bexarotene, immune checkpoint inhibitors (ICPi), and tyrosine kinase inhibitors (TKIs), while chemotherapy may induce hypothyroidism more often than initially considered. The path forward for the management of anticancer treatment-induced hypothyroidism in patients with solid non-thyroid tumors is an integrated approach grounded on 5 pillars: prevention, vigilance, diagnosis, treatment and monitoring. Current challenges concerning anticancer treatment-induced hypothyroidism await counteraction, namely awareness of the growing list of related anticancer treatments, identification of predictive factors, counteraction of diagnostic pitfalls, tuning of thyroid hormone replacement, and elucidation of its prognostic significance. Close collaboration of oncologists with endocrinologists will provide optimal patient care.

Nonspecific Interstitial Pneumonitis in a Child Associated With Hashimoto Thyroiditis

Interstitial lung disease (ILD) is a rare disease defined as a specific type of chronic fibrosing interstitial pneumonitis whose effects are limited to the lung. Nonspecific interstitial pneumonia (NSIP) was defined as a histopathological form that can be seen in the presence of large different clinical and radiological features.

The exact role of thyroid hormone in the pathogenetic mechanism of idiopathic interstitial pneumonitis (IIP) is unclear. But there is a suggestion that the thyroid hormone plays a role in pulmonary inflammation and fibrosis. In this case report, we described the presentation of NSIP which was associated with Hashimoto thyroiditis.

The Clinical Relevance of Hypothyroidism in Patients with Solid Non-Thyroid Cancer: A Tantalizing Conundrum

Hypothyroidism in patients with solid non-thyroid cancer is a tantalizing entity, integrating an intriguing thyroid hormones (THs)-cancer association with the complexity of hypothyroidism itself. The present narrative review provides a comprehensive overview of the clinical relevance of hypothyroidism in solid non-thyroid cancer. Hypothyroidism in patients with solid non-thyroid cancer is reminiscent of hypothyroidism in the general population, yet also poses distinct challenges due to the dual role of THs in cancer: promoting versus inhibitory. Close collaboration between oncologists and endocrinologists will enable the prompt and personalized diagnosis and treatment of hypothyroidism in patients with solid non-thyroid cancer. Clinical data indicate that hypothyroidism is a predictor of a decreased or increased risk of solid non-thyroid cancer and is a prognostic factor of favorable or unfavorable prognosis in solid non-thyroid cancer. However, the impact of hypothyroidism with respect to the risk and/or prognosis of solid non-thyroid cancer is not a consistent finding. To harness hypothyroidism, or THs replacement, as a personalized anticancer strategy for solid non-thyroid cancer, four prerequisites need to be fulfilled, namely: (i) deciphering the dual THs actions in cancer; (ii) identifying interventions in THs status and developing agents that block tumor-promoting THs actions and/or mimic anticancer THs actions; (iii) appropriate patient selection; and (iv) counteracting current methodological limitations.

3,5,3'-Triiodothyronine-Loaded Liposomes Inhibit Hepatocarcinogenesis Via Inflammation-Associated Macrophages

Background

Hepatocellular carcinoma (HCC) is inflammation-related cancer. Persistent inflammatory injury of the liver is an important factor mediating the occurrence and development of liver cancer. Hepatic macrophages play an important role in the inflammatory microenvironment, which mediates tumor immune escape, tumor growth, and metastasis. Previous studies have suggested that L-3,5,3-triiodothyronine (T3) can regulate inflammation; however, its use is associated with serious cardiac side effects, and its role in hepatocarcinogenesis remains unclear. In this study, we aimed to develop an effective T3 delivery system with reduced cardiac toxicity and to explore its effects on HCC occurrence.

Methods

T3 liposomes (T3-lipo) were prepared using the thin-film hydration method, and their characteristics, including particle size, polydispersity index, zeta potential, encapsulation efficiency, drug loading, drug release, and stability, were evaluated in vitro. We assessed the effect of T3-lipo on hepatocarcinogenesis in diethylnitrosamine (DEN)–induced primary HCC in rats and examined the biodistribution of T3 and T3-lipo by high-performance liquid chromatography–mass spectrometry. Furthermore, we explored the potential molecular mechanism of T3-lipo in hepatocarcinogenesis by immunohistochemistry and immunofluorescence analyses, Bio-Plex assays, real-time polymerase chain reaction analysis, and Western blotting assays.

