A Combination of Kidney Ischemia and Injection of Isolated Mitochondria Leads to Activation of Inflammation and Increase in Mortality Rate in Rats.

We studied the development of acute kidney injury and animal death in the model of combined injury caused by kidney ischemia/reperfusion with simultaneous systemic administration of mitochondria. It was found that intraperitoneal injection of isolated mitochondria led to the appearance of mitochondrial DNA in the peripheral blood that could activate innate immunity. After administration of mitochondria, as well as after renal ischemia/reperfusion, proinflammatory changes were observed, primarily leukocytosis and granulocytosis. The combination of ischemia/reperfusion with injection of mitochondria caused a sharp increase in animal death, which may indicate a direct link between activation of TLR-signaling and high mortality of patients with combined injuries and multiple-organ failure in intensive care units. Treatment with mitochondria-targeted antioxidant increased animal survival, which indicated the participation of mitochondrial ROS in the development of systemic inflammatory response and death caused by acute renal failure.

Nonphosphorylating Oxidation in Mitochondria and Related Processes.

The mechanism of oxidative phosphorylation and its regulation remain one of the main problems of bioenergetics. Efficiency of the mitochondrial energization is determined by the relationship between the rate of generation of electrochemical potential of hydrogen ions and the rate of its expenditure on the synthesis of ATP and the use of ATP in endergonic reactions. Uncoupling (partial or complete), which occurs in the process of uncontrolled and controlled leakage of ions through the inner mitochondrial membrane, on the one hand leads to the decrease in the relative synthesis of ATP, and on the other, being consistent with the law of conservation of energy, leads to the formation of heat, generation of which is an essential function of the organism. In addition to increased thermogenesis, the increase of non-phosphorylating oxidation of various substrates is accompanied by the decrease in transmembrane potential, production of reactive oxygen species, and activation of oxygen consumption, water and carbon dioxide production, increase in the level of intracellular ADP and acidification of the cytosol. In this analysis, each of these factors will be considered separately for its role in regulating metabolism.

Comparative Study of the Severity of Renal Damage in Newborn and Adult Rats under Conditions of Ischemia/Reperfusion and Endotoxin Administration.

Oxidative kidney injury was compared in newborn and adult rats under conditions of ischemia/reperfusion and in experimental model of systemic inflammation induced by endotoxin (LPS of bacterial cell wall) administration. Oxidative stress in the kidney accompanied both experimental models, but despite similar oxidative tissue damage, kidney dysfunction in neonates was less pronounced than in adult animals. It was found that neonatal kidney has a more potent regenerative potential with higher level of cell proliferation than adult kidney, where the level proliferating cell antigen (PCNA) increased only on day 2 after ischemia/reperfusion. The pathological process in the neonatal kidney developed against the background of active cell proliferation, and, as a result, proliferating cells could almost immediately replace the damaged structures. In the adult kidney, regeneration of the renal tissue was activated only after significant loss of functional nephrons and impairment of renal function.

Bacterial Therapy and Mitochondrial Therapy.

Current methods for treatment of cellular and organ pathologies are extremely diverse and constantly evolving, going beyond the use of drugs, based on chemical interaction with biological targets to normalize the functions of the system. Because pharmacological approaches are often untenable, recent strategies in the therapy of different pathological conditions are of particular interest through introducing into the organism of some living system or its components, in particular, bacteria or isolated subcellular structures such as mitochondria. This review describes the most interesting and original examples of therapy using bacteria and mitochondria, which in perspective can dramatically change our views on the principles for the treatment of many diseases. Thus, we analyze such therapeutic effects from the perspective of the similarities between mitochondria and bacteria as the evolutionary ancestors of mitochondria.

Do Mitochondria Have an Immune System?

The question if mitochondria have some kind of immune system is not trivial. The basis for raising this question is the fact that bacteria, which are progenitors of mitochondria, do have an immune system. The CRISPR system in bacteria based on the principle of RNA interference serves as an organized mechanism for destroying alien nucleic acids, primarily those of viral origin. We have shown that mitochondria are also a target for viral attacks, probably due to a related organization of genomes in these organelles and bacteria. Bioinformatic analysis performed in this study has not given a clear answer if there is a CRISPR-like immune system in mitochondria. However, this does not preclude the possibility of mitochondrial immunity that can be difficult to decipher or that is based on some principles other than those of CRISPR.

