Effect of SARS-CoV-2 BNT162b2 mRNA vaccine on thyroid autoimmunity: A twelve-month follow-up study.

Objectives: Graves' disease (GD) has been highlighted as a possible adverse effect of the respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccine. However, it is unknown if the SARS-CoV-2 vaccine disrupts thyroid autoimmunity. We aimed to present long-term follow-up of thyroid autoimmunity after the SARS-CoV-2 BNT162b2 mRNA vaccine. Methods: Serum samples collected from seventy Japanese healthcare workers at baseline, 32 weeks after the second dose (pre-third dose), and 4 weeks after the third dose of the vaccine were analyzed. The time courses of anti-SARS-CoV-2 spike immunoglobulin G (IgG) antibody, thyroid-stimulating hormone receptor antibody (TRAb), and thyroid function were evaluated. Anti-thyroglobulin antibodies (TgAb) and anti-thyroid peroxidase antibodies (TPOAb) were additionally evaluated in thirty-three participants. Results: The median age was 50 (IQR, 38-54) years and 69% were female. The median anti-spike IgG antibody titer was 17627 (IQR, 10898-24175) U/mL 4 weeks after the third dose. The mean TRAb was significantly increased from 0.81 (SD, 0.05) IU/L at baseline to 0.97 (SD, 0.30) IU/L 4 weeks after the third dose without functional changes. An increase in TRAb was positively associated with female sex (ß = 0.32, P = 0.008) and low basal FT4 (ß = -0.29, P = 0.02) and FT3 (ß = -0.33, P = 0.004). TgAb was increased by the third dose. Increase in TgAb was associated with history of the thyroid diseases (ß = 0.55, P <0.001). Conclusions: SARS-CoV-2 BNT162b2 mRNA vaccine can disrupt thyroid autoimmunity. Clinicians should consider the possibility that the SARS-CoV-2 vaccine may disrupt thyroid autoimmunity.

Glucotoxicity-induced suppression of Cox6a2 expression provokes ß-cell dysfunction via augmented ROS production.

Oxidative stress is a deteriorating factor for pancreatic ß-cells under chronic hyperglycemia in diabetes. However, the molecular mechanism underlying the increase in oxidative stress in ß-cells under diabetic conditions remains unclear. We demonstrated previously that the selective alleviation of glucotoxicity ameliorated the downregulation of several ß-cell factors, including Cox6a2. Cox6a2 encodes a subunit of the respiratory chain complex IV in mitochondria. In this study, we analyzed the role of Cox6a2 in pancreatic ß-cell function and its pathophysiological significance in diabetes mellitus. Cox6a2-knockdown experiments in MIN6-CB4 cells indicated an increased production of reactive oxygen species as detected by CellROX Deep Red reagent using flow cytometry. In systemic Cox6a2-knockout mice, impaired glucose tolerance was observed under a high-fat high-sucrose diet. However, insulin resistance was reduced when compared with control littermates. This indicates a relative insufficiency of ß-cell function. To examine the transcriptional regulation of Cox6a2, ATAC-seq with islet DNA was performed and an open-chromatin area within the Cox6a2 enhancer region was detected. Reporter gene analysis using this area revealed that MafA directly regulates Cox6a2 expression. These findings suggest that the decreased expression of Cox6a2 increases the levels of reactive oxygen species and that Mafa is associated with decreased Cox6a2 expression under glucotoxic conditions.

Mafa Enables Pdx1 to Effectively Convert Pancreatic Islet Progenitors and Committed Islet α-Cells Into ß-Cells In Vivo.

Among the therapeutic avenues being explored for replacement of the functional islet ß-cell mass lost in type 1 diabetes (T1D), reprogramming of adult cell types into new ß-cells has been actively pursued. Notably, mouse islet α-cells will transdifferentiate into ß-cells under conditions of near ß-cell loss, a condition similar to T1D. Moreover, human islet α-cells also appear to poised for reprogramming into insulin-positive cells. Here we have generated transgenic mice conditionally expressing the islet ß-cell-enriched Mafa and/or Pdx1 transcription factors to examine their potential to transdifferentiate embryonic pan-islet cell Ngn3-positive progenitors and the later glucagon-positive α-cell population into ß-cells. Mafa was found to both potentiate the ability of Pdx1 to induce ß-cell formation from Ngn3-positive endocrine precursors and enable Pdx1 to produce ß-cells from α-cells. These results provide valuable insight into the fundamental mechanisms influencing islet cell plasticity in vivo.

Beneficial effects of sodium-glucose cotransporter 2 inhibitors for preservation of pancreatic ß-cell function and reduction of insulin resistance.

Type 2 diabetes mellitus is characterized by insulin resistance in various insulin target tissues, such as the liver, adipose tissue, and skeletal muscle, and insufficient insulin secretion from pancreatic ß-cells. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, which are newly developed antidiabetic agents, decrease blood glucose levels by enhancing urinary glucose excretion and thereby function in an insulin-independent manner. Sodium-glucose cotransporter 2 inhibitors exert beneficial effects to reduce insulin resistance and preserve pancreatic ß-cell function. In addition, SGLT2 inhibitors exhibit a variety of beneficial effects in various insulin target tissues, such as amelioration of fatty liver, reduction of visceral fat mass, and increasing glucose uptake in skeletal muscle. Furthermore, SGLT2 inhibitors protect pancreatic ß-cells against glucose toxicity and preserve insulin secretory capacity. Together, these observations indicate that SGLT2 inhibitors are promising newly developed antidiabetic agents that are gaining attention in both clinical medicine and basic research.

