Effects of exposure to hyperbaric oxygen on oxidative stress in rats with type II collagen-induced arthritis

Optimized oxygen therapy improves sleep deprivation-induced cardiac dysfunction through gut microbiota

Adequate sleep is of paramount importance for relieving stress and restoring mental vigor. However, the adverse physiological and pathological responses resulting from sleep insufficiency or sleep deprivation (SD) are becoming increasingly prevalent. Currently, the impact of sleep deficiency on gut microbiota and microbiota-associated human diseases, especially cardiac diseases, remains controversial. Here, we employed the following methods: constructed an experimental sleep-deprivation model in mice; conducted 16S rRNA sequencing to investigate the changes in gut microbiota; through fecal microbiota transplantation (FMT) experiments, transplanted fecal microbiota from sleep-deprived mice to other mice; established an environment with a 30% oxygen concentration to explore the therapeutic effects of oxygen therapy on gut microbiota-associated cardiac fibrosis and dysfunction; and utilized transcriptome data to study the underlying mechanisms of oxygen therapy. The results revealed that: sleep-deprived mice exhibited weakness, depression-like behaviors, and dysfunction in multiple organs. Pathogenic cardiac hypertrophy and fibrosis occurred in sleep-deprived mice, accompanied by poor ejection fraction and fractional shortening. 16S rRNA sequencing indicated that sleep deprivation induced pathogenic effects on gut microbiota, and similar phenomena were also observed in mice that received fecal microbiota from sleep-deprived mice in the FMT experiments. The environment with a 30% oxygen concentration effectively alleviated the pathological impacts on cardiac function. Transcriptome data showed that oxygen therapy targeted several hypoxia-dependent pathways and inhibited the production of cardiac collagen. In conclusion, these results demonstrate the significance of sufficient sleep for gut microbiota and may represent a potential therapeutic strategy, where the oxygen environment exerts a protective effect on insomniacs through gut microbiota.

C-reactive protein lowers the serum level of IL-17, but not TNF-α, and decreases the incidence of collagen-induced arthritis in mice

The biosynthesis of C-reactive protein (CRP) in the liver is increased in inflammatory diseases including rheumatoid arthritis. Previously published data suggest a protective function of CRP in arthritis; however, the mechanism of action of CRP remains undefined. The aim of this study was to evaluate the effects of human CRP on the development of collagen-induced arthritis (CIA) in mice which is an animal model of autoimmune inflammatory arthritis. Two CRP species were employed: wild-type CRP which binds to aggregated IgG at acidic pH and a CRP mutant which binds to aggregated IgG at physiological pH. Ten CRP injections were given on alternate days during the development of CIA. Both wild-type and mutant CRP reduced the incidence of CIA, that is, reduced the number of mice developing CIA; however, CRP did not affect the severity of the disease in arthritic mice. The serum levels of IL-17, IL-6, TNF-α, IL-10, IL-2 and IL-1β were measured: both wild-type and mutant CRP decreased the level of IL-17 and IL-6 but not of TNF-α, IL-10, IL-2 and IL-1β. These data suggest that CRP recognizes and binds to immune complexes, although it was not clear whether CRP functioned in its native pentameric or in its structurally altered pentameric form in the CIA model. Consequently, ligand-complexed CRP, through an as-yet undefined mechanism, directly or indirectly, inhibits the production of IL-17 and eventually protects against the initiation of the development of arthritis. The data also suggest that IL-17, not TNF-α, is critical for the development of autoimmune inflammatory arthritis.

Acupotomy Improves Synovial Hypoxia, Synovitis and Angiogenesis in KOA Rabbits

Purpose

Knee osteoarthritis (KOA) is a chronic inflammatory disease highly associated with intra-articular hypertension, hypoxia and angiogenesis of synovial tissue. Our previous studies showed that acupotomy could treat KOA in a variety of ways, including reducing cartilage deterioration and enhancing biomechanical qualities. However, the mechanism of hypoxia and angiogenesis induced by acupotomy in KOA synovium remains unclear. This study looked for the benign intervention of acupotomy in synovial pathology.

