Regulation Of Tissue Metabolism Research Articles

Effect of <i>Bifidobacterium bifidum</i> supernatant on the morphological and functional characteristics of human fibroblasts in real time during an <i>in vitro</i> experiment

Currently, there is an active search for exogenous stimulators of repair and regeneration processes. In the recent decades, some data on the immunotropic activity of bifidobacteria have been accumulated. The key role in healing of wound defects belongs to fibroblasts due to the secretion of the extracellular matrix components, metabolites, signal factors for the surrounding cells, and tissue metabolism regulation. The paper presents the results of the study of the effect of Bifidobacterium bifidum supernatant (10 ml/mL) on the morphological and functional properties of human fibroblasts in real time during the in vitro experiment. In our work, we used the reference strain B. bifidum 791 (All-Russian Collection of Industrial Microorganisms of the State Research Institute for Genetics and Selection of Industrial Microorganisms “Genetika”, Deposit No. AS-1247) used in the production of the probiotic product “Bifidumbacterin” (ZAO “Ecopolis”, the city of Kovrov), and adult human fibroblasts (cell line LECH-4 (81)) (laboratory of cell cultures ENIIVI, the city of Yekaterinburg). Structural and functional studies were conducted on co-culture days 1, 3, 7, 14, 21, and 28. The products of B. bifidum secondary metabolism have a stressful effect on the morphological and functional state of fibroblasts on the first day. The processes of proliferation are stimulated in the culture in the experiment (2.67±0.24) compared with the control group (0.75±0.15) (p < 0.01) without blocking apoptosis in the cell. This leads to the increase in the production of extracellular matrix proteins, both collagen (pg/mL) (400±19 against 110±25 in the control group), and elastin (ng/mL) 395±30 and 125±29). Co-culture of fibroblasts within 24 hours in the experimental sample leads to a massive “release” of the CD44 receptor (p < 0.05), compared to the control group which is confirmed by phenotypic changes (r = 0.66). The decrease of CD105+, CD44+ receptors (p < 0.05), compared with the control group and the increase of CD29+ expression (p < 0.05) is observed on days 1 and 3. Activated fibroblasts have an altered secretory phenotype that produces cytokines of various types such as TGF-b (r = 0.78), IL-6 (r = 0.57), IL-1b (r = 0.75), IL-8 (r = 0.63). The maximum adaptation of cells in the experimental system is registered on the 7th day, which correlates with morphometric (r = 0.59) and cytometric (r = 0.71) studies. The received data contribute to understanding of the mechanisms of the immunoregulatory influence of normal biota (in the bifidobacteria model) on the repair and regeneration processes.

Inhibition of histone lysine demethylase 6A promotes chondrocytic activity and attenuates osteoarthritis development through repressing H3K27me3 enhancement of Wnt10a.

Histone hypermethylation represses gene transcription, which affects cartilage homeostasis or joint remodeling. Trimethylation of lysine 27 of histone 3 (H3K27me3) changes epigenome signatures, regulating tissue metabolism. This study aimed to investigate whether loss of H3K27me3 demethylase Kdm6a function affected osteoarthritis development. We revealed that chondrocyte-specific Kdm6a knockout mice developed relatively long femurs and tibiae as compared to wild-type mice. Kdm6a deletion mitigated osteoarthritis symptoms, including articular cartilage loss, osteophyte formation, subchondral trabecular bone loss, and irregular walking patterns of destabilized medial meniscus-injured knees. In vitro, loss of Kdm6a function compromised the loss in expression of key chondrocyte markers Sox9, collagen II, and aggrecan and improved glycosaminoglycan production in inflamed chondrocytes. RNA sequencing showed that Kdm6a loss changed transcriptomic profiles, which contributed to histone signaling, NADPH oxidase, Wnt signaling, extracellular matrix, and cartilage development in articular cartilage. Chromatin immunoprecipitation sequencing uncovered that Kdm6a knockout affected H3K27me3 binding epigenome, repressing Wnt10a and Fzd10 transcription. Wnt10a was, among others, functional molecules regulated by Kdm6a. Forced Wnt10a expression attenuated Kdm6a deletion-induced glycosaminoglycan overproduction. Intra-articular administration with Kdm6a inhibitor GSK-J4 attenuated articular cartilage erosion, synovitis, and osteophyte formation, improving gait profiles of injured joints. In conclusion, Kdm6a loss promoted transcriptomic landscapes contributing to extracellular matrix synthesis and compromised epigenetic H3K27me3-mediated promotion of Wnt10a signaling, preserving chondrocytic activity to attenuate osteoarthritic degeneration. We highlighted the chondroprotective effects of Kdm6a inhibitor for mitigating the development of osteoarthritic disorders.

