Transcriptome analysis supports viral infection and fluoride toxicity as contributors to chronic kidney disease of unknown etiology (CKDu) in Sri Lanka

PURPOSE

Chronic kidney disease of unknown etiology (CKDu), having epidemic characteristics, is being diagnosed increasingly in certain tropical regions of the world, mainly Latin America and Sri Lanka. They have been observed primarily in farming communities and current hypotheses point toward many environmental and occupational triggers. CKDu does not have common etiologies of chronic kidney disease (CKD) such as hypertension, diabetes, or autoimmune disease. We aimed to understand the molecular processes underlying CKDu in Sri Lanka using transcriptome analysis.

METHODS

RNA extracted from whole blood was reverse transcribed and used for microarray analysis using the Human HT-12 v.4 array (Illumina). Pathway analysis was carried out using ingenuity pathway analysis (IPA-Qiagen). Microarray results were validated using real-time PCR of five selected genes.

RESULTS

Pathways related to innate immune response, including interferon signaling, inflammasome signaling and TREM1 signaling had the most significant positive activation z scores, where as EIF2 signaling and mTOR signaling had the most significant negative activation z scores. Pathways previously linked to fluoride toxicity; G-protein activation, Cdc42 signaling, Rac signaling and RhoA signaling were activated in CKDu patients. The most significantly activated biological functions were cell death, cell movement and antimicrobial response. Significant toxicological functions were mitochondrial dysfunction, oxidative stress and apoptosis.

CONCLUSIONS

Based on the molecular pathway analysis in CKDu patients and review of literature, viral infections and fluoride toxicity appear to be contributing to the molecular mechanisms underlying CKDu.

Expanding CAPD in Low-Resource Settings: A Distance Learning Approach

BACKGROUND

Despite growing need, treatment for end-stage renal disease is limited in low- and middle-income countries due to resource restraints. We describe the development of an educational curriculum and quality improvement program to support continuous ambulatory peritoneal dialysis (CAPD) performed primarily by non-nephrology providers in Sri Lanka.

METHODS

We developed a program of education, outcome tracking, and expert consultation to support providers in Kandy, Sri Lanka. Education included videos and in-person didactics covering core topics in CAPD. Event-tracking sheets recorded root causes and management of infections and hospitalizations. Conferences reviewed clinical cases and overall clinic management. We evaluated the patient census, peritonitis rates, and root causes and management of infections over 1 year.

RESULTS

The curriculum was published through the International Society of Nephrology online academy. High provider turnover limited curriculum assessments. The CAPD patient census rose from 63 to 116 during the year. The peritonitis rate declined significantly, from 0.8 episodes per patient-year in the first 6 months to 0.4 in the latter 6 months, though the most common root causes of peritonitis, related to contamination events and hygiene, persisted. The appropriate ascertainment of culture data and prescription of antibiotics also increased.

CONCLUSIONS

Our project supported the expansion of a CAPD program in a resource-limited setting, while also improving peritonitis outcomes. Ongoing challenges include ensuring a durable educational system for rotating providers, tracking outcomes beyond peritonitis, and formalizing management protocols. Our program can serve as an example of how established dialysis programs can support the burgeoning work of providers in resource-limited setting.

Potential diagnostic biomarkers for chronic kidney disease of unknown etiology (CKDu) in Sri Lanka: a pilot study

Background

In Sri Lanka, there exists chronic kidney disease of both known (CKD) and unknown etiologies (CKDu). Identification of novel biomarkers that are customized to the specific causative factors would lead to early diagnosis and clearer prognosis of the diseases. This study aimed to find genetic biomarkers in blood to distinguish and identify CKDu from CKD as well as healthy populations from CKDu endemic and non-endemic areas of Sri Lanka.

Methods

The expression patterns of a selected panel of 12 potential genetic biomarkers were analyzed in blood using RT-qPCR. Fold changes of gene expressions in early and late stages of CKD and CKDu patients, and an apparently healthy population of a CKDu endemic area, Girandurukotte (GH) were calculated relative to apparently healthy volunteers from a CKDu non-endemic area, Kandy (KH) of Sri Lanka, using the comparative CT method.

Results

Significant differences were observed between KH and early stage CKDu for both the insulin-like growth factor binding protein 1 (IGFBP1; p = 0.012) and kidney injury molecule-1 (KIM1; p = 0.003) genes, and KH and late stage CKD and CKDu for the glutathione-S-transferase mu 1 (GSTM1; p < 0.05) gene. IGFBP1 and KIM1 genes showed significant difference between the early and late stage CKDu (p < 0.01). The glutamate cysteine ligase catalytic subunit (GCLC) gene had significantly different expression between KH and all the other study groups (p < 0.01). The GH group was significantly different from the KH group for the oxidative stress related genes, G6PD, GCLC and GSTM1 (p < 0.01), and also the KIM1 gene (p = 0.003). IGFBP1, insulin-like growth factor binding protein 3 (IGFBP3), fibronectin 1 (FN1) and KIM1 showed significant correlations with serum creatinine, and IGFBP1, KIM1 and kallikrein 1 (KLK1) with eGFR (p < 0.05).

Conclusion

A panel consisting of IGFBP1, KIM1, GCLC and GSTM1 genes could be used in combination for early screening of CKDu, whereas these genes in addition with FN1, IGFBP3 and KLK1 could be used to monitor progression of CKDu. The regulation of these genes has to be studied on larger populations to validate their efficiency for further clinical use.