Methods

The rabbits were divided into 3 groups, Normal group, KOA group, and KOA + Acupotomy (Apo) group, with 11 rabbits in each group. The KOA rabbit model was established by the modified Videman method with six weeks. The KOA + Apo group performed the intervention. The tendon insertion of vastus medialis, vastus lateralis, rectus femoris, biceps femoris, and anserine bursa were selected as treatment points in rabbits. Rabbits were treated once every 7 days for 3 weeks. We observed the intra-articular pressure and oxygen partial pressure (BOLD MRI). The synovial morphology was monitored by Hematoxylin-Eosin Staining (HE Staining). The expression of hypoxia-inducible transcription factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), interleukin-1β (IL-1β) and tumour necrosis factor-α (TNF-α) was detected using Immunohistochemical (IHC), Western Blot and Enzyme-Linked Immunosorbent Assay (ELISA).

Results

Acupotomy reduced intra-articular hypertension and improved the synovial oxygen situation, synovial inflammatory and angiogenesis. HIF-1α, VEGF, IL-1β and TNF-α expression were downregulated by acupotomy.

Conclusion

Acupotomy may reduce inflammation and angiogenesis in KOA rabbit by reducing abnormally elevated intra-articular pressure and improving synovial oxygen environment. The above may provide a new theoretical foundation for acupotomy treatment of KOA.

Effects of Combined Allogenic Adipose Stem Cells and Hyperbaric Oxygenation Treatment on Pathogenesis of Osteoarthritis in Knee Joint Induced by Monoiodoacetate

The beneficial effects of HBO in inflammatory processes make it an attractive type of treatment for chronic arthritis. In addition, the effects of combination therapy based on adipose stem cells and HBO on OA progression have not been fully investigated. The current study explored the efficacy of intra-articular injection of allogeneic adipose-derived mesenchymal stem cells (ADMSCs) combined with hyperbaric oxygenation treatment (HBO) in a rat osteoarthritis (OA) model. The rat OA model was induced by intra-articular injection of monoiodoacetate (MIA) and 7 days after application of MIA rats were divided into five groups: healthy control (CTRL), osteoarthritis (OA), ADMSCs (ADS), the HBO+ADS^21day and HBO+ADS^28day groups. A single dose of 1 × 10⁶ allogeneic ADMSCs suspended in sterile saline was injected into the knee joint alone or in combination with HBO treatment. Rats were sacrificed at 3 or 4 weeks after MIA injection. Treatment outcomes were evaluated by radiographic, morphological and histological analysis and by specific staining of articular cartilage. We also measured the level of inflammatory and pro/antioxidative markers. We confirmed that combined treatment of ADMSCs and HBO significantly improved the regeneration of cartilage in the knee joint. Rtg score of knee joint damage was significantly decreased in the HBO+ADS^21day and HBO+ADS^28day groups compared to the OA. However, the positive effect in the HBO+ADS^28day group was greater than the HBO+ADS^21day group. The articular cartilage was relatively normal in the HBO+ADS^28day group, but moderate degeneration was observed in the HBO+ADS^21day compared to the OA group. These findings are in line with the histopathological results. A significantly lower level of O₂⁻. was observed in the HBO+ADS^28day group but a higher NO level compared to the HBO+ADS^21day group. Moreover, in the HBO+ADS^28day group significantly higher concentrations of IL-10 were observed but there was no significant difference in proinflammatory cytokine in serum samples. These results indicate that a single intra-articular injection of allogeneic ADMSCs combined with HBO efficiently attenuated OA progression after 28 days with greater therapeutic effect compared to alone ADMSCs or after 3 weeks of combined treatment. Combined treatment might be an effective treatment for OA in humans.

Quercetin mitigates rheumatoid arthritis by inhibiting adenosine deaminase in rats

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease characterized by synovial proliferation and bone destruction. Adenosine deaminase (ADA) is a key inflammatory enzyme that increases joint stiffness and pain in RA. In this study, we evaluated the in-silico, and in vivo inhibitory effect of quercetin isolated from Egyptian Fenugreek on ADA enzyme activity. We also determined the combinatorial effect of quercetin on methotrexate mediated anti-inflammatory efficacy and toxicity. In-silico molecular docking was conducted and confirmed in an in vivo RA rat model. The results showed that the inhibition constant of quercetin on joint ADA by docking and in-vitro was 61.9 and 55.5 mM, respectively. Therefore, quercetin exhibits anti-inflammatory effect in a rat RA model as evidenced by reducing the specific activity of ADA in joint tissues, lower jaw volume, enhance body weight, downregulate ADA gene expression, reduce levels of RA cytokines interleukin-1^β, interleukin-6, tumor necrosis factor-α, also, rheumatoid factor, C-reactive protein, and anti-cyclic citrullinated peptide RA biomarker levels. These findings demonstrate that the purified quercetin has a promising anti-inflammatory effect against RA disease through its inhibitory effects on the ADA enzyme. Furthermore, isolated quercetin improved the anti-inflammatory efficacy of methotrexate, reduced its toxic effects by increasing antioxidant enzymes and reducing oxidative stress.

