Marina I. Buyan

We explored the possibility of antioxidant and antifibrotic effects of panthenol (PL) associated with modulation of coenzyme A (CoA) biosynthesis in the liver in a rat model of chronic obstructive cholestasis induced by bile duct ligation (BDL). We found that PL increased alcohol dehydrogenase (ADH) activity in the liver of BDL rats. PL and its analog pantethine increased pantothenate kinase (PANK) activity, restored hepatic CoA levels reduced by BDL, lowered protein-bound CoA, and normalized impaired mitochondrial functions associated with induced oxidative stress after BDL. These effects were accompanied by decreased collagen deposition and improved morphological features of hepatocytes. In contrast, PANK inhibitor, hopantenic acid (HPA), reduced hepatic CoA levels, aggravated hepatocellular damage, and promoted fibrosis. In the human hepatic stellate cell line LX-2, PL exhibited no cytotoxicity over a wide concentration range, increased intracellular CoA levels, decreased reactive oxygen species (ROS) production, and attenuated collagen accumulation associated with oxidative stress in vitro. Importantly, inhibition of ADH by 4-methylpyrazole completely abolished the protective effects of panthenol, indicating that its activity depends on metabolic pathways involving CoA. Notably, PL did not directly reduce H₂O₂ or superoxide anion radical production in cell-free systems but significantly suppressed lipid peroxidation in liposomes and red blood cells in vitro. Ultimately, these findings indicate that the antioxidant and antifibrotic effects of PL are associated with modulation of CoA metabolism and enhanced resistance of biological membranes to oxidative damage.

Drug-induced nephrotoxicity is a leading cause of acute kidney injury (AKI) and subsequent chronic kidney disease. Nephrotoxicity often develops as a consequence of treatment with commonly prescribed aminoglycoside antibiotics, and remains a significant clinical challenge. One approach to treating AKI and its associated complications is caloric restriction or its pharmacological mimetics. This study aimed to evaluate the effects of caloric restriction mimetic hydroxycitrate (HC) in gentamicin-induced nephrotoxicity, with particular focus on the influence of treatment duration and the underlying molecular mechanisms. In vitro renal tubular epithelial cells models were used to assess HC’s effects on viability, proliferation, and autophagy activation. For in vivo validation, rats with gentamicin-induced AKI received HC treatment via two distinct regimens (3-week and 7-week administration). Experiments on renal tubule cells showed that HC significantly increased cell viability and proliferation and led to the activation of autophagy. In the rat model, only the 7-week administration of HC demonstrated significantly attenuated renal dysfunction in gentamicin-induced AKI. Moreover, it reduced macrophage infiltration, increased renal cell tolerance to apoptosis, activated autophagy, and reduced oxidative stress. Thus, our results indicate that 7-week HC administration could be used as a prophylactic strategy against antibiotic nephrotoxicity, exerting its effects by promoting autophagy, resisting apoptosis, and attenuating oxidative damage.

In this study, in a culture of renal epithelial cells, we identified those expressing nestin, a cytoskeletal protein associated with stem/progenitor/activated/proliferating cell states. A mouse expressing GFP under the nestin promoter was used, followed by cell isolation and culture. It is hypothesized that this can be used to assess the stem/progenitor/activated/proliferating cell level in a mixed kidney cell culture. Both nestin-positive and nestin-negative cells were demonstrated to be present in the culture. After visualization, cells were attached to a glass slide with a grid, fixed, and prepared for electron microscopy analysis, with each cell visually identified by light microscopy being analyzed. Electron microscopy revealed tight interactions between nestin-positive and nestin-negative cells. Significant differences in the ultrastructure of nestin-positive and nestin-negative cells were observed. Nestin-positive cells were distinguished by a high ribosome content, indicating high protein-synthesizing activity. In the nestin–GFP-high (sorted) population examined by electron microscopy, vesicle-containing protrusions were frequently observed. These cells could contain multiple nuclei of varying sizes and had a high content of lysosomes. No significant differences in mitochondrial ultrastructure were observed in nestin-positive and -negative cells, although functional characteristics evaluated by the membrane potential probe differed.