Results

Compared with T3, T3-lipo had an enhanced inhibitory effect on hepatocarcinogenesis and reduced cardiac side effects in DEN-induced primary HCC in rats. Mechanistically, T3-lipo were absorbed by hepatic macrophages and regulated the secretion of inflammatory cytokines in macrophages by inhibiting inflammatory signaling pathways.

Conclusions

T3-lipo may suppress hepatocarcinogenesis by regulating the inflammatory microenvironment in the liver and reduce the cardiac side effects meanwhile.

Roles and new Insights of Macrophages in the Tumor Microenvironment of Thyroid Cancer

Although most thyroid cancers have a good and predictable prognosis, the anaplastic, medullary, and refractory thyroid cancers still prone to recurrence and metastasis, resulting in poor prognosis. Although a number of newly developed targeted therapies have begun to be indicated for the above types of thyroid cancer in recent years, their ability to improve overall survival remain hindered by low efficacy. As the largest component of immune cells in tumor microenvironment, tumor-associated macrophages play a key role in the invasion and metastasis of thyroid cancer. There is much evidence that the immune system, tumor microenvironment and cancer stem cell interactions may revolutionize traditional therapeutic directions. Tumor-associated macrophages have been extensively studied in a variety of tumors, however, research on the relationship between thyroid cancer and macrophages is still insufficient. In this review, we summarize the functions of tumor-associated macrophages in different types of thyroid cancer, their cytokines or chemokines effect on thyroid cancer and the mechanisms that promote tumor proliferation and migration. In addition, we discuss the mechanisms by which tumor-associated macrophages maintain the stemness of thyroid cancer and potential strategies for targeting tumor-associated macrophages to treat thyroid cancer.

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.

Thyroid Gland Organoids: Current models and insights for application in tissue engineering

The incidence of treatment of thyroid disease and consequential hypothyroidism has been increasing over the past few years. To maintain adequate thyroid hormone levels, these patients require daily supplementation with levothyroxine (L-T4) for the rest of their lives. However, a large part of these patients experiences difficulties due to the medication, which causes a decrease in their quality of life. Regenerative medicine through tissue engineering could provide a potential therapy by establishing tissue engineering models, such as those employing thyroid-derived organoids. The development of such treatment options may replace the need for additional hormonal replacement therapy. This review aims to highlight the current knowledge on thyroid regenerative medicine using organoids for tissue engineering, and to discuss insights into potential methods to optimize thyroid engineering culture systems. Finally, we will describe several challenges faced when utilising these models.

Triiodothyronine (T3) Induces Limited Transcriptional and DNA Methylation Reprogramming in Human Monocytes

Thyroid hormones have immunomodulatory roles, but their effects on the transcriptome and epigenome of innate immune cell types remain unexplored. In this study, we investigate the effects of triiodothyronine (T3) on the transcriptome and methylome of human monocytes in vitro, both in resting and lipopolysaccharide (LPS)-stimulated conditions. In resting monocytes, 5 µM T3 affected the expression of a small number of monocyte-to-macrophage differentiation-associated genes, including TLR4 (p-value < 0.05, expression fold change >1.5). T3 attenuated a small proportion of monocyte-to-macrophage differentiation-associated DNA methylation changes, while specifically inducing DNA methylation changes at several hundred differentially methylated CpG probes (DMPs) (p-value < 0.05, Δβ > 0.05). In LPS-stimulated monocytes, the presence of T3 attenuated the effect of 27% of LPS-induced DMPs (p-value < 0.05, Δβ > 0.05). Interestingly, co-stimulation with T3 + LPS induced a unique DNA methylation signature that was not observed in the LPS-only or T3-only exposure groups. Our results suggest that T3 induces limited transcriptional and DNA methylation remodeling in genes enriched in metabolism and immune processes and alters the normal in vitro LPS response. The overlap between differentially expressed genes and genes associated with DMPs was minimal; thus, other epigenetic mechanisms may underpin the expression changes. This research provides insight into the complex interplay between thyroid hormones, epigenetic remodeling, and transcriptional dynamics in monocytes.

