Characterization of cytoskeletal and structural effects of INF2 variants causing glomerulopathy and neuropathy.

Focal segmental glomerulosclerosis (FSGS) is a common glomerular injury leading to end-stage renal disease. Monogenic FSGS is primarily ascribed to decreased podocyte integrity. Variants between residues 184 and 245 of INF2, an actin assembly factor, produce the monogenic FSGS phenotype. Meanwhile, variants between residues 57 and 184 cause a dual-faceted disease involving peripheral neurons and podocytes (Charcot-Marie-Tooth CMT/FSGS). To understand the molecular basis for INF2 disorders, we compared structural and cytoskeletal effects of INF2 variants classified into two subgroups: One (G73D, V108D) causes the CMT/FSGS phenotype, and the other (T161N, N202S) produces monogenic FSGS. Molecular dynamics analysis revealed that all INF2 variants show distinct flexibility compared to the wild-type INF2 and could affect stability of an intramolecular interaction between their N- and C-terminal segments. Immunocytochemistry of cells expressing INF2 variants showed fewer actin stress fibers, and disorganization of cytoplasmic microtubule arrays. Notably, CMT/FSGS variants caused more prominent changes in mitochondrial distribution and fragmentation than FSGS variants and these changes correlated with the severity of cytoskeletal disruption. Our results indicate that CMT/FSGS variants are associated with more severe global cellular defects caused by disrupted cytoskeleton-organelle interactions than are FSGS variants. Further study is needed to clarify tissue-specific pathways and/or cellular functions implicated in FSGS and CMT phenotypes.

Mechanism of cystogenesis by Cd79a-driven, conditional mTOR activation in developing mouse nephrons.

Polycystic kidney disease (PKD) is a common genetic disorder arising from developmental and postnatal processes. Defects in primary cilia and their signaling (eg, mTOR) underlie the pathogenesis. However, how mTOR regulates tubular integrity remains unclear. The paucity of faithful models has limited our understanding of pathogenesis and, therefore, the refinement of therapeutic targets. To understand the role of mTOR in early cystogenesis, we studied an in-house mouse model, Cd79a-Cre;Tsc1ff. (Cd79a-Tsc1 KO hereafter), recapitulating human autosomal-dominant PKD histology. Cre-mediated Tsc1 depletion driven by the promoter for Cd79a, a known B-cell receptor, activated mTORC1 exclusively along the distal nephron from embryonic day 16 onward. Cysts appeared in the distal nephron at 1 weeks of age and mice developed definite PKD by 4 weeks. Cd79a-Tsc1 KO tubule cells proliferated at a rate comparable to controls after birth but continued to divide even after postnatal day 14 when tubulogenesis is normally completed. Apoptosis occurred only after 9 weeks. During postnatal days 7-11, pre-cystic Cd79a-Tsc1 KO tubule cells showed cilia elongation, aberrant cell intercalation, and mitotic division, suggesting that defective cell planar polarity (PCP) may underlie cystogenesis. mTORC1 was activated in a portion of cyst-lining cells and occasionally even when Tsc1 was not depleted, implying a non-autonomous mechanism. Our results indicate that mTORC1 overactivation in developing distal tubules impairs their postnatal narrowing by disrupting morphogenesis, which orients an actively proliferating cell toward the elongating axis. The interplay between mTOR and cilium signaling, which coordinate cell proliferation with PCP, may be essential for cystogenesis.

Hypercalcemia Owing to Overproduction of 1,25-Dihydroxyvitamin D3 in Fetal Lung Adenocarcinoma: Case Report.

