Pathology of the thyroid in severe acute respiratory syndrome

The Association of Thyroid Hormone Changes with Inflammatory Status and Prognosis in COVID-19

BACKGROUND

COVID-19 infection may have multiorgan effects in addition to effects on the lungs and immune system. Recently, studies have found thyroid function abnormalities in COVID-19 cases which were interpreted as euthyroid sick syndrome (ESS) or destructive thyroiditis. Therefore, in this study, we aimed to evaluate the thyroid function status and thyroid autoimmunity in COVID-19 patients. Material and Method. 205 patients were included. The medical history and laboratory parameters at admission were collected from medical records. Serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), thyroid peroxidase antibody, and thyroglobulin antibody were measured, and patients were classified according to thyroid function status.

RESULTS

34.1% of the patients were euthyroid. Length of hospitalization (p < 0.001), rate of oxygen demand (p < 0.001), and intensive care unit (ICU) admission (p=0.022) were lower, and none of the euthyroid patients died. 108 (52.6%) patients were classified to have ESS, 57 were classified as mild, and 51 were moderate. The inflammatory parameters were higher in patients with moderate ESS. In cluster analysis, a high-risk group with a lower median FT3 value (median = 2.34 ng/L; IQR = 0.86), a higher median FT4 value (median = 1.04 ng/dL; IQR = 0.33), and a lower median TSH value (median = 0.62 mIU/L; IQR = 0.59) included 8 of 9 died patients and 25 of the 31 patients that were admitted to ICU. Discussion. Length of hospitalization, oxygen demand, ICU admission, and mortality were lower in euthyroid patients. Moreover, none of the euthyroid patients died. In conclusion, evaluation of thyroid function tests during COVID-19 infection may give information about the prognosis of disease.

Thyroid Function Analysis in 50 Patients with COVID-19: A Retrospective Study

Background: Since the outbreak of the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in December 2019, it has affected >200 countries, areas, or territories in 6 continents. At present, whether COVID-19 has an effect on thyroid function is unclear. The aim of this study was to evaluate thyroid function in patients with COVID-19. Methods: Clinical manifestations, laboratory results, and chest computed tomography scans were retrospectively reviewed for 50 patients with laboratory-confirmed COVID-19 without a history of thyroid disease who underwent thyroid function testing during their course of COVID-19 infection and after recovery. They were admitted to the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China, between January and March 2020. Healthy participants who underwent routine physical checkups and non-COVID-19 pneumonia patients with a similar degree of severity during the same period were included in the study as the control group. Thyroid hormone and thyrotropin (TSH) levels were analyzed and compared between the COVID-19 and control groups. Results: TSH lower than the normal range was present in 56% (28/50) of the patients with COVID-19. The levels of TSH and serum total triiodothyronine (TT3) of the patients with COVID-19 were significantly lower than those of the healthy control group and non-COVID-19 pneumonia patients. The more severe the COVID-19, the lower the TSH and TT3 levels were, with statistical significance (p < 0.001). The degree of the decreases in TSH and TT3 levels was positively correlated with the severity of the disease. The total thyroxine (TT4) level of the patients with COVID-19 was not significantly different from the control group. All the patients did not receive thyroid hormone replacement therapy. After recovery, no significant differences in TSH, TT3, TT4, free triiodothyronine (fT3), and free thyroxine (fT4) levels were found between the COVID-19 and control groups. Conclusions: The changes in serum TSH and TT3 levels may be important manifestations of the courses of COVID-19.

Coronavirus Disease 2019 and the Thyroid - Progress and Perspectives

SARS-CoV-2 infection (COVID-19) is currently a tremendous global health problem. COVID-19 causes considerable damage to a wide range of vital organs most prominently the respiratory system. Recently, clinical evidence for thyroidal insults during and after COVID-19 has been accumulated. As of today, almost all non-neoplastic thyroid diseases, i.e., Graves' disease, Hashimoto's thyroiditis, subacute, painless and postpartum thyroiditis, have been reported as a complication of COVID-19, and causality by the virus has been strongly implicated in all of them. Similar thyroid problems have been reported in the past with the SARS-CoV outbreak in 2002. In this review, we briefly look back at the reported evidence of alteration in thyroid functionality and thyroid diseases associated with SARS-CoV and then proceed to examine the issue with COVID-19 in detail, which is then followed by an in-depth discussion regarding a pathogenetic link between Coronavirus infection and thyroid disease.

The Association Between COVID-19 and Thyroxine Levels: A Meta-Analysis

OBJECTIVES

Recently, a number of reports have described the potential relationship between COVID-19 and thyroid hormones, but the results were conflicting. We performed a meta-analysis to evaluate the effect of the severity of COVID-19 on thyroid-related hormones and the effect of thyroid-related hormones on the outcome of COVID-19 in order to try to confirm the association between the serum levels of free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) and the severity or mortality of coronavirus-19 patients.

METHODS

The methodology was already registered in the International Prospective Register of Systematic Reviews (PROSPERO) database, and the protocol number is CRD42021269246. Systematic searches were carried out on the Cochrane Library, Embase, PubMed and Web of Science databases on November 15, 2021. We set up the literature search strategy based on the following keywords: [(T3 OR FT3 OR triiodothyronine) or (T4 OR FT4 OR thyroxine) or (TSH or thyrotropin)] and (COVID-19 OR SARS-CoV-2), without time restrictions.

RESULTS

Twenty studies satisfied the inclusion/exclusion criteria and were included in the meta-analysis. A total of 3609 patients were enrolled in the study. From the analysis of the included studies, the incidence of thyroid-related hormone abnormalities was higher in patients with severe COVID-19, and the serum levels of FT3 and TSH were lower than those of patients with nonsevere COVID-19. However, the difference in the FT4 levels was not significant. Similar characteristics were shown between survivors and nonsurvivors. In addition, the outcomes of the meta-analysis showed that patients with abnormal thyroid-related hormones had greater mortality.

CONCLUSIONS

Low FT3 serum levels, low FT4 serum levels and low TSH serum levels may increase the mortality of COVID-19 patients during admission. On the other hand, the higher the severity level of COVID-19, the higher the probability of decreases in the FT3, FT4, TSH levels.

Spectrum of Endocrine Dysfunction and Association With Disease Severity in Patients With COVID-19: Insights From a Cross-Sectional, Observational Study

INTRODUCTION

Evidence on new-onset endocrine dysfunction and identifying whether the degree of this dysfunction is associated with the severity of disease in patients with COVID-19 is scarce.

PATIENTS AND METHODS

Consecutive patients enrolled at PGIMER Chandigarh were stratified on the basis of disease severity as group I (moderate-to-severe disease including oxygen saturation <94% on room air or those with comorbidities) (n= 35) and group II (mild disease, with oxygen saturation >94% and without comorbidities) (n=49). Hypothalamo-pituitary-adrenal, thyroid, gonadal axes, and lactotroph function were evaluated. Inflammatory and cell-injury markers were also analysed.

