Pleiotropic effects of PPAR-α – from benchside to bedside

Here we review literature data on properties of a member of nuclear hormone receptors - peroxisome proliferator-activated receptor-α. It was shown that PPARα was expressed on different cells including dendritic cells, macrophages, B- and T-cells. We discuss structure of natural and synthetic ligands of PPARa, molecular and cellular mechanisms of PPARa regulation of lipid and carbohydrate cellular metabolism. PPARa activity in hepatocytes results in decrease of intracellular concentrations of lipid acids. This leads to reduction of VLDL cholesterol, increase in HDL-cholesterol and decrease in triglycerides in plasma of patients taking PPARα agonists. Modulation of PPARa activity may change multiple biological effects of glucocorticoids (GCS) and insulin resistance. It is assumed that PPARα agonists reduce side effects of GCS and at the same time enhance their anti-inflammatory activity due to transrepression of NF-kB. We analyzed the results of several randomized studies, meta-analyses devoted to assessment of efficacy and safety of PPARa agonist fenofibrate in patients with type 2 diabetes mellitus with high risk of micro- and macrovascular events. The studies showed good safety profile of monotherapy with fibrates as well as of their combinations with statins, ezetimibe. Fibrates reduced not only cardiovascular events but also overall mortality. We present the data on the role of PPARa in control of glucose and lipid metabolism in subpopulations of innate and adaptive immunity cells. The data show that glucose and lipid metabolism play an important role in the fate of cells of innate and adaptive immunity. The metabolic state of lymphocytes has dynamic nature and depends on their functional activity. Transition from dormant cells with relatively low metabolism rate to activated and proliferating cells is accompanied with increase of metabolic demands. This transition is supported with the switch from oxidative metabolism to anaerobic glycolysis (Warburg effect) after antigen recognition by T-cells and B-cells. It was shown that granulocytes, dendritic cells and M1 macrophages were dependent on glucose metabolism during their activation while M2 macrophages were dependent on fatty acids oxidation. In contrast with lymphocytes, activated myeloid cells do not proliferate well but still have increased glycolysis which is necessary for their effector function. It is stressed that modulation of immune cells metabolism via PPARα gives new opportunities to modulate intensity and duration of immune responses in chronic diseases. We analyze studies performed on animal models of some chronic diseases, human patients with rheumatoid arthritis and different phenotypes of osteoarthritis. Most of the studies showed clinical efficacy and pleiotropic effects of PPARα agonists: antiinflammatory, immunomodulating and lipid modulating, primarily reduction of triglycerides and increase in HDL-C. The presented literature data suggest efficacy of PPARα agonists against individual components of polypathies. This could reduce risk of polypharmacy and reduce direct treatment costs. It is not unlikely that the use of PPARα agonists in a patient with multimorbidity could prevent acquiring a new disease. These are merely suggestions and much effort and time is required to perform large-scale randomized controlled studies evaluating new indications for the use of PPARa agonists

Polymorbidity, ageing of immune system and low-grade systemic inflammation: a challenge for modern medicine

The  review  article  considers the  data  from  literature that  concern polymorbidity aspects,  its interrelations with ageing of immune system and lo-grade immune ageing, mechanisms of genesis, approaches to its prevention and treatment. Evolution of “comorbidity” and “polymorbidity” terms is traced, an updated definition of polymorbidity is proposed. The  world-wide incidence of polymorbidity is increased and  now it reaches  23-25%  in general  population, and up to 98%, in elderly people  (> 65 years old).  The risk factors  of polymorbidity are considered, like as its social burden due to high costs for healthcare, high mortality rates, excessive treatment provided by multidisciplinary specialists.  We present  evidence  for common molecular and cellular  mechanisms involved  in ageing and polymorbidity, being unified  by the term  “inflammaging” which represents a low-grade chronic systemic  inflammation associated with  ageing.  The  data  are  presented that concern the “inflammaging” development with involvement of ageing cells from innate and adaptive immunity systems,  different   pro and  anti-inflammatory mediators, lifelong  antigenic load.  The  data  are  analyzed concerning functional and  structural changes  in the  inborn and  adaptive  immune system  in ageing,  role of these changes  in “inflammaging” persistence and development of polymorbid conditions. There  are complex interactions shown between  the bodily senescence and immune ageing, with similar underlying mechanisms in some cases, however, being quite different  in other  instances. With age, upon  existing risk factors,  the changed adaptive  immunity in most people  is not able to full-scale  coping  with chronic antigenic load,  thus increasing the risk of diseases. Moreover, in many elderly people these changes are compensated by steady activation of the innate immunity cells. It is noted  that the aging events and development of disease (polymorbidity) cannot be considered distinct entities, since they can interact, being, however, basically different in their nature. In future, one should concentrate our efforts on elucidation of molecular and cellular mechanisms of these interactions, solution of the  tasks  oriented for development of such  interventions that  could  be able  to  reduce  harmful consequences of ageing and to use useful effects for health  maintenance and reaching maximal longevity