Hypercalcemia is a common electrolyte abnormality in malignancy and is largely caused by activation of parathyroid hormone (PTH) pathways. We report the case of a 76-year-old man with hypercalcemia primarily owing to 1,25-dihydroxyvitamin D3 overproduction from a high-grade fetal lung adenocarcinoma. Histologically, the tumor itself and tumor-adjacent macrophages were positive for the CYP27B1 protein, a key enzyme that generates 1,25-dihydroxyvitamin D3. Suppression was observed in serum PTH and PTH-related hormone levels, suggesting hypercalcemia is independent of the PTH pathway. Serum calcium level returned to normal after surgical resection of the lung cancer, supporting extrarenal overproduction of 1,25-dihydroxyvitamin D3 elicited by the tumors is the cause of hypercalcemia in this patient.

Serum Brain-Derived Neurotrophic Factor and Myostatin Levels Are Associated With Skeletal Muscle Mass in Kidney Transplant Recipients.

BACKGROUND: Sarcopenia, or reduced muscle mass, can be an important complication in kidney transplant recipients. The skeletal muscles were recently reported to secrete various myokines, such as brain-derived neurotrophic factor (BDNF) and myostatin, to regulate their mass, function, or both. The aim of the present study was to analyze the interrelationship between myokines (BDNF and myostatin) and skeletal muscle mass in kidney transplant recipients. METHODS: The study population comprised 40 patients who underwent kidney transplantation at Kansai Medical University Hospital. Twenty patients had low skeletal muscle mass index (SMI) values, as measured on dual-energy x-ray absorptiometry, and were categorized into 2 groups (low SMI and normal). RESULTS: Mean serum BDNF levels were 15.7 ng/mL in the low SMI group and 17.8 ng/mL in the normal group (P = .013). Mean serum myostatin levels were 362 pg/mL in the low SMI and 267 pg/mL in the normal group (P = .024). There was a significant positive correlation among metabolic equivalents and serum BDNF levels (r = 0.817; P < .001) and a significant negative correlation among metabolic equivalents and serum myostatin levels (r = -0.541; P < .001). Receiver operating characteristic analysis showed that serum BDNF and level of area under curve was 0.712, and serum myostatin level of area under the curve was 0.690. Serum BDNF and myostatin levels showed no significant difference. CONCLUSION: These results suggest that BDNF and myostatin are potential biomarkers of reduced muscle mass in kidney transplant recipients.

Positive renal familial history in IgA nephropathy is associated with worse renal outcomes: a single-center longitudinal study.

BACKGROUND: IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Although most IgAN cases are sporadic, few show a familial aggregation. However, the prevalence and prognosis of IgAN individuals with positive familial history (FH) of renal disorders remains uncertain. To address these issues, we conducted a longitudinal observational study on a single-institution cohort of patients with biopsy-proven IgAN. METHODS: A total of 467 IgAN patients who underwent renal biopsy during 1994 to 2019 were ascertained to have positive- or negative-FH by history taking and were followed for an average of 8.9 years. We compared the clinical and pathological features of the two subgroups. The primary outcome, a composite of a hard endpoint (end-stage renal disease [ESRD]) and surrogate endpoint (a 50% or more reduction in the estimated glomerular filtration rate [eGFR] from baseline), was evaluated. To estimate the risk for progression to ESRD, a Cox proportional hazards analysis was performed for a subset of patients who underwent follow-up for > 2 years and had an eGFR > 30 mL/min/1.73 m2 at baseline (n = 389; observation, 8.7 years). RESULTS: Positive-FH subtype accounted for 11.6% (n = 54) of all IgAN patients. At baseline, there were no significant differences between the positive- and negative-FH subgroups regarding age, sex, comorbid disease, MEST-C score, observation period, and therapeutic interventions. However, the eGFR value at baselines was significantly lower in the positive-FH subgroup than in the negative-FH subgroup (P < 0.01). On multivariate analysis, positive-FH emerged an independent determinant of poorer renal outcomes (odds ratio, 2.31; 95% confidence interval, 1.10-4.85; P = 0.03), after adjusting for confounding factors. eGFR at follow-up was significantly lower in the positive-FH subgroup than in the negative-FH subgroup after adjustment for age and observation period. CONCLUSIONS: Positive-FH was found in 11.6% of all IgAN patients, consistent with the incidence seen in previous literature. A significantly lower eGFR at baseline and last follow-up and unfavorable renal outcomes in the positive-FH subgroup suggest that certain genetic risk factors predisposing to renal failure may exist in a fraction of our IgAN cohort. (331 words).