RESULTS

Patients in group I had higher prevalence of hypocortisolism (38.5 vs 6.8%, p=0.012), lower ACTH (16.3 vs 32.1pg/ml, p=0.234) and DHEAS (86.29 vs 117.8µg/dl, p= 0.086) as compared to group II. Low T3 syndrome was a universal finding, irrespective of disease severity. Sick euthyroid syndrome (apart from low T3 syndrome) (80.9 vs 73.1%, p= 0.046) and atypical thyroiditis (low T3, high T4, low or normal TSH) (14.3 vs 2.4%, p= 0.046) were more frequent in group I than group II. Male hypogonadism was also more prevalent in group I (75.6% vs 20.6%, p=0.006) than group II, with higher prevalence of both secondary (56.8 vs 15.3%, p=0.006) and primary (18.8 vs 5.3%, p=0.006) hypogonadism. Hyperprolactinemia was observed in 42.4% of patients without significant difference between both groups.

CONCLUSION

COVID-19 can involve multiple endocrine organs and axes, with a greater prevalence and degree of endocrine dysfunction in those with more severe disease.

Graves' Thyrotoxicosis Following SARS-CoV-2 Infection

Objective

Graves’ disease is an autoimmune thyroid disease that is thought to develop following environmental exposure in patients with genetic predisposition. Our objective is to present the first report of Graves’ disease onset immediately following recovery from mild coronavirus disease 2019 (COVID-19), a close temporal occurrence that should be studied further.

Methods

We describe the clinical course and laboratory features, including thyroid function studies, antibody testing, and polymerase chain reaction testing for severe acute respiratory syndrome coronavirus 2.

Results

A 21-year-old woman with prediabetes, obesity, asthma, and gastroesophageal reflux disease presented to the emergency department reporting 3 days of tachycardia, palpitations, anxiety, and shortness of breath. Laboratory investigation revealed a thyroid-stimulating hormone level of 0.01 (0.30-5.00) mcIU/mL with a free thyroxine level of 3.8 (0.6-1.6) ng/dL, prompting endocrinology consultation. On physical examination, she had mild diffuse thyromegaly without tenderness and a history, which included hypothyroidism in her mother. Antibody testing results demonstrated thyroid-stimulating immunoglobulin and thyrotropin receptor antibody levels of 2.6 (<1.3) thyroid-stimulating immunoglobulin index and 17 (0.00-1.75) IU/L, respectively. Sixteen days before presenting to the ED, she was diagnosed with COVID-19 by polymerase chain reaction test after reporting typical symptoms, including fever. Infectious symptoms resolved within 10 days. She achieved clinical and laboratory improvements with a combination of methimazole and beta blocker therapy.

Conclusion

This case documents the occurrence of Graves’ thyrotoxicosis following mild symptomatic COVID-19. Whether the preceding infection is coincidental or contributed to GD development requires definitive studies. This presentation may align with the theory of a viral link in the development of autoimmune thyroid disease in those with genetic predisposition.

Delayed Onset of Central Hypocortisolism in a Patient Recovering From COVID-19

Objective

The objective of this report is to highlight the possible but little-known association between coronavirus disease 2019 (COVID-19) and delayed onset of central hypocortisolism, which may be of significant clinical importance.

Methods

We describe a patient who developed new-onset central hypocortisolism in the convalescent phase of mild COVID-19, which has not been previously reported.

Results

A 47-year-old man with recent COVID-19 upper respiratory tract infection developed new-onset persistent dyspepsia and eosinophilia for which multiple investigations were normal. He was eventually diagnosed with central hypocortisolism, as evidenced by 8 AM cortisol level of 19 nmol/L (normal, 133-537 nmol/L) and adrenocorticotropic hormone of 7.1 ng/mL (normal, 10.0-60.0 ng/mL). He was started on hydrocortisone, which led to resolution of both dyspepsia and eosinophilia. At the same time, an interesting thyroid function trend was observed—an initial increase in both free thyroxine and thyroid stimulating hormone was followed by temporary central hypothyroidism before subsequent spontaneous recovery. On follow-up 3 weeks later, the patient remained hypocortisolemic.

Conclusion

COVID-19 may be associated with the delayed onset of central hypocortisolism in its convalescent phase. Although various mechanisms are possible, hypothalamic-pituitary activation during systemic illness, followed by a rebound decrease in activity after recovery, is consistent with the clinical course and thyroid function trend in this patient. It is essential that physicians consider endocrinopathies in the differential diagnosis of such cases, given the risk of life-threatening adrenal crises and their possible contribution to persistent symptoms following recovery from COVID-19.

Road Map to Understanding SARS-CoV-2 Clinico-Immunopathology and COVID-19 Disease Severity

SARS-CoV-2, a novel coronavirus, was first identified in Wuhan, China in December 2019. The rapid spread of the virus worldwide prompted the World Health Organization (WHO) to declare COVID-19 a pandemic in March 2020. COVID-19 discontinuing's a global health crisis. Approximately 80% of the patients infected with SARS-CoV-2 display undetectable to mild inflammation confined in the upper respiratory tract. In remaining patients, the disease turns into a severe form affecting almost all major organs predominantly due to an imbalance of innate and adaptive arms of host immunity. The purpose of the present review is to narrate the virus's invasion through the system and the host's reaction. A thorough discussion on disease severity is also presented regarding the behavior of the host's immune system, which gives rise to the cytokine storm particularly in elderly patients and those with comorbidities. A multifaceted yet concise description of molecular aspects of disease progression and its repercussion on biochemical and immunological features in infected patients is tabulated. The summary of pathological, clinical, immunological, and molecular accounts discussed in this review is of theranostic importance to clinicians for early diagnosis of COVID-19 and its management.

Subacute thyroiditis as a presenting manifestation of COVID-19: a report of an exceedingly rare clinical entity

The SARS-CoV-2 has wreaked havoc globally and has claimed innumerable lives all over the world. The symptoms of this disease may range from mild influenza-like symptoms to severe acute respiratory distress syndrome with high morbidity and mortality. With improved diagnostic techniques and better disease understanding, an increased number of cases are being reported with extrapulmonary manifestations of this disease ranging from renal and gastrointestinal to cardiac, hepatic, neurological and haematological dysfunction. Subacute thyroiditis is a self-limiting and painful thyroid gland inflammation most often secondary to viral infections. We report a case of subacute thyroiditis in a 58-year-old gentleman presenting with a painful swelling in the neck who was subsequently detected to be positive for SARS-CoV-2. We seek to highlight the broad clinical spectrum of the COVID-19 by reporting probably the first case of subacute thyroiditis possibly induced by SARS-CoV-2 infection from India.

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.

