Ultrastructure expansion microscopy (U-ExM) of mouse and human kidneys for analysis of subcellular structures

Ultrastructure expansion microscopy (U-ExM) involves the physical magnification of specimens embedded in hydrogels, which allows for super-resolution imaging of subcellular structures using a conventional diffraction-limited microscope. Methods for expansion microscopy exist for several organisms, organs, and cell types, and used to analyze cellular organelles and substructures in nanoscale resolution. Here, we describe a simple step-by-step U-ExM protocol for the expansion, immunostaining, imaging, and analysis of cytoskeletal and organellar structures in kidney tissue. We detail the critical modified steps to optimize isotropic kidney tissue expansion, and preservation of the renal cell structures of interest. We demonstrate the utility of the approach using several markers of renal cell types, centrioles, cilia, the extracellular matrix, and other cytoskeletal elements. Finally, we show that the approach works well on mouse and human kidney samples that were preserved using different fixation and embedding conditions. Overall, this protocol provides a simple and cost-effective approach to analyze both preclinical and clinical renal samples in high detail, using conventional lab supplies and standard widefield or confocal microscopy.

Quantitative assessment of glomerular basement membrane collagen IV α chains in paraffin sections from patients with focal segmental glomerulosclerosis and Alport gene variants

Focal segmental glomerulosclerosis (FSGS) lesions have been linked to variants in COL4A3/A4/A5 genes, which are also mutated in Alport syndrome. Although it could be useful for diagnosis, quantitative evaluation of glomerular basement membrane (GBM) type IV collagen (colIV) networks is not widely used to assess these patients. To do so, we developed immunofluorescence imaging for collagen α5(IV) and α1/2(IV) on kidney paraffin sections with Airyscan confocal microscopy that clearly distinguishes GBM collagen α3α4α5(IV) and α1α1α2(IV) as two distinct layers, allowing quantitative assessment of both colIV networks. The ratios of collagen α5(IV):α1/2(IV) mean fluorescence intensities (α5:α1/2 intensity ratios) and thicknesses (α5:α1/2 thickness ratios) were calculated to represent the levels of collagen α3α4α5(IV) relative to α1α1α2(IV). The α5:α1/2 intensity and thickness ratios were comparable across all 11 control samples, while both ratios were significantly and markedly decreased in all patients with pathogenic or likely pathogenic Alport COL4A variants, supporting validity of this approach. Thus, with further validation of this technique, quantitative measurement of GBM colIV subtype abundance by immunofluorescence, may potentially serve to identify the subgroup of patients with FSGS lesions likely to harbor pathogenic COL4A variants who could benefit from genetic testing.

Alport syndrome and Alport kidney diseases - elucidating the disease spectrum

PURPOSE OF REVIEW

With the latest classification, variants in three collagen IV genes, COL4A3 , COL4A4 , and COL4A5 , represent the most prevalent genetic kidney disease in humans, exhibiting diverse, complex, and inconsistent clinical manifestations. This review breaks down the disease spectrum and genotype-phenotype correlations of kidney diseases linked to genetic variants in these genes and distinguishes "classic" Alport syndrome (AS) from the less severe nonsyndromic genetically related nephropathies that we suggest be called "Alport kidney diseases".

RECENT FINDINGS

Several research studies have focused on the genotype-phenotype correlation under the latest classification scheme of AS. The historic diagnoses of "benign familial hematuria" and "thin basement membrane nephropathy" linked to heterozygous variants in COL4A3 or COL4A4 are suggested to be obsolete, but instead classified as autosomal AS by recent expert consensus due to a significant risk of disease progression.

SUMMARY

The concept of Alport kidney disease extends beyond classic AS. Patients carrying pathogenic variants in any one of the COL4A3/A4/A5 genes can have variable phenotypes ranging from completely normal/clinically unrecognizable, hematuria without or with proteinuria, or progression to chronic kidney disease and kidney failure, depending on sex, genotype, and interplays of other genetic as well as environmental factors.

A Case of Congenital Nephrotic Syndrome with Crescents Caused by a Novel Compound Heterozygous Pairing of NPHS1 Genetic Variants

Congenital nephrotic syndrome is an autosomal recessive inherited disorder that manifests as steroid-resistant massive proteinuria in the first three months of life. Defects in the glomerular filtration mechanism are the primary etiology. We present a child who developed severe nephrotic syndrome at two weeks of age and eventually required a bilateral nephrectomy. Genetic testing revealed compound heterozygous variants in NPHS1 including a known pathogenic variant and a missense variant of uncertain significance. Light microscopy revealed crescent formation-an atypical finding in congenital nephrotic syndrome caused by nephrin variants-in addition to focal segmental and global glomerulosclerosis. Electron microscopy showed diffuse podocyte foot process effacement. Confocal and Airyscan immunofluorescence microcopy showed aggregation of nephrin in the podocyte cell body that is not a result of diffuse podocyte foot process effacement as seen in minimal change disease. These findings confirm the novel variant as pathogenic.

Ultrastructure expansion microscopy (U-ExM) of mouse and human kidneys for analysis of subcellular structures

Ultrastructure expansion microscopy (U-ExM) involves the physical magnification of specimens embedded in hydrogels, which allows for super-resolution imaging of subcellular structures using a conventional diffraction-limited microscope. Methods for expansion microscopy exist for several organisms, organs, and cell types, and used to analyze cellular organelles and substructures in nanoscale resolution. Here, we describe a simple step-by-step U-ExM protocol for the expansion, immunostaining, imaging, and analysis of cytoskeletal and organellar structures in kidney tissue. We detail the critical modified steps to optimize isotropic kidney tissue expansion, and preservation of the renal cell structures of interest. We demonstrate the utility of the approach using several markers of renal cell types, centrioles, cilia, the extracellular matrix, and other cytoskeletal elements. Finally, we show that the approach works well on mouse and human kidney samples that were preserved using different fixation and storage conditions. Overall, this protocol provides a simple and cost-effective approach to analyze both pre-clinical and clinical renal samples in high detail, using conventional lab supplies and standard widefield or confocal microscopy.