TREM2 is thyroid hormone regulated making the TREM2 pathway druggable with ligands for thyroid hormone receptor

Triggering receptor expressed on myeloid cells-2 (TREM2) is a cell surface receptor on macrophages and microglia that senses and responds to disease-associated signals to regulate the phenotype of these innate immune cells. The TREM2 signaling pathway has been implicated in a variety of diseases ranging from neurodegeneration in the central nervous system to metabolic disease in the periphery. Here, we report that TREM2 is a thyroid hormone-regulated gene and its expression in macrophages and microglia is stimulated by thyroid hormone and synthetic thyroid hormone agonists (thyromimetics). Our findings report the endocrine regulation of TREM2 by thyroid hormone, and provide a unique opportunity to drug the TREM2 signaling pathway with orally active small-molecule therapeutic agents.

PECULIARITIES OF THYROID STATUS OF PRESCHOOL CHILDREN WITH ACUTE BRONCHITIS

OBJECTIVE

The aim: The aim of this study was to determine the characteristics of thyroid status (thyroid hormone, total and free fractions of triiodothyronine and thyroxine, reversible triiodothyronine, antibodies to thyroperoxidase) of preschool children with acute bronchitis.

PATIENTS AND METHODS

Materials and methods: We examined 135 preschool children (from 3 to 6 years old) with acute bronchitis (main group) and 28 apparently healthy subjects who were in the control group. It used clinical-anamnestic, laboratory and instrumental research methods. Evaluation of the course of acute bronchitis was carried out in the acute period of the disease. All results were statistically processed using the SPSS 26 package.

RESULTS

Results: In 33 % of patients with acute bronchitis there are subclinical abnormalities of thyroid hormones, which manifest themselves in the form of euthyroid sick syndrome. Namely, we found an increased concentration of reversible triiodothyronine in the serum, as well as a decrease in total triiodothyronine and its free fraction.

CONCLUSION

Conclusions: In patients with acute bronchitis in almost every third case there are functional shifts in hormonal status, which are manifested in the form of the first variant of the euthyroid sick syndrome.

The Intriguing Thyroid Hormones-Lung Cancer Association as Exemplification of the Thyroid Hormones-Cancer Association: Three Decades of Evolving Research

Exemplifying the long-pursued thyroid hormones (TH)-cancer association, the TH-lung cancer association is a compelling, yet elusive, issue. The present narrative review provides background knowledge on the molecular aspects of TH actions, with focus on the contribution of TH to hallmarks of cancer. Then, it provides a comprehensive overview of data pertinent to the TH-lung cancer association garnered over the last three decades and identifies obstacles that need to be overcome to enable harnessing this association in the clinical setting. TH contribute to all hallmarks of cancer through integration of diverse actions, currently classified according to molecular background. Despite the increasingly recognized implication of TH in lung cancer, three pending queries need to be resolved to empower a tailored approach: (1) How to stratify patients with TH-sensitive lung tumors? (2) How is determined whether TH promote or inhibit lung cancer progression? (3) How to mimic the antitumor and/or abrogate the tumor-promoting TH actions in lung cancer? To address these queries, research should prioritize the elucidation of the crosstalk between TH signaling and oncogenic signaling implicated in lung cancer initiation and progression, and the development of efficient, safe, and feasible strategies leveraging this crosstalk in therapeutics.

Transcriptional and Histochemical Signatures of Bone Marrow Mononuclear Cell-Mediated Resolution of Synovitis