Endocrine and metabolic aspects of the COVID-19 pandemic

COVID-19 infection has tremendously impacted our daily clinical practice as well as our social living organization. Virtually all organs and biological systems suffer from this new coronavirus infection, either because the virus targets directly specific tissues or because of indirect effects. Endocrine diseases are not an exception and some of endocrine organs are at risk of direct or indirect lesion by COVID-19. Although there is still no evidence of higher predisposition to contract the infection in patients with diabetes and/or obesity, the coexistence of these conditions contributes to a worse prognosis because both conditions confer an impaired immunologic system. Cytokines storm can be amplified by these two latter conditions thereby leading to multisystemic failure and death. Glycaemic control has been demonstrated to be crucial to avoiding long hospital stays, ICU requirement and also prevention of excessive mortality. Endocrine treatment modifications as a consequence of COVID-19 infection are required in a proactive manner, in order to avoid decompensation and eventual hospital admission. This is the case of diabetes and adrenal insufficiency in which prompt increase of insulin dosage and substitutive adrenal steroids through adoption of the sick day's rules should be warranted, as well as easy contact with the health care provider through telematic different modalities. New possible endocrinological targets of COVID-19 have been recently described and warrant a full study in the next future.

Macrophage Activation in the Synovium of Healthy and Osteoarthritic Equine Joints

Synovitis is a major component of osteoarthritis and is driven primarily by macrophages. Synovial macrophages are crucial for joint homeostasis (M2-like phenotype), but induce inflammation (M1-like) when regulatory functions become overwhelmed. Macrophage phenotypes in synovium from osteoarthritic and healthy joints are poorly characterized; however, comparative knowledge of their phenotypes during health and disease is paramount for developing targeted treatments. This study compared patterns of macrophage activation in healthy and osteoarthritic equine synovium and correlated histology with cytokine/chemokine profiles in synovial fluid. Synovial histology and immunohistochemistry for M1-like (CD86), M2-like (CD206, IL-10), and pan macrophage (CD14) markers were performed on biopsies from 29 healthy and 26 osteoarthritic equine joints. Synovial fluid cytokines (MCP-1, IL-10, PGE2, IL-1β, IL-6, TNF-α, IL-1ra) and growth factors (GM-CSF, SDF-1α+β, IGF-1, and FGF-2) were quantified. Macrophage phenotypes were not as clearly defined in vivo as they are in vitro. All macrophage markers were expressed with minimal differences between OA and normal joints. Expression for all markers increased proportionate to synovial inflammation, especially CD86. Synovial fluid MCP-1 was higher in osteoarthritic joints while SDF-1 and IL-10 were lower, and PGE2 concentrations did not differ between groups. Increased CD14/CD86/CD206/IL-10 expression was associated with synovial hyperplasia, consistent with macrophage recruitment and activation in response to injury. Lower synovial fluid IL-10 could suggest that homeostatic mechanisms from synovial macrophages became overwhelmed preventing inflammation resolution, resulting in chronic inflammation and OA. Further investigations into mechanisms of arthritis resolution are warranted. Developing pro-resolving therapies may provide superior results in the treatment of OA.

Reinterpreting patterns of variation in human thyroid function: An evolutionary ecology perspective

Two hundred million people worldwide experience some form of thyroid disorder, with women being especially at risk. However, why human thyroid function varies between populations, individuals, and across the lifespan has attracted little research to date. This limits our ability to evaluate the conditions under which patterns of variation in thyroid function are best understood as 'normal' or 'pathological'. In this review, we aim to spark interest in research aimed at understanding the causes of variation in thyroid phenotypes. We start by assessing the biomedical literature on thyroid imbalance to discuss the validity of existing reference intervals for diagnosis and treatment across individuals and populations. We then propose an evolutionary ecological framework for understanding the phylogenetic, genetic, ecological, developmental, and physiological causes of normal variation in thyroid function. We build on this approach to suggest testable predictions for how environmental challenges interact with individual circumstances to influence the onset of thyroid disorders. We propose that dietary changes, ecological disruptions of co-evolutionary processes during pregnancy and with pathogens, emerging infections, and exacerbated stress responses can contribute to explaining the onset of thyroid diseases. For patients to receive the best personalized care, research into the causes of thyroid variation at multiple levels is needed.

Thyroid Function Test in COVID-19 Patients: A Cross-Sectional Study in a Tertiary Care Hospital

CONTEXT

There is scarcity of data on thyroid function abnormality in COVID-19 patients in world literature.

AIMS

The objective of this study was to assess thyroid function tests in hospitalized patients of COVID-19.

SETTINGS AND DESIGN

Sixty (60) patients with COVID-19 detected by RT-PCR admitted in General Medicine isolation ward and COVID block of a tertiary care teaching hospital were selected by semi-purposive sampling.

MATERIALS AND METHODS

These patients were assessed for thyroid function tests, including total T3, free T3, total T4, free T4, TSH and anti-TPO antibody along with other baseline investigations. Patients with pre-existing thyroid-related ailments, those on levothyroxine or anti-thyroid drugs or other drugs known to interfere with the results were excluded.

RESULTS

There were 43.3% patients in mild, 26.7% in moderate, and 30% in severe category, according to local COVID-19 severity classification protocol. 35% patients had one or more abnormality in the thyroid function, low TSH being the most common (18.33%). 9.1% patients had characteristic pattern of thyroiditis. In most of the others thyroid function did not match any typical pattern. There was no significant difference in any of the parameters of the thyroid function test between mild, moderate, and severe groups.

CONCLUSION

Thyroid function may be abnormal in all categories of patients during COVID-19 infection, even in absence of pre-existing thyroid ailments. Although low TSH is the commonest abnormality and typical pattern of thyroiditis can be seen in a subsection of patients, in majority of the patients, thyroid function abnormality does not follow any characteristic pattern and likely represents a combination of thyroiditis and sick euthyroid syndrome in different points of its spectrum.

Euthyroid Sick Syndrome in Patients With COVID-19

BACKGROUND

Coronavirus disease 2019 (COVID-19) has been shown to affect almost every organ throughout the body. However, it is not clear whether the thyroid gland is impaired in COVID-19 patients. Euthyroid sick syndrome (ESS) is usually associated with the disease severity and deterioration prognosis in critical illness. In this study, the thyroid function of COVID-19 patients was assessed and factors associated with outcomes were analyzed to determine the potential predictive value of ESS.

METHODS

Clinical and laboratory data of COVID-19 patients with or without ESS in Changsha, China, were collected and analyzed on admission. Kaplan-Meier curve and cox regression model were utilized to determine the correlation between ESS and the endpoints. Subsequently, a receiver operating characteristic (ROC) curve was plotted to evaluate the predictive performances of FT3 and C-reactive protein (CRP) in the disease severity.

RESULTS

Forty-one (27.52%) cases of COVID-19 patients diagnosed with ESS. ESS patients had higher proportions of fever, shortness of breath, hypertension, diabetes, and severe events than those of non-ESS patients. The levels of erythrocyte sedimentation rate and C-reactive protein, and the positive rate of procalcitonin were significantly higher, whereas the lymphocyte count was apparently lower in ESS patients than in non-ESS patients. The regression analysis showed that ESS was significantly associated with the disease severity of COVID-19 (HR = 2.515, 95% CI: 1.050-6.026, P = 0.039). The areas under the curve (AUCs) for predicting the severe disease were [0.809 (95% CI 0.727-0.892), P < 0.001] and [0.792 (95% CI 0.689-0.895), P < 0.001] for FT3 and CRP, respectively.