A Case of Extranodal NK/T-cell Lymphoma Infiltrating Kidneys, Presenting With Hematuria and Proteinuria With False-Positive Serum Anti-proteinase 3, and Mimicking Granulomatosis With Polyangiitis

We report a case of misdiagnosed extranodal NK/T-cell lymphoma, nasal type, mimicking granulomatosis with polyangiitis (GPA). A 30-year-old male presented with chronic non-resolving right paranasal sinusitis for two years accompanied by multiple generalized cutaneous nodules, and subnephrotic-range proteinuria. Biopsies from skin lesions and paranasal sinuses demonstrated leukocytoclastic vasculitis and necrotizing granulomatous inflammation, respectively. Serum proteinase 3 (PR3)-antineutrophilic cytoplasmic antibody (ANCA) was positive, suggesting the diagnosis of GPA based on the 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology Classification Criteria for GPA. A kidney biopsy was not pursued due to the cause of glomerulonephritis (GN) being clinically evident, per the KDIGO 2021 GN Clinical Practice Guidelines. Immunosuppression was administered, which led to a transient improvement in clinical symptoms. However, subsequent kidney biopsy and other organ biopsies with cytogenic and molecular tests eventually confirmed extranodal NK/T-cell lymphoma infiltrating kidneys, skin, and paranasal sinuses. Physicians should always consider the possibility of hematologic malignancy in young adults presenting with multiple-organ involvement with vasculitic lesions or pauci-immune crescentic GN, albeit positive ANCA serologies. Kidney biopsy with cytogenic support should be performed to exclude threatening diseases, especially in atypical cases such as in young patients despite a context of compatible manifestations with other syndromes.

Effect of canagliflozin in non-diabetic obese patients with albuminuria: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Sodium-glucose co-transporter 2 inhibitor (SGLT2i) has been shown to improve renal outcomes in both diabetic and non-diabetic kidney disease. However, the effect of SGLT2i on renal outcomes in patients with non-diabetic obesity is still not established.

MATERIALS AND METHODS

In this double-blind, randomized controlled trial, we assigned non-diabetic patients with body mass index (BMI) ≥ 25 kg/m2, persistent 24-hour urine albumin-creatinine ratio (UACR) ≥ 10 mg/gCr, and estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73m2, who had been treated with renin-angiotensin system blockade, to canagliflozin 100 mg daily or placebo for 24 weeks. The reduction in UACR and eGFR at 12 and 24 weeks were explored. (Thai Clinical Trials Registry 20190203003).

RESULTS

Of 247 non-diabetic obese patients screened, 32 patients met inclusion criteria and underwent randomization. The median baseline of UACR was 69.1 mg/gCr. There were no statistically significant differences in albuminuria reduction between the groups at 12 weeks and 24 weeks. The estimated GFR in the canagliflozin group decreased significantly from baseline at 12 weeks (-5.39 mL/min/1.73m2; 95% CI -9.81 to -0.97; p = 0.017) but not at 24 weeks (-1.16 mL/min/1.73m2; 95% CI -5.58 to 3.26; p = 0.66), and there was no significant change from baseline in the placebo group at both 12 and 24 weeks.

CONCLUSION

Canagliflozin 100 mg daily was well tolerated but did not significantly reduce UACR in non-diabetic obese patients with microalbuminuria. However, a significant temporary decline in eGFR might reflect a subtle reduction in glomerular hyperfiltration.

Constipation and clinical outcomes in peritoneal dialysis: Results from Thailand PDOPPS

BACKGROUND

Patient-reported outcome measures (PROMs) are widely recognized as valuable predictors of clinical outcomes in peritoneal dialysis (PD). Our study aimed to explore the connections between patient-reported constipation and clinical outcomes.

METHODS

We assessed constipation in patients across 22 facilities participating in the Thailand Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS) from 2014 to 2017. Constipation diagnosis utilized objective assessment tools such as the Bristol stool form scale (BSFS) and a self-reported questionnaire known as the constipation severity score (CSS). The BSFS is a 7-level scale that visually inspects feces based on texture and morphology, while the CSS measures constipation duration and severity using a 5-point Likert scale for various factors. We employed Cox proportional hazards model regression to determine the associations between constipation and clinical outcomes, including mortality, hemodialysis (HD) transfer and peritonitis.

RESULTS

Among 975 randomly selected PD patients from 22 facilities, 845 provided written informed consent, and 729 completed CSS questionnaire. Constipation was prevalent in the PD population (13%), particularly among older patients, those who were caregiver dependent, had diabetes and poorer nutritional status (indicated by lower time-averaged serum albumin, potassium, creatinine and phosphate concentrations). Twenty-seven percent of which experiencing symptoms of constipation for over a year. Notably, self-reported constipation at baseline was significantly associated with a shorter time to first peritonitis and higher rates of peritonitis and death. However, no significant association was found between constipation and HD transfer after adjusting for various factors, including age, gender, PD vintage, comorbidities, shared frailty by study sites and serum albumin.

CONCLUSION

Patient-reported constipation independently correlated with increased risks of peritonitis and all-cause mortality, though no such correlation was observed with HD transfer. These findings underscore the need for further investigation to identify effective interventions for constipation in PD patients.

Exploring hospital practice types and their impact on glomerular pathologic patterns: Insights from the largest kidney biopsy cohort in Thailand

BACKGROUND

This study aims to investigate the influence of different kidney biopsy practices on the prevalence of glomerular pathologic patterns in the largest kidney biopsy registry in Thailand.

METHODS

We conducted a retrospective review of kidney biopsy records from the period between 2000 and 2014. The records were obtained from 2 major institutions: King Chulalongkorn Memorial Hospital, a large university-based hospital, and the Kidney Center Bangkok Hospital, which provides pathology services to hospitals throughout Thailand. The study included native kidney biopsies from all provinces in Thailand, excluding paediatric patients, kidney transplant recipients, and cases of inadequate and repeated biopsies. Patient demographics, indications for biopsy, and final glomerular diagnoses were compared across different hospital practice settings: university (UVH), private (PVH) and public (PBH).