Direct Interaction of Mitochondrial Cytochrome c Oxidase with Thyroid Hormones: Evidence for Two Binding Sites.

Thyroid hormones regulate tissue metabolism to establish an energy balance in the cell, in particular, by affecting oxidative phosphorylation. Their long-term impact is mainly associated with changes in gene expression, while the short-term effects may differ in their mechanisms. Our work was devoted to studying the short-term effects of hormones T2, T3 and T4 on mitochondrial cytochrome c oxidase (CcO) mediated by direct contact with the enzyme. The data obtained indicate the existence of two separate sites of CcO interaction with thyroid hormones, differing in their location, affinity and specificity to hormone binding. First, we show that T3 and T4 but not T2 inhibit the oxidase activity of CcO in solution and on membrane preparations with Ki ≈ 100–200 μM. In solution, T3 and T4 compete in a 1:1 ratio with the detergent dodecyl-maltoside to bind to the enzyme. The peroxidase and catalase partial activities of CcO are not sensitive to hormones, but electron transfer from heme a to the oxidized binuclear center is affected. We believe that T3 and T4 could be ligands of the bile acid-binding site found in the 3D structure of CcO by Ferguson-Miller’s group, and hormone-induced inhibition is associated with dysfunction of the K-proton channel. A possible role of this interaction in the physiological regulation of the enzyme is discussed. Second, we find that T2, T3, and T4 inhibit superoxide generation by oxidized CcO in the presence of excess H2O2. Inhibition is characterized by Ki values of 0.3–5 μM and apparently affects the formation of O2●− at the protein surface. The second binding site for thyroid hormones presumably coincides with the point of tight T2 binding on the Va subunit described in the literature.

Immunolocalization of the complement component C1q in the mucous membrane of the human duodenum (duodenitis II-III degree)

In order to establish the supposed role of the complement system in the regulation of homeostasis and defense reactions in the intestinal epithelium, an immunofluorescent analysis was conducted of localizing the C1q complement component in the inflamed mucosa of the human duodenum (DM) (duodenitis II-III degree) using C1q-specific antibodies. The findings suggest a pronounced presence of the C1q complement component in various DM areas during inflammation, both in the epithelial layer and in the lamina propria, where C1q is localized in the region of the basolateral membrane of enterocytes and some free cells, presumably neutrophils, macrophages and mast cells. A C1q-specific reaction in the epithelial cells and secretory ducts of the duodenal glands indicates a possible secretion of C1q. Co-localization of C1q, cathepsin G and cell adhesion proteins in the DM epithelium implies their interaction in the regulation of tissue metabolism, modification and maintenance of the barrier properties of the intestinal epithelium in normal and with inflammation.

Vascularisation in regenerative therapeutics and surgery.

Vascularisation is often deemed the holy grail of tissue engineering because it is one of the key preconditions that determine the in vivo viability of tissue constructs. Given that a well-developed vascular network allows greater complexity in tissue design and helps regulate tissue metabolism, it appears that the overall outcome of engineered tissue implants depends on the success of microvessel formation, maturation and patterning. Current approaches to vascularising tissue include both in vivo and ex vivo techniques, where blood vessel formation is either spontaneous or guided by physical or biochemical factors. The success of these strategies can then be monitored and evaluated for clinical benefit through numerous standard and novel strategies. Despite the impressive progress in the field of tissue engineering in recent times, there are still numerous technical, immunological, surgical and ethical challenges to overcome. Future prospects in this field are likely to depend on the adoption of a wide-ranging approach incorporating a combination of salient themes such as genetic manipulation, modular assembly and bioreactor coupling. Where applicable, the potential contributions of nanobiotechnology to tissue vascularisation will be discussed as appropriate.

Estrogen-associated regulation of the bone tissue remodeling

The important role of an estrogen in a bone tissue metabolism regulation is proved. Irrefutable evidence of estrogen direct influence on bone tissue cell function through estrogen receptors is obtained. As a result of estrogen linking with the receptors, an estrogen is capable to activate tens of genes in osteoblasts and osteoclasts. The result of foregoing is the increase of osteoblasts and osteocytes functional activity, and also increase of the osteoclasts apoptosis and the osteoclastogenesis inhibition. Finally, these properties of the estrogen predetermine their protective role against the bone resorption.

