The effect of iNOS inhibitors and hyperbaric oxygen treatment in a rat model of experimental colitis

The role of hyperbaric oxygen therapy in the treatment of radiation lesions

INTRODUCTION

Cancer remains one of the leading causes of death worldwide, with 50-60% of patients requiring radiotherapy during the course of treatment. Patients' survival rate has increased significantly, with an inevitable increase in the number of patients experiencing side effects from cancer therapy. One such effect is late radiation injuries in which hyperbaric oxygen therapy appears as complementary treatment. With this work we intend to divulge the results of applying hyperbaric oxygen therapy among patients presenting radiation lesions in our Hyperbaric Medicine Unit.

MATERIALS AND METHODS

Retrospective analysis of clinical records of patients with radiation lesions treated at the Hyperbaric Medicine Unit assessed by the scale Late Effects of Normal Tissues-Subjective, Objective, Management, Analytical (LENT-SOMA) before and after treatment, between October 2014 and September 2019 were included. Demographic characteristics, primary tumor site, subjective assessment of the LENT-SOMA scale before and after treatment were collected and a comparative analysis (Students t test) was done.

RESULTS

88 patients included: 33 with radiation cystitis, 20 with radiation proctitis, 13 with osteoradionecrosis of the mandible and 22 with radiation enteritis. In all groups, there was a significant decrease (p < 0.005) in the subjective parameter of the LENT-SOMA scale.

DISCUSSION

Late radiation lesions have a major influence on patients' quality of life. In our study hyperbaric oxygen therapy presents as an effective therapy after the failure of conventional treatments.

CONCLUSION

Hyperbaric oxygen therapy is an effective complementary therapy in the treatment of refractory radiation lesions.

Hyperbaric oxygen therapy as a potential treatment for post-traumatic stress disorder associated with traumatic brain injury

Traumatic brain injury (TBI) describes the presence of physical damage to the brain as a consequence of an insult and frequently possesses psychological and neurological symptoms depending on the severity of the injury. The recent increased military presence of US troops in Iraq and Afghanistan has coincided with greater use of improvised exploding devices, resulting in many returning soldiers suffering from some degree of TBI. A biphasic response is observed which is first directly injury-related, and second due to hypoxia, increased oxidative stress, and inflammation. A proportion of the returning soldiers also suffer from post-traumatic stress disorder (PTSD), and in some cases, this may be a consequence of TBI. Effective treatments are still being identified, and a possible therapeutic candidate is hyperbaric oxygen therapy (HBOT). Some clinical trials have been performed which suggest benefits with regard to survival and disease severity of TBI and/or PTSD, while several other studies do not see any improvement compared to a possibly poorly controlled sham. HBOT has been shown to reduce apoptosis, upregulate growth factors, promote antioxidant levels, and inhibit inflammatory cytokines in animal models, and hence, it is likely that HBOT could be advantageous in treating at least the secondary phase of TBI and PTSD. There is some evidence of a putative prophylactic or preconditioning benefit of HBOT exposure in animal models of brain injury, and the optimal time frame for treatment is yet to be determined. HBOT has potential side effects such as acute cerebral toxicity and more reactive oxygen species with long-term use, and therefore, optimizing exposure duration to maximize the reward and decrease the detrimental effects of HBOT is necessary. This review provides a summary of the current understanding of HBOT as well as suggests future directions including prophylactic use and chronic treatment.

Hyperbaric oxygen therapy ameliorates TNBS-induced acute distal colitis in rats

BACKGROUND

This study investigated the therapeutic effects of hyperbaric oxygen in experimental acute distal colitis focusing on its effect on the production of pro-inflammatory cytokines, nitric oxide and hypoxia-inducible factor 1alpha.

METHODS

Colitis was induced with a rectal infusion of 150 mg/kg of TNBS under anesthesia with Ketamine (50 mg/kg) and Xylazine (10 mg/kg). Control animals received only rectal saline. After colitis induction, animals were subjected to two sessions of hyperbaric oxygen and were then euthanized. The distal intestine was resected for macroscopic analysis, determination of myeloperoxidase activity, western-blotting analyses of inducible nitric oxide synthase and cyclooxygenase-2 expression and immunohistochemical analysis of hypoxia-inducible factor 1alpha and cyclooxygenase-2. Cytokines levels in the distal intestine were measured using an enzyme-linked immunosorbent assay.