The effects of systemic ozone application and hyperbaric oxygen therapy on knee osteoarthritis: an experimental study in rats

OBJECTIVE

To evaluate the effects of systemic medical ozone (O₃) application and hyperbaric oxygen (HBO) therapy on surgically induced knee osteoarthritis (OA) in a rat model.

MATERIALS AND METHODS

We performed anterior cruciate ligament transection (ACLT) in order to create experimental OA in the right knees of 27 male rats. The left knee joints of all rats were sham-operated without ACLT as the negative control group. The rats were randomly assigned into three groups: (1) control group, which received no treatment; (2) O₃ group, which received intraperitoneal 30 μg medical O₃; (3) HBO group, which received HBO therapy for 60 minutes twice a day. We sacrificed the rats on the tenth week after the operation. We evaluated the degree of OA using Mankin scores.

RESULTS

As a result of histopathological examination, the mean Mankin scores in the right knees with ACLT were 8.17 ± 2.12 in the control group, 6.22 ± 1.56 in the HBO group, and 4.72 ± 1.30 in the O₃ group. The differences between the O₃ group and the HBO group and the O₃ group and the control group were found to be statistically significant (p 0.001, p 0.039, respectively). There was no difference between the HBO group and the control group (p 0.086).

CONCLUSIONS

The results of the present study show that systemic medical O₃ application was more effective than HBO therapy and may reduce development of cartilage damage and prevent OA formation.

Effects of Hyperbaric Oxygen on T helper 17/regulatory T Polarization in Antigen and Collagen-induced Arthritis: Hypoxia-inducible Factor-1α as a Target

Objectives

We sought to investigate and prove the effect of hyperbaric oxygen therapy (HBOT) on T helper 17 (Th17)/regulatory T (Treg) cell polarization through changes in the expression of hypoxia-inducible factor-1 alpha (HIF-1α) in rheumatoid arthritis (RA) animal model.

Methods

We used antigen and collagen-induced arthritis (ACIA) as a RA animal model. Sixteen male BALB/c models of ACIA mice were divided into two groups, the non-HBOT group as the control group and the HBOT group as the treatment group. Expression of HIF-1α, Th17 anti-cluster differentiation 196 (CD196), and Treg anti-interleukine 2 receptor β-chain cells (IL-2Rβ) in tissue from the left knee joint tissue were determined histologically. Oxidative stress and systemic inflammation were assessed by levels of superoxide dismutase (SOD), interleukin 17a (IL-17a), C-reactive protein (CRP), and rheumatoid factor (RF) using the enzyme-linked immune-sorbent assay. The degree of arthritis was assessed by clinical scoring of paw swelling and the diameter of paw swelling.

Results

We found a significant decrease (p < 0.050) in the expression of HIF-1α, Th17 (CD196), IL-17a, RF levels, and the clinical scores and the diameter of paw swelling when comparing both groups. There was no significant decrease in the level of CRP in the treatment group compared to the control group. The expression of Treg (IL-2Rβ) increased significantly (p < 0.050) and the level of SOD increased but not significantly (p > 0.050) in the treatment group compared to the control group.

Conclusions

HBOT has effects on the polarization of Th17 to Treg through a decrease in expression of HIF-1α in mice with ACIA. HBOT is recommended for use as a support therapy for RA in combination with drug therapy.

Effects of exposure to mild hyperbaric oxygen during unloading on muscle properties in rats

This study investigated the effects of exposure to mild hyperbaric oxygen during unloading on the properties of the soleus muscle in rats, because exposure to mild hyperbaric oxygen enhances oxidative metabolism in cells and tissues. Therefore, exposure to mild hyperbaric oxygen should inhibit the unloading-induced degenerative changes in skeletal muscles. One group of 7-week-old male Wistar rats were unloaded by hindlimb suspension for 2 weeks (HU, n = 12). A second group of age-matched rats were exposed to mild hyperbaric oxygen at 1317 hPa with 40% oxygen for 3 h a day during hindlimb suspension (HU + MHO, n = 12). A third group of age-matched rats without hindlimb suspension and exposure to mild hyperbaric oxygen were assigned as the controls (WR, n = 12). Soleus muscle weight (per body weight), succinate dehydrogenase (SDH) activity, and peroxisome proliferator-activated receptor γ coactivator-1α (Pgc-1α) mRNA levels were lower in the HU and HU + MHO groups than in the WR group, and these were higher in the HU + MHO group than in the HU group. The unloading-induced type shift from type I to type IIA fibers was inhibited by exposure to mild hyperbaric oxygen during unloading. It is concluded that the unloading-induced decrease in soleus muscle weight (per body weight) and type shift from type I to type IIA fibers in the soleus muscle were partially inhibited by exposure to mild hyperbaric oxygen during unloading.