RESULTS

A total of 5893 eligible native kidney biopsies were identified from a pool of 7005 biopsies conducted over a 15-year period in 25 provinces throughout Thailand. The 3 most common indications for biopsy were suspected kidney involvement in systemic lupus erythematosus (SLE) (29%), nephrotic syndrome (NS) (29%), and acute glomerulonephritis (AGN)/rapidly progressive glomerulonephritis (RPGN) (13%). The leading indication for biopsy differed across practice types, with suspected kidney involvement in SLE being the primary indication in UVH, while NS took precedence in both PBH and PVH practices. Notably, UVH performed fewer kidney biopsies for asymptomatic urinary abnormalities and diabetes-related indications compared with PVH and PBH. The leading glomerular diagnoses correlated with the biopsy indications, with lupus nephritis (LN) being the most common diagnosis in UVH and PBH practices, whiles immunoglobulin A nephropathy was the predominant diagnosis in PVH practice.

CONCLUSION

Hospital practice types significantly impact the prevalence of glomerular pathologic diagnosis patterns in kidney biopsy data, highlighting the importance of considering this influence in epidemiological comparisons.

Clinicopathological Characteristics and Impacts on Clinical Outcomes of Thrombotic Microangiopathy Lesions in Patients with Immunoglobulin A Nephropathy in Thailand

INTRODUCTION

More reports of thrombotic microangiopathy (TMA) in immunoglobulin A (IgA) nephropathy suggest its association with poor clinical outcomes. However, the prevalence and clinical significance of TMA in IgA nephropathy have not been widely studied in different populations.

METHODS

Kidney biopsies of all patients with primary IgA nephropathy from 1995 to 2015 at the King Chulalongkorn Memorial Hospital, Thailand, were retrospectively reviewed and reclassified by two pathologists following the Oxford MEST-C classification. TMA lesions were detected based solely on light microscopic findings. Associations between the presence of TMA and clinical data, other pathologic findings, and clinical outcomes were studied.

RESULTS

Among 267 patients with primary IgA nephropathy, 166 had adequate clinical data and kidney tissues for the analysis. TMA was observed in 21 patients (13%) and was associated with higher mean arterial pressure (MAP), history of malignant hypertension, higher proteinuria, and lower estimated glomerular filtration rate (eGFR) at diagnosis compared to those without TMA. According to the Oxford MEST-C classification, TMA showed a significant association with severe tubular atrophy/interstitial fibrosis (T2) but not with mesangial hypercellularity (M1), endocapillary hypercellularity (E1), segmental glomerulosclerosis (S1), or crescents (C1-2). After a median follow-up of 50 months, patients with TMA had a significantly higher risk of progression to end-stage kidney disease (ESKD) (hazard ratio [HR] 5.8, 95% confidence interval [CI]: 3.1-10.9) and all-cause mortality (HR 3.4, 95% CI: 1.3-8.8). After adjusting for baseline eGFR, MAP, proteinuria, and other pathological lesions, TMA remained an independent predictor of ESKD (adjusted HR 2.4, 95% CI: 1.1-5.4).

CONCLUSIONS

Kidney TMA in IgA nephropathy is associated with advanced disease stages, carries a poor prognosis, and thus should be considered in the pathological classification of IgA nephropathy.

Assisted peritoneal dialysis performed by caregivers and its association with patient outcomes

BACKGROUND

Although caregivers allow peritoneal dialysis (PD) patients with disabilities the opportunity to perform PD, it is crucial to clarify the safety and effectiveness of assisted PD performed by caregivers compared to self-PD.

METHODS

PD patients from 22 PD centres in Thailand were prospectively followed in the Peritoneal Dialysis Outcomes and Practice Patterns Study during 2016-2017. Patients receiving assisted PD performed by caregivers were matched 1:1 with self-PD patients using propensity scores calculated by logistic regression. The associations between assisted PD and risk of mortality, peritonitis and permanent transfer to haemodialysis (HD) were assessed by multivariable competing risk regression.

RESULTS

Of 778 eligible patients, 447 (57%) required assisted PD performed by caregivers. Most of the caregivers were family members (98%), while the rest were non-family paid caregivers (2%). Patient factors associated with assisted PD were older age, female gender, lower educational level, cardiovascular comorbidities, diabetes, automated PD modality, poorer functional status and lower blood chemistries (albumin, creatinine, sodium, potassium and phosphate). After 1:1 matching, the baseline characteristics were adequately matched, and 269 patients in each group were analysed. Compared with self-PD, assisted PD was significantly associated with an increased risk of all-cause mortality (adjusted sub-hazard ratio: 2.15, 95% confidence interval: 1.24-3.74). There were no differences in the occurrences of peritonitis and permanent HD transfer between the groups.

CONCLUSIONS

Assisted PD was required by more than half of Thai PD patients and was independently associated with a higher mortality risk. This may reflect causal effect or confounding by indication.

Efficacy of Potassium Supplementation in Hypokalemic Patients Receiving Peritoneal Dialysis: A Randomized Controlled Trial

RATIONALE & OBJECTIVE

Hypokalemia is a common electrolyte abnormality in patients on peritoneal dialysis (PD) and has been associated with increased risks of peritonitis and death. Whether correction of hypokalemia improves these outcomes is unknown.

STUDY DESIGN

Multicenter, open-label, prospective, randomized controlled trial.

SETTING & PARTICIPANTS

Adult (aged ≥18 years) PD patients with hypokalemia (defined as at least 3 values or an average value <3.5 mEq/L in the past 6 months). Randomization was stratified according to center and residual urine output (≤100 or >100 mL/day).

INTERVENTIONS

Random assignment to either protocol-based potassium supplementation (titratable dose of oral potassium chloride to maintain serum potassium of 4-5 mEq/L) or conventional potassium supplementation (reactive supplementation when serum potassium is <3.5 mEq/L) over 52 weeks. Treatment groups were compared using intention-to-treat analyses implemented using Cox proportional hazards regression.