QUANTIFICATION OF MITOCHONDRIAL MORPHOLOGY IN SITU.

Structural organization of mitochondria reflects their functional status and largely is an index of the cell viability. The indirect parameter to assess the functional state of mitochondria and cells is the degree of fragmentation, i. e. a ratio of long or branched mitochondrial structures to rounded mitochondria. The critical need for such evaluations requires the creation of an approach, that allows on the basis of confocal images of mitochondria stained with a fluorescent probe, to create an integral picture of the three-dimensional organization of mitochondria. In the present study, we tested three approaches to analyze the structural architecture of mitochondria under norm and fission induced by oxidative stress. We have revealed that while the most informative way of analysis is a three-dimensional reconstruction based on series of confocal images taken in Z-dimension, however, with some limitations it is plausible to use more simple algorithms of analysis, including that one that uses unitary two-dimensional images. Further improvement of these methods of image analysis will allow more comprehensive analysis of mitochondrial architecture under norm and different pathological states. It may also provide quantification of a number of mitochondrial parameters determining morpho-functional state of mitochondria primarily their absolute and relative volumes and give additional information on three-dimensional organization of mitochondriome.

Diseases and Aging: Gender Matters.

At first glance, biological differences between male and female sex seem obvious, but, in fact, they affect a vast number of deeper levels apart from reproductive function and related physiological features. Such differences affect all organizational levels including features of cell physiology and even functioning of separate organelles, which, among other things, account for such global processes as resistance to diseases and aging. Understanding of mechanisms underlying resistance of one of the sexes to pathological processes and aging will allow taking into consideration gender differences while developing drugs and therapeutic approaches, and it will provide an opportunity to reproduce and enhance such resistance in the more vulnerable gender. Here we review physiological as well as cellular and biological features of disease course including aging that are affected by gender and discuss potential mechanisms behind these processes. Such mechanisms include features of oxidative metabolism and mitochondrial functioning.

Mitodiversity.

Here, in addition to the previously coined term "mitobiota", we introduce the term "mitodiversity" for various phenotypic and genetic heterogeneities of mitochondria within the same cell or organ. Based on data on the mitochondrial transmembrane potential determined both in situ and in vitro under normal conditions and after organ ischemia/reperfusion, such heterogeneity is most evident under pathologic conditions. Herein, a part of the mitochondrial population with transmembrane potential typical of the normal state is sustained even under a pathological condition that, perhaps, underlies the development of ways of reversing pathology back to the normal state. The membrane potentials of isolated mitochondria were shown to directly correlate with the magnitude of side-scattered light depicting internal structure of mitochondria. We analyzed possible interpretations of data on mitochondrial membrane potential obtained using fluorescent probes. We suggest a possible mechanism underlying retention of fluorescent probes inside the cells and mitochondria.

Microbiota and mitobiota. Putting an equal sign between mitochondria and bacteria.

The recent revival of old theories and setting them on modern scientific rails to a large extent are also relevant to mitochondrial science. Given the widespread belief that mitochondria are symbionts of ancient bacterial origin, the processes inherent to mitochondrial physiology can be revised based on their comparative analysis with possible involvement of bacteria. Such comparison combined with discussion of the role of microbiota in pathogenesis allows discussion of the role of "mitobiota" (we introduce this term) as the combination of different phenotypic manifestations of mitochondria in the organism reflecting pathological changes in the mitochondrial genome. When putting an equal sign between mitochondria and bacteria, we find similarity between the mitochondrial and bacterial theories of cancer. The presence of the term "bacterial infection" suggests "mitochondrial infection", and mitochondrial (oxidative) theory of aging can in some way be transformed into a "bacterial theory of aging". The possible existence of such processes and the data confirming their presence are discussed in this review. If such a comparison has the right to exist, the homeostasis of "mitobiota" is of not lesser physiological importance than homeostasis of microbiota, which has been so intensively discussed recently.