Immune-complex glomerulonephritis with a membranoproliferative pattern in Frasier syndrome: a case report and review of the literature.

BACKGROUND: Mutations in the Wilms tumor 1 gene cause a spectrum of podocytopathy ranging from diffuse mesangial sclerosis to focal segmental glomerulosclerosis. In a considerable fraction of patients with Wilms tumor 1 mutations, the distinctive histology of immune-complex-type glomerulonephritis has been reported. However, the clinical relevance and etiologic mechanisms remain unknown. CASE PRESENTATION: A 5-year-old child presented with steroid-resistant nephrotic range proteinuria. Initial renal biopsy revealed predominant diffuse mesangial proliferation with a double-contour and coexisting milder changes of focal segmental glomerulosclerosis. Immunofluorescence and electron microscopy revealed a full-house-pattern deposition of immune complexes in the subendothelial and paramesangial areas. Serial biopsies at 6 and 8 years of age revealed that more remarkable changes of focal segmental glomerulosclerosis had developed on top of the initial proliferative glomerulonephritis. Identification of a de novo Wilms tumor 1 splice donor-site mutation in intron 9 (NM_024426.6:c.1447 + 4C > T) and 46,XY-gonadal dysgenesis led to the diagnosis of Frasier syndrome. CONCLUSIONS: Our findings, together with those of others, point to the importance of heterogeneity in clinicopathological phenotypes caused by Wilms tumor 1 mutations and suggest that immune-complex-mediated membranoproliferative glomerulopathy should be considered as a histological variant.

Transcription factor MafB in podocytes protects against the development of focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is a common cause of steroid-resistant nephrotic syndrome. Spontaneous remission of FSGS is rare and steroid-resistant FSGS frequently progresses to renal failure. Many inheritable forms of FSGS have been described, caused by mutations in proteins that are important for podocyte function. Here, we show that a basic leucine zipper transcription factor, MafB, protects against FSGS. MAFB expression was found to be decreased in the podocytes of patients with FSGS. Moreover, conditional podocyte-specific MafB-knockout mice developed FSGS with massive proteinuria accompanied by depletion of the slit diaphragm-related proteins (Nphs1 and Magi2), and the podocyte-specific transcription factor Tcf21. These findings indicate that MafB plays a crucial role in the pathogenesis of FSGS. Consistent with this, adriamycin-induced FSGS and attendant proteinuria were ameliorated by MafB overexpression in the podocytes of MafB podocyte-specific transgenic mice. Thus, MafB could be a new therapeutic target for FSGS.

Biallelic variants/mutations of IL1RAP in patients with steroid-sensitive nephrotic syndrome.

Nephrotic syndrome (NS) is a renal disease characterized by severe proteinuria and hypoproteinemia. Although several single-gene mutations have been associated with steroid-resistant NS, causative genes for steroid-sensitive NS (SSNS) have not been clarified. While seeking to identify causative genes associated with SSNS by whole-exome sequencing, we found compound heterozygous variants/mutations (c.524T>C; p.I175T and c.662G>A; p.R221H) of the interleukin-1 receptor accessory protein (IL1RAP) gene in two siblings with SSNS. The siblings' parents are healthy, and each parent carries a different heterozygous IL1RAP variant/mutation. Since IL1RAP is a critical subunit of the functional interleukin-1 receptor (IL-1R), we investigated the effect of these variants on IL-1R subunit function. When stimulated with IL-1ß, peripheral blood mononuclear cells from the siblings with SSNS produced markedly lower levels of cytokines compared with cells from healthy family members. Moreover, IL-1R with a variant IL1RAP subunit, reconstituted on a hematopoietic cell line, had impaired binding ability and low reactivity to IL-1ß. Thus, the amino acid substitutions in IL1RAP found in these NS patients are dysfunctional variants/mutations. Furthermore, in the kidney of Il1rap-/- mice, the number of myeloid-derived suppressor cells, which require IL-1ß for their differentiation, was markedly reduced although these mice did not show significantly increased proteinuria in acute nephrotic injury with lipopolysaccharide treatment. Together, these results identify two IL1RAP variants/mutations in humans for the first time and suggest that IL1RAP might be a causative gene for familial NS.