RESULTS

Hyperbaric oxygen therapy attenuated the severity of acute distal colitis, with reduced macroscopic damage score. This effect was associated with prevention in the increase of pro-inflammatory cytokine production; myeloperoxidase activity, in the expression of inducible nitric oxide synthase and cyclooxygenase-2. Finally, hyperbaric oxygen inhibited the acute distal colitis-induced up-regulation of hypoxia-inducible factor 1alpha.

CONCLUSIONS

The results indicate that hyperbaric oxygen attenuates the severity of acute distal colitis through the down-regulation of pro-inflammatory events.

Spray-dried extract of Phyllanthus niruri L. reduces mucosal damage in rats with intestinal inflammation

Objectives

In this study, the preventive intestinal anti-inflammatory activity of spray-dried extract of P. niruri (SDEPn) was tested in the model of acetic acid (10%)-induced ulcerative colitis in the rat.

Methods

Colitis animals were given orally at doses 25, 100 and 200 mg/kg. Colons tissue was analysed by macroscopic score, by histopathology score, by the immunohistochemical examination of tumour necrosis factor alpha, p53 and interferon gamma; by spectroscopic ultraviolet-visible spectrophotometry (UV/VIS) analysis of the levels of myeloperoxidase, malonaldehyde and total glutathione.

Key Findings/Result

Pretreatment of the extract to colitic rats significantly attenuated colonic macroscopic damage induced by acetic acid (P &lt; 0.01). Spray-dried extract of P. niruri prevented glutathione depletion (P &lt; 0.001) and malondialdehyde levels (P &lt; 0.05) declined. Spray-dried extract of P. niruri significantly reduced microscopic damage to tissues, such as leukocyte infiltration accompanied by a significant reduction in myeloperoxidase activity (P &lt; 0.5). Immunohistochemistry revealed a decline in the TNF-α, IFN-γ and p53 protein (P &lt; 0.05).

Conclusion

Spray-dried extract of P. niruri has a beneficial effect in the acute phase of acetic acid-induced colitis in the rat, which is probably related to its antioxidant properties.

iNOS expression and osteocyte apoptosis in idiopathic, non-traumatic osteonecrosis

BACKGROUND AND PURPOSE

Non-traumatic osteonecrosis is a progressive disease with multiple etiologies. It affects younger individuals more and more, often leading to total hip arthroplasty. We investigated whether there is a correlation between inducible nitric oxide synthase (iNOS) expression and osteocyte apoptosis in non-traumatic osteonecrosis.

PATIENTS AND METHODS

We collected and studied 20 human idiopathic, non-traumatic osteonecrosis femoral heads. Subchondral bone samples in the non-sclerotic region (n = 30), collected from osteoarthritis patients, were used as controls. Spontaneously hypertensive rats were used as a model for osteonecrosis in the study. We used scanning electron microscopy, TUNEL assay, and immunohistochemical staining to study osteocyte changes and apoptosis.

RESULTS

The morphology of osteocytes in the areas close to the necrotic region changed and the number of apoptotic osteocytes increased in comparison with the same region in control groups. The expression of iNOS and cytochrome C in osteocytes increased while Bax expression was not detectable in osteonecrosis samples. Using spontaneously hypertensive rats, we found a positive correlation between iNOS expression and osteocyte apoptosis in the osteonecrotic region. iNOS inhibitor (aminoguanidine) added to the drinking water for 5 weeks reduced the production of iNOS and osteonecrosis compared to a control group without aminoguanidine.

INTERPRETATION

Our findings show that increased iNOS expression can lead to osteocyte apopotosis in idiopathic, non-traumatic osteonecrosis and that an iNOS inhibitor may prevent the progression of the disease.