Mild hyperbaric oxygen: mechanisms and effects

Adequate oxygen supply by exposure to mild hyperbaric oxygen at appropriately high atmospheric pressure (1266-1317 hPa) and increased oxygen concentration (35-40% oxygen) has a possibility of improving the oxidative metabolism in cells and tissues without barotrauma and excessive production of reactive oxygen species. Therefore, metabolic syndrome and lifestyle-related diseases, including type 2 diabetes and hypertension, in rats were inhibited and/or improved by exposure to mild hyperbaric oxygen. It accelerated the growth-induced increase in oxidative capacity of the skeletal muscle in rats and inhibited the age-related decrease in oxidative capacity of the skeletal muscle in mice. A decrease in dopaminergic neurons in the substantia nigra of mice with Parkinson's disease was inhibited by exposure to mild hyperbaric oxygen. This review describes the beneficial effects of exposure to mild hyperbaric oxygen on some metabolic diseases and their perspectives.

Unloading-induced atrophy and decreased oxidative capacity of the soleus muscle in rats are reversed by pre- and postconditioning with mild hyperbaric oxygen

Our aim was to determine the effects of pre- and/or postconditioning with mild hyperbaric oxygen (1.25 atmospheric pressure, 36% oxygen for 3 h/day) on the properties of the soleus muscle that was atrophied by hindlimb suspension-induced unloading. Twelve groups of 8-week-old rats were housed under normobaric conditions (1 atmospheric pressure, 20.9% oxygen) or exposed to mild hyperbaric oxygen for 2 weeks. Ten groups then were housed under normobaric conditions for 2 weeks with their hindlimbs either unloaded via suspension or not unloaded. Six groups subsequently were either housed under normobaric conditions or exposed to mild hyperbaric oxygen for 2 weeks: the suspended groups were allowed to recover under reloaded conditions (unrestricted normal cage activity). Muscle weights, cross-sectional areas of all fiber types, oxidative capacity (muscle succinate dehydrogenase activity and fiber succinate dehydrogenase staining intensity) decreased, and a shift of fibers from type I to type IIA and type IIC was observed after hindlimb unloading. In addition, mRNA levels of peroxisome proliferator-activated receptor γ coactivator-1α decreased, whereas those of forkhead box-containing protein O1 increased after hindlimb unloading. Muscle atrophy and decreased oxidative capacity were unaffected by either pre- or postconditioning with mild hyperbaric oxygen. In contrast, these changes were followed by a return to nearly normal levels after 2 weeks of reloading when pre- and postconditioning were combined. Therefore, a combination of pre- and postconditioning with mild hyperbaric oxygen can be effective against the atrophy and decreased oxidative capacity of skeletal muscles associated with hindlimb unloading.

Flavonoid quercetin-methotrexate combination inhibits inflammatory mediators and matrix metalloproteinase expression, providing protection to joints in collagen-induced arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of synovial tissues in joints, leading to progressive destruction of cartilage and joints. The disease-modifying anti-rheumatic drugs currently in use have side-effects. Thus, there is an urgent need for safe anti-inflammatory therapies for RA. This study aimed to evaluate the therapeutic effect of the flavonoid quercetin on arthritis in mice immunized with type II collagen (CII). An arthritis model was established in C57/BL6 mice by intradermal administration of chicken CII mixed with Freund's complete adjuvant. Quercetin (30 mg/kg orally) and methotrexate (0.75 mg intraperitoneally twice a week) were administered to investigate their protective effects against collagen-induced arthritis (CIA). Levels of tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, and the matrix metalloproteinases (MMP), 3, and 9 were detected to assess the anti-inflammatory effect of quercetin. The mRNA expression of MMP3, MMP9, CCL2, and TNF-α was also measured by quantitative real-time PCR. Quercetin significantly alleviated joint inflammation by reducing the levels of circulating cytokines and MMPs. There was a significant decrease in the expression of TNFα and MMP genes in the ankle joints of arthritic mice. A significant reduction in the levels of knee-joint inflammatory mediators were observed with combined quercetin and methotrexate treatment. Thus, quercetin has the potential to prevent joint inflammation and could be used as an adjunct therapy for RA patients who have an inadequate response to anti-rheumatic monotherapy.