The creatinine/cystatin C ratio provides effective evaluation of muscle mass in kidney transplant recipients.

INTRODUCTION: Measuring muscle mass is an important step in detecting sarcopenia. The evaluation of sarcopenia is also important for kidney transplant recipients. Methods for estimating muscle mass have been established using computed tomography or magnetic resonance imaging, which are considered the gold standards. But these methods are invasive and costly, and there is a need for a more practical and simple method using blood samples from kidney transplant recipients. METHODS: The study population was 62 patients who underwent kidney transplantation at Kansai Medical University Hospital, and were evaluated from August to October 2017. Muscle mass was measured using dual-energy X-ray absorptiometry. Serum creatinine and cystatin C levels were measured by immunoassay. RESULTS: We analyzed 62 transplant recipients who met the inclusion criteria (20 females and 42 males, mean age of 45.6 ± 12.7 years). The creatinine/cystatin C ratio in the male group was > 1, whereas the creatinine/cystatin C ratio in the female group was < 1. Muscle mass was significantly larger in the male group than the female group. There was a significant positive correlation between the skeletal muscle index and creatinine/cystatin C ratio in the male (r = 0.553; p < 0.001) and female groups (r = 0.675; p < 0.001). CONCLUSION: The creatinine/cystatin C ratio is appropriate for evaluating muscle mass in kidney transplant recipients.

A Nationwide Survey on Danon Disease in Japan.

Danon disease, an X-linked dominant cardioskeletal myopathy, is caused by primary deficiency of lysosome-associated membrane protein-2 (LAMP-2). To clarify the clinicopathological features and management, we performed the first nationwide, questionnaire-based survey on Danon disease in Japan. A total of 39 patients (17 males, 22 females) from 20 families were identified in the analysis. All patients had cardiomyopathy. Of the 21 patients who died, 20 (95%) died of cardiac failure or sudden cardiac arrest. Most patients had hypertrophic cardiomyopathy. Wolf⁻Parkinson⁻White syndrome was present at a comparatively high incidence (54% in males, 22% in females). Only one female patient received a heart transplant, which is the most effective therapy. Histopathologically, all male patients showed autophagic vacuoles with sarcolemmal features in muscle. Half of the probands showed de novo mutations. Male patients showed completely absent LAMP-2 expression in muscle. In contrast, female patients showed decreased LAMP-2 expression, which is suggested to reflect LAMP-2 haploinsufficiency due to a heterozygous null mutation. In conclusion, Danon disease is an extremely rare muscular disorder in Japan. Cardiomyopathy is the most significant prognostic factor and the main cause of death. Our findings suggest that the present survey can extend our understanding of the clinical features of this rare disease.

Homozygous splicing mutation in NUP133 causes Galloway-Mowat syndrome.