Osteoimmunology: an interdisciplinary approach to studying the relationships between immune and bone cells

In this review, we discuss molecular and cellular mechanisms underlying cross-talk between immune cells and bone cells, both in healthy conditions and in some diseases. We provide short description of the main cell populations of bone tissue, i.e., osteoblasts, osteoclasts, osteocytes, bone marrow macrophages, OsteoMacs, and their effects on immune cells during bone modeling and remodeling. The data are presented on regulatory molecular pathways of bone marrow cell activity, T and B cells, macrophages, and formation of “endosteal niche” by the bone cells. We describe the key system of bone tissue homeostasis: RANK/RANKL/ OPG, which regulates differentiation of osteoclasts and bone destruction. In addition, RANK/RANKL/ OPG system modulates maturation and activity of various T and B cell subsets. We present the data on pleiotropic effects of T cells, B cells, dendritic cells, macrophage subpopulations, Tregs, NK cells, neutrophils upon differentiation and function of osteoblasts and osteoclasts. These effects promote accumulation and maintenance of the bone mass. We describe mechanisms of these effects based on direct cell-to-cell contacts and various soluble mediators and intracellular signaling pathways. A brief characteristic of some diseases is provided with concomitant dysfunction of immune cells and bone cells which play a decisive pathogenetic role (fractures, rheumatoid arthritis, periodontitis, postmenopausal osteoporosis, multiple myeloma). It was shown that the destructive bone inflammation, both in RA and periodontitis, leads to loss of bone mass, being featured by similar pathophysiological mechanisms involving immune and bone cell populations. Therapy of these diseases requires newer treatment strategies aimed not only at pro-inflammatory cytokines, but for increased bone resorption. We describe involvement of activated T cells, their cytokines into the pathogenesis of postmenopausal osteoporosis, thus providing a rationale for the novel term of “immunoporosis”, coined in 2018. The relationships between multiple myeloma cells and bone marrow microenvironment are provided. This cross-talk is based on contact cell-cell interactions, as well as due to effects of soluble mediators upon osteoclasts, stromal cells, and osteoblasts. These effects result in osteolysis, loss of bone mass, and myeloma progression. In conclusion, the relationships between the immune and bone cell populations suggest that they function as an entire regulatory system. This consideration provides a framework for the development of new therapeutic targets for the treatment of bone and immune system disorders

CLINICAL AND IMMUNOLOGICAL CHARACTERISTICS OF DIABETES-ASSOCIATED OSTEOARTHRITIS

Osteoarthritis (OA) has been shown to be a heterogeneous disease. Diabetes mellitus (DM)associated represents a special OA subtype. Its clinical and immunological characteristics are poorly understood. To assess immune phenotype of the diabetes-associated OA and appropriate relationship between its clinical manifestations and cytokine concentrations in peripheral blood, we examined 78 patients with generalized OA including 52 patients in experimental group (82.6% females) who exhibited clinical manifestations of OA preceded by DM type II for, at least, 1 year, and 26 OA diabetes-free patients (84.6% females). We found that clinical manifestations of DM-associated OA were associated with increased body weight, more pronounced level of joint pains, longer duration of morning stiffness, decreased functionality of hands and large joints, impaired quality of life and more severe clinical pattern of the illness. Pronounced clinical manifestations in OA patients were more typical to the patients who required insulin therapy. The patients with DM type II-associated OA had elevated levels of proinflammatory (IL-6, IL-18) and reduced serum concentrations of anti-infammatory cytokines (IL-10, adiponectin), thus suggesting more pronounced systemic inflammation in patients of the first group. Concentrations of circulating IL-6 correlated with several functional indexes of OA severity. In conclusion, the DM-associated OA represents a special subtype of osteoarthritis, and deserves further studies of its immune pathogenesis and development of new treatment strategies

Efficacy and safety of curcumin in patients with metabolic phenotype of osteoarthritis: A pilot study