Sex-related differences of morphometric, densitometric, and geometric parameters of tibia and tarsometatarsal bone in 14-month-old ostriches (Struthio camelus)

The aim of the current study was to investigate basic morphometric, geometric, and densitometric parameters of tibia and tarsometatarsus in 14-mo-old male and female ostriches, and interrelationships between these parameters. The study was conducted on 20 tibiae and 20 tarsometatarsal bones of the left pelvic limb derived from 20 healthy 14-mo-old ostriches (Struthio camelus): 10 males and 10 females. The following parameters were determined using peripheral quantitative computed tomography: bone mineral content (BMC), volumetric bone mineral density (vBMD), cortical content (CRT_CNT), cortical density (CRT_DEN), trabecular content, trabecular density (TRAB_DEN), bone area (TOT_A), trabecular area (TRAB_A), cortical area (CRT_A), cortical thickness (CRT_THK_C), periosteal circumference (PERI_C), endocortical circumference (ENDO_C), and strength-strain index (SSI) in the metaphysis and diaphysis of the bones. Statistical evaluation of the obtained results was performed using Student's t-test, and the Pearson correlation coefficient between the investigated parameters was determined. The obtained results have shown significant differences in proximal metaphysis between males and females when evaluating such parameters as CRT_DEN, TOT_A, TRAB_A, PERI_C, SSI in tibia (P < 0.05), and BMC, vBMD, TRAB_DEN, CRT_CNT, TOT_A, TRAB_A, cortical area, PERI_C, ENDO_C, SSI in tarsometatarsus (P < 0.05). Significant differences between the 2 sexes were found in all the investigated parameters of diaphysis of tibia, except for CRT_DEN and ENDO_C (P < 0.05). Significant positive correlations between BW and bone weight were found (P < 0.05). Furthermore, numerous correlations of morphometric, geometric, and densitometric parameters of metaphysis and diaphysis of the tibia and tarsometatarsus were stated (P < 0.05). In conclusion, the present investigation demonstrated sex-related differences in morphometric, densitometric, and geometric properties of tibia and tarsometatarsus in 14-mo-old ostriches. Numerous correleations observed between the investigated parameters have shown that ostrich tibia and tarsometatarsus may present a valuable model for further studies on bone tissue metabolism regulation in breeding birds.

Normal glucose uptake in the brain and heart requires an endothelial cell-specific HIF-1α–dependent function

Although intimately positioned between metabolic substrates in the bloodstream and the tissue parenchymal cells that require these substrates, a major role of the vascular endothelium in the regulation of tissue metabolism has not been widely appreciated. We hypothesized that via control of transendothelial glucose transport and contributing paracrine mechanisms the endothelium plays a major role in regulating organ and tissue glucose metabolism. We further hypothesized that the hypoxia-inducible factor -1α (HIF-1α) plays an important role in coordinating these endothelial functions. To test these hypotheses, we generated mice with endothelial cell-specific deletion of HIF-1α. Loss of HIF in the endothelium resulted in significantly increased fasting blood glucose levels, a blunted insulin response with delayed glucose clearance from the blood after i.v. loading, and significantly decreased glucose uptake into the brain and heart. Endothelial HIF-1α knockout mice also exhibited a reduced cerebrospinal fluid/blood glucose ratio, a finding consistent with reduced transendothelial glucose transport and a diagnostic criterion for the Glut1 deficiency genetic syndrome. Endothelial cells from these mice demonstrated decreased Glut1 levels and reduced glucose uptake that was reversed by forced expression of Glut1. These data strongly support an important role of the vascular endothelium in determining whole-organ glucose metabolism and indicate that HIF-1α is a critical mediator of this function.

The Importance of Collagen Fibers in Vertebrate Biology

Collagen fibers form the basic structural components of extracellular matrix (ECM) of vertebrates that serve to: (1) store elastic energy during muscular deformation, (2) transmit stored energy into joint movement, and (3) transfer excess energy from the joint back to the attached muscles for dissipation. They also act as mechanotransducers by transferring stress borne by the musculoskeleton to the attached cells in order to either up - or down - regulate tissue metabolism as a result of changes in mechanical loading. Finally, they prevent premature mechanical failure of tissues by limiting deformation of most ECMs and organs.