Mild hyperbaric oxygen inhibits the decrease of dopaminergic neurons in the substantia nigra of mice with MPTP-induced Parkinson's disease

We examined whether exposure to mild hyperbaric oxygen inhibits the decrease of dopaminergic neurons in the substantia nigra of a neurotoxic animal model with Parkinson's disease. Mice injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride and probenecid twice a week were divided into two groups: mice with mild hyperbaric oxygen and those without. The mice with mild hyperbaric oxygen were exposed to 1317hPa with 45% oxygen for 3h, three times a week. The decrease in dopaminergic neurons of mice with Parkinson's disease was inhibited by 11 weeks of exposure to mild hyperbaric oxygen. We conclude that exposure to mild hyperbaric oxygen is effective in preventing the progression of Parkinson's disease.

Non-thermal atmospheric plasma ameliorates imiquimod-induced psoriasis-like skin inflammation in mice through inhibition of immune responses and up-regulation of PD-L1 expression

Plasma medicine is an emerging novel therapeutic field. It has been reported that plasma can kill bacteria, promote wound healing and induce apoptosis of tumor cells. However, the effects of plasma on immune cells and immune related skin diseases have not been well studied. In this study, we demonstrated that non-thermal atmospheric plasma (NTP) treatment could inhibit psoriasis-like skin inflammation in mice. NTP treatment in imiquimod-induced psoriasis-like mouse skin inhibited increases in epithelial cell thickness and expression of pro-inflammatory molecules compared to ones without the NTP treatment. In addition, differentiation of Th17 cells, an important cell type for pathogenesis of psoriasis, was inhibited in the NTP-treated mouse lymph nodes. It was also demonstrated that liquid type plasma (LTP), which is also known as indirect plasma, inhibited Th17 cell differentiation in vitro. Other in vitro experiments showed that LTP inhibited bone marrow-derived dendritic cell activation. Interestingly, LTP enhanced PD-L1 expression in HaCaT cells, suggesting that NTP may inhibit unwanted over-activation of T cells through increased PD-L1 expression. Taken together, these results suggest that NTP may be used in treatment of CD4+ T cell-mediated autoimmune diseases such as psoriasis.

Mild Hyperbaric Oxygen Inhibits Growth-related Decrease in Muscle Oxidative Capacity of Rats with Metabolic Syndrome

Aim: We examined the effects of mild hyperbaric oxygen on the properties of the soleus muscle in rats with metabolic syndrome.

Methods: Five-week-old metabolic syndrome (SHR/NDmcr-cp, cp/cp) rats were divided into normobaric (CP) and mild hyperbaric oxygen (CP-H) groups (n = 5/group). In addition, 5-week-old Wistar rats were assigned as the normobaric control (WR) group (n = 5). The CP-H group was exposed to 1.25 atmospheres absolute with 36% oxygen for 3 h daily for 16 weeks. Succinate dehydrogenase (SDH) activity and mRNA levels of peroxisome proliferator-activated receptor γ coactivator-1α (Pgc-1α) in the soleus muscle were examined. The fiber type composition, cross-sectional areas, and SDH staining intensity in the soleus muscle were also examined.

Results: The CP-H group showed lower fasting and nonfasting blood glucose, glycated hemoglobin, total cholesterol, triglyceride, insulin, and systolic blood pressure levels; higher adiponectin levels; and higher SDH activity and mRNA levels of Pgc-1α in the muscle than the CP group. Compared with the CP group, the CP-H group had a lower percentage of type I fibers and observed type IIA fibers in the muscle. The CP-H group also had higher SDH staining intensity of type I and type IIC fibers in the muscle than the CP group. No differences in these values were observed in the muscles of the WR and CP-H groups.

Conclusion: Mild hyperbaric oxygen inhibited growth-related increase in blood glucose levels and decrease in muscle oxidative capacity of rats with metabolic syndrome because of improved oxidative metabolism.