The aim of this study was to assess efficacy and safety of curcumin in metabolic syndrome- associated osteoarthritis (MetS-OA). All patients provided written informed consent. Knee OA was diagnosed according to American College of Rheumatology criteria; MetS was diagnosed according to Russian Scientific Society of Cardiology Guidelines. The study had before-and-after design. The main inclusion criteria were presence of knee OA and MetS, levels of global health assessment and pain assessment more than 50 mm using 0-100 visual analogue scale (VAS). The main outcome was VAS global. The other outcomes were VAS pain, Knee injury and Osteoarthritis Outcome Score (KOOS) consisting of five subscales: pain (KOOS pain), other symptoms (KOOS symptoms), activities in daily living (KOOS ADL), function in sport and recreation (KOOS Sport/Rec) and knee related Quality of life (KOOS QoL). The level of depression was measured using PHQ- 9. For pain, proportion of patients achieving minimal clinically important improvement (MCII) was assessed using the cut-offs of (a) 15 of 100 for absolute improvement and 20% for relative improvement.The treatment consisted of C. longa extract 1000 mg/day for 4 weeks. The assessments were performed on baseline and 4 weeks thereafter. Eighteen women with MetS-OA of the knee were included in the study.At the end of treatment, there were significant improvements in the VAS global scale by an average 33.9 mm (p = 0.001), VAS pain by 25 mm (p = 0.001). There was a trend towards improvement in PHQ-9 by 2.9 (p = 0.05). The mean improvement in KOOS pain was 11 (p = 0.001). KOOS symptoms improved by 9 (p = 0.025), KOOS ADL - by 12.4 (p = 0.001), KOOS Sport/Rec by 10.3 (p = 0.044), and KOOS QOL by 14.4 (p = 0.009). The proportion of patients achieving clinically significant improvement (MCII) were nine (56%) for both global health and pain. There were no adverse events during the study. The findings of this study suggest clinical efficacy and safety of C. Longa in MetS-associated knee OA. There is a need for large controlled studies to confirm these results

CLINICAL EFFICACY AND SAFETY OF ADEMETIONINE IN PATIENTS WITH DIABETES-ASSOCIATED OSTEOARTHRITIS: A CROSS-OVER PILOT STUDY

Osteoarthritis (OA) is one of most common rheumatic diseases, and currently there is no effective pharmacological treatment of OA. It has been suggested that lack of effective treatment is, in part, due to the disease heterogeneity which may lead to development of several OA subtypes (phenotypes). Diabetes-associated OA is among the proposed OA phenotypes. The key mechanism involved into inflammatory and degenerative changes in OA is a decrease in DNA methylation suggested for several cell types, that was also demonstrated in type 2 diabetes mellitus. Therefore, pharmacological increase of DNA methylation may be an effective treatment strategy which may exert pleiotropic effects in diabetes-associated OA. In a randomized crossover study, we have evaluated efficacy and safety of ademetionine, a methyl group donor, in comparison with chondroitine sulfate in patients with OA associated with type 2 diabetes mellitus. The patients were randomly assigned to sequential treatment of chondroitine sulfate/ademetionine or ademetionine/chondroitine sulfate during one month, with a washout period of 2 weeks. The primary endpoint was pain measured according to visual analogue scale (VAS). Painful symptoms, as well as function and disease signs in knee, hip and hand joints were also assessed with KOOS, WOMAC, and FIHOA scales. General performance was assessed with SF–36 scale. To evaluate systemic inflammation, we measured serum IL-6, IL-18, adiponectin, and CRP using ELISA technique. Concentrations of serum cartilage destruction biomarkers (aggrecan and antibodies to collagen type II) were assessed by ELISA. Serum lipid levels were measured with standard method; glycated hemoglobin was assessed with liquid chromatography. Ten patients (all women, age 61.7-74.2 year with BMI of 1.1-38.4 kg/m2) were included in the study. It has been demonstrated that ademetionine showed a statistically significant analgetic effect (decrease in VAS pain), improved knee function and reduced symptoms in knee joints (as measured by KOOS subscales), and did not influence the levels of systemic inflammation or cartilage destruction biomarkers. There was also no change in lipid levels and glycated hemoglobin concentrations. Ademetionine was well tolerated, no serious adverse events occurred during the treatment. In conclusion, ademetionine does not have pleiotropic pharmacological effects in diabetes-associated OA. Its potential application in cases of different comorbidities requires further studies

Combination treatment of patients with metabolic phenotype of osteoarthritis: an exploratory study