OUTCOME

The primary outcome was time from randomization to first peritonitis episode (any organism). Secondary outcomes were all-cause mortality, cardiovascular mortality, hospitalization, and conversion to hemodialysis.

RESULTS

A total of 167 patients with time-averaged serum potassium concentrations of 3.33 ± 0.28 mEq/L were enrolled from 6 PD centers: 85 were assigned to receive protocol-based treatment, and 82 were assigned to conventional treatment. The median follow-up time was 401 (IQR, 315-417) days. During the study period, serum potassium levels in the protocol-based treatment group increased to 4.36 ± 0.70 mEq/L compared with 3.57 ± 0.65 mEq/L in the group treated conventionally (mean difference, 0.66 [95% CI, 0.53-0.79] mEq/L; P < 0.001). The median time to first peritonitis episode was significantly longer in the protocol-based group (223 [IQR, 147-247] vs 133 [IQR, 41-197] days, P = 0.03). Compared with conventional treatment, the protocol-based group had a significantly lower hazard of peritonitis (HR, 0.47 [95% CI, 0.24-0.93]) but did not differ significantly with respect to any of the secondary outcomes. Asymptomatic hyperkalemia (>6 mEq/L) without characteristic electrocardiographic changes occurred in 3 patients (4%) in the protocol-based treatment group.

LIMITATIONS

Not double-masked.

CONCLUSIONS

Compared with reactive potassium supplementation when the serum potassium level falls below 3.5 mEq/L, protocol-based oral potassium treatment to maintain a serum potassium concentration in the range of 4-5 mEq/L may reduce the risk of peritonitis in patients receiving PD who have hypokalemia.

TRIAL REGISTRATION

Registered at the Thai Clinical Trials Registry with study number TCTR20190725004.

An ex vivo culture model of kidney podocyte injury reveals mechanosensitive, synaptopodin-templating, sarcomere-like structures

Chronic kidney diseases are widespread and incurable. The biophysical mechanisms underlying them are unclear, in part because material systems for reconstituting the microenvironment of relevant kidney cells are limited. A critical question is how kidney podocytes (glomerular epithelial cells) regenerate foot processes of the filtration apparatus following injury. Recently identified sarcomere-like structures (SLSs) with periodically spaced myosin IIA and synaptopodin appear in injured podocytes in vivo. We hypothesized that SLSs template synaptopodin in the initial stages of recovery in response to microenvironmental stimuli and tested this hypothesis by developing an ex vivo culture system that allows control of the podocyte microenvironment. Results supported our hypothesis. SLSs in podocytes that migrated from isolated kidney glomeruli presented periodic synaptopodin-positive clusters that nucleated peripheral, foot process-like extensions. SLSs were mechanoresponsive to actomyosin inhibitors and substrate stiffness. Results suggest SLSs as mechanobiological mediators of podocyte recovery and as potential targets for therapeutic intervention.

Urinary red blood cell-derived microparticles and phosphatidylserine-exposing red blood cells in glomerular and non-glomerular hematuria patients

BACKGROUND

Distinguishing glomerular hematuria (GH) from non-glomerular hematuria (NGH) is important for treating the cause of hematuria. We aimed to determine red blood cell-derived microparticles (RMPs) and phosphatidylserine (PS)-exposing red blood cells (RBCs) and evaluate their use for diagnosing GH and NGH patients.

METHODS

All patients received a physical assessment and urological examination. Dysmorphic RBCs (dRBCs) and acanthocytes were examined using a light microscope. The urinary RMPs and PS-exposing RBCs were determined using flow cytometry.

RESULTS

The ratio of RMPs to RBCs was higher in GH patients (n = 29) than in NGH patients (n = 29) (1.06 vs. 0.18). The value of the sum of the PS-exposing RBCs plus RMPs divided by the number of RBCs was higher in GH patients than in NGH patients (48.3% vs. 19.4%). The percentage of RBCs was higher in GH patients than in NGH patients (54.5% vs. 21.8%). Similarly, both the percentages of acanthocytes and of non-acanthocytes were higher in GH patients than in NGH patients (29% vs. 7.7% and 25.4% vs. 14.2%, respectively). The ROC-AUC of the number of PS-exposing RBCs plus RMPs divided by the number of RBCs was 0.9 (95% CI, 0.82-0.97), and the RMPs:RBCs ratio was 0.88 (95% CI, 0.79-0.98). The ROC-AUCs of the dRBCs and acanthocytes were 0.85 (95% CI, 0.78-0.95) and 0.88 (95% CI, 0.8-0.97), respectively.

CONCLUSIONS

Patients with GH have higher numbers of urinary RMPs and PS-exposing RBCs. These parameters have the potential to be predictive tools for classifying GH in the future.

Oral Health-Related Quality of Life, A Proxy of Poor Outcomes in Patients on Peritoneal Dialysis

Introduction

We sought to evaluate the associations of poor oral health hygiene with clinical outcomes in patients receiving peritoneal dialysis (PD).

Methods

As part of the multinational Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS), PD patients from 22 participating PD centers throughout Thailand were enrolled from May 2016 to December 2019. The data were obtained from questionnaires that formed part of the PDOPPS. Oral health-related quality of life (HRQoL) used in this study was the short form of the oral health impact profile (oral health impact profile [OHIP]-14, including 7 facets and 14 items). Patient outcomes were assessed by Kaplan-Meier analysis. Cox proportional hazards model regression was used to estimate associations between oral HRQoL and clinical outcomes.