Mild Hyperbaric Oxygen Improves Decreased Oxidative Capacity of Spinal Motoneurons Innervating the Soleus Muscle of Rats with Type 2 Diabetes

Rats with type 2 diabetes exhibit decreased oxidative capacity, such as reduced oxidative enzyme activity, low-intensity staining for oxidative enzymes in fibers, and no high-oxidative type IIA fibers, in the skeletal muscle, especially in the soleus muscle. In contrast, there are no data available concerning the oxidative capacity of spinal motoneurons innervating skeletal muscle of rats with type 2 diabetes. This study examined the oxidative capacity of motoneurons innervating the soleus muscle of non-obese rats with type 2 diabetes. In addition, this study examined the effects of mild hyperbaric oxygen at 1.25 atmospheres absolute with 36 % oxygen for 10 weeks on the oxidative capacity of motoneurons innervating the soleus muscle because mild hyperbaric oxygen improves the decreased oxidative capacity of the soleus muscle in non-obese rats with type 2 diabetes. Spinal motoneurons innervating the soleus muscle were identified using nuclear yellow, a retrograde fluorescent neuronal tracer. Thereafter, the cell body sizes and succinate dehydrogenase activity of identified motoneurons were analyzed. Decreased succinate dehydrogenase activity of small-sized alpha motoneurons innervating the soleus muscle was observed in rats with type 2 diabetes. The decreased succinate dehydrogenase activity of these motoneurons was improved by mild hyperbaric oxygen. Therefore, we concluded that rats with type 2 diabetes have decreased oxidative capacity in motoneurons innervating the soleus muscle and this decreased oxidative capacity is improved by mild hyperbaric oxygen.

Hyperoxygenation attenuated a murine model of atopic dermatitis through raising skin level of ROS

Atopic dermatitis (AD) is a chronic inflammatory skin disease resulting from excessive stimulation of immune cells. Traditionally, reactive oxygen species (ROS) have been implicated in the progression of inflammatory diseases, but several opposing observations suggest the protective role of ROS in inflammatory disease. Recently, we demonstrated ROS prevented imiquimod-induced psoriatic dermatitis through enhancing regulatory T cell function. Thus, we hypothesized AD might also be attenuated in elevated levels of ROS through tissue hyperoxygenation, such as by hyperbaric oxygen therapy (HBOT) or applying an oxygen-carrying chemical, perfluorodecalin (PFD). Elevated levels of ROS in the skin have been demonstrated directly by staining with dihydroethidum as well as indirectly by immunohistochemistry (IHC) for indoleamine 2,3-dioxygenase (IDO). A murine model of AD was developed by repeated application of a chemical irritant (1% 2,4-dinitrochlorobenzene) and house dust mite (Dermatophagoide farinae) extract on one ear of BALB/c mice. The results showed treatment with HBOT or PFD significantly attenuated AD, comparably with 0.1% prednicarbate without any signs of side effects, such as telangiectasia. The expressions of interleukin-17A and interferon-γ were also decreased in the AD lesions by treatment with HBOT or PFD. Enhanced expression of IDO and reduced level of hypoxia-inducible factor-1α, in association with increased frequency of FoxP3⁺ regulatory T cells in the AD lesions, might be involved in the underlying mechanism of oxygen therapy. Taken together, it was suggested that tissue hyperoxygenation, by HBOT or treatment with PFD, might attenuate AD through enhancing skin ROS level.

Reactive oxygen species prevent imiquimod-induced psoriatic dermatitis through enhancing regulatory T cell function

Psoriasis is a chronic inflammatory skin disease resulting from immune dysregulation. Regulatory T cells (Tregs) are important in the prevention of psoriasis. Traditionally, reactive oxygen species (ROS) are known to be implicated in the progression of inflammatory diseases, including psoriasis, but many recent studies suggested the protective role of ROS in immune-mediated diseases. In particular, severe cases of psoriasis vulgaris have been reported to be successfully treated by hyperbaric oxygen therapy (HBOT), which raises tissue level of ROS. Also it was reported that Treg function was closely associated with ROS level. However, it has been only investigated in lowered levels of ROS so far. Thus, in this study, to clarify the relationship between ROS level and Treg function, as well as their role in the pathogenesis of psoriasis, we investigated imiquimod-induced psoriatic dermatitis (PD) in association with Treg function both in elevated and lowered levels of ROS by using knockout mice, such as glutathione peroxidase-1^−/− and neutrophil cytosolic factor-1^−/− mice, as well as by using HBOT or chemicals, such as 2,3-dimethoxy-1,4-naphthoquinone and N-acetylcysteine. The results consistently showed Tregs were hyperfunctional in elevated levels of ROS, whereas hypofunctional in lowered levels of ROS. In addition, imiquimod-induced PD was attenuated in elevated levels of ROS, whereas aggravated in lowered levels of ROS. For the molecular mechanism that may link ROS level and Treg function, we investigated the expression of an immunoregulatory enzyme, indoleamine 2,3-dioxygenase (IDO) which is induced by ROS, in PD lesions. Taken together, it was implied that appropriately elevated levels of ROS might prevent psoriasis through enhancing IDO expression and Treg function.