Osteoarthritis (OA) may result from impaired ability of synovial macrophages to resolve joint inflammation. Increasing macrophage counts in inflamed joints through injection with bone marrow mononuclear cells (BMNC) induces lasting resolution of synovial inflammation. To uncover mechanisms by which BMNC may affect resolution, in this study, differential transcriptional signatures of BMNC in response to normal (SF) and inflamed synovial fluid (ISF) were analyzed. We demonstrate the temporal behavior of co-expressed gene networks associated with traits from related in vivo and in vitro studies. We also identified activated and inhibited signaling pathways and upstream regulators, further determining their protein expression in the synovium of inflamed joints treated with BMNC or DPBS controls. BMNC responded to ISF with an early pro-inflammatory response characterized by a short spike in the expression of a NF-ƙB- and mitogen-related gene network. This response was associated with sustained increased expression of two gene networks comprising known drivers of resolution (IL-10, IGF-1, PPARG, isoprenoid biosynthesis). These networks were common to SF and ISF, but more highly expressed in ISF. Most highly activated pathways in ISF included the mevalonate pathway and PPAR-γ signaling, with pro-resolving functional annotations that improve mitochondrial metabolism and deactivate NF-ƙB signaling. Lower expression of mevalonate kinase and phospho-PPARγ in synovium from inflamed joints treated with BMNC, and equivalent IL-1β staining between BMNC- and DPBS-treated joints, associates with accomplished resolution in BMNC-treated joints and emphasize the intricate balance of pro- and anti-inflammatory mechanisms required for resolution. Combined, our data suggest that BMNC-mediated resolution is characterized by constitutively expressed homeostatic mechanisms, whose expression are enhanced following inflammatory stimulus. These mechanisms translate into macrophage proliferation optimizing their capacity to counteract inflammatory damage and improving their general and mitochondrial metabolism to endure oxidative stress while driving tissue repair. Such effect is largely achieved through the synthesis of several lipids that mediate recovery of homeostasis. Our study reveals candidate mechanisms by which BMNC provide lasting improvement in patients with OA and suggests further investigation on the effects of PPAR-γ signaling enhancement for the treatment of arthritic conditions.

Acid Sphingomyelinase Controls Early Phases of Skeletal Muscle Regeneration by Shaping the Macrophage Phenotype

Skeletal muscle regeneration is a complex process involving crosstalk between immune cells and myogenic precursor cells, i.e., satellite cells. In this scenario, macrophage recruitment in damaged muscles is a mandatory step for tissue repair since pro-inflammatory M1 macrophages promote the activation of satellite cells, stimulating their proliferation and then, after switching into anti-inflammatory M2 macrophages, they prompt satellite cells' differentiation into myotubes and resolve inflammation. Here, we show that acid sphingomyelinase (ASMase), a key enzyme in sphingolipid metabolism, is activated after skeletal muscle injury induced in vivo by the injection of cardiotoxin. ASMase ablation shortens the early phases of skeletal muscle regeneration without affecting satellite cell behavior. Of interest, ASMase regulates the balance between M1 and M2 macrophages in the injured muscles so that the absence of the enzyme reduces inflammation. The analysis of macrophage populations indicates that these events depend on the altered polarization of M1 macrophages towards an M2 phenotype. Our results unravel a novel role of ASMase in regulating immune response during muscle regeneration/repair and suggest ASMase as a supplemental therapeutic target in conditions of redundant inflammation that impairs muscle recovery.

Thyroid hormone suppression in feeder pigs following polymicrobial or porcine reproductive and respiratory syndrome virus-2 challenge

Thyroid hormones are powerful regulators of growth, development, and basal metabolic rate and can be dysregulated under conditions of severe stress or illness. To understand the role of these hormones in porcine disease response, serum samples were obtained from three batches of nursery-aged pigs (n = 208) exposed to a natural polymicrobial disease challenge with an array of bacterial and viral pathogens. Levels of total thyroxin (T4) and triiodothyronine (T3) assessed in sera by radioimmunoassay, decreased significantly by 14 days post-exposure (DPE). Levels of T3 partially rebounded by 48 DPE, while T4 levels remain depressed. Post-exposure T3 and T4 levels were positively correlated with acute and long-term average daily gain (ADG). Cross-sectional sampling of animals maintained at the high health source farms, showed no equivalent change in either hormone when managed under standard industrial conditions. To further elucidate the effect of porcine reproductive and respiratory syndrome virus (PRRSV)-infection on thyroid hormone levels, archived sera over 42 days post inoculation (DPI) from nursery pigs (N = 190) challenged with one of two PRRSV2 strains by the PRRS Host Genetics Consortium were similarly assessed, with animals selected in a two-by-two design, to investigate biological extremes in ADG and viral load (VL). All animals showed a similar decrease in both thyroid hormones reaching a minimum at 7 DPI and returning to near pre-challenge levels by 42 DPI. Post-challenge T3 and T4 levels were significantly greater in high ADG groups, with no significant association with VL or strain. The results of this study demonstrate porcine susceptibility to thyroid disruption in response to disease challenge and demonstrate a relationship between this response and growth performance.

