The thyroid gland is the largest endocrine organ in the human body， and its dysfunction can cause varying degrees of liver injury， leading to liver failure in severe cases. Patients with hyperthyroidism have a relatively high incidence rate of liver dysfunction， manifesting as hepatocellular injury or cholestatic liver injury， while hypothyroidism is closely associated with metabolic dysfunction-associated fatty liver disease. Autoimmune thyroid diseases， including Hashimoto’s thyroiditis and subacute thyroiditis， are commonly comorbid with autoimmune liver disease. In addition， medications such as antithyroid drugs， amiodarone， and immune checkpoint inhibitors can cause severe liver injury through direct toxicity or immune-mediated mechanisms. Although significant progress has been achieved in related diagnosis and treatment techniques in recent years， there are still many challenges in pathogenesis， individualized treatment strategies， early warning， and prognostic evaluation. This article systematically reviews the research advances in liver injury associated with thyroid dysfunction and proposes the directions for future research， in order to provide guidance for clinical diagnosis and treatment.

OBJECTIVETo investigate the role of transforming growth factor-beta1 (TGF-beta1)/Smad4 pathway in development of renal fibrosis in streptozotocin (STZ)-induced diabetic nephropathy (DN) rats and explore its possible mechanism.

METHODSMale Wistar rats weighing 180-220 g were divided into 5 groups: group A (normal control), group B [diabetes mellitus (DM) 2 weeks], group C (DM 4 weeks), group D (DM 8 weeks), and group E (DM 16 weeks). Except for the normal control group, other groups were induced DM by single injection of STZ (55 mg/kg) respectively. Blood glucose level, serum creatinine, and 24-hour urine protein were examined. Expressions of TGF-beta1 and Smad4 protein and mRNA in kidney were detected using immunohistochemical technique, Western blot, and real-time PCR. mRNA expressions of stromelysin-1 (MMP-3), tissue inhibitor of metalloproteinase-1 (TIMP-1), and collagen In in kidney were also detected by real-time PCR.

RESULTSThe levels of blood glucose, serum creatinine, and 24-hour urine protein in rats of group B, C, D, and E were higher than those of the control group. With the progression of renal fibrosis, the expressions of TGF-beta1 and Smad4 protein and mRNA in kidney of diabetic rats elevated. In addition, the renal MMP-3 mRNA expression diminished in diabetic rats, while TIMP-1 and collagen III mRNA increased.

CONCLUSIONSIn STZ-induced diabetic rats, the TGF-beta1/Smad4 appears to play an important role in renal fibrosis of DN. The increased expression of TGF-beta1 and Smad4 might result in the transcriptional regulation of downstream target genes of TGF-beta1/Smad4 pathway, which contributes to the progression of renal fibrosis in diabetic rats.

Animals ; Base Sequence ; DNA Primers ; Diabetes Mellitus, Experimental ; metabolism ; Down-Regulation ; Extracellular Matrix ; metabolism ; Kidney ; metabolism ; Male ; Rats ; Rats, Wistar ; Signal Transduction ; Smad4 Protein ; genetics ; metabolism ; Transforming Growth Factor beta1 ; genetics ; metabolism