OBJECTIVE: Galloway-Mowat syndrome (GAMOS) is a neural and renal disorder, characterized by microcephaly, brain anomalies, and early onset nephrotic syndrome. Biallelic mutations in WDR73 and the 4 subunit genes of the KEOPS complex are reported to cause GAMOS. Furthermore, an identical homozygous NUP107 (nucleoporin 107kDa) mutation was identified in 4 GAMOS-like families, although biallelic NUP107 mutations were originally identified in steroid-resistant nephrotic syndrome. NUP107 and NUP133 (nucleoporin 133kDa) are interacting subunits of the nuclear pore complex in the nuclear envelope during interphase, and these proteins are also involved in centrosome positioning and spindle assembly during mitosis. METHODS: Linkage analysis and whole exome sequencing were performed in a previously reported GAMOS family with brain atrophy and steroid-resistant nephrotic syndrome. RESULTS: We identified a homozygous NUP133 mutation, c.3335-11T>A, which results in the insertion of 9bp of intronic sequence between exons 25 and 26 in the mutant transcript. NUP133 and NUP107 interaction was impaired by the NUP133 mutation based on an immunoprecipitation assay. Importantly, focal cortical dysplasia type IIa was recognized in the brain of an autopsied patient and focal segmental glomerulosclerosis was confirmed in the kidneys of the 3 examined patients. A nup133-knockdown zebrafish model exhibited microcephaly, fewer neuronal cells, underdeveloped glomeruli, and fusion of the foot processes of the podocytes, which mimicked human GAMOS features. nup133 morphants could be rescued by human wild-type NUP133 mRNA but not by mutant mRNA. INTERPRETATION: These data indicate that the biallelic NUP133 loss-of-function mutation causes GAMOS. Ann Neurol 2018;84:814-828.

A familial case of Galloway-Mowat syndrome due to a novel TP53RK mutation: a case report.

BACKGROUND: Galloway-Mowat syndrome (GAMOS) is a rare hereditary renal-neurological disease characterized by early-onset steroid-resistant nephrotic syndrome in combination with microcephaly and brain anomalies. Recently, novel causative mutations for this disease have been identified in the genes encoding the four KEOPS subunits: OSGEP, TP53RK, TPRKB, and LAGE3. CASE PRESENTATION: We detected a novel homozygous TP53RK mutation (NM_033550, c.194A > T, p.Lys65Met) using whole exome sequencing in a familial case of GAMOS with three affected siblings. All three patients manifested similar phenotypes, including very early-onset nephrotic syndrome (8 days, 1 day, and 1 day after birth, respectively), microcephaly, dysmorphic faces, and early fatality (10 months, 21 days, and 25 days of age, respectively). One patient also showed hiatal hernia with gastric volvulus. Renal biopsy performed on one patient revealed focal segmental glomerulosclerosis with severe tubulo-interstitial changes. CONCLUSION: We report on a familial case of GAMOS with three affected siblings carrying a novel homozygous TP53RK mutation. To our knowledge, this is only the second report on GAMOS in association with a TP53RK mutation.

A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome.

Focal segmental glomerulosclerosis (FSGS) is a leading cause of end-stage renal disease in children and adults. Genetic factors significantly contribute to early-onset FSGS, but the etiologies of most adult cases remain unknown. Genetic studies of monogenic syndromic FSGS exhibiting extra-renal manifestations have uncovered an unexpected biological role for genes in the development of both podocytes and other cellular lineages. To help define these roles, we studied two unrelated families with FSGS associated with Duane Retraction Syndrome, characterized by impaired horizontal eye movement due to cranial nerve malformation. All four affected individuals developed FSGS and Duane Retraction Syndrome in their first to second decade of life, manifested as restricted abduction together with globe retraction and narrowed palpebral fissure on attempted adduction. Hypoplasia of the abducens nerves and hearing impairment occurred in severely affected individuals. Genetic analyses revealed that affected individuals harbor a rare heterozygous substitution (p.Leu239Pro) in MAFB, a leucine zipper transcription factor. Luciferase assays with cultured monocytes indicated that the substitution significantly reduced transactivation of the F4/80 promoter, the known MAFB recognition element. Additionally, immunohistochemistry indicated reduced MAFB expression in the podocytes of patients. Structural modeling suggested that the p.Leu239Pro substitution in the DNA-binding domain possibly interferes with the stability of the adjacent zinc finger. Lastly, podocytes in neonatal mice with p.Leu239Pro displayed impaired differentiation. Thus, MAFB mutations impair development and/or maintenance of podocytes, abducens neurons and the inner ear. The interactions between MAFB and regulatory elements in these developing organs are likely highly specific based on spatiotemporal requirements.