CONCLUSION

ESS was significantly associated with the disease severity and inflammatory parameters in COVID-19 patients.

Thyrotoxicosis in patients with COVID-19: the THYRCOV study

OBJECTIVE

This study assessed thyroid function in patients affected by the coronavirus disease-19 (COVID-19), based on the hypothesis that the cytokine storm associated with COVID-19 may influence thyroid function and/or the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may directly act on thyroid cells, such as previously demonstrated for SARS-CoV-1 infection.

DESIGN AND METHODS

This single-center study was retrospective and consisted in evaluating thyroid function tests and serum interleukin-6 (IL-6) values in 287 consecutive patients (193 males, median age: 66 years, range: 27-92) hospitalized for COVID-19 in non-intensive care units.

RESULTS

Fifty-eight patients (20.2%) were found with thyrotoxicosis (overt in 31 cases), 15 (5.2%) with hypothyroidism (overt in only 2 cases), and 214 (74.6%) with normal thyroid function. Serum thyrotropin (TSH) values were inversely correlated with age of patients (rho -0.27; P < 0.001) and IL-6 (rho -0.41; P < 0.001). In the multivariate analysis, thyrotoxicosis resulted to be significantly associated with higher IL-6 (odds ratio: 3.25, 95% confidence interval: 1.97-5.36; P < 0.001), whereas the association with age of patients was lost (P = 0.09).

CONCLUSIONS

This study provides first evidence that COVID-19 may be associated with high risk of thyrotoxicosis in relationship with systemic immune activation induced by the SARS-CoV-2 infection.

Thyroid disorders and SARS-CoV-2 infection: From pathophysiological mechanism to patient management

The World Health Organization (WHO) declared the COVID-19 epidemic to be a global pandemic in March 2020. COVID-19 is an infection caused by SARS-CoV-2, a coronavirus that utilizes the angiotensin-2 converting enzyme to penetrate thyroid and pituitary cells, and may result in a “cytokine storm”. Based on the pathophysiological involvement of the pituitary-thyroid axis, the current review discusses the diagnosis of abnormal thyroid function test, and the management of patients presenting with thyrotoxicosis, thyroid-associated orbitopathy and hypothyroidism in the context of SARS-CoV-2 infection.

Why COVID-19 Transmission Is More Efficient and Aggressive Than Viral Transmission in Previous Coronavirus Epidemics?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing a pandemic of coronavirus disease 2019 (COVID-19). The worldwide transmission of COVID-19 from human to human is spreading like wildfire, affecting almost every country in the world. In the past 100 years, the globe did not face a microbial pandemic similar in scale to COVID-19. Taken together, both previous outbreaks of other members of the coronavirus family (severe acute respiratory syndrome (SARS-CoV) and middle east respiratory syndrome (MERS-CoV)) did not produce even 1% of the global harm already inflicted by COVID-19. There are also four other CoVs capable of infecting humans (HCoVs), which circulate continuously in the human population, but their phenotypes are generally mild, and these HCoVs received relatively little attention. These dramatic differences between infection with HCoVs, SARS-CoV, MERS-CoV, and SARS-CoV-2 raise many questions, such as: Why is COVID-19 transmitted so quickly? Is it due to some specific features of the viral structure? Are there some specific human (host) factors? Are there some environmental factors? The aim of this review is to collect and concisely summarize the possible and logical answers to these questions.

COVID-19 and Thyroid: Progress and Prospects

The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread worldwide. A number of serious effects on various organs and systems have been reported in humans, and recently emerging evidence on the potential association between the infection and thyroid dysfunction are attracting attention from the scientific community. This editorial critically summarizes the main findings on this topic published so far and defines research lines according to the translational approach from the bench to the bed to epidemiological studies and back again, aimed at patient care and effective public health measures.

Endocrine Significance of SARS-CoV-2's Reliance on ACE2

The current COVID-19 pandemic is the most disruptive event in the past 50 years, with a global impact on health care and world economies. It is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), a coronavirus that uses angiotensin-converting enzyme 2 (ACE2) as an entry point to the cells. ACE2 is a transmembrane carboxypeptidase and member of the renin-angiotensin system. This mini-review summarizes the main findings regarding ACE2 expression and function in endocrine tissues. We discuss rapidly evolving knowledge on the potential role of ACE2 and SARS coronaviruses in endocrinology and the development of diabetes mellitus, hypogonadism, and pituitary and thyroid diseases.

Endocrine Involvement in COVID-19: Mechanisms, Clinical Features, and Implications for Care

Coronavirus 2019 (COVID -19) has rapidly emerged as a global pandemic with multi-system involvement. Involvement of the endocrine system is expected in COVID-19 as the interplay between severe acute respiratory syndrome corona virus-2 (SARS CoV-2) and the endocrine system occurs at multiple levels. The widespread presence of ACE-2 receptors on various tissues suggests scope for direct viral infection. The interactions via the activation of inflammatory mediators and indirect immune-mediated damage are also postulated. Evidence so far suggests that COVID-19 can cause functional hypopituitarism by direct and indirect effects on the hypothalamo-pituitary axis resulting in inappropriate adrenal response to stress. Several reports highlight possible immune-mediated damage to thyroid glands resulting in subacute thyroiditis. COVID-19 is implicated in precipitating hyperglycemia in known diabetics and uncovering insulin resistance in those previously undiagnosed. COVID-19 has also been shown to trigger Type 1 Diabetes with ketosis. Various mechanisms including direct virus-induced beta cell apoptosis and immune-mediated beta-cell damage have been demonstrated. The presence of virus in semen has unclear clinical significance at present. In this mini-review summarize the endocrine manifestations reported so far in COVID-19 disease and explore mechanisms to decipher how SARS CoV-2 may affect various endocrine organs.

Sudden Cardiac Arrest in a Patient With Myxedema Coma and COVID-19

SARS-CoV-2 infection is associated with significant lung and cardiac morbidity but there is a limited understanding of the endocrine manifestations of coronavirus disease 2019 (COVID-19). Although thyrotoxicosis due to subacute thyroiditis has been reported in COVID-19, it is unknown whether SARS-CoV-2 infection can also lead to decompensated hypothyroidism. We present the first case of myxedema coma (MC) in COVID-19 and we discuss how SARS-CoV-2 may have precipitated multiorgan damage and sudden cardiac arrest in our patient. A 69-year-old woman with a history of small cell lung cancer presented with hypothermia, hypotension, decreased respiratory rate, and a Glasgow Coma Scale score of 5. The patient was intubated and administered vasopressors. Laboratory investigation showed elevated thyrotropin, very low free thyroxine, elevated thyroid peroxidase antibody, and markedly elevated inflammatory markers. SARS-CoV-2 test was positive. Computed tomography showed pulmonary embolism and peripheral ground-glass opacities in the lungs. The patient was diagnosed with myxedema coma with concomitant COVID-19. While treatment with intravenous hydrocortisone and levothyroxine were begun the patient developed a junctional escape rhythm. Eight minutes later, the patient became pulseless and was eventually resuscitated. Echocardiogram following the arrest showed evidence of right heart dysfunction. She died 2 days later of multiorgan failure. This is the first report of SARS-CoV-2 infection with MC. Sudden cardiac arrest likely resulted from the presence of viral pneumonia, cardiac arrhythmia, pulmonary emboli, and MC-all of which were associated with the patient's SARS-CoV-2 infection.