Results

Of 5090 PD participants, 675 were randomly selected, provided informed consent, and completely responded to the OHIP-14 questionnaire. The median follow-up time of the study was 3.5 (interquartile range = 2.7–5.1 months) years. Poor oral health was associated with lower educational levels, diabetes, older age, marriage, and worse nutritional indicators (including lower time-averaged serum albumin and phosphate concentrations). After adjusting for age, sex, comorbidities, serum albumin, shared frailty by study sites, and PD vintage, poor oral health was associated with increased risks of peritonitis (adjusted hazard ratio [HR] = 1.45, 95% confidence interval [CI]: 1.06–2.00) and all-cause mortality (adjusted HR = 1.55, 95% CI: 1.04–2.32) but not hemodialysis (HD) transfer (adjusted HR = 1.89, 95% CI: 0.87–4.10) compared to participants with good oral health.

Conclusion

Poor oral health status was present in one-fourth of PD patients and was independently associated with a higher risk of peritonitis and death.

Predictors and outcomes of peritoneal dialysis-related infections due to filamentous molds (MycoPDICS)

Introduction

We sought to evaluate the predictors and outcomes of mold peritonitis in patients with peritoneal dialysis (PD).

Methods

This cohort study included PD patients from the MycoPDICS database who had fungal peritonitis between July 2015-June 2020. Patient outcomes were analyzed by Kaplan Meier curves and the Log-rank test. Multivariable Cox proportional hazards model regression was used to estimating associations between fungal types and patients’ outcomes.

Results

The study included 304 fungal peritonitis episodes (yeasts n = 129, hyaline molds n = 122, non-hyaline molds n = 44, and mixed fungi n = 9) in 303 patients. Fungal infections were common during the wet season (p <0.001). Mold peritonitis was significantly more frequent in patients with higher hemoglobin levels, presentations with catheter problems, and positive galactomannan (a fungal cell wall component) tests. Patient survival rates were lowest for non-hyaline mold peritonitis. A higher hazard of death was significantly associated with leaving the catheter in-situ (adjusted hazard ratio [HR] = 6.15, 95%confidence interval [CI]: 2.86–13.23) or delaying catheter removal after the diagnosis of fungal peritonitis (HR = 1.56, 95%CI: 1.00–2.44), as well as not receiving antifungal treatment (HR = 2.23, 95%CI: 1.25–4.01) or receiving it for less than 2 weeks (HR = 2.13, 95%CI: 1.33–3.43). Each additional day of antifungal therapy beyond the minimum 14-day duration was associated with a 2% lower risk of death (HR = 0.98, 95%CI: 0.95–0.999).

Conclusion

Non-hyaline-mold peritonitis had worse survival. Longer duration and higher daily dosage of antifungal treatment were associated with better survival. Deviations from the 2016 ISPD Peritonitis Guideline recommendations concerning treatment duration and catheter removal timing were independently associated with higher mortality.

Spiritual Well-Being and Its Relationship with Patient Characteristics and Other Patient-Reported Outcomes in Peritoneal Dialysis Patients: Findings from the PDOPPS

BACKGROUND

Spiritual well-being (SWB), an individual's understanding of the meaning and purpose of life, may help patients with chronic or terminal illnesses cope with their disease. This study aimed to assess SWB in patients on peritoneal dialysis (PD), as well as its relationship with patient characteristics and patient-reported outcomes (PRO).

METHODS

The data were obtained from questionnaires that formed part of the PD Outcomes and Practice Patterns Study (PDOPPS). Measures used in this study were SWB scores derived from the WHO Quality of Life, Spirituality, Religiousness, and Personal Beliefs (WHOQOL-SRPB) tool including 32 items from 8 facets; physical (PCS) and mental component summary (MCS) scores of the 12-Item Short-Form Health Survey (SF-12), Center of Epidemiologic Studies Depression Scale-10 (CES-D-10) scores, burden of kidney disease scores, and functional status scores.

RESULTS

Overall, 529 out of 848 participants (62%) completely responded to the questionnaires and were included in the analysis. Over two-thirds of PD patients (70%) had moderate or higher SWB scores. The SWB scores were significantly lower in patients with age > 65 years and unemployed status. SWB scores positively correlated with higher PCS, MCS, burden of kidney disease scores, and functional status scores, while negatively correlated with depression scores by CES-D-10 scale. Patients who reported significant depressive symptoms (CES-D-10 score ≥ 10) had significantly lower SWB scores.

CONCLUSION

Better SWB was significantly associated with better health-related QOL (HRQOL) and the absence of depressive symptoms. SWB may be an essential consideration in the delivery of high-quality PD.

Three-Dimensional Visualization of the Podocyte Actin Network Using Integrated Membrane Extraction, Electron Microscopy, and Machine Learning

BACKGROUND

Actin stress fibers are abundant in cultured cells, but little is known about them in vivo. In podocytes, much evidence suggests that mechanobiologic mechanisms underlie podocyte shape and adhesion in health and in injury, with structural changes to actin stress fibers potentially responsible for pathologic changes to cell morphology. However, this hypothesis is difficult to rigorously test in vivo due to challenges with visualization. A technology to image the actin cytoskeleton at high resolution is needed to better understand the role of structures such as actin stress fibers in podocytes.

METHODS

We developed the first visualization technique capable of resolving the three-dimensional cytoskeletal network in mouse podocytes in detail, while definitively identifying the proteins that comprise this network. This technique integrates membrane extraction, focused ion-beam scanning electron microscopy, and machine learning image segmentation.

RESULTS

Using isolated mouse glomeruli from healthy animals, we observed actin cables and intermediate filaments linking the interdigitated podocyte foot processes to newly described contractile actin structures, located at the periphery of the podocyte cell body. Actin cables within foot processes formed a continuous, mesh-like, electron-dense sheet that incorporated the slit diaphragms.

CONCLUSIONS

Our new technique revealed, for the first time, the detailed three-dimensional organization of actin networks in healthy podocytes. In addition to being consistent with the gel compression hypothesis, which posits that foot processes connected by slit diaphragms act together to counterbalance the hydrodynamic forces across the glomerular filtration barrier, our data provide insight into how podocytes respond to mechanical cues from their surrounding environment.