Mutations in six nephrosis genes delineate a pathogenic pathway amenable to treatment.

No efficient treatment exists for nephrotic syndrome (NS), a frequent cause of chronic kidney disease. Here we show mutations in six different genes (MAGI2, TNS2, DLC1, CDK20, ITSN1, ITSN2) as causing NS in 17 families with partially treatment-sensitive NS (pTSNS). These proteins interact and we delineate their roles in Rho-like small GTPase (RLSG) activity, and demonstrate deficiency for mutants of pTSNS patients. We find that CDK20 regulates DLC1. Knockdown of MAGI2, DLC1, or CDK20 in cultured podocytes reduces migration rate. Treatment with dexamethasone abolishes RhoA activation by knockdown of DLC1 or CDK20 indicating that steroid treatment in patients with pTSNS and mutations in these genes is mediated by this RLSG module. Furthermore, we discover ITSN1 and ITSN2 as podocytic guanine nucleotide exchange factors for Cdc42. We generate Itsn2-L knockout mice that recapitulate the mild NS phenotype. We, thus, define a functional network of RhoA regulation, thereby revealing potential therapeutic targets.

Small-Vessel Vasculopathy Due to Aberrant Autophagy in LAMP-2 Deficiency.

Lysosomal associated membrane protein 2 (LAMP2) is physiologically implicated in autophagy. A genetic LAMP2 defect causes Danon disease, which consists of two major phenotypes of myopathy and cardiomyopathy. In addition, arteriopathy may manifest on rare occasions but the pathological basis remains unknown. We encountered two Danon families that developed small-vessel vasculopathy in the coronary or cerebral arteries. To investigate the underlying mechanisms, we characterized the biological features of LAMP-2-deficient mice and cultured cells. LAMP-2-deficient mice at 9-24 months of age showed medial thickening with luminal stenosis due to proliferation of vascular smooth muscle cells (VSMC) in muscular arteries. Ultrastructural analysis of VSMC revealed various autophagic vacuoles scattered throughout the cytoplasm, suggesting impaired autophagy of long-lived metabolites and degraded organelles (i.e., mitochondria). The VSMC in Lamp2 null mice expressed more vimentin but less α-smooth muscle actin (α-SMA), indicating a switch from contractile to synthetic phenotype. Silencing of LAMP2 in cultured human brain VSMC showed the same phenotypic transition with mitochondrial fragmentation, enhanced mitochondrial respiration, and overproduction of reactive oxygen species (ROS). These findings indicate that LAMP-2 deficiency leads to arterial medial hypertrophy with the phenotypic conversion of VSMC, resulting from age-dependent accumulation of cellular waste generated by aberrant autophagy.

Long-term clinicopathologic observation in a case of steroid-resistant nephrotic syndrome caused by a novel Crumbs homolog 2 mutation.

Recent advances in high-throughput sequencing for clinical genetic testing have revealed novel disease-causing genes, such as Crumbs homolog 2 (CRB2) for early-onset steroid-resistant nephrotic syndrome (SRNS). We report the long-term clinicopathologic observation of a Japanese female patient with SRNS caused by a newly identified compound heterozygous mutation of CRB2 (p.Arg628Cys and p.Gly839Trp located in the 10th and 11th epidermal growth factor-like domains, respectively). She was initially examined during a mass urinary screening for 3.5-year-old children in Japan. Although she developed long-standing SRNS without any extrarenal clinical signs thereafter, her renal function was well-preserved over the next 17 years. In total, six sequential renal biopsy specimens revealed histologic alterations ranging from minor glomerular abnormalities to advanced focal segmental glomerulosclerosis (FSGS). A genetic analysis for SRNS performed at 19 years of age revealed a newly identified compound heterozygous mutation in CRB2. Glomerular CRB2 immunoreactivity in biopsy specimens from the patient was scanty, whereas intense expression was observed in those from patients with idiopathic FSGS or in controls. To our knowledge, this is the first report regarding a long-term outcome in a case of SRNS due to an identified CRB2 mutation. Although the phenotype of CRB2 mutation-related syndrome is now expanding, we believe that this case might provide a novel clinicopathologic aspect of this syndrome.