Lithium salts -- simple but magic.

For many decades pharmacological drugs based on lithium salts have been successfully used in psychiatry to treat bipolar disorder, and they remain the "gold standard" of pharmacological therapy of patients with this disease. At the same time, over recent years in experiments in vitro and in vivo a plethora of evidence has accumulated on a positive effect of lithium ions in other areas including their neuro-, cardio-, and nephroprotective properties, regulation of stem cells functions, regulation of inflammation, and others. Numerous studies have shown that the effect of lithium ions involves several mechanisms; however, one of its main targets in the implementation of most of the effects is glycogen synthase kinase 3ß, a key enzyme in various pathological and protective signaling pathways in cells. However, one of the main limitations of the use of lithium salts in clinics is their narrow therapeutic window, and the risk of toxic side effects. This review presents the diversity of effects of lithium ions on the organism emphasizing their potential clinical applications with minimal undesirable side effects. In the end, we present a schematic "Lithiometer", comparing the range of Li(+) concentrations that might be used for the treatment of acute pathologies with possible toxic effects of Li(+).

Perspectives of mitochondrial medicine.

Mitochondrial medicine was established more than 50 years ago after discovery of the very first pathology caused by impaired mitochondria. Since then, more than 100 mitochondrial pathologies have been discovered. However, the number may be significantly higher if we interpret the term "mitochondrial medicine" more widely and include in these pathologies not only those determined by the genetic apparatus of the nucleus and mitochondria, but also acquired mitochondrial defects of non-genetic nature. Now the main problems of mitochondriology arise from methodology, this being due to studies of mitochondrial activities under different models and conditions that are far from the functioning of mitochondria in a cell, organ, or organism. Controversial behavior of mitochondria ("friends and foes") to some extent might be explained by their bacterial origin with possible preservation of "egoistic" features peculiar to bacteria. Apparently, for normal mitochondrial functioning it is essential to maintain homeostasis of a number of mitochondrial elements such as mitochondrial DNA structure, membrane potential, and the system of mitochondrial quality control. Abrogation of these elements can cause a number of pathologies that have become subjects of mitochondrial medicine. Some approaches to therapy of mitochondrial pathologies are discussed.

The phenoptosis problem: what is causing the death of an organism? Lessons from acute kidney injury.

Programmed execution of various cells and intracellular structures is hypothesized to be not the only example of elimination of biological systems - the general mechanism can also involve programmed execution of organs and organisms. Modern rating of programmed cell death mechanisms includes 13 mechanistic types. As for some types, the mechanism of actuation and manifestation of cell execution has been basically elucidated, while the causes and intermediate steps of the process of fatal failure of organs and organisms remain unknown. The analysis of deaths resulting from a sudden heart arrest or multiple organ failure and other acute and chronic pathologies leads to the conclusion of a special role of mitochondria and oxidative stress activating the immune system. Possible mechanisms of mitochondria-mediated induction of the signaling cascades involved in organ failure and death of the organism are discussed. These mechanisms include generation of reactive oxygen species and damage-associated molecular patterns in mitochondria. Some examples of renal failure-induced deaths are presented with mechanisms and settings determined by some hypothetical super system rather than by the kidneys themselves. This system plays the key role in the process of physiological senescence and termination of an organism. The facts presented suggest that it is the immune system involved in mitochondrial signaling that can act as the system responsible for the organism's death.

[Low-molecular weight inhibitors of bacterial DNA-dependent RNA polymerase].

In this review, current data on low molecular weight inhibitors of bacterial RNA polymerases, both classical and those recently discovered, are summarised. This area has progressed rapidly in recent years largely due to availability of high-resolution structures of RNA polymerase and its complexes with inhibitors. The structural information, together with biochemical data, allows to understand molecular mechanisms of transcription inhibition by rifampicin, sorangicin, tagetitoxin, streptolydigin, and microcin J25. In its turn, the mechanistic understanding of the action of these inhibitors provides better understanding of transcription mechanism and RNA polymerase structure-function.