Uremia Impedes Skeletal Myocyte Myomixer Expression and Fusogenic Activity: Implication for Uremic Sarcopenia.

In patients with chronic kidney disease (CKD), skeletal muscle mass and function are known to occasionally decline. However, the muscle regeneration and differentiation process in uremia has not been extensively studied. In mice with CKD induced by adenine-containing diet, the tibialis anterior muscle injured using a barium chloride injection method recovered poorly as compared to control mice. In the cultured murine skeletal myocytes, stimulation with indoxyl sulfate (IS), a representative uremic toxin, morphologically jeopardized the differentiation, which was counteracted by L-ascorbic acid (L-AsA) treatment. Transcriptome analysis of cultured myocytes identified a set of genes whose expression was down-regulated by IS stimulation but up-regulated by L-AsA treatment. Gene silencing of myomixer, one of the genes in the set, impaired myocyte fusion during differentiation. By contrast, lentiviral overexpression of myomixer compensated for a hypomorphic phenotype caused by IS treatment. The split-luciferase technique demonstrated that IS stimulation negatively affected early myofusion activity that was rescued by L-AsA treatment. Lastly, in mice with CKD compared with control mice, myomixer expression in the muscle tissue in addition to the muscle weight after the injury was reduced, both of which were restored with L-AsA treatment. Collectively, data showed that the uremic milieu impairs the expression of myomixer and impedes the myofusion process. Considering frequent musculoskeletal injuries in uremic patients, defective myocyte fusion followed by delayed muscle damage recovery could underlie their muscle loss and weakness.

ß2-adrenergic receptor agonist counteracts skeletal muscle atrophy and oxidative stress in uremic mice.

In patients with chronic kidney disease, skeletal muscle dysfunction is associated with mortality. Uremic sarcopenia is caused by ageing, malnutrition, and chronic inflammation, but the molecular mechanism and potential therapeutics have not been fully elucidated yet. We hypothesize that accumulated uremic toxins might exert a direct deteriorative effect on skeletal muscle and explore the pharmacological treatment in experimental animal and culture cell models. The mice intraperitoneally injected with indoxyl sulfate (IS) after unilateral nephrectomy displayed an elevation of IS concentration in skeletal muscle and a reduction of instantaneous muscle strength, along with the predominant loss of fast-twitch myofibers and intramuscular reactive oxygen species (ROS) generation. The addition of IS in the culture media decreased the size of fully differentiated mouse C2C12 myotubes as well. ROS accumulation and mitochondrial dysfunction were also noted. Next, the effect of the ß2-adrenergic receptor (ß2-AR) agonist, clenbuterol, was evaluated as a potential treatment for uremic sarcopenia. In mice injected with IS, clenbuterol treatment increased the muscle mass and restored the tissue ROS level but failed to improve muscle weakness. In C2C12 myotubes stimulated with IS, although ß2-AR activation also attenuated myotube size reduction and ROS accumulation as did other anti-oxidant reagents, it failed to augment the mitochondrial membrane potential. In conclusion, IS provokes muscular strength loss (uremic dynapenia), ROS generation, and mitochondrial impairment. Although the ß2-AR agonist can increase the muscular mass with ROS reduction, development of therapeutic interventions for restoring skeletal muscle function is still awaited.

Uremic Sarcopenia: Clinical Evidence and Basic Experimental Approach.

Sustained physical activity extends healthy life years while a lower activity due to sarcopenia can reduce them. Sarcopenia is defined as a decrease in skeletal muscle mass and strength due not only to aging, but also from a variety of debilitating chronic illnesses such as cancer and heart failure. Patients with chronic kidney disease (CKD), who tend to be cachexic and in frail health, may develop uremic sarcopenia or uremic myopathy due to an imbalance between muscle protein synthesis and catabolism. Here, we review clinical evidence indicating reduced physical activity as renal function deteriorates and explore evidence-supported therapeutic options focusing on nutrition and physical training. In addition, although sarcopenia is a clinical concept and difficult to recapitulate in basic research, several in vivo approaches have been attempted, such as rodent subtotal nephrectomy representing both renal dysfunction and muscle weakness. This review highlights molecular mechanisms and promising interventions for uremic sarcopenia that were revealed through basic research. Extensive study is still needed to cast light on the many aspects of locomotive organ impairments in CKD and explore the ways that diet and exercise therapies can improve both outcomes and quality of life at every level.