Subacute thyroiditis associated with COVID-19

We report a case of a hospitalised patient with COVID-19 who developed subacute thyroiditis in association with SARS-COV-2 infection. The patient presented with tachycardia, anterior neck pain and thyroid function tests revealing hyperthyroidism together with consistent ultrasonographic evidence suggesting subacute thyroiditis. Treatment with corticosteroids resulted in rapid clinical resolution. This case illustrates that subacute thyroiditis associated with viruses such as SARS-CoV-2 should be recognised as a complication of COVID-19 and considered as a differential diagnosis when infected patients present with tachycardia without evidence of progression of COVID-19 illness.

[Basic clinical characteristics in the first 100 fatal cases of COVID-19 in Colombia]

The basic clinical characteristics of the first 100 fatal cases from COVID-19 in Colombia were analyzed based on reports from the National Institute of Health (INS) since the beginning of the pandemic. Since the INS records do not include clinical variables of comorbidity in the total number of cases reported as positive, but only in patients with fatal outcome, comorbidities, age and sex available in the daily INS reports were reviewed. Their frequency was identified and mortality risk behavior for the analyzed variables was established and compared with the behavior described in the international literature. Of the 100 cases, 63 were male, the mean age was 65.75 ± 18.11 years, and in 22 of them no comorbidity had been reported. The most frequently reported comorbidities were arterial hypertension (35%), diabetes mellitus (21%), cardiovascular and cerebrovascular disease (19%), chronic obstructive pulmonary disease (16%), obesity (12%), smoking (9%) and thyroid disease (8%). Patients over 60 years of age presented a higher risk of mortality (OR 10.31, IC95% 6.67-15.94, p < 0.0001). Ten percent of the deceased patients were under 60 years of age and did not present comorbidity.

PATHOLOGICAL ANATOMY OF INFECTION CAUSED BY SARS-COV-2

Autopsy data from 80 patients who died of the COVID-19 infection were analysed. Using macro- and microscopic studies, specific features of pathological processes in various organs were identified. The obtained experimental data, along with information from literature sources, allowed conclusions to be drawn about the mechanisms of damaging internal organs and body systems, as well as assumptions to be made about individual links in the pathogenesis of COVID-19. The thanatogenesis of the disease and the main causes of death are discussed, including acute cardiopulmonary failure, acute renal failure, pulmonary thromboembolism, shock involving multiple organ failure and sepsis. The critical importance of autopsy is emphasized, which provides valuable information on the morphological substrate for this infection closely associated with possible clinical manifestations.

The Impact of SARS-Cov-2 Virus Infection on the Endocrine System

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has spread across the globe rapidly causing an unprecedented pandemic. Because of the novelty of the disease, the possible impact on the endocrine system is not clear. To compile a mini-review describing possible endocrine consequences of SARS-CoV-2 infection, we performed a literature survey using the key words Covid-19, Coronavirus, SARS CoV-1, SARS Cov-2, Endocrine, and related terms in medical databases including PubMed, Google Scholar, and MedARXiv from the year 2000. Additional references were identified through manual screening of bibliographies and via citations in the selected articles. The literature review is current until April 28, 2020. In light of the literature, we discuss SARS-CoV-2 and explore the endocrine consequences based on the experience with structurally-similar SARS-CoV-1. Studies from the SARS -CoV-1 epidemic have reported variable changes in the endocrine organs. SARS-CoV-2 attaches to the ACE2 system in the pancreas causing perturbation of insulin production resulting in hyperglycemic emergencies. In patients with preexisting endocrine disorders who develop COVID-19, several factors warrant management decisions. Hydrocortisone dose adjustments are required in patients with adrenal insufficiency. Identification and management of critical illness-related corticosteroid insufficiency is crucial. Patients with Cushing syndrome may have poorer outcomes because of the associated immunodeficiency and coagulopathy. Vitamin D deficiency appears to be associated with increased susceptibility or severity to SARS-CoV-2 infection, and replacement may improve outcomes. Robust strategies required for the optimal management of endocrinopathies in COVID-19 are discussed extensively in this mini-review.

Subacute Thyroiditis After Sars-COV-2 Infection

CONTEXT

Subacute thyroiditis (SAT) is a thyroid disease of viral or postviral origin. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that began in Wuhan, China, has spread rapidly worldwide and Italy has been severely affected by this outbreak.

OBJECTIVES

The objective of this work is to report the first case of SAT related to SARS-CoV-2 infection.

METHODS

We describe the clinical, laboratory, and imaging features of an 18-year-old woman who came to our attention for fever, neck pain radiated to the jaw, and palpitations occurring 15 days after a SARS-CoV-2-positive oropharyngeal swab. Coronavirus disease 2019 (COVID-19) had been mild and the patient had completely recovered in a few days.

RESULTS

At physical examination the patient presented with a slightly increased heart rate and a painful and enlarged thyroid on palpation. At laboratory exams free thyroxine and free triiodothyronine were high, thyrotropin undetectable, and inflammatory markers and white blood cell count elevated. Bilateral and diffuse hypoechoic areas were detected at neck ultrasound. One month earlier, thyroid function and imaging both were normal. We diagnosed SAT and the patient started prednisone. Neck pain and fever recovered within 2 days and the remaining symptoms within 1 week. Thyroid function and inflammatory markers normalized in 40 days.

CONCLUSIONS

We report the first case of SAT after a SARS-CoV-2 infection. We alert clinicians to additional and unreported clinical manifestations associated with COVID-19.

Combination of four clinical indicators predicts the severe/critical symptom of patients infected COVID-19

BACKGROUND

Despite the death rate of COVID-19 is less than 3%, the fatality rate of severe/critical cases is high, according to World Health Organization (WHO). Thus, screening the severe/critical cases before symptom occurs effectively saves medical resources.

METHODS AND MATERIALS

In this study, all 336 cases of patients infected COVID-19 in Shanghai to March 12th, were retrospectively enrolled, and divided in to training and test datasets. In addition, 220 clinical and laboratory observations/records were also collected. Clinical indicators were associated with severe/critical symptoms were identified and a model for severe/critical symptom prediction was developed.

RESULTS

Totally, 36 clinical indicators significantly associated with severe/critical symptom were identified. The clinical indicators are mainly thyroxine, immune related cells and products. Support Vector Machine (SVM) and optimized combination of age, GSH, CD3 ratio and total protein has a good performance in discriminating the mild and severe/critical cases. The area under receiving operating curve (AUROC) reached 0.9996 and 0.9757 in the training and testing dataset, respectively. When the using cut-off value as 0.0667, the recall rate was 93.33 % and 100 % in the training and testing datasets, separately. Cox multivariate regression and survival analyses revealed that the model significantly discriminated the severe/critical cases and used the information of the selected clinical indicators.