Protein-Bound Uremic Toxins Lowering Effect of Sevelamer in Pre-Dialysis Chronic Kidney Disease Patients with Hyperphosphatemia: A Randomized Controlled Trial

P-cresyl sulfate and indoxyl sulfate are strongly associated with cardiovascular events and all-cause mortality in chronic kidney disease (CKD). This randomized controlled trial was conducted to compare the effects between sevelamer and calcium carbonate on protein-bound uremic toxins in pre-dialysis CKD patients with hyperphosphatemia. Forty pre-dialysis CKD patients with persistent hyperphosphatemia were randomly assigned to receive either 2400 mg of sevelamer daily or 1500 mg of calcium carbonate daily for 24 weeks. A significant decrease of total serum p-cresyl sulfate was observed in sevelamer therapy compared to calcium carbonate therapy (mean difference between two groups −5.61 mg/L; 95% CI −11.01 to −0.27 mg/L; p = 0.04). There was no significant difference in serum indoxyl sulfate levels (p = 0.36). Sevelamer had effects in terms of lowering fibroblast growth factor 23 (p = 0.01) and low-density lipoprotein cholesterol levels (p = 0.04). Sevelamer showed benefits in terms of retarding CKD progression. Changes in vascular stiffness were not found in this study.

Implementation of PDOPPS in a middle-income country: Early lessons from Thailand

BACKGROUND

Despite the implementation of a 'Peritoneal Dialysis (PD) First' policy in Thailand since 2008, nationwide PD practices and patients' outcomes have rarely been reported.

METHODS

As part of the multinational PD Outcomes and Practice Patterns Study (PDOPPS), PD patients from 22 PD centres from different geographic regions, sizes and affiliations, representing Thailand PD facilities, have been enrolled starting in May 2016. Demographic, clinical and laboratory data and patients' outcomes were prospectively collected and analysed.

RESULTS

The pilot and implementation phases demonstrated excellent concordance between study data and validation data collected at enrolment. In the implementation phase, 848 PD patients (including 262 (31%) incident PD patients) were randomly sampled from 5090 patients in participating centres. Almost all participants (95%) performed continuous ambulatory PD (CAPD), and a high proportion had hypoalbuminemia (67%, serum albumin < 3.5 g/dL), anaemia (42%, haemoglobin <10 g/dL) and hypokalaemia (37%, serum potassium < 3.5 mmol/L). The peritonitis rate was 0.40 episodes/year, but the culture-negative rate was high (0.13 episodes/year, 28% of total episodes). The patients from PD clinics located in Bangkok metropolitan region had higher socio-economic status, more optimal nutritional markers, blood chemistries, haemoglobin level and lower peritonitis rates compared to the provincial regions, emphasizing the centre effect on key success factors in PD.

CONCLUSIONS

Participation in the PDOPPS helps unveil the critical barriers to improving outcomes of PD patients in Thailand, including a high prevalence of hypokalaemia, anaemia, poor nutritional status and culture-negative peritonitis. These factors should be acted upon to formulate solutions and implement quality improvement on a national level.

Barriers to and constraints of acute peritoneal dialysis in acute kidney injury: A nationwide survey

This national survey of barriers to and constraints of acute peritoneal dialysis (aPD) in acute kidney injury (AKI) was performed by distributing an online questionnaire to all medical directors of public dialysis units registered with the Nephrology Society of Thailand during September-November 2019. One hundred and thirteen adult facilities responded to the survey covering 75 from 76 provinces (99%) of Thailand. aPD was performed in 66 centres (58%). In facilities where aPD practice was available, the utilization rate was relatively low (<10 cases/year) and limited to specific conditions, including HIV seropositive patients, previous receiving dialysis education and plan and difficult vascular access creation. Only 9% of facilities performed aPD routinely, but interestingly all such units permitted bedside catheter insertion by the nephrologists or internists. The major constraints placed on aPD practice were PD catheter insertion competency, timely catheter insertion support and the medical supporting team's knowledge/competency deficits. aPD for AKI is underutilized in Thailand and limited by the inability to undertake timely PD catheter insertion and knowledge and competency deficits.

Association between self-reported appetite and clinical outcomes of peritoneal dialysis patients: Findings from a low middle-income country

AIM

Patient-reported outcome measures (PROM) has gained international recognition as important predictors of clinical outcomes in peritoneal dialysis (PD). We sought to understand the associations between patient-reported appetite and clinical outcomes.

METHODS

In the Thailand Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS), 690 of 848 randomly selected PD patients from 22 facilities reported their appetite by using the short form (three items) of the Appetite and Diet Assessment Tool (ADAT), between 2016 and 2018. In this questionnaire, the patients rated their appetite as well as a change in appetite over time. Cox proportional hazards model regression was used to estimating associations between self-reported appetite and clinical outcomes, including mortality, haemodialysis (HD) transfer and peritonitis.

RESULTS

Half of the PD patients reported a good appetite, whereas 34% and 16% reported fair and poor appetites, respectively. Poor appetite was more prevalent among female, diabetic, congestive heart failure, older age and patients who had worse nutritional indicators, including lower time-averaged serum albumin and serum creatinine concentrations, as well as a higher proportions of hypokalaemia and severe hypoalbuminemia (serum albumin <3 g/dl). After adjusting for age, sex, comorbidities, and PD vintage, poor appetite was associated with increased risks of peritonitis (adjusted hazard ratio [HR] 1.73, 95% confidence interval [CI] 1.14-2.62), HD transfer (adjusted HR 2.25, 95% CI 1.24-4.10) and all-cause mortality (adjusted HR 1.60, 95% CI 1.08-2.39) compared to patients with good appetite.

CONCLUSION

Patient-reported poor appetite was independently associated with higher risks of peritonitis, HD transfer and all-cause mortality. This warrants further investigation to identify effective interventions.

Association of Local Unit Sampling and Microbiology Laboratory Culture Practices With the Ability to Identify Causative Pathogens in Peritoneal Dialysis-Associated Peritonitis in Thailand

Introduction

This describes variations in facility peritoneal dialysis (PD) effluent (PDE) culture techniques and local microbiology laboratory practices, competencies, and quality assurance associated with peritonitis, with a specific emphasis on factors associated with culture-negative peritonitis (CNP).