Proliferative Glomerulonephritis with Monoclonal Immunoglobulin Deposits without Conspicuous Mesangial Proliferation, Complicated with Squamous Cell Lung Carcinoma.

We performed a renal biopsy for nephrotic syndrome in a patient with squamous cell lung carcinoma, which can worsen the prognosis. Chemoradiation therapy was effective for the cancer and proteinuria; we thus inferred that the nephrotic syndrome had been closely associated with the carcinoma. A pathological analysis of the kidney showed monoclonality for λ chain, satisfying the diagnostic criteria of proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID); however, conspicuous mesangial proliferation was not observed. This is the first case of PGNMID complicated with lung carcinoma; furthermore, our findings underscore the importance of examining renal lesions and assessing monoclonality in cancer patients.

Lipotoxicity in Kidney, Heart, and Skeletal Muscle Dysfunction.

Dyslipidemia is a common nutritional and metabolic disorder in patients with chronic kidney disease. Accumulating evidence supports the hypothesis that prolonged metabolic imbalance of lipids leads to ectopic fat distribution in the peripheral organs (lipotoxicity), including the kidney, heart, and skeletal muscle, which accelerates peripheral inflammation and afflictions. Thus, lipotoxicity may partly explain progression of renal dysfunction and even extrarenal complications, including renal anemia, heart failure, and sarcopenia. Additionally, endoplasmic reticulum stress activated by the unfolded protein response pathway plays a pivotal role in lipotoxicity by modulating the expression of key enzymes in lipid synthesis and oxidation. Here, we review the molecular mechanisms underlying lipid deposition and resultant tissue damage in the kidney, heart, and skeletal muscle, with the goal of illuminating the nutritional aspects of these pathologies.

IL-6-producing Renal Cell Carcinoma Causing Renal and Endocrine Paraneoplastic Syndromes.

An 83-year-old man with stable chronic kidney disease (CKD) exhibited a sudden increase in urinary N-acetyl-ß-D-glucosaminidase and protein excretion, suggesting aggravated kidney damage. Simultaneously, he lost diabetic control, requiring up to 54 units of insulin daily. A detailed examination revealed the presence of renal cell carcinoma, which was surgically resected and confirmed to be interleukin-6-positive by immunohistochemistry. Postoperatively, his uni-nephrectomy necessitated hemodialysis, but the patient's insulin resistance was ameliorated; no medication was required to control diabetes, suggesting that the tumor had caused the insulin resistance. This report describes a case of a tumor secreting interleukin-6, which affects both the control of diabetes and CKD progression.

Atypical cause of intractable diarrhea in a hemodialysis patient, masked by Clostridium difficile-associated diarrhea and ischemic colitis: a case report.

BACKGROUND: Patients with end-stage kidney disease (ESKD) most commonly complain of gastrointestinal symptoms, such as diarrhea. Diarrhea negatively affects patient quality of life and has miscellaneous etiologies, such as Clostridium difficile-associated diarrhea (CDAD) and ischemic colitis. However, it is sometimes extremely difficult to determine the true etiology given the comorbidities and complications the patients have. A rare cause of diarrhea is ulcerative colitis (UC), which commonly affects the rectum and proximal colon in a continuous fashion. UC with rectal sparing or segmental distribution, although atypical, sometimes leads to misdiagnosis. Herein, we present a case of UC in a patient on hemodialysis with intractable diarrhea; we initially considered that the diarrhea was caused by CDAD and ischemic colitis. CASE PRESENTATION: A 69-year-old man with a history of hypertension, bilateral thalamic hemorrhage, and decreased kidney function was admitted to our hospital because of congestive heart failure. Volume control was impossible due to renal dysfunction and he was started on hemodialysis. Thereafter, he received various antibiotics for bacterial infections. Simultaneously, he experienced continuous watery, and sometimes bloody, diarrhea, which was diagnosed as CDAD owing to a positive stool test for Clostridium difficile toxins. Antibiotic treatment for CDAD did not result in symptom relief. Subsequently, we performed colon biopsy via colonoscopy, and the pathology showed virtually no inflammation with rectal sparing and segmental distributions. These findings favored the presence of ischemic colitis due to arteriosclerosis and ESKD rather than infections. He died of cardiac arrest before the diarrhea was alleviated. Finally, UC was revealed on autopsy as the main cause of the uncontrollable diarrhea. CONCLUSIONS: Patients with ESKD have a greater risk of developing CDAD and ischemic colitis, which have clinical features that sometimes overlap with those of UC, as in the present case. This case emphasizes the importance of correctly diagnosing the etiology of intractable diarrhea and the fact that other diarrhea etiologies can obscure the existence of inflammatory bowel disease, which should be considered and treated properly when patients on hemodialysis present with intractable diarrhea.

