TYK2 signaling promotes the development of autoreactive CD8+ cytotoxic T lymphocytes and type 1 diabetes.

Tyrosine kinase 2 (TYK2), a member of the JAK family, has attracted attention as a potential therapeutic target for autoimmune diseases. However, the role of TYK2 in CD8+ T cells and autoimmune type 1 diabetes (T1D) is poorly understood. In this study, we generate Tyk2 gene knockout non-obese diabetes (NOD) mice and demonstrate that the loss of Tyk2 inhibits the development of autoreactive CD8+ T-BET+ cytotoxic T lymphocytes (CTLs) by impairing IL-12 signaling in CD8+ T cells and the CD8+ resident dendritic cell-driven cross-priming of CTLs in the pancreatic lymph node (PLN). Tyk2-deficient CTLs display reduced cytotoxicity. Increased inflammatory responses in ß-cells with aging are dampened by Tyk2 deficiency. Furthermore, treatment with BMS-986165, a selective TYK2 inhibitor, inhibits the expansion of T-BET+ CTLs, inflammation in ß-cells and the onset of autoimmune T1D in NOD mice. Thus, our study reveals the diverse roles of TYK2 in driving the pathogenesis of T1D.

Living donor liver transplantation for a patient with acute liver failure following thyroid storm: a case report.

BACKGROUND: Thyroid storm can be complicated by liver dysfunction, which may occasionally progress to acute liver failure. We herein report a case of acute liver failure following thyroid storm that was treated with living donor liver transplantation after resuscitation from cardiopulmonary arrest. CASE REPORT: The patient was a woman in her 40 s who had been diagnosed with an abnormal thyroid function. She suffered from fatigue and vomiting, and was found to have consciousness disorder, a fever, and tachycardia with a neck mass. She was diagnosed with thyroid storm and was referred to our hospital. After arrival, she went into cardiopulmonary arrest and veno-arterial extracorporeal membrane oxygenation was initiated. In addition to treatment for thyroid storm with antithyroid drugs, steroids, and plasma exchange, extracorporeal life support was required for 5 days. However, despite improvements in her thyroid function, her liver function deteriorated. We planned living donor liver transplantation for acute liver failure after ensuring the recovery and control of the thyroid function following total thyroidectomy. The donor was her husband who donated the right lobe of his liver. Although she experienced acute cellular rejection after surgery, and other complications-including intra-abdominal hemorrhaging and ischemic changes in the intestine-her liver function and general condition gradually improved. One year after living donor liver transplantation, the patient was in a good condition with a normal liver function. CONCLUSIONS: To our knowledge, this is the first report of living donor liver transplantation in a patient with acute liver failure following thyroid storm. Liver transplantation should be recognized as an effective treatment for acute liver failure following thyroid storm.

RENAL FUNCTION AND PLASMA RENIN ACTIVITY AS POTENTIAL FACTORS CAUSING HYPERKALEMIA IN PATIENTS WITH THYROID CARCINOMA UNDERGOING THYROID HORMONE WITHDRAWAL FOR RADIOACTIVE IODINE THERAPY.

Objective: Hypothyroidism is not commonly considered a cause of hyperkalemia. We previously reported that hyperkalemia was observed mainly in elderly patients treated with renin-angiotensin-aldosterone system (RAS) inhibitors when levothyroxine treatment was withdrawn for the thyroidectomized patients with thyroid carcinoma to undergo radioactive iodine treatment. Here, we investigated whether acute hypothyroidism causes hyperkalemia in patients who were not treated with RAS inhibitors. We also investigated factors influencing potassium metabolism in hypothyroid patients. Methods: We conducted a single-center, prospective cohort study of 46 Japanese patients with thyroid carcinoma undergoing levothyroxine withdrawal prior to radioiodine therapy. All patients were normokalemic before levothyroxine withdrawal. Blood samples were analyzed 3 times: before, and at 3 and 4 weeks after levothyroxine withdrawal. We investigated factors that may be associated with the elevation of serum potassium levels from a euthyroid state to a hypothyroid state. Results: None of the patients developed symptomatic hyperkalemia. The mean serum potassium level was significantly higher at 4 weeks after levothyroxine withdrawal compared to baseline. The serum sodium levels, the estimated glomerular filtration rate (eGFR), and the plasma renin activity (PRA) decreased significantly as hypothyroidism advanced. In contrast, the plasma levels of adrenocorticotropic hormone, cortisol, aldosterone, and antidiuretic hormone were not changed, while serum thyroid hormone decreased. At 4 weeks after their levothyroxine withdrawal, the patients' serum potassium values were significantly correlated with the eGFR and the PRA. Conclusion: Acute hypothyroidism can cause a significant increase in the serum potassium level, which may be associated with a decreased eGFR and decreased circulating RAS. Abbreviations: ACTH = adrenocorticotropic hormone; ADH = antidiuretic hormone; ATPase = adenosine triphosphatase; eGFR = estimated glomerular filtration rate; HbA1c = glycated hemoglobin; K+ = potassium; Na+ = sodium; PRA = plasma renin activity; RAS = renin-angiotensin-aldosterone system; T4 = thyroxine; TSH = thyroid-stimulating hormone.