Thyroid and COVID-19: a review on pathophysiological, clinical and organizational aspects

BACKGROUND

Thyroid dysfunction has been observed in patients with COVID-19, and endocrinologists are requested to understand this clinical issue. Pandemic-related restrictions and reorganization of healthcare services may affect thyroid disease management.

OBJECTIVE AND METHODS

To analyze and discuss the relationship between COVID-19 and thyroid diseases from several perspectives. PubMed/MEDLINE, Google Scholar, Scopus, ClinicalTrial.gov were searched for this purpose by using free text words and medical subject headings as follows: "sars cov 2", "covid 19", "subacute thyroiditis", "atypical thyroiditis", "chronic thyroiditis", "hashimoto's thyroiditis", "graves' disease", "thyroid nodule", "differentiated thyroid cancer", "medullary thyroid cancer", "methimazole", "levothyroxine", "multikinase inhibitor", "remdesivir", "tocilizumab". Data were collected, analyzed, and discussed to answer the following clinical questions: "What evidence suggests that COVID-19 may induce detrimental consequences on thyroid function?"; "Could previous or concomitant thyroid diseases deteriorate the prognosis of COVID-19 once the infection has occurred?"; "Could medical management of thyroid diseases influence the clinical course of COVID-19?"; "Does medical management of COVID-19 interfere with thyroid function?"; "Are there defined strategies to better manage endocrine diseases despite restrictive measures and in-hospital and ambulatory activities reorganizations?".

RESULTS

SARS-CoV-2 may induce thyroid dysfunction that is usually reversible, including subclinical and atypical thyroiditis. Patients with baseline thyroid diseases are not at higher risk of contracting or transmitting SARS-CoV-2, and baseline thyroid dysfunction does not foster a worse progression of COVID-19. However, it is unclear whether low levels of free triiodothyronine, observed in seriously ill patients with COVID-19, may worsen the disease's clinical progression and, consequently, if triiodothyronine supplementation could be a tool for reducing this burden. Glucocorticoids and heparin may affect thyroid hormone secretion and measurement, respectively, leading to possible misdiagnosis of thyroid dysfunction in severe cases of COVID-19. High-risk thyroid nodules require a fine-needle aspiration without relevant delay, whereas other non-urgent diagnostic procedures and therapeutic interventions should be postponed.

DISCUSSION

Currently, we know that SARS-CoV-2 could lead to short-term and reversible thyroid dysfunction, but thyroid diseases seem not to affect the progression of COVID-19. Adequate management of patients with thyroid diseases remains essential during the pandemic, but it could be compromised because of healthcare service restrictions. Endocrine care centers should continuously recognize and classify priority cases for in-person visits and therapeutic procedures. Telemedicine may be a useful tool for managing patients not requiring in-person visits.

Beyond classic concepts in thyroid homeostasis: Immune system and microbiota

It has long been known that thyroid hormones have implications for multiple physiological processes and can lead to serious illness when there is an imbalance in its metabolism. The connections between thyroid hormone metabolism and the immune system have been extensively described, as they can participate in inflammation, autoimmunity, or cancer progression. In addition, changes in the normal intestinal microbiota involve the activation of the immune system while triggering different pathophysiological disorders. Recent studies have linked the microbiota and certain bacterial fragments or metabolites to the regulation of thyroid hormones and the general response in the endocrine system. Even if the biology and function of the thyroid gland has attracted more attention due to its pathophysiological importance, there are essential mechanisms and issues related to it that are related to the interplay between the intestinal microbiota and the immune system and must be further investigated. Here we summarize additional information to uncover these relationships, the knowledge of which would help establish new personalized medical strategies.

Reduced thyroxine production in young household contacts of tuberculosis patients increases active tuberculosis disease risk

In the current study, we followed 839 household contacts (HHCs) of tuberculosis (TB) patients for 2 years and identified the factors that enhanced the development of TB. Fourteen of the 17 HHCs who progressed to TB were in the 15- to 30-year-old age group. At baseline (the “0“ time point, when all the individuals were healthy), the concentration of the thyroid hormone thyroxine (T4) was lower, and there were increased numbers of Tregs in PBMCs of TB progressors. At baseline, PBMCs from TB progressors stimulated with early secretory antigenic target 6 (ESAT-6) and 10 kDa culture filtrate antigen (CFP-10) produced less IL-1α. Thyroid hormones inhibited Mycobacterium tuberculosis (Mtb) growth in macrophages in an IL-1α–dependent manner. Mtb-infected Thra1^PV/+ (mutant thyroid hormone receptor) mice had increased mortality and reduced IL-1α production. Our findings suggest that young HHCs who exhibit decreased production of thyroid hormones are at high risk of developing active TB disease.