Treatment of osteoarthritis (OA) patients with comorbidities can be challenging due to adverse events and non-sufficient efficacy of modern drugs. A safe and effective alternative could be the methods of traditional medicine and their combinations. The aim of this study was to evaluate efficacy and safety of combination of curcuma-based parapharmaceutical preparation and acupuncture in metabolic phenotype of OA (MPOA). The trial design was pilot open-label “before – after” study with the duration of 12 weeks. The patients with MPOA received parapharmaceutical preparation Epigenorm Antivir in a daily dose of 1000 mg and underwent 15-20 sessions of classical acupuncture. We enrolled twenty three women with metabolic syndrome (MS), clinical and radiographic signs of gonarthrosis, mean age 66.5 years, mean body mass index 34.5. At the end of treatment there was a decrease in pain levels according to visual analogue scale (VAS) (before 65 (12.7), after 24.6 (21.0), р=0.001), WOMAC pain scale (before 210.6 (102.2), after 103 (80.8), p = 0.014), KOOS (before 47.8 (12.1), after 66.7 (16.2), р = 0.001). The treatment resulted in statistically significant improvement of daily and social activities, role functioning, and quality of life. The results were clinically significant as evidenced by the moderate (Cohen d > 0.5) and large (Cohen d > 0.8) effect sizes of most outcome changes in accordance with the Cohen classification. The clinical improvement was accompanied by the decrease in MS components – LDL cholesterol (before 3.26 (0.26) mmol/l, after 2.43 (0.2) mmol/l, р = 0.001), triglycerides (before 2.02 (0.16) mmol/l, after 1.31 (0.1) mmol/l, р = 0.005). The treatment resulted in the reduction of systemic inflammation as evidenced by the decrease in the concentrations of TNFα (before 15.9 (1.2) pg/ml, after 12.4 (0.8), р = 0.002), histamine (before 1.6 (0.2) ng/ml, after 0.7 (0.2) pg/ml, р = 0.034), IL-18 (before 208.8 (32.6 ) pg/ml, after 160.0 (26.0) pg/ml, р = 0.002) and CRP (before 6.05 (1.3) mg/l, after 3.2 (0.7) mg/l, р = 0.022). At the same time there was an increase of concentration of IL-10 (before 1.5 (0.7) pg/ml, after 3.8 (1.2), р = 0,006) and adiponectin (before 34.0 (5.6) pg/ml, after 40.0 (6.9), р = 0.034). The treatment was well tolerated, no serious adverse events were registered. The pleiotropic actions of combination treatment occured probably due to synergistic effects of herbal therapies and acupunctures. The results provide a rationale for larger scale, randomized controlled double-blind clinical trials

Clinical and immunological features of metabolic phenotype of osteoarthritis

Forty women with gonarthrosis were included in this study. The main group consisted of 19 patients having osteoarthritis (OA) with metabolic syndrome (MS), the control group consisted of 21 patients with OA but without MS. It was found that metabolic phenotype of gonarthrosis, i.e. OA with concomitant MS, was different from OA without MS in terms of pain measured with visual analogue scale (VAS) (65 mm in the main group vs 47 mm in control group, р = 0.001) and other OA symptoms in accordance with Knee Osteoarthritis Outcome Scale (KOOS) (43.2 points in the main group vs 76.1 points in the control group, р = 0.001). These main distinguishing features were associated with low quality of life measured with non-specific questionnaire Short Form -36 (SF-36) (30 points in the main group and 40 points in the control) and clinically significant signs of depression, detected with Patient Health Questionnaire-9 (PHQ-9) (12 points in the main group and 7 points in the control group). The metabolic phenotype of gonarthrosis was characterized with laboratory features of low-grade systemic inflammation as evidenced by increased CRP (11.4 mg/ml in the main group vs 3.2 mg/ml in the control group, р = 0.03), IL-6 (2.6 pg/ml in the main group vs 0.7 pg/ml in the control group, р = 0.001), IL-18 (196.6 pg/ml in the main group vs 61.4 pg/ml in the control group, р = 0.001) in the peripheral blood serum, as well as increase in antibodies against Col2 (27.1 ng/ml in the main vs 5.5 ng/ml in the control group, р = 0.01) , and dyslipidaemia — increase in LDL-cholesterol (5.5 mmol/l in the main group vs 5.9 mmol/l in the control group, р = 0.032) and triglycerides (2.026 mmol/l in the main group and 1.36 mmol/l in the control gropu, р = 0.02). In conclusion, MS-associated OA phenotype occurs due to pathogenetic similarities between OA and MS (syntropy) based on systemic low grade inflammation. This OA phenotype is not well studied and needs further research to develop new treatments targeting these two comorbid disorders as a single disease