Effect of γ-tocotrienol in counteracting oxidative stress and joint damage in collagen-induced arthritis in rats

Tocotrienols exhibit a significant anti-inflammatory and antioxidant effect in numerous human diseases. However, the anti-inflammatory and antioxidant effects of tocotrienols in arthritic conditions are not well documented. Therefore, the effect of γ-tocotrienol supplementation against oxidative stress and joint pathology in collagen-induced arthritis in rats was investigated in the present study. Adult female Dark Agouti rats were randomly divided into groups: Control, γ-tocotrienol alone, arthritis alone and arthritis with γ-tocotrienol. Arthritis was induced using 4 mg/kg body weight collagen in complete Freund's adjuvant. The rats were treated orally with 5 mg/kg body weight of γ-tocotrienol between day 21 and day 45. After 45 days, serum C-reactive protein (CRP), tumor necrosis factor (TNF)-α, superoxide dismutase (SOD) and total glutathione (GSH) assays were conducted. γ-tocotrienol significantly reduced the arthritis-induced changes in body weight, CRP, TNF-α, SOD and the total GSH levels. There was a significant reduction in the arthritis-induced histopathological changes in the γ-tocotrienol treatment group. The data indicated that administration of γ-tocotrienol resulted in a significant antioxidant and anti-inflammatory effect on collagen-induced arthritis; therefore, γ-tocotrienol may have therapeutic potential as a long-term anti-arthritic agent in rheumatoid arthritis therapy.

The Effects of Platycodin D, a Saponin Purified from Platycodi Radix, on Collagen-Induced DBA/1J Mouse Rheumatoid Arthritis

The object of this study is to observe the effects of platycodin D, a saponin purified from Platycodi Radix, on mice collagen-induced arthritis (CIA). A daily dose of 200, 100, and 50 mg/kg platycodin D was administered orally to male DBA/1J mice for 40 days after initial collagen immunization. To ascertain the effects administering the collagen booster, CIA-related features (including body weight, poly-arthritis, knee and paw thickness, and paw weight increase) was measured from histopathological changes in the spleen, left popliteal lymph node, third digit, and the knee joint regions. CIA-related bone and cartilage damage improved significantly in the platycodin D-administered CIA mice. Additionally, myeloperoxidase (MPO) levels in the paw were reduced in platycodin D-treated CIA mice compared to CIA control groups. The level of malondialdehyde (MDA), an indicator of oxidative stress, decreased in a dose-dependent manner in the platycodin D group. Finally, the production of IL-6 and TNF-α, involved in rheumatoid arthritis pathogenesis, was suppressed by treatment with platycodin D. Taken together, these results suggest that platycodin D is a promising new effective antirheumatoid arthritis agent, exerting anti-inflammatory, antioxidative and immunomodulatory effects in CIA mice.

Effects of Calcium Gluconate, a Water Soluble Calcium Salt on the Collagen-Induced DBA/1J Mice Rheumatoid Arthritis

This study examined the effects of calcium (Ca) gluconate on collagen-induced DBA mouse rheumatoid arthritis (CIA). A single daily dose of 200, 100 or 50 mg/kg Ca gluconate was administered orally to male DBA/1J mice for 40 days after initial collagen immunization. To ascertain the effects administering the collagen booster, CIA-related features (including body weight, poly-arthritis, knee and paw thickness, and paw weight increase) were measured from histopathological changes in the spleen, left popliteal lymph node, third digit and the knee joint regions. CIA-related bone and cartilage damage improved significantly in the Ca gluconate- administered CIA mice. Additionally, myeloperoxidase (MPO) levels in the paw were reduced in Ca gluconate-treated CIA mice compared to CIA control groups. The level of malondialdehyde (MDA), an indicator of oxidative stress, decreased in a dosedependent manner in the Ca gluconate group. Finally, the production of IL-6 and TNF-α, involved in rheumatoid arthritis pathogenesis, were suppressed by treatment with Ca gluconate. Taken together, these results suggest that Ca gluconate is a promising candidate anti-rheumatoid arthritis agent, exerting anti-inflammatory, anti-oxidative and immunomodulatory effects in CIA mice.