Thyroid hormone disorders: a predictor of mortality in patients with septic shock defined by Sepsis-3?

Decreased serum thyroid hormone levels and their prediction of mortality in septic patients are still controversial, especially with the evolution of the definition of sepsis. This study aimed to assess the ability of thyroid hormone disorders to predict the early mortality of patients with septic shock defined by Sepsis-3. Sixty-three adult patients with septic shock admitted to a university hospital emergency intensive care unit (EICU) were studied. Serum free T3 (FT3), free T4 (FT4), thyroid stimulating hormone (TSH), C-reactive protein (CRP), procalcitonin (PCT), and lactate levels were determined and compared with survival status and organ dysfunction. Among the 63 patients studied, lower serum FT3 and FT4 levels were significantly associated with higher sequential organ failure assessment (SOFA) scores. Patients with septic shock with lower levels of FT3 (≤ 1.70 pmol/L) and FT4 (≤ 9.99 pmol/L) had significantly increased 28-day mortality. There was no significant difference in the serum TSH level between the survivor and nonsurvivor groups. The areas under the receiver operating characteristic curves for FT3 and FT4 levels were associated with 28-day mortality (0.92 and 0.89, respectively) and were higher than that for SOFA (0.82), CRP (0.65) and lactate (0.59). The decrease in serum levels of FT3 and FT4 in patients with septic shock is associated with the severity of organ dysfunction and 28-day mortality. Early detection of serum FT3 and FT4 levels could help clinicians to identify patients at high risk of clinical deterioration.

Molecular Biomarkers Associated with Early-Onset Symptomatic Intracranial Atherosclerosis

Purpose

Previous studies have shown a rising incidence of early-onset symptomatic intracranial atherosclerosis (sICAS), which has brought a severe economic burden to social development. This study aimed to evaluate the molecular biomarkers associated with early-onset sICAS and to seek possible intervention strategies for early prevention.

Patients and Methods

We consecutively recruited patients with sICAS and divided them into two groups based on age: early-onset sICAS group as age ≤60 years old and late-onset sICAS group as age >60 years old. We collected and compared the demographic data and laboratory results of each group. A bivariate logistic regression model was applied to evaluate the independent molecular biomarkers of early-onset sICAS.

Results

A total of 1007 subjects with sICAS were enrolled in this study, comprising 519 patients in the early-onset sICAS group and 488 patients in the late-onset sICAS group. Bivariate logistic regression analysis demonstrated an increased level of white blood cell, platelet, albumin globulin ratio, free triiodothyronine, and a decreased level of total bile acid, urea nitrogen, high-density lipoprotein, homocysteine, and fibrinogen in the early-onset sICAS group when compared to the late-onset group.

Conclusion

Our study showed the relevance between early sICAS and circulating levels of different molecular biomarkers. Detection of these related molecular biomarkers may provide a simple way for early sICAS preventions in the future.

Physiological Role and Use of Thyroid Hormone Metabolites - Potential Utility in COVID-19 Patients

Thyroxine and triiodothyronine (T3) are classical thyroid hormones and with relatively well-understood actions. In contrast, the physiological role of thyroid hormone metabolites, also circulating in the blood, is less well characterized. These molecules, namely, reverse triiodothyronine, 3,5-diiodothyronine, 3-iodothyronamine, tetraiodoacetic acid and triiodoacetic acid, mediate both agonistic (thyromimetic) and antagonistic actions additional to the effects of the classical thyroid hormones. Here, we provide an overview of the main factors influencing thyroid hormone action, and then go on to describe the main effects of the metabolites and their potential use in medicine. One section addresses thyroid hormone levels in corona virus disease 19 (COVID-19). It appears that i) the more potently-acting molecules T3 and triiodoacetic acid have shorter half-lives than the less potent antagonists 3-iodothyronamine and tetraiodoacetic acid; ii) reverse T3 and 3,5-diiodothyronine may serve as indicators for metabolic dysregulation and disease, and iii) Nanotetrac may be a promising candidate for treating cancer, and resmetirom and VK2809 for steatohepatitis. Further, the use of L-T3 in the treatment of severely ill COVID-19 patients is critically discussed.