Time dependence of cyclic tensile strain on collagen production in tendon fascicles

Mechanical loading is a regulator of tissue metabolism in tendon, which may lead to alterations in structural and mechanical properties via mechanotransduction processes. The present study investigated specified responses of tenocyte metabolism in isolated tendon fascicles subjected to four loading regimes. Cyclic tensile strain of 3% amplitude superimposed on a 2% static strain was applied to the fascicles for 10 min, 1, 6 or 24 h of a 24-h incubation period. Collagen synthesis, assessed by [ 3H]-proline incorporation, was upregulated by the 24 h straining regime, but was inhibited by the 10-min regime. Cyclic strain enhanced the retention of newly synthesised collagen within the matrix. More than 90% of the newly synthesised collagen was retained in all cases, but the long-term application of cyclic strain had less pronounced effects on the retention. These results indicate that collagen synthesis by tenocytes is controlled by a complex mechanosensitive process with a temporal component.

Prevention of Adipose Tissue Depletion during Food Deprivation in Angiotensin Type 2 Receptor-Deficient Mice

Angiotensin (Ang) II is produced locally in various tissues, but its role in the regulation of tissue metabolism is still unclear. Recent studies have revealed the role of type 2 Ang II receptor (AT2R) in the control of energy homeostasis and lipid metabolism. The contribution of the AT2R to adaptation to starvation was tested using AT2R-deficient (AT2R (y)(/-)) mice. Fasted AT2R (y)(/-) mice exhibited a lower loss of adipose tissue weight associated to a decreased free fatty acid (FFA) release from stored lipids than the controls. In vitro studies show that Ang II causes an AT1R-mediated antilipolytic effect in isolated adipocytes. AT1R expression is up-regulated by fasting in both genotypes, but the increase is more pronounced in AT2R (y/-) mice. In addition, the increased muscle beta-oxidation displayed in AT2R (y/-) mice on a fed state, persists after fasting compared with wild-type mice. In liver from fed mice, AT2R deficiency did not modify the expression of genes involved in fatty acid oxidation. However, in response to fasting, the large increase of the expression of this subset of genes exhibited by wild-type mice, was impaired in AT2R (y/-) mice. Taken together, decreased lipolytic capacity and increased muscle fatty acid oxidation participate in the decreased plasma FFA observed in fasted AT2R (y/-) mice and could account for the lower FFA metabolism in the liver. These data reveal an important physiological role of AT2R in metabolic adaptations to fasting.

Arguments for revision of classification of hypoxic states

Hypoxia always leads to dysfunction of organs and culminates in the fatal outcome. The principles of classification of the hypoxic states were formulated in 1930-s. The first successful cardiac transplantation posed the problem of dividing of circulatory cardiovascular hypoxia into two subdivisions: hypoxia associated with impaired cardiac contractility (cardiac insufficiency) and hypoxia resulting from vascular smooth muscle cell. Here we attempted to improve classification of hypoxic states on the basis of new medical achievements. The proposed classification considers the following hypoxic states: 1) exogenous hypoxia; 2) respiratory hypoxia; 3) hypoxia resulting from cardiac insufficiency; 4) hypoxia provoked by vascular smooth muscle dysfunction; 5) hemic hypoxia; 6) tissue hypoxia; and 7) combined hypoxia. There are specific and pathogenically substantiated methods for correction of all elements of the “hypoxic chain” that regulate tissue metabolism at the cellular and subcellular level both in the whole organism and in individual organs. These methods open new vistas in biology and medicine, in particular, in transplantology.

Heat and matter distribution in body tissues and the determination of tissue blood flow by local clearance methods

Differential forms of Fick's perfusion principle are combined with the heat conduction and matter diffusion equations and a metabolic term to give partial differential equations for the distribution in space and time of heat and matter in living, perfused tissues at the millimeter level of observational detail. The theory is characterized by well-known parameters local rate of blood flow per unit volume of tissue, diffusion, heat conduction and solubility coefficients of the substance of interest in the tissue, rate of production or consumption of the substance of interest per unit volume of tissue, and a venous exit parameter relating instantaneous concentrations in a volume element of tissue and in venous blood issuing from that volume element. The heat distribution case is illustrated by analyzing existing steady state (time independent) and transient (time dependent) data obtained by the Gibbs thermoelectric probe method for determining tissue blood flow. Fluctuation properties of capillary blood flow are used to help explain the steady state data. A possible general role of such fluctuations in tissue metabolic regulation is conjectured. Methods are given for analyzing the transient data to obtain tissue blood flow. The matter distribution case is illustrated by application to Kety's radioactive tracer local clearance method.