Effects of hyperbaric oxygen on nitric oxide generation in humans

BACKGROUND

Hyperbaric oxygen (HBO2) has been suggested to affect nitric oxide (NO) generation in humans. Specific NO synthases (NOSs) use L-arginine and molecular oxygen to produce NO but this signaling radical may also be formed by serial reduction of the inorganic anions nitrate and nitrite. Interestingly, commensal facultative anaerobic bacteria in the oral cavity are necessary for the first step to reduce nitrate to nitrite. The nitrate-nitrite-NO pathway is greatly potentiated by hypoxia and low pH in contrast to classical NOS-dependent NO generation. We investigated the effects of HBO2 on NO generation in healthy subjects including orally and nasally exhaled NO, plasma and salivary nitrate and nitrite as well as plasma cGMP and plasma citrulline/arginine ratio. In addition, we also conducted in-vitro experiments in order to investigate the effects of hyperoxia on nitrate/nitrite metabolism and NO generation by oral bacteria.

METHODS

Two separate HBO2 experiments were performed. In a cross-over experiment (EXP1) subjects breathed air at 130 kPa (control) or oxygen at 250 kPa for 100 minutes and parameters were measured before and after exposure. In experiment 2 (EXP 2) measurements were performed also during HBO2 at 250 kPa for 110 minutes.

RESULTS

HBO2 acutely reduced orally and nasally exhaled NO by 30% and 16%, respectively. There was a marked decrease in salivary nitrite/nitrate ratio during and after HBO2, indicating a reduced bacterial conversion of nitrate to nitrite and NO. This was supported by in vitro experiments with oral bacteria showing that hyperoxia inhibited bacterial nitrate and nitrite reduction leading to reduced NO generation. Plasma nitrate was unaffected by HBO2 while plasma nitrite was reduced during HBO2 treatment. In contrast, plasma cGMP increased during HBO2 as did citrulline/arginine ratio after treatment and control.

CONCLUSION

HBO2-exposure in humans affects NO generation in the airways and systemically differently. These data suggest that the individual NOSs as well as the nitrate-nitrite-NO pathway do not respond in a similar way to HBO2.

Ethanol Extract of Antrodia camphorata Grown on Germinated Brown Rice Suppresses Inflammatory Responses in Mice with Acute DSS-Induced Colitis

The anti-inflammatory activity of Antrodia camphorata (AC) grown on germinated brown rice (CBR) extract was evaluated in vitro and in vivo. CBR suppressed the release of nitric oxide (NO) and prostaglandin (PG) E2 from lipopolysaccharide-(LPS-)stimulated RAW264.7 cells. CBR inhibited the level of inducible nitric oxide synthase (iNOS) and cyclooxygenase-(COX-)2 proteins, and it activated p38-MAPK, extracellular signal-related kinases (ERK), and NF-κB in LPS-stimulated RAW264.7 macrophages. LPS-induced tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) mRNA expression was reduced in CBR-treated RAW264.7 cells. In concert with in vitro data, CBR suppressed the levels of dextran-sulfate-sodium-(DSS-)induced iNOS and COX-2 proteins in the colon tissue. CBR treatment inhibited activated p38-MAPK, ERK, and NF-κB proteins in the colon tissue of DSS-induced mice. TNF-α and IL-6 mRNA expression was reduced in DSS+CBR-treated mice. The disease activity index and histological scores were significantly lower in CBR-treated mice (500 mg/kg/day) than in DSS-treated mice (P < 0.05 versus DSS). This is the first report of anti-inflammatory activity of CBR in DSS-induced acute colitis. These results suggest that CBR is a promising, potential agent for preventing acute colitis through the inhibition of NF-κB signaling and its upstream signaling molecules, including MAPKs.

Crohn's disease and hyperbaric oxygen therapy

PURPOSE

Evaluate the application of Hyperbaric Oxygen Therapy (HBO) in patients with Crohn's disease (CD) refractory to pharmacologic therapy, who developed abdominal, anorectal or skin complications.