Glomeruloid hemangioma associated with TAFRO syndrome.

Glomeruloid hemangioma is a rare cutaneous lesion that has been considered as a specific cutaneous marker of POEMS syndrome. Herein, we present the first case of glomeruloid hemangioma associated with TAFRO syndrome, a unique variant of idiopathic multicentric Castleman disease. The patient is a 74-year-old woman presented with fever, cervical lymphadenopathy, thrombocytopenia, bilateral pleural effusions and ascites. Biopsy of the lymph node revealed multicentric Castleman disease-like histology and bone marrow biopsy showed mild reticulin fibrosis, consistent with TAFRO syndrome. The patient simultaneously developed multiple skin lesions, which were histologically confirmed as glomeruloid hemangioma. Multiple immunoglobulin-positive granules were detected in the proliferating endothelial cells. Glomeruloid hemangioma is not specific to POEMS syndrome and can be a manifestation of TAFRO syndrome.

Evaluating the Efficacy of Double-Filtration Plasmapheresis in Treating Five Patients With Drug-Resistant Pemphigus.

Double-filtration plasmapheresis is an effective and safe treatment for pemphigus. We retrospectively evaluated the decrease in autoantibody titer and pemphigus disease area index following double-filtration plasmapheresis in five patients with moderate to severe pemphigus, who were physically and/or serologically unresponsive to 1.0 mg/kg per day of prednisolone and other supportive drugs and ointments. The percentage reduction in autoantibodies 85.6 ± 14.4% (P = 0.00014), and that in pemphigus disease area index was 75.4 ± 24.3% (P = 0.0023). No side-effects were observed. All patients exhibited clinical improvement after undergoing double-filtration plasmapheresis, and the prednisolone dose was reduced by 41 ± 8.9 mg (P = 0.0005) approximately 3 months after double-filtration plasmapheresis. To our knowledge, this is the first report evaluating the efficacy of double-filtration plasmapheresis with pemphigus disease area index, and it demonstrated that double-filtration plasmapheresis is a safe "subtracting" treatment for patients with drug-resistant pemphigus.

A novel case of renal pathergy reaction in a Behçet's disease patient complicated by IgA vasculitis.

BACKGROUND: A pathergy reaction is defined as a hyperreactivity of the skin in response to minimal trauma, which is important in the diagnosis of Behçet's disease (BD). However, a pathergy reaction may not be restricted to the skin, and little is known about whether an invasive medical procedure can induce the reaction. Here we present a pathergy reaction induced by renal biopsy, an invasive procedure. CASE PRESENTATION: A 46-year-old man who was diagnosed with IgA vasculitis (IgAV) at the age of 38 was treated with prednisolone and mizoribine. However, complications such as common carotid arteritis or recurrent oral ulcer suggested the possibility of another pathophysiology. Later, increasing urine protein developed, suggesting disease aggravation. However, renal biopsy showed arteriosclerotic changes caused mainly by hypertension, negating exacerbation. After renal biopsy, his renal dysfunction and body temperature fluctuated, and detailed examinations revealed recurrent oral and genital ulcers and a folliculitis-like rash on his scrotum. Later, he complained of myodesopsia caused by hemorrhage in the ocular fundus due to occlusive vasculitis. Complete BD was diagnosed after development of the symptoms, and he was treated with prednisolone and colchicine. CONCLUSION: Co-occurrence of BD with IgAV is very rare and may be associated with immune disorders. Interestingly, a renal biopsy revealed BD, which was masked by the presence of IgAV, and elucidated the etiology of the unexplainable symptoms. To the best of our knowledge, this is the first report of renal pathergy. This case enlightens clinicians to the fact that not only a needle stimulation but also an invasive procedure can cause a pathergy reaction.