Liver macrophages and inflammation in physiology and physiopathology of non-alcoholic fatty liver disease

Non‐alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome, being a common comorbidity of type 2 diabetes and with important links to inflammation and insulin resistance. NAFLD represents a spectrum of liver conditions ranging from steatosis in the form of ectopic lipid storage, to inflammation and fibrosis in nonalcoholic steatohepatitis (NASH). Macrophages that populate the liver play important roles in maintaining liver homeostasis under normal physiology and in promoting inflammation and mediating fibrosis in the progression of NAFLD toward to NASH. Liver macrophages are a heterogenous group of innate immune cells, originating from the yolk sac or from circulating monocytes, that are required to maintain immune tolerance while being exposed portal and pancreatic blood flow rich in nutrients and hormones. Yet, liver macrophages retain a limited capacity to raise the alarm in response to danger signals. We now know that macrophages in the liver play both inflammatory and noninflammatory roles throughout the progression of NAFLD. Macrophage responses are mediated first at the level of cell surface receptors that integrate environmental stimuli, signals are transduced through multiple levels of regulation in the cell, and specific transcriptional programmes dictate effector functions. These effector functions play paramount roles in determining the course of disease in NAFLD and even more so in the progression towards NASH. The current review covers recent reports in the physiological and pathophysiological roles of liver macrophages in NAFLD. We emphasise the responses of liver macrophages to insulin resistance and the transcriptional machinery that dictates liver macrophage function.

Role of Macrophages in the Endocrine System

Macrophages are cells of the innate immune system that play myriad roles in the body. Macrophages are known to reside in endocrine glands, and a body of evidence now suggests that these cells interact closely with endocrine cells. Immune-endocrine interactions are important in the development of endocrine glands and their functioning during physiological states, and also become key players in pathophysiological states. Through gene expression profiling, diverse subpopulations of tissue macrophages have been discovered within endocrine organs; this has important implications for disease pathogenesis and potential pharmacotherapy. The molecular basis for the crosstalk between macrophages and endocrine cells is being unraveled, and allows the identification of multiple points for pharmacologic intervention. Macrophages in adipose tissue and pancreatic islets are key players in the process of metaflammation (metabolic inflammation) that underlies the development of insulin resistance, metabolic syndrome, diabetes mellitus, and non-alcoholic fatty liver disease. In the ovary, they play important roles in ovarian folliculogenesis and ovulation, whereas in the male reproductive tract they regulate spermatogenesis through the regulation of steroidogenesis by Leydig cells. We summarize the diverse roles played by macrophages in the endocrine system and identify potential targets for pharmacotherapy in endocrine disorders.

Exacerbated age-related hearing loss in mice lacking the p43 mitochondrial T3 receptor

BACKGROUND

Age-related hearing loss (ARHL), also known as presbycusis, is the most common sensory impairment seen in elderly people. However, the cochlear aging process does not affect people uniformly, suggesting that both genetic and environmental (e.g., noise, ototoxic drugs) factors and their interaction may influence the onset and severity of ARHL. Considering the potential links between thyroid hormone, mitochondrial activity, and hearing, here, we probed the role of p43, a N-terminally truncated and ligand-binding form of the nuclear receptor TRα1, in hearing function and in the maintenance of hearing during aging in p43-/- mice through complementary approaches, including in vivo electrophysiological recording, ultrastructural assessments, biochemistry, and molecular biology.

RESULTS

We found that the p43-/- mice exhibit no obvious hearing loss in juvenile stages, but that these mice developed a premature, and more severe, ARHL resulting from the loss of cochlear sensory outer and inner hair cells and degeneration of spiral ganglion neurons. Exacerbated ARHL in p43-/- mice was associated with the early occurrence of a drastic fall of SIRT1 expression, together with an imbalance between pro-apoptotic Bax, p53 expression, and anti-apoptotic Bcl2 expression, as well as an increase in mitochondrial dysfunction, oxidative stress, and inflammatory process. Finally, p43-/- mice were also more vulnerable to noise-induced hearing loss.

