Biology subjects

Lehto, M.

Publications and source records attributed to Lehto, M..

4 recordsLinked to original sources

bioRxiv2025

Long-chain polyphosphates induce glomerular microthrombi and exacerbate LPS-induced acute kidney injury in mouse

Polyphosphates are evolutionarily conserved anionic polymers mediating pleiotropic functions in eukaryotes and prokaryotes, depending on their chain-length. Bacteria typically synthetize long-chains, while human platelets harbour exclusively medium-chains. Polyphosphate-mediated lung and liver-injury have been reported in experimental mouse models but their effects on the kidney remain undefined. Here we assessed kidney histopathology and cytokine levels following intravenous administration of medium-chain (P100) and long-chain (P700) polyphosphates and their synergistic effects with lipopolysaccharides (LPS) in mice. We found that P700 induced albuminuria, renal Kim-1 and Lcn2 transcription, focal renal damage with glomerular microthrombi, tubular degeneration, granular phenotype of slit diaphragm components nephrin and ZO1, and enlarged electron dense vesicles in podocyte cytoplasm indicating lysosome swelling. P700 combined with LPS induced marked multifocal acute tubular necrosis in the cortex, and augmented LPS-induced proinflammatory cytokine levels. No notable effects were seen with P100, indicating that PolyP-mediated kidney injury development is dependent on chain-length. We conclude that long-chain polyphosphates may play a procoagulant role behind kidney injury, by inducing microthrombi characteristic of thrombotic microangiopathy and augmenting cytokine levels under inflammatory conditions.

pathology↗

bioRxiv2025

Parsing glomerular and tubular structure variability in high-throughput kidney organoid culture

High variability in stem cell research is a well-known limiting phenomenon, with technical variation across experiments and laboratories often surpassing variation caused by genotypic effects of induced pluripotent stem cell (iPSC) lines. Evaluation of kidney organoid protocols and culture conditions across laboratories remains scarce in the literature. We used the original air-medium interface protocol to evaluate kidney organoid success rate and reproducibility with several human iPSC lines, including a novel patient-derived GRACILE syndrome iPSC line. Organoid morphology was assessed with light microscopy and immunofluorescence-stained maturing glomerular and tubular structures. The protocol was further adapted to four microplate-based high-throughput approaches utilizing spheroid culture steps. Quantitative high-content screening analysis of the nephrin-positive podocytes and ECAD-positive tubular cells revealed that the choice of approach and culture conditions were significantly associated with structure development. The culture approach, iPSC line, experimental replication, and initial cell number explained 35-77% of the variability in the logit-transformed proportion of nephrin and ECAD-positive area, when fitted into multiple linear models. Our study highlights the benefits of high-throughput culture and multivariate techniques to better distinguishing sources of technical and biological variation in morphological analysis of organoids. Our microplate-based high-throughput approach is easily adaptable for other laboratories to combat organoid size variability.

developmental biology↗

bioRxiv2025

Free acid β-hydroxybutyrate supplementation does not ameliorate dextran sodium sulfate-induced colitis similar to ketogenic diet in male mice

High-fat, low-carbohydrate ketogenic diets have been found to alleviate experimental colitis in rodents. These diets lead to increased endogenous production and utilization of ketone bodies, such as {beta}-hydroxybutyrate (BHB), and supplementation with exogenous ketones has arisen as a potential alternative to ketogenic diets. This study aimed to investigate how continuous high-dose feeding with free acid BHB influences experimental colitis compared to a ketogenic diet with the hypothesis that BHB would also alleviate the inflammation. We fed nine-week-old C57BL/6J male mice for four weeks with one of three diets: a low-fat control diet, a ketogenic diet, or a low-fat diet supplemented with free acid R-BHB and then induced colonic inflammation with dextran sodium sulfate (DSS). We assessed macroscopic and histological changes in the colon, intestinal permeability to fluorescein isothiocyanate dextran, colonic mRNA expression of tight junction proteins and inflammatory markers, fecal calprotectin, and microbiota composition. While the ketogenic diet alleviated DSS-induced weight loss, macroscopic changes, and histological lesions, the BHB-supplemented diet did not have the same effect. The pre-DSS composition of the microbiota was drastically different between the diet groups which may partly explain the different outcomes. In conclusion, high-dose supplementation with free acid BHB may not produce the same benefits as ketogenic diet in the context of colonic inflammation.

pharmacology and toxicology↗

bioRxiv2021

L-type calcium channel blocker increases VEGF concentrations in retinal cells and human serum

ObjectiveVascular endothelial growth factor (VEGF) plays a key role in diabetic retinopathy (DR). L-type calcium channel blockers (LTCCBs) have been widely used as antihypertensive medication (AHM), but their association with VEGF and DR is still unclear. Therefore, we explored the effect of LTCCBs compared to other AHMs on VEGF concentrations in retinal cells and human serum. Furthermore, we evaluated the association between the use of LTCCBs and the risk of severe diabetic eye disease (SDED). Research design and methodsMuller cells (MIO-M1) were cultured as per recommended protocol and treated with LTCCBs and other AHMs. VEGF secreted from cells were collected at 24 hours intervals. In an interventional study, 39 individuals received LTCCBs or other AHM for four weeks with a four-week wash-out placebo period between treatments. VEGF was measured during the medication and placebo periods. Finally, we evaluated the risk of SDED associated with LTCCB usage in 192 individuals from the FinnDiane Study in an oberservational setting. ResultsIn the cell cultures, medium VEGF concentration increased time-dependently after amlodipine (p<0.01) treatment, but not after losartan (p>0.01), or lisinopril (p>0.01). Amlodipine, but no other AHM, increased serum VEGF concentration (p<0.05) during the interventional clinical study. The usage of LTCCB was not associated with the risk of SDED in the observational study. ConclusionsLTCCB increases VEGF concentrations in retinal cells and human serum. However, the usage of LTCCBs does not appear to be associated with SDED in adults with type 1 diabetes.

pharmacology and toxicology↗