CONCLUSION

The model was robust and effective in predicting the severe/critical COVID cases.

COVID-19: the endocrine opportunity in a pandemic

The 2019 Coronavirus disease (COVID-19) pandemic has disrupted the social, economical and medical system worldwide. Although it is strictly an infectious disease, its intricate bidirectional relationship with various non-communicable metabolic diseases and endocrinological factors has been observed. While diabetes, hypertension, obesity have been found to be independent risk factors for COVID-19 disease severity and mortality, more inclination towards sedentary lifestyle, psychosocial stress at this critical time may be the harbingers of metabolic syndrome. Thus, endocrinologists have a great opportunity to play their role to combat this pandemic. This paper examines how various endocrinological disorders influence the dynamics of COVID-19 and vice versa. Moreover, it also intends to review the clinical guidelines to be adopted in practice of endocrinology in this trying time.

Endocrine changes in SARS-CoV-2 patients and lessons from SARS-CoV

Coronavirus infection outbreaks have occurred frequently in the last two decades and have led to significant mortality. Despite the focus on reducing mortality by preventing the spread of the virus, patients have died due to several other complications of the illness. The understanding of pathological mechanisms and their implications is continuously evolving. A number of symptoms occur in these patients due to the involvement of various endocrine glands. These clinical presentations went largely unnoticed during the first outbreak of severe acute respiratory syndrome (SARS) in 2002–2003. A few of these derangements continued during the convalescence phase and sometimes occurred after recovery. Similar pathological and biochemical changes are being reported with the novel coronavirus disease outbreak in 2020. In this review, we focus on these endocrine changes that have been reported in both SARS coronavirus and SARS coronavirus-2. As we battle the pandemic, it becomes imperative to address these underlying endocrine disturbances that are contributing towards or predicting mortality of these patients.

Possible long-term endocrine-metabolic complications in COVID-19: lesson from the SARS model

The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is centralizing the interest of the scientific world. In the next months, long-term consequences on the endocrine system may arise following COVID-19. In this article, we hypothesized the effects of SARS-CoV-2 taking into account what learned from the severe acute respiratory syndrome coronavirus (SARS-CoV) that caused SARS in 2003.

Thyroid disease in the time of COVID-19

The novel coronavirus disease COVID-19 is produced by SARS-CoV-2. WHO has declared COVID-19 as a public health emergency, with the most susceptible populations (requiring ventilation) being the elderly, pregnant women and people with associated co-morbidities including heart failure, uncontrolled diabetes, chronic obstructive pulmonary disease, asthma and cancer. However, such general guidance does not provide information regarding COVID-19 risks in patients with suffering from pre-existing thyroid problems, and furthermore, we do not know whether patients with COVID-19 (symptomatic or without symptoms), who have not previously had thyroid issues develop endocrine thyroid dysfunction after infection. The European Society for Endocrinology recently published a statement on COVID-19 and endocrine diseases (Endocrine, 2020); however, thyroid diseases were not mentioned specifically. We have therefore reviewed the current literature on thyroid diseases (excluding cancer) and COVID-19, including data from the previous coronavirus pandemic caused by the SARS-associated coronavirus (SARS-CoV), a member of the same family Coronaviridae leading to severe acute respiratory syndrome (SARS). At the moment there are no data suggesting that thyroid patients are at higher risk of COVID-19, but this requites further research and data analysis.

Reaction of Human Monoclonal Antibodies to SARS-CoV-2 Proteins With Tissue Antigens: Implications for Autoimmune Diseases

We sought to determine whether immune reactivity occurs between anti-SARS-CoV-2 protein antibodies and human tissue antigens, and whether molecular mimicry between COVID-19 viral proteins and human tissues could be the cause. We applied both human monoclonal anti-SARS-Cov-2 antibodies (spike protein, nucleoprotein) and rabbit polyclonal anti-SARS-Cov-2 antibodies (envelope protein, membrane protein) to 55 different tissue antigens. We found that SARS-CoV-2 antibodies had reactions with 28 out of 55 tissue antigens, representing a diversity of tissue groups that included barrier proteins, gastrointestinal, thyroid and neural tissues, and more. We also did selective epitope mapping using BLAST and showed similarities and homology between spike, nucleoprotein, and many other SARS-CoV-2 proteins with the human tissue antigens mitochondria M2, F-actin and TPO. This extensive immune cross-reactivity between SARS-CoV-2 antibodies and different antigen groups may play a role in the multi-system disease process of COVID-19, influence the severity of the disease, precipitate the onset of autoimmunity in susceptible subgroups, and potentially exacerbate autoimmunity in subjects that have pre-existing autoimmune diseases. Very recently, human monoclonal antibodies were approved for use on patients with COVID-19. The human monoclonal antibodies used in this study are almost identical with these approved antibodies. Thus, our results can establish the potential risk for autoimmunity and multi-system disorders with COVID-19 that may come from cross-reactivity between our own human tissues and this dreaded virus, and thus ensure that the badly-needed vaccines and treatments being developed for it are truly safe to use against this disease.

Thyroid Function Abnormalities in COVID-19 Patients

PURPOSE

The novel coronavirus COVID-19, has caused a worldwide pandemic, impairing several human organs and systems. Whether COVID-19 affects human thyroid function remains unknown.

METHODS

Eighty-four hospitalized COVID-19 patients in the First Affiliated Hospital, Zhejiang University School of Medicine (Hangzhou, China) were retrospectively enrolled in this study, among which 22 cases had complete records of thyroid hormones. In addition, 91 other patients with pneumonia and 807 healthy subjects were included as controls.

RESULTS

We found that levels of total triiodothyronine (TT3) and thyroid stimulating hormone (TSH) were lower in COVID-19 patients than healthy group (p < 0.001). Besides, TSH level in COVID-19 patients was obviously lower than non-COVID-19 patients (p < 0.001). Within the group of COVID-19, 61.9% (52/84) patients presented with thyroid function abnormalities and the proportion of thyroid dysfunction was higher in severe cases than mild/moderate cases (74.6 vs. 23.8%, p < 0.001). Patients with thyroid dysfunction tended to have longer viral nucleic acid cleaning time (14.1 ± 9.4 vs. 10.6 ± 8.3 days, p = 0.088). To note, thyroid dysfunction was also associated with decreased lymphocytes (p < 0.001) and increased CRP (p = 0.002). The correlation between TT3 and TSH level seemed to be positive rather than negative in the early stage, and gradually turned to be negatively related over time.

CONCLUSION

Thyroid function abnormalities are common in COVID-19 patients, especially in severe cases. This might be partially explained by nonthyroidal illness syndrome.