Oxygen concentration-dependent oxidative stress levels in rats

Introduction. We determined derivatives of reactive oxygen metabolites (dROMs) as an index of oxidative stress level (oxidant capacity) and biochemical antioxidant potential (BAP) as an index of antioxidant capacity in rats exposed to different oxygen concentrations. Methods. Male Wistar rats were exposed to 14.4%, 20.9%, 35.5%, 39.8%, 62.5%, and 82.2% oxygen at 1 atmosphere absolute for 24 h. Serum levels of dROMs and BAP were examined by using a free radical and antioxidant potential determination device. The morphological characteristics of red blood cells were examined by phase contrast microscopy. Results. There were no differences in the levels of dROMs in rats exposed to 14.4%, 20.9%, and 35.5% oxygen. However, the levels of dROMs increased in the rats exposed to 39.8% and 62.5% oxygen. The levels of dROMs were the highest in the rats exposed to 82.2% oxygen. There were no differences in the levels of BAP with respect to the oxygen concentration. Morphological changes in the red blood cells induced by oxidative attack from reactive oxygen species were observed in the rats exposed to 39.8%, 62.5%, and 82.2% oxygen. Conclusion. Our results suggest that exposure to oxygen concentrations higher than 40% for 24 h induces excessive levels of oxidative stress in rats.

Effect of exposure to hyperbaric oxygen on diabetes-induced cataracts in mice

BACKGROUND

The growth-associated increase in the blood glucose level of animals with Type 2 diabetes is inhibited by moderate hyperbaric exposure at 1.25 atmospheres absolute (ata) with 36% oxygen, presumably due to an increase in oxidative metabolism. However, there are no data available regarding the effect of moderate hyperbaric oxygen (HBO) on diabetes-induced cataracts.

METHODS

Four-week-old mice with Type 2 diabetes and cataracts were exposed to 1.25 ata with 36% oxygen, 6 h daily, for 12 weeks, followed by normal conditions at 1 ata with 21% oxygen for 16 weeks (cataract + hyperbaric group). Levels of blood glucose and derivatives of reactive oxygen metabolites (dROMs), used as an index of oxidative stress, and the turbidities of the lenses from these mice at 4, 8, 12, 16, and 32 weeks of age were compared with those of control and diabetic (cataract group) mice not exposed to HBO.

RESULTS

Non-fasting and fasting blood glucose levels were lower in the cataract + hyperbaric group at 12, 16, and 32 weeks of age than in the age-matched cataract group. The levels of dROMs were lower in the cataract + hyperbaric group at 16 and 32 weeks of age than in the age-matched cataract group. The turbidities of the peripheral and central regions of the lenses were lower in the cataract + hyperbaric group at 12, 16, and 32 weeks of age than in the age-matched cataract group.

CONCLUSIONS

Hyperbaric exposure at 1.25 ata with 36% oxygen delays cataract development and progression in mice with Type 2 diabetes.

Modulation of C-reactive protein and tumour necrosis factor-α in collagen-induced arthritis in Dark Agouti rats: impact of collagen concentration on severity of arthritis

OBJECTIVES

The study investigated the effect of collagen-induced arthritis in Dark Agouti (DA) rats on the level of C-reactive protein and inflammatory cytokine tumour necrosis factor-alpha (TNF-α).

SUBJECTS

Female Dark Agouti (DA) rats.

METHODS

Three different dosages of (2 mg/kg of body weight, 3 mg/kg of body weight and 4 mg/kg of body weight) collagen and complete Freund's adjuvant suspension were tested. After 45 days, serum C-reactive protein, TNF-α, superoxide dismutase and total glutathione assays were done. Radiographic and histopathological changes in the joints were compared.

RESULTS

All three groups showed signs of arthritic changes, confirmed by histopathological and radiographic changes. Severe arthritic changes were seen in the rats injected with 4 mg/kg of body weight of collagen. There was a significant increase in C-reactive protein, TNF-α, super oxide dismutase and total glutathione levels in the plasma in arthritis rats and the changes were more significant with 4 mg/kg of collagen.

CONCLUSION

These results demonstrated that the optimal dose to inject to experimental animals in order to get server arthritic changes was 4 mg/kg of collagen with complete Freund's adjuvant suspension. Severe arthritis changes induced significant elevation in plasma C-reactive protein and TNF-α levels.