Late-onset Cerebrotendinous Xanthomatosis with a Novel Mutation in the CYP27A1 Gene.

Cerebrotendinous xanthomatosis (CTX) is a rare, autosomal recessive, inborn disruption in bile acid synthesis characterized by severe systemic xanthomas, cataracts and neurological injuries occurring before adolescence without elevation of the serum cholesterol or triglyceride levels. CTX is caused by a deficiency of the mitochondrial enzyme sterol 27-hydroxylase, which is encoded by the CYP27A1 gene. We herein report a 50-year-old Japanese woman with late-onset CTX who had no relevant symptoms before the development of bilateral Achilles tendon xanthomas in middle age. A genetic analysis revealed a compound heterozygous mutation in the CYP27A1 gene with a previously known missense mutation (NM_000784.3:c.1421 G>A) and a novel frame shift mutation of NM_000784.3:c.1342_1343insCACC.

A case of glycogenic hepatopathy developed in a patient with new-onset fulminant type 1 diabetes: the role of image modalities in diagnosing hepatic glycogen deposition including gradient-dual-echo MRI.

Glycogenic hepatopathy (GH) has been reported as a very rare and under recognized complication in long-standing poorly controlled type 1 diabetes (T1D) patients. GH is characterized by transient elevation of liver transaminase and hepatomegaly caused by reversible and excessive glycogen accumulation in hepatocytes. It has been reported that GH is indistinguishable from non-alcoholic fatty liver disease, which is more commonly seen in diabetic patients, even after a history is taken and a physical examination or imaging studies have been performed. GH can only be diagnosed by liver biopsy. We here demonstrate a 21-year-old male patient with new-onset fulminant T1D complicated with diabetic ketoacidosis who subsequently developed GH just after the initiation of insulin treatment. The marked liver dysfunction (serum levels of aspartate aminotransferase 769 IU/L and alanine aminotransferase 1348 IU/L) and hepatomegaly improved spontaneously via glycemic control without any specific treatments thereafter. Moreover, the insulin requirement dramatically decreased from 168 to 80 units per day as GH improved, suggesting a potential role of GH in insulin resistance. GH was diagnosed based on the histological findings of the liver in our case, but we were able to predict GH before the biopsy based on the findings in the gradient-dual-echo magnetic resonance imaging sequence combined with ultrasound and/or computed tomography examinations of the liver.

Successful treatment of chronic lupus myocarditis with prednisolone and mizoribine.

A 36-year-old female patient who was diagnosed with chronic myocarditis as an initial manifestation of systemic lupus erythematosus (SLE) was admitted to our hospital. At her third occurrence of heart failure, we performed an endomyocardial biopsy and proved chronic myocarditis with SLE. Subsequently, she was treated with prednisolone and the immunosuppressive agent mizoribine (MZR), and her cardiac function improved. We describe for the first time treatment with MZR for chronic cardiac involvement of SLE.

Evidence of both extra- and intracellular cysteine targets of protein modification for activation of RET kinase.

By use of a specifically sulfhydryl group-reactive chemical, 1,4-butanediyl-bismethanethiosulfonate (BMTS), we studied the localization of oxidative stress-responsive target cysteines for activation of a receptor-type protein tyrosine kinase, c-RET. The chemical, which reacted with RET proteins on the cell surface for sulfhydryl-linked aggregation, induced autophosphorylation and activation of RET kinase. When extracellular domain-deleted RET mutant (RET-PTC-1) cells were exposed to BMTS, neither the molecular status nor the activity of the enzyme was affected, suggesting that the target cysteines of BMTS to which cells were exposed for reaction are located in the cysteine-rich region of the extracellular domain of RET kinase. Despite this result, the exposure of a subcellular form of c-RET or RET-PTC-1 kinase isolated by immunoprecipitation to BMTS did induce activation of the enzyme. These results suggest that cysteines in both the extracellular and the intracellular domains of RET can work as target sites of accessible BMTS and possibly other oxidative elements for structural modification and activation of RET kinase.