Outcomes of Patients With Hypothyroidism and COVID-19: A Retrospective Cohort Study

Coronavirus diseases (COVID-19) is associated with high rates of morbidity and mortality and worse outcomes have been reported for various morbidities. The impact of pre-existing hypothyroidism on COVID-19 outcomes remains unknown. The aim of the present study was to identify a possible association between hypothyroidism and outcomes related to COVID-19 including hospitalization, need for mechanical ventilation, and all-cause mortality. All patients with a laboratory confirmed COVID-19 diagnosis in March 2020 in a large New York City health system were reviewed. Of the 3703 COVID-19 positive patients included in present study, 251 patients (6.8%) had pre-existing hypothyroidism and received thyroid hormone therapy. Hypothyroidism was not associated with increased risk of hospitalization [Adjusted Odds Ratio (OR_adj): 1.23 (95% Confidence Interval (CI): 0.88- 1.70)], mechanical ventilation [OR_adj: 1.17 (95% CI: 0.81-1.69)] nor death [OR_adj: 1.07 (95% CI: 0.75-1.54)]. This study provides insight into the role of hypothyroidism on the outcomes of COVID-19 positive patients, indicating that no additional precautions or consultations are needed. However, future research into the potential complications of COVID-19 on the thyroid gland and function is warranted.

Severe acute respiratory syndrome coronavirus envelope protein regulates cell stress response and apoptosis

Severe acute respiratory syndrome virus (SARS-CoV) that lacks the envelope (E) gene (rSARS-CoV-ΔE) is attenuated in vivo. To identify factors that contribute to rSARS-CoV-ΔE attenuation, gene expression in cells infected by SARS-CoV with or without E gene was compared. Twenty-five stress response genes were preferentially upregulated during infection in the absence of the E gene. In addition, genes involved in signal transduction, transcription, cell metabolism, immunoregulation, inflammation, apoptosis and cell cycle and differentiation were differentially regulated in cells infected with rSARS-CoV with or without the E gene. Administration of E protein in trans reduced the stress response in cells infected with rSARS-CoV-ΔE or with respiratory syncytial virus, or treated with drugs, such as tunicamycin and thapsigargin that elicit cell stress by different mechanisms. In addition, SARS-CoV E protein down-regulated the signaling pathway inositol-requiring enzyme 1 (IRE-1) of the unfolded protein response, but not the PKR-like ER kinase (PERK) or activating transcription factor 6 (ATF-6) pathways, and reduced cell apoptosis. Overall, the activation of the IRE-1 pathway was not able to restore cell homeostasis, and apoptosis was induced probably as a measure to protect the host by limiting virus production and dissemination. The expression of proinflammatory cytokines was reduced in rSARS-CoV-ΔE-infected cells compared to rSARS-CoV-infected cells, suggesting that the increase in stress responses and the reduction of inflammation in the absence of the E gene contributed to the attenuation of rSARS-CoV-ΔE.

To identify potential mechanisms mediating the in vivo attenuation of SARS-CoV lacking the E gene (rSARS-CoV-ΔE), the effect of the presence of the E gene on host gene expression was studied. In rSARS-CoV-ΔE-infected cells, the expression of at least 25 stress response genes was preferentially upregulated, compared to cells infected with rSARS-CoV. E protein supplied in trans reversed the increase in stress response genes observed in cells infected with rSARS-CoV-ΔE or with respiratory syncytial virus, and by treatment with drugs causing stress by different mechanisms. Furthermore, in the presence of the E protein a subset (IRE-1 pathway), but not two others (PERK and ATF-6), of the unfolded protein response was also reduced. Nevertheless, the activation of the unfolded protein response to control cell homeostasis was not sufficient to alleviate cell stress, and an increase in cell apoptosis in cells infected with the virus lacking E protein was observed. This apoptotic response was probably induced to protect the host by limiting virus production and dissemination. In cells infected with rSARS-CoV-ΔE, genes associated with the proinflammatory pathway were down-regulated compared to cells infected with virus expressing E protein, supporting the idea that a reduction in inflammation was also relevant in the attenuation of the virus deletion mutant.

Coronavirus gene 7 counteracts host defenses and modulates virus virulence

Transmissible gastroenteritis virus (TGEV) genome contains three accessory genes: 3a, 3b and 7. Gene 7 is only present in members of coronavirus genus a1, and encodes a hydrophobic protein of 78 aa. To study gene 7 function, a recombinant TGEV virus lacking gene 7 was engineered (rTGEV-Δ7). Both the mutant and the parental (rTGEV-wt) viruses showed the same growth and viral RNA accumulation kinetics in tissue cultures. Nevertheless, cells infected with rTGEV-Δ7 virus showed an increased cytopathic effect caused by an enhanced apoptosis mediated by caspase activation. Macromolecular synthesis analysis showed that rTGEV-Δ7 virus infection led to host translational shut-off and increased cellular RNA degradation compared with rTGEV-wt infection. An increase of eukaryotic translation initiation factor 2 (eIF2α) phosphorylation and an enhanced nuclease, most likely RNase L, activity were observed in rTGEV-Δ7 virus infected cells. These results suggested that the removal of gene 7 promoted an intensified dsRNA-activated host antiviral response. In protein 7 a conserved sequence motif that potentially mediates binding to protein phosphatase 1 catalytic subunit (PP1c), a key regulator of the cell antiviral defenses, was identified. We postulated that TGEV protein 7 may counteract host antiviral response by its association with PP1c. In fact, pull-down assays demonstrated the interaction between TGEV protein 7, but not a protein 7 mutant lacking PP1c binding motif, with PP1. Moreover, the interaction between protein 7 and PP1 was required, during the infection, for eIF2α dephosphorylation and inhibition of cell RNA degradation. Inoculation of newborn piglets with rTGEV-Δ7 and rTGEV-wt viruses showed that rTGEV-Δ7 virus presented accelerated growth kinetics and pathology compared with the parental virus. Overall, the results indicated that gene 7 counteracted host cell defenses, and modified TGEV persistence increasing TGEV survival. Therefore, the acquisition of gene 7 by the TGEV genome most likely has provided a selective advantage to the virus.