Preserving expression of Pdx1 improves ß-cell failure in diabetic mice.

Pdx1, a ß-cell-specific transcription factor, has been shown to play a crucial role in maintaining ß-cell function through transactivation of ß-cell-related genes. In addition, it has been reported that the expression levels of Pdx1 are compromised under diabetic conditions in human and rodent models. We therefore aimed to clarify the possible beneficial role of Pdx1 against ß-cell failure and generated the transgenic mouse that expressed Pdx1 conditionally and specifically in ß cells (ßPdx1) and crossed these mice with Ins2Akita diabetic mice. Whereas Pdx1 mRNA levels were reduced in Ins2Akita mice compared with their non-diabetic littermates, the mRNA levels of Pdx1 were significantly recovered in the islets of ßPdx1; Ins2Akita mice. The ßPdx1; Ins2Akita mice exhibited significantly improved glucose tolerance, compared with control Ins2Akita littermates, accompanied by increased insulin secretion after glucose loading. Furthermore, histological examination demonstrated that ßPdx1; Ins2Akita mice had improved localization of SLC2A2 (GLUT2), and quantitative RT-PCR showed the recovered expression of Mafa and Gck mRNAs in the islets of ßPdx1; Ins2Akita mice. These findings suggest that the sustained expression of Pdx1 improves ß-cell failure in Ins2Akita mice, at least partially through the preserving expression of ß-cell-specific genes as well as improved localization of GLUT2.

Sustained expression of GLP-1 receptor differentially modulates ß-cell functions in diabetic and nondiabetic mice.

Glucagon-like peptide 1 (GLP-1) has been shown to play important roles in maintaining ß-cell functions, such as insulin secretion and proliferation. While expression levels of GLP-1 receptor (Glp1r) are compromised in the islets of diabetic rodents, it remains unclear when and to what degree Glp1r mRNA levels are decreased during the progression of diabetes. In this study, we performed real-time PCR with the islets of db/db diabetic mice at different ages, and found that the expression levels of Glp1r were comparable to those of the islets of nondiabetic db/misty controls at the age of four weeks, and were significantly decreased at the age of eight and 12 weeks. To investigate whether restored expression of Glp1r affects the diabetic phenotypes, we generated the transgenic mouse model Pdx1(PB)-CreER(TM); CAG-CAT-Glp1r (ßGlp1r) that allows for induction of Glp1r expression specifically in ß cells. Whereas the expression of exogenous Glp1r had no measurable effect on glucose tolerance in nondiabetic ßGlp1r;db/misty mice, ßGlp1r;db/db mice exhibited higher glucose and lower insulin levels in blood on glucose challenge test than control db/db littermates. In contrast, four weeks of treatment with exendin-4 improved the glucose profiles and increased serum insulin levels in ßGlp1r;db/db mice, to significantly higher levels than those in control db/db mice. These differential effects of exogenous Glp1r in nondiabetic and diabetic mice suggest that downregulation of Glp1r might be required to slow the progression of ß-cell failure under diabetic conditions.

Short-term selective alleviation of glucotoxicity and lipotoxicity ameliorates the suppressed expression of key ß-cell factors under diabetic conditions.

Alleviation of hyperglycaemia and hyperlipidemia improves pancreatic ß-cell function in type 2 diabetes. However, the underlying molecular mechanisms are still not well clarified. In this study, we aimed to elucidate how the expression alterations of key ß-cell factors are altered by the short-term selective alleviation of glucotoxicity or lipotoxicity. We treated db/db mice for one week with empagliflozin and/or bezafibrate to alleviate glucotoxicity and/or liptotoxicity, respectively. The gene expression levels of Pdx1 and Mafa, and their potential targets, insulin 1, Slc2a2, and Glp1r, were higher in the islets of empagliflozin-treated mice, and levels of insulin 2 were higher in mice treated with both reagents, than in untreated mice. Moreover, compared to the pretreatment levels, Mafa and insulin 1 expression increased in empagliflozin-treated mice, and Slc2a2 increased in combination-treated mice. In addition, empagliflozin treatment enhanced ß-cell proliferation assessed by Ki-67 immunostaining. Our date clearly demonstrated that the one-week selective alleviation of glucotoxicity led to the better expression levels of the key ß-cell factors critical for ß-cell function over pretreatment levels, and that the alleviation of lipotoxicity along with glucotoxicity augmented the favorable effects under diabetic conditions.

Vitamin D deficiency is significantly associated with retinopathy in young Japanese type 1 diabetic patients.

The aim of this study was to examine the possible association of vitamin D deficiency with diabetic retinopathy in 75 young Japanese type 1 diabetic patients. A multivariate regression analysis, duration of diabetes and vitamin D deficiency were independent determinants of diabetic retinopathy.

Aniridia with a heterozygous PAX6 mutation in which the pituitary function was partially impaired.

We herein report the case of a woman with aniridia and with a heterozygous PAX6 mutation. Pax6 is a transcription factor involved in the development of several organs, including the eye, pancreas and pituitary. The patient had been diagnosed with aniridia in childhood and was found to have impaired glucose tolerance with a heterozygous PAX6 mutation 12 years prior to the current admission. Hormone stimulating tests revealed a slightly impaired pituitary function, including subtle hypogonadotropic hypogonadism and borderline growth hormone (GH) deficiency. The present case is the first report of a slightly impaired pituitary function in an aniridia patient with a heterozygous PAX6 mutation.