Limited effects of systemic or renal lipoprotein lipase deficiency on renal physiology and diseases.

Lipoprotein lipase (LPL) is an enzyme that catalyzes the hydrolysis of circulating triglyceride and the transport of fatty acids into cells. Its activity is positively regulated by insulin, and insulin resistance is associated with low LPL activity and subsequent hypertriglyceridemia. The involvement of hypertriglyceridemia in chronic kidney disease (CKD) is still under the debate in a clinical setting. Therefore, we aimed to study the role of hypertriglyceridemia in the disease using mice with systemic or renal-specific LPL deficiency. Systemic LPL deficiency was characterized by hypertriglyceridemia, but not renal injury or dyslipidemia-related conditions, such as fatty liver. Furthermore, the LPL deficiency-induced hypertriglyceridemia was not associated with a worsening of the CKD phenotype or atherosclerosis, even when CKD was induced by 5/6 nephrectomy. Next, because LPL-mediated fatty acid uptake may be important for energy metabolism in proximal tubular epithelial cells (PTECs), the role of renal LPL in renal physiology was studied by generating mice lacking LPL specifically in PTECs. These mice showed no abnormalities in their histology or renal reabsorption of micro molecules. These findings suggest that systemic and renal lipid abnormalities caused by LPL deficiency do not cause or worsen the development of renal injury, and provide novel insight regarding the potential role of lipotoxicity in the pathogenesis of obesity-related kidney injury.

Rivaroxaban-related acute kidney injury in a patient with IgA vasculitis.

Anticoagulants have recently been recognised as a cause of acute kidney injury (AKI). We describe the case of a 75-year-old man with IgA vasculitis and atrial fibrillation treated with rivaroxaban, who presented with macroscopic haematuria and an acute decline in renal function. Two months before referral, he noted palpable purpuric lesions and was diagnosed with IgA vasculitis based on skin biopsy findings; the skin lesion disappeared following treatment with a steroid external preparation. Renal biopsy revealed glomerular haemorrhage and red blood cell casts. Although rivaroxaban was withdrawn, his kidney function worsened and he was started on haemodialysis. His renal function did not recover. To the best of our knowledge, this is the first case of direct oral anticoagulant (DOAC)-related AKI in systemic vasculitis. During DOAC therapy, close monitoring of a patient's urinalysis results and their renal function may be required for patients with systemic vasculitis to avoid AKI.

Idiopathic Chyluria with Nephrotic-range Proteinuria and Hypothyroidism.

The patient was a 75-year-old man who was admitted to our hospital because of fatigue, leg edema and heavy proteinuria. Due to his cloudy urine and elevated triglyceride level in his urine, he was diagnosed with chyluria. Tests for infectious disease were negative, and lymphoscintigraphy showed no blockage in the lymphatic system. He was therefore diagnosed with idiopathic chyluria. Hypothyroidism was also found and his cloudy urine and heavy proteinuria disappeared without dietary modifications after starting levothyroxine treatment for hypothyroidism. The patient is currently being followed up in an outpatient clinic and is doing well, with no recurrence of chyluria.