Coronavirus gene 7 counteracts host defenses and modulates virus virulence

Transmissible gastroenteritis virus (TGEV) genome contains three accessory genes: 3a, 3b and 7. Gene 7 is only present in members of coronavirus genus a1, and encodes a hydrophobic protein of 78 aa. To study gene 7 function, a recombinant TGEV virus lacking gene 7 was engineered (rTGEV-Δ7). Both the mutant and the parental (rTGEV-wt) viruses showed the same growth and viral RNA accumulation kinetics in tissue cultures. Nevertheless, cells infected with rTGEV-Δ7 virus showed an increased cytopathic effect caused by an enhanced apoptosis mediated by caspase activation. Macromolecular synthesis analysis showed that rTGEV-Δ7 virus infection led to host translational shut-off and increased cellular RNA degradation compared with rTGEV-wt infection. An increase of eukaryotic translation initiation factor 2 (eIF2α) phosphorylation and an enhanced nuclease, most likely RNase L, activity were observed in rTGEV-Δ7 virus infected cells. These results suggested that the removal of gene 7 promoted an intensified dsRNA-activated host antiviral response. In protein 7 a conserved sequence motif that potentially mediates binding to protein phosphatase 1 catalytic subunit (PP1c), a key regulator of the cell antiviral defenses, was identified. We postulated that TGEV protein 7 may counteract host antiviral response by its association with PP1c. In fact, pull-down assays demonstrated the interaction between TGEV protein 7, but not a protein 7 mutant lacking PP1c binding motif, with PP1. Moreover, the interaction between protein 7 and PP1 was required, during the infection, for eIF2α dephosphorylation and inhibition of cell RNA degradation. Inoculation of newborn piglets with rTGEV-Δ7 and rTGEV-wt viruses showed that rTGEV-Δ7 virus presented accelerated growth kinetics and pathology compared with the parental virus. Overall, the results indicated that gene 7 counteracted host cell defenses, and modified TGEV persistence increasing TGEV survival. Therefore, the acquisition of gene 7 by the TGEV genome most likely has provided a selective advantage to the virus.

Endocrine cells of the adenohypophysis in severe acute respiratory syndrome (SARS)

It is known that severe acute respiratory syndrome (SARS), a severe infectious illness, which caused an epidemic in Asia in 2003, has extensive and complex effects on human organ systems. It has been reported that the serum levels of prolactin (PRL), follicle stimulating hormone (FSH), and luteinizing hormone (LH) of SARS patients are significantly higher than those of control groups, while estradiol (E2), pregnancy hormone (P), and thyroid stimulating hormone (TSH) are considerably lower than those of normal controls. This phenomenon suggests that the adenohypophyseal endocrine cells in SARS patients may be damaged. However, up to now there has been no direct histological investigation on the endocrine cells of patients' pituitary. Here we investigated the endocrine cells in the adenohypophysis obtained from autopsies of 5 SARS patients. The immunohistochemistry and quantitative image results showed that compared with control cases, both the number of positive cells and the staining intensity of immunoreactivity for growth hormone, TSH, and adrenocorticotrophic hormone in these cells were remarkably decreased, while that of PRL, FSH, and LH were significantly increased in all SARS cases studied. These findings indicated that alterations occurred in the patients' adenohypophyseal endocrine cells, and these changes were consistent with the serum levels of relevant endocrine hormones reported previously. It appears that changes in these endocrine cells and their hormones are affected by the severity of this new infectious disease.

Molecular and Biochemical Characterization of the SARS-CoV Accessory Proteins ORF8a, ORF8b and ORF8ab

A novel coronavirus was identified as the aetiological agent for the global outbreak of severe acute respiratory syndrome (SARS) at the beginning of the twenty-first century. The SARS coronavirus genome encodes for proteins that are common to all members of the coronavirus, i.e. replicase polyproteins (pp1a and pp1b) and structural proteins (spike, membrane, nucleocapsid and envelope), as well as eight accessory proteins. The accessory proteins have been designated as open reading frames (ORF) 3a, 3b, 6, 7a, 7b, 8a, 8b and 9b, and they do not show significant homology to viral proteins of other known coronaviruses. Epidemiological studies have revealed that the part of the viral genome that encodes for ORF8a and ORF8b showed major variations and the animal isolates contain an additional 29-nucleotide sequence which is absent in most of the human isolates. As a result, ORF8a and ORF8b in the human isolates become one ORF, termed ORF8ab. In this chapter, we will discuss the genetic variation in the ORF8 region, expression of ORF8a, ORF8b and ORF8ab during infection, cellular localization and posttranslational modification of ORF8a, ORF8b and ORF8ab, participation of ORF8a, ORF8b and ORF8ab in viral–viral interactions, their effects on other viral proteins and impact on viral replication and/or pathogenesis.

Signaling Pathways of SARS-CoV In Vitro and In Vivo

Severe acute respiratory syndrome (SARS) is a respiratory illness with variable symptoms that was recognized as the first near-pandemic infectious disease of the twenty-first century. A novel human coronavirus, named SARS coronavirus (SARS-CoV), derived from SARS patients was reported as the etiologic agent of SARS. Studying the signaling pathways of SARS-infected cells is key to understanding the molecular mechanism of SARS viral infection. Cell death is observed in cultured Vero E6 cells after SARS-CoV infection. From SARS-CoV infection to cell death, p38 mitogen-activated protein kinase (MAPK) is a key participant in the determination of cell death and survival. Two signaling pathways comprising signal transducer and activator of transcription 3 (STAT3) and p90 ribosomal S6 kinase (p90RSK) are downstream of p38 MAPK. AKT and JNK (Jun NH₂-terminal kinase) signaling pathways are important to establish persistent infection of SARS-CoV in Vero E6 cells. Expression studies of SARS-CoV proteins indicate that the viral proteins are able to activate signaling pathways of host cells. The study of signaling pathways in SARS-CoV patients is difficult to perform compared with in vitro studies due to the effects of the human immune system. This review highlights recent progress in characterizing signal transduction pathways in SARS-CoV-infected cells in vitro and in vivo.

Severe acute respiratory syndrome coronavirus triggers apoptosis via protein kinase R but is resistant to its antiviral activity

In this study, infection of 293/ACE2 cells with severe acute respiratory syndrome coronavirus (SARS-CoV) activated several apoptosis-associated events, namely, cleavage of caspase-3, caspase-8, and poly(ADP-ribose) polymerase 1 (PARP), and chromatin condensation and the phosphorylation and hence inactivation of the eukaryotic translation initiation factor 2alpha (eIF2alpha). In addition, two of the three cellular eIF2alpha kinases known to be virus induced, protein kinase R (PKR) and PKR-like endoplasmic reticulum kinase (PERK), were activated by SARS-CoV. The third kinase, general control nonderepressible-2 kinase (GCN2), was not activated, but late in infection the level of GCN2 protein was significantly reduced. Reverse transcription-PCR analyses revealed that the reduction of GCN2 protein was not due to decreased transcription or stability of GCN2 mRNA. The specific reduction of PKR protein expression by antisense peptide-conjugated phosphorodiamidate morpholino oligomers strongly reduced cleavage of PARP in infected cells. Surprisingly, the knockdown of PKR neither enhanced SARS-CoV replication nor abrogated SARS-CoV-induced eIF2alpha phosphorylation. Pretreatment of cells with beta interferon prior to SARS-CoV infection led to a significant decrease in PERK activation, eIF2alpha phosphorylation, and SARS-CoV replication. The various effects of beta interferon treatment were found to function independently on the expression of PKR. Our results show that SARS-CoV infection activates PKR and PERK, leading to sustained eIF2alpha phosphorylation. However, virus replication was not impaired by these events, suggesting that SARS-CoV possesses a mechanism to overcome the inhibitory effects of phosphorylated eIF2alpha on viral mRNA translation. Furthermore, our data suggest that viral activation of PKR can lead to apoptosis via a pathway that is independent of eIF2alpha phosphorylation.