CONCLUSIONS

These results demonstrate for the first time a requirement for p43 in the maintenance of hearing during aging and highlight the need to probe the potential link between human THRA gene polymorphisms and/or mutations and accelerated age-related deafness or some adult-onset syndromic deafness.

TREM2 is thyroid hormone regulated making the TREM2 pathway druggable with ligands for thyroid hormone receptor

Triggering receptor expressed on myeloid cells-2 (TREM2) is a cell surface receptor on macrophages and microglia that senses and responds to disease associated signals to regulate the phenotype of these innate immune cells. The TREM2 signaling pathway has been implicated in a variety of diseases ranging from neurodegeneration in the central nervous system to metabolic disease in the periphery. We report here that TREM2 is a thyroid hormone regulated gene and its expression in macrophages and microglia is stimulated by thyroid hormone. Both endogenous thyroid hormone and sobetirome, a synthetic thyroid hormone agonist drug, suppress pro-inflammatory cytokine production from myeloid cells including macrophages that have been treated with the SARS-CoV-2 spike protein which produces a strong, pro-inflammatory phenotype. Thyroid hormone agonism was also found to induce phagocytic behavior in microglia, a phenotype consistent with activation of the TREM2 pathway. The thyroid hormone antagonist NH-3 blocks the anti-inflammatory effects of thyroid hormone agonists and suppresses microglia phagocytosis. Finally, in a murine experimental autoimmune encephalomyelitis (EAE) multiple sclerosis model, treatment with Sob-AM2, a CNS-penetrating sobetirome prodrug, results in increased Trem2 expression in disease lesion resident myeloid cells which correlates with therapeutic benefit in the EAE clinical score and reduced damage to myelin. Our findings represent the first report of endocrine regulation of TREM2 and provide a unique opportunity to drug the TREM2 signaling pathway with orally active small molecule therapeutic agents.

Dynamic Interactions Between the Immune System and the Neuroendocrine System in Health and Disease

The immune system and the neuroendocrine system share many common features. Both consist of diverse components consisting of receptors and networks that are widely distributed throughout the body, and both sense and react to external stimuli which, on the one hand control mechanisms of immunity, and on the other hand control and regulate growth, development, and metabolism. It is thus not surprising, therefore, that the immune system and the neuroendocrine system communicate extensively. This article will focus on bi-directional immune-endocrine interactions with particular emphasis on the hormones of the hypothalamus-pituitary-thyroid (HPT) axis. New findings will be discussed demonstrating the direct process through which the immune system-derived thyroid stimulating hormone (TSH) controls thyroid hormone synthesis and bone metamorphosis, particularly in the context of a novel splice variant of TSHβ made by peripheral blood leukocytes (PBL). Also presented are the ways whereby the TSHβ splice variant may be a contributing factor in the development and/or perpetuation of autoimmune thyroid disease (AIT), and how systemic infection may elicit immune-endocrine responses. The relationship between non-HPT hormones, in particular adipose hormones, and immunity is discussed.

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.

Prospective role of thyroid disorders in monitoring COVID-19 pandemic

COVID-19 pandemic has affected more than 200 countries and 1.3 million individuals have deceased within eleven months. Intense research on COVID-19 occurrence and prevalence enable us to understand that comorbidities play a crucial role in spread and severity of SARS-CoV-2 infection. Chronic kidney disease, diabetes, respiratory diseases and hypertension are among the various morbidities that are prevalent in symptomatic COVID-19 patients. However, the effect of altered thyroid-driven disorders cannot be ignored. Since thyroid hormone critically coordinate and regulate the major metabolism and biochemical pathways, this review is on the potential role of prevailing thyroid disorders in SARS-CoV-2 infection. Direct link of thyroid hormone with several disorders such as diabetes, vitamin D deficiency, obesity, kidney and liver disorders etc. suggests that the prevailing thyroid conditions may affect SARS-CoV-2 infection. Further, we discuss the oxidative stress-induced aging is associated with the degree of SARS-CoV-2 infection. Importantly, ACE2 protein which facilitates the host-cell entry of SARS-CoV-2 using the spike protein, are highly expressed in individuals with abnormal level of thyroid hormone. Altogether, we report that the malfunction of thyroid hormone synthesis may aggravate SARS-CoV-2 infection and thus monitoring the thyroid hormone may help in understanding the pathogenesis of COVID-19.