Methods

Peritonitis data were prospectively collected from 22 Thai PD centers between May 2016 and October 2017 as part of the Peritoneal Dialysis Outcomes and Practice Patterns Study. The first cloudy PD bags from PD participants with suspected peritonitis were sent to local and central laboratories for comparison of pathogen identification. The associations between these characteristics and CNP were evaluated.

Results

CNP was significantly more frequent in local laboratories (38%) compared with paired PDE samples sent to the central laboratory (12%, P < 0.05). Marked variations were observed in PD center practices, particularly with respect to specimen collection and processing, which often deviated from International Society for Peritoneal Dialysis Guideline recommendations, and laboratory capacities, capabilities, and certification. Lower rates of CNP were associated with PD nurse specimen collection, centrifugation of PDE, immediate transfer of samples to the laboratory, larger hospital size, larger PD unit size, availability of an on-site nephrologist, higher laboratory capacity, and laboratory ability to perform aerobic cultures, undertake standard operating procedures in antimicrobial susceptibilities, and obtain local accreditation.

Conclusion

There were large variations in PD center and laboratory capacities, capabilities, and practices, which in turn were associated with the likelihood of culturing and correctly identifying organisms responsible for causing PD-associated peritonitis. Deviations in practice from International Society for Peritoneal Dialysis guideline recommendations were associated with higher CNP rates.

The culture from peritoneal dialysis catheter enhances yield of microorganism identification in peritoneal dialysis-related peritonitis

An additional yield of culture from the removed peritoneal dialysis (PD) catheter in diagnosis of pathogen causing refractory peritonitis was assessed in 118 eligible patients from 7 PD centers. Peritoneal dialysis fluid (PDF) culture identified organisms in 86 (72.9%) patients, while the catheter culture identified organisms in 55 (46.6%) patients. PD catheter culture could additionally identify organisms in 19 patients whose PDF culture were negative, increasing the positive culture rate to 89%, in other word 16.1% reducing the culture-negative rate. PD catheter culture provided additional yield, especially in fungal and enterococcal infections.

An early experience of Check List to Improve Patient Self-care and Product Defect Report in Continuous Ambulatory Peritoneal Dialysis (CLIP-SP) study

An increase in number of peritoneal dialysis patients and demand for peritoneal dialysis products following implementation of "PD First" policy in Thailand has led to logistics supply chain challenges and inherent product quality problems. Available evidences suggested that defective peritoneal dialysis products may predispose the patients to peritonitis. Thailand Clinical Practice Guideline for Peritoneal Dialysis 2017 recommends the patients to check peritoneal dialysis products themselves before use. In this report, we present our early experience from the Check List to Improve Patient Self-care and Product Defect Report in Continuous Ambulatory Peritoneal Dialysis study, a cluster randomized trial conducted in 22 peritoneal dialysis centers in Thailand. Patients from 11 randomly selected sites were asked to use the check list to report any product quality defects. The peritoneal dialysis product check list required patients to check the expiration date, glucose concentration, clarity, color, and integrity of bags of peritoneal dialysis fluid as well as the peritoneal dialysis connectors prior to each use. Among 338 patients who had received the check list from 5 centers, 28 returned the reports, detecting 8 defects out of 3960 products in total (0.2%). Although the obtained check list reports were not perfectly completed, they were comprehensible and provided important information on product defects which meant that the check list was simple enough for the patients and/or caregivers to follow. In conclusion, despite low response rate and incomplete report in this early phase analysis, the check list provides important information on product defects while an impact of these defects on peritoneal dialysis outcomes requires a further investigation.

Interferon-Inducible Protein 10 and Disease Activity in Systemic Lupus Erythematosus and Lupus Nephritis: A Systematic Review and Meta-Analysis

There is increasing evidence of a correlation between interferon-inducible protein 10 (IP-10) and disease activity of systemic lupus erythematosus (SLE) and lupus nephritis (LN). We conducted a comprehensive search on IP-10 using MEDLINE, Scopus, and Cochrane electronic databases from the beginning to the end of December 2017. All studies that compared serum and/or urine IP-10 between active SLE/LN patients and any control groups were identified and included in this systematic review and meta-analysis. The mean difference (MD) of IP-10 level among active SLE and LN patients, as well as the correlation of IP-10 with disease activity, were meta-analyzed using a random-effects model. From 23 eligible studies, 15 provided adequate data for meta-analysis. Serum IP-10 was significantly elevated in patients with active SLE compared to non-active SLE patients (MD 356.5 pg/mL, 95% CI 59.6 to 653.4, p = 0.019). On the other hand, the levels of serum IP-10 was not different between active LN and non-active LN. However, serum IP-10 was positively correlated with disease activity like SLE disease activity index (SLEDAI) (pooled r = 0.29, 95% CI 0.22 to 0.35, p < 0.001). Furthermore, urine IP-10 tended to be higher in patients with active LN compared to non-active LN patients but this did not reach statistical significance (MD 3.47 pg/mgCr × 100, 95% CI -0.18 to 7.12, p = 0.06). Nevertheless, urine IP-10 was positively correlated with renal SLEDAI (pooled r = 0.29, 95% CI 0.05 to 0.50, p = 0.019). In conclusion, serum and urine IP-10 levels may be useful in monitoring the disease activity of SLE and LN. Serum IP-10 was correlated with systemic disease whereas urine IP-10 was a useful biomarker for detecting active LN.

National feasibility survey of peritoneal dialysis key performance indicators in Thailand from provider perspective

BACKGROUND

Peritoneal dialysis (PD) has been the main method of renal replacement therapy under the "PD First" policy in Thailand since 2008. Initially, the proposed 13 key performance indicators (KPIs) raised feasibility concerns because of inequitable distribution of resources such as laboratory facilities and/or specialized health-care staff for PD care throughout the country.