Comparative analysis of the expression of the soluble IL-7 receptor in patients with arthropathy

Arthropathy is one of the most prevalent diseases, which are based on the destruction and remodeling of cartilage and bone tissue. The inflammation that precedes destruction can be caused by mechanical stress on the joints, or by autoimmune reactions. Recently, IL-7 is considered as one of the key cytokines that promote the production of matrix metalloproteinases, catabolic enzymes, T cell-mediated activation of monocytes, and maturation of osteoclasts. The soluble form of the IL-7 receptor can help prolong the lifespan of IL-7 and thereby it ensures the bioavailability of the cytokine and mediates effect of IL-7 on cells. The aim of this study was to determine the soluble form of the IL-7 receptor (sIL-7R) in the blood plasma of patients with rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA) and psoriasis vulgaris (PS), as well as healthy individuals. The RA patients included in the study had moderate to high disease activity according to the DAS28 index. Patients with PsA predominantly had moderate and low disease activity (DAS28) and were characterized by mild to moderate disease severity (PASI). In accordance with the PASI index, patients with PS with mild and severe severity of the disease were included in the study. All patients with OA had a metabolic phenotype that is accompanied by an elevated body mass index.sIL-7R was determined in blood plasma by enzyme-linked immunosorbent assay. It was found that in patients with arthropathy, the level of soluble form of IL-7 was increased relative to healthy individuals, with the exception of the group of patients with PsA. Also, a high concentration of sIL-7R was observed in patients with PS. Analyzing the clinical characteristics of the patients, we found that sIL-7R levels were elevated in RA and PsA patients with high disease activity by DAS28. In addition, positive correlations were found between the concentration of sIL-7R and DAS28 in RA and PsA. In patients with PsA with moderate severity of the disease (PASI), the concentration of sIL-7R was also increased relative to donor's values. On the contrary, in patients with PS, a high level of sIL-7R was noted regardless of the severity of the disease. In patients with OA, no relationship was found between sIL-7R levels and clinical parameters.Thus, an elevated level of sIL-7R in patients with arthropathy may indicate the involvement of IL-7 and its receptor system in the pathogenesis of joint diseases. The IL-7 receptor may become a promising target both in the treatment of joint diseases and other autoimmune diseases, including psoriasis

Влияние модуляторов метилирования ДНК на продукцию остеопротегерина ревматоидными фибробластоподобными синовиоцитами in vitro, их миграцию и инвазию

Objective. The purpose of the research was to study the effect of DNA methylation modulators on the production of proinflammatory cytokines by fibroblast-like synovial cells (FLC).Materials and methods. We used the cells derived from the synovial tissue of 6 patients with active rheumatoid arthritis (RA) after 3–7 in vitro culturing passages.Results. There was an IL-1β-induced up-regulation of osteoprotegerin (OPG) synthesis in the RA FLC cultures. The addition of methylating compounds S-Adenosyl methionine (SAMe) and genistein into the cultures resulted in a statistically significant decrease in the production of OPG, while the addition of the demethylating agent hydralazine did not change the synthesis of the cytokine. All three DNA methylation modulators used at different concentrations significantly reduced the percentage of spontaneous migration and invasion of FLC in the Boyden chamber.Conclusion. Enzymes and molecular complexes involved in DNA methylation could be potential therapeutic targets, and in vitro FLC cultures of RA patients can be used as a model for preclinical screening of new drug compounds. Цель. Изучить влияние модуляторов метилирования ДНК на продукцию провоспалительных цитокинов фибробластоподобными синовиальными клетками (ФСК).Материалы и методы. Использовались клетки, полученные из синовиальной ткани шести больных активным ревматоидным артритом (РА) после 3–7 пассажей культивирования in vitro.Результаты. Установлено, что культуры ФСК больных РА при стимуляции IL-1β увеличивают продукцию остеопротегерина (ОПГ). Внесение в культуры метилирующих соединений – S-аденозилметионина (SAMе) и генистеина – приводило к статистически значимому снижению продукции ОПГ, а добавление деметилирующего агента гидралазина не меняло синтез цитокина. Все три используемых модулятора метилирования ДНК в разных концентрациях статистически значимо снижали количество спонтанно мигрировавших и инвазивных ФСК в камере Бойдена.Заключение. Ферменты и молекулярные комплексы, участвующие в процессах метилирования ДНК, являются потенциальными терапевтическими мишенями, а культура ФСК больных РА in vitro может быть моделью для доклинического скрининга новых лекарственных соединений.