Determinants of the Change in Arterial Stiffness in Peritoneal Dialysis Patients.

Arterial stiffness is an important risk factor for cardiovascular disease (CVD) in patients with end-stage renal failure. However, little is known about the factors that contribute to arterial rigidity in peritoneal dialysis (PD) patients. The aim of this study was to define the pattern and determinants of the longitudinal change in arterial stiffness after PD initiation.Arterial stiffening was estimated for 46 PD patients by using brachial-ankle pulse wave velocity (baPWV) and carotid intima-media thickness (cIMT). The cross-sectional relationship between the arterial markers and their clinical determinants was studied. The longitudinal effects of blood pressure (BP), body fluid status, and glucose were studied over the two years after initiating PD.Multivariate analysis showed that higher baPWV was associated positively with urinary protein excretion (P < 0.001), systolic BP (P = 0.001), and hemoglobin A1c (P = 0.003). In contrast, increased cIMT correlated with smoking (P = 0.004) and hypoalbuminemia (P = 0.04), suggesting that endothelial dysfunction is implicated in the atherogenic process. Neither cIMT nor baPWV correlated significantly with other PD-related covariates of volume overload, peritoneal solute transport, kidney function, and C-reactive protein. Longitudinal observation demonstrated that BP had a greater influence on baPWV changes than hyperglycemia or fluid status.Our study indicates that 1) baPWV represent an arterial marker that integrates multifactorial interaction between modifiable variables including BP and plasma glucose; and 2) intervention aimed at controlling BP as well as nutritional conditions (glucose and albumin) may reduce CVD risk in PD patients.

Evaluation of physical activity in sarcopenic conditions of kidney transplantation recipients.

INTRODUCTION: Sarcopenia is an involuntary decline in skeletal muscle mass, strength, and function that normally proceed with aging but may develop faster under some chronic disease conditions. In this study, we compared the physical activity between sarcopenia and non-sarcopenia subgroups in kidney transplant recipients. METHODS: Fifty-eight recipients (42 males and 16 females) were enrolled in this study. Mean age of the recipients was 46.6 ± 12.7 years. Mean duration of dialysis was 2.8 ± 4.0 years. Diagnostic criteria for sarcopenia referred to those of the Asia Working Group for Sarcopenia. The physical activity was assessed using the International Physical Activity Questionnaire, and the intensity of physical activity was expressed in metabolic equivalents (MET). RESULTS: Based on the skeletal muscle mass index (SMI) as well as functional index (HGS, walking speed), the participants were classified into the three subgroups: 12 patients (20.7%) with sarcopenia (Group 1), 25 (43.1%) with presarcopenia (Group 2), and 21 (36.2%) non-sarcopenia (Group 3). Analysis with ANOVA and pairwise comparisons showed that physical activity measured as total MET-min/week was significantly greater in Group 2 (1292 ± 633) than in Group (1484 ± 262). Moreover, physical activity of Group 3 (2461 ± 1339)-min/week was significantly greater than those of Groups 1 and 2. CONCLUSIONS: Our data indicate that physical activity is restricted under presarcopenia and sarcopenia after kidney transplantation. Considering that the recipient age is now increasing, proper management of sarcopenia may become more crucial to improve the kidney survival and lifetime prognosis of the kidney transplant recipients.