METHODS

Data availability and goals from the health-care providers' perspective were explored using an online questionnaire survey for all PD centers registered with the Nephrology Society of Thailand from May to June 2016. The availability of essential data required for each KPI indicator to achieve the desired target was assessed using a 5-point Likert scale.

RESULTS

Of the 197 centers, 119 responded to the survey (response rate of 60.41%). PD indicators with a high percentage of strongly disagree or disagree were "PD adequacy measured in the last 12 months" (26.83%), "Total weekly Kt/V ≥ 1.7" (24.59%), "3-year PD technique survival" (21.31%), "Serum parathyroid levels within 150 to 500 pg/mL" (16.94%), and a "3-year PD patient survival" (19.01%). As many as 34.17%, 39.19%, 27.27%, 28.93%, and 22.00%, respectively, did not anticipate that the targets could be achieved. Based on the findings from this survey, the national committee concluded that these indicators be removed, and only eight PD indicators were launched.

CONCLUSION

Given the importance of KPIs for quality assurance and financial reimbursement, inputs from health-care providers especially data availability and achievement of targets should be considered to ensure feasibility before the final list of indicators are launched.

Intraperitoneal Cefepime Monotherapy Versus Combination Therapy of Cefazolin Plus Ceftazidime for Empirical Treatment of CAPD-Associated Peritonitis: A Multicenter, Open-Label, Noninferiority, Randomized, Controlled Trial

RATIONALE & OBJECTIVE

Compared to combination therapy, intraperitoneal (IP) cefepime monotherapy for continuous ambulatory peritoneal dialysis (CAPD)-associated peritonitis may provide potential benefits in lowering staff burden, shortening time-consuming antibiotic preparation, and reducing bag contamination risk. This study sought to evaluate whether cefepime monotherapy is noninferior to combination regimens.

STUDY DESIGN

Multicenter, open-label, noninferiority, randomized, controlled trial.

SETTING & PARTICIPANTS

Adult incident peritoneal dialysis (PD) patients with CAPD-associated peritonitis in 8 PD centers in Thailand.

INTERVENTIONS

Random assignment to either IP monotherapy of cefepime, 1g/d, or IP combination of cefazolin and ceftazidime, 1g/d, both given as continuous dosing.

OUTCOMES

Primary end point: resolution of peritonitis at day 10 (primary treatment response).

SECONDARY OUTCOMES

initial response (day 5), complete cure (relapse/recurrence-free response 28 days after treatment completion), relapsing/recurrent peritonitis, and death from any cause. Noninferiority would be confirmed for the primary outcome if the lower margin of the 1-sided 95% CI was not less than-10% for difference in the primary response rate. A 2-sided 90% CI was used to demonstrate the upper or lower border of the 1-sided 95% CI.

RESULTS

There were 144 eligible patients with CAPD-associated peritonitis, of whom 70 and 74 patients were in the monotherapy and combination-therapy groups, respectively. Baseline demographic and clinical characteristics were not different between the groups. The primary response was 82.6% in the monotherapy group and 81.1% in the combination-therapy group (treatment difference, 1.5%; 90% CI, -9.1% to 12.1%; P=0.04). There was no significant difference in the monotherapy group compared with the combination-therapy group in terms of initial response rate (65.7% vs 60.8%; treatment difference, 4.9%; 95% CI, -10.8% to 20.6%; P=0.5) and complete cure rate (80.0% vs 80.6%; treatment difference, -0.6%; 95% CI, -13.9% to 12.8%; P=0.7). Relapsing and recurrent peritonitis occurred in 4.6% and 4.6% of the monotherapy group and 4.2% and 5.6% of the combination-therapy group (P=0.9and P=0.8, respectively). There was nominally higher all-cause mortality in the monotherapy group (7.1% vs 2.7%; treatment difference, 4.4%; 95% CI, -2.6% to 11.5%), but this difference was not statistically significant (P = 0.2).

LIMITATION

Not double blind.

CONCLUSIONS

IP cefepime monotherapy was noninferior to conventional combination therapy for resolution of CAPD-associated peritonitis at day 10 and may be a reasonable alternative first-line treatment.

FUNDING

This study is supported by The Kidney Foundation of Thailand (R5879), Thailand; Rachadaphiseksompotch Fund (RA56/006) and Rachadaphicseksompotch Endorsement Fund (CU-GRS_61_06_30_01), Chulalongkorn University, Thailand; National Research Council of Thailand (156/2560), Thailand; and Thailand Research Foundation (IRG5780017), Thailand.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT02872038.

Intracatheter Antifungal Lock Leading to Detrimental Complications

As peritoneal dialysis (PD)-related fungal infection is associated with a high mortality rate, the international guidelines recommend immediate removal of the PD catheter in conjunction with at least 2-weeks of antifungal treatment. Some authors have reported successful management of such cases without removing the PD catheter - by instilling an antifungal lock into the retained PD catheter. However, the use of antifungal locks has generally not been well accepted as the standard treatment for fungal peritonitis in PD patients. We report two cases where antifungal lock were performed in PD patients presented with PD-related fungal infection that not only had no effect on abating the infection but also causing paradoxical outcomes.

Transcatheter Examination of the Peritoneal Dialysis Catheter with the SpyGlass Direct Visualization System: A New Aid in Diagnosis and Salvation of Ultrafiltration Failure from Partial Catheter Obstruction

Mechanical complications in peritoneal dialysis (PD), including intraluminal clogging of the PD catheter by fibrin, omentum, or blood clot, are major causes of outflow problems and, in rare cases, lead to technical failure. To visualize an intraluminal image of patients undergoing PD with ineffective ultrafiltration (UF), a SpyGlass fiber optic probe was inserted into the catheter, together with SpyBite biopsy forceps, should the removal of clogging materials be needed. Applying these transcatheter devices in 2 PD patients with unexplained UF failure led to the demonstration of omental plugging at the catheter tip in the first patient and demonstration of intraluminal blood clots in the second patient from whom clots were removal successfully. Both patients achieved better UF volume thereafter without procedure-related complications.