Severe injuries and some pathologies associated with massive bleeding, such as maternal hemorrhage, gastrointestinal and perioperative bleeding, and rupture of an aneurysm, often lead to major blood loss and the development of hemorrhagic shock. A sharp decrease in circulating blood volume triggers a vicious cycle of vasoconstriction and coagulopathy leading to ischemia of all internal organs and, in severe decompensated states, ischemia of the brain and heart. The basis of tissue damage and dysfunction in hemorrhagic shock is an interruption in the supply of oxygen and substrates for energy production to the cells, making the mitochondria a source and target of oxidative stress and proapoptotic signaling. Based on these mechanisms, different strategies are proposed to treat the multiple organ failure that occurs in shock. The main direction of such treatment is to provide the cells with a sufficient amount of substrates that utilize oxidative phosphorylation at different stages and increase the efficiency of energy production by the mitochondria. These strategies include restoring the efficiency of mitochondrial complexes, for example, by restoring the nicotinamide adenine dinucleotide (NAD) pool. Another direction is approaches to minimize oxidative stress as well as apoptosis, which are primarily dependent on the mitochondria. There are also a number of other methods to reduce mitochondrial dysfunction and improve the quality of the mitochondrial population. In this review, we consider such strategies for the treatment of hemorrhagic shock and show the promise of therapeutic approaches aimed at restoring the bioenergetic functions of the cell and protecting mitochondria.

The positive effects of female sex hormones, particularly estradiol and progesterone, have been observed in treatment of various pathologies. Acute kidney injury (AKI) is a common condition in hospitalized patients in which the molecular mechanisms of hormone action are poorly characterized. In this study, we investigated the influence of estradiol and progesterone on renal cells during ischemic injury. We performed both in vivo experiments on female and male rats and in vitro experiments on renal tubular cells (RTCs) obtained from the kidneys of intact animals of different sexes. Since mitochondria play an important role in the pathogenesis of AKI, we analyzed the properties of individual mitochondria in renal cells, including the area, roundness, mitochondrial membrane potential, and mitochondrial permeability transition pore (mPTP) opening time. We found that pre-treatment with progesterone or estradiol attenuated the severity of ischemia/reperfusion (I/R)-induced AKI in female rats, whereas in male rats, these hormones exacerbated renal dysfunction. We demonstrated that the mPTP opening time was higher in RTCs from female rats than that in those from male rats, which may be one of the reasons for the higher tolerance of females to ischemic injury. In RTCs from the kidneys of male rats, progesterone caused mitochondrial fragmentation, which can be associated with reduced cell viability. Thus, therapy with progesterone or estradiol displays quite different effects depending on sex, and could be only effective against ischemic AKI in females.

Many organs undergo negative changes during aging that affect their functions and ability to regenerate. In particular, the kidneys become more susceptible to acute injury and are more likely to develop chronic kidney disease with age. One of the reasons for this may be a decrease in the number of resident renal progenitor cells. This review addresses age-related changes that occur in the kidneys at the histological and molecular levels, including those related to the cell cycle, mitochondrial function, oxidative stress, and chronic inflammation. We described the available studies on resident renal stem cells, their niches, morphology, possible markers, and the dynamics of their numbers during the aging process. The reasons for the age-related decline in renal regenerative potential are considered based on molecular and cellular mechanisms.

A kidney is an organ with relatively low basal cellular regenerative potential. However, renal cells have a pronounced ability to proliferate after injury, which undermines that the kidney cells are able to regenerate under induced conditions. The majority of studies explain yielded regeneration either by the dedifferentiation of the mature tubular epithelium or by the presence of a resident pool of progenitor cells in the kidney tissue. Whether cells responsible for the regeneration of the kidney initially have progenitor properties or if they obtain a “progenitor phenotype” during dedifferentiation after an injury, still stays the open question. The major stumbling block in resolving the issue is the lack of specific methods for distinguishing between dedifferentiated cells and resident progenitor cells. Transgenic animals, single-cell transcriptomics, and other recent approaches could be powerful tools to solve this problem. This review examines the main mechanisms of kidney regeneration: dedifferentiation of epithelial cells and activation of progenitor cells with special attention to potential niches of kidney progenitor cells. We attempted to give a detailed description of the most controversial topics in this field and ways to resolve these issues.