METHODS

Fourteen selected patients with refractory CD and treated at the School of Medicine of Ribeirao Preto, University of Sao Paulo (FMRP-USP) and at the Center of Hyperbaric Medicine, São Paulo Hospital (CEMEHI) were submitted to HBO.

RESULTS

Of the 14 patients evaluated, 11 had a satisfactory response.

CONCLUSION

HBO has shown benefits in patients with CD refractory to pharmacologic therapy.

Effects of hyperoxia exposure on metabolic markers and gene expression in 3T3-L1 adipocytes

Adipose tissue often becomes poorly oxygenated in obese subjects. This feature may provide cellular mechanisms involving chronic inflammation processes such as the release of pro-inflammatory cytokines and macrophage infiltration. In this context, the purpose of the present study was to determine whether a hyperoxia exposure on mature adipocytes may influence the expression of some adipokines and involve favorable changes in specific metabolic variables. Thus, 3T3-L1 adipocytes (14 days differentiated) were treated with 95 % oxygen for 24 h. Cell viability, intra and extracellular reactive oxygen species (ROS) content, glucose uptake, as well as lactate and glycerol concentrations were measured in the culture media. Also, mRNA levels of hypoxia-inducible factor (HIF)-1α, leptin, interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, peroxisome proliferator-activated receptor (PPAR)-γ, adiponectin, and angiopoietin-related protein (ANGPTL)4 were analyzed. Hyperoxia treatment increased intra and extracellular ROS content, reduced glucose uptake and lactate release and increased glycerol release. Additionally, a higher oxygen tension led to an upregulation of the expression of IL-6, MCP-1, and PPAR-γ, while ANGPTL4 was downregulated in the hyperoxia group with respect to control. The present data shows that hyperoxia treatment seems to produce an inflammatory response due to the release of ROS and the upregulation of pro-inflammatory adipokines, such as IL-6 and MCP-1. On the other hand, hyperoxia may have an indirect effect on insulin sensitivity due to the upregulation of PPAR-γ signaling as well as a possible modulation of both glucose and lipid metabolic markers. To our knowledge, this is the first study analyzing the effect of hyperoxia in 3T3-L1 adipocytes.

Hyperbaric oxygen therapy: can it prevent irradiation-induced necrosis?

Radiosurgery is an important non-invasive procedure for the treatment of tumors and vascular malformations. However, in addition to killing target tissues, cranial irradiation induces damage to adjacent healthy tissues leading to neurological deterioration in both pediatric and adult patients, which is poorly understood and insufficiently treatable. To minimize irradiation damage to healthy tissue, not the optimal therapeutic irradiation dose required to eliminate the target lesion is used but lower doses. Although the success rate of irradiation surgery is about 95%, 5% of patients suffer problems, most commonly neurological, that are thought to be a direct consequence of irradiation-induced inflammation. Although no direct correlation has been demonstrated, the appearance and disappearance of inflammation that develops following irradiation commonly parallel the appearance and disappearance of neurological side effects that are associated with the neurological function of the irradiated brain regions. These observations have led to the hypothesis that brain inflammation is causally related to the observed neurological side effects. Studies indicate that hyperbaric oxygen therapy (HBOT) applied after the appearance of irradiation-induced neurological side effects reduces the incidence and severity of those side effects. This may result from HBOT reducing inflammation, promoting angiogenesis, and influencing other cellular functions thereby suppressing events that cause the neurological side effects. However, it would be significantly better for the patient if rather than waiting for neurological side effects to become manifest they could be avoided. This review examines irradiation-induced neurological side effects, methods that minimize or resolve those side effects, and concludes with a discussion of whether HBOT applied following irradiation, but before manifestation of neurological side effects may prevent or reduce the appearance of irradiation-induced neurological side effects.

Hyperbaric oxygen treatment for inflammatory bowel disease: a systematic review and analysis

Background

Traditionally, hyperbaric oxygen treatment (HBOT) has been used to treat a limited repertoire of disease, including decompression sickness and healing of problem wounds. However, some investigators have used HBOT to treat inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis.

Methods

Comprehensive searches were conducted in 8 scientific databases through 2011 to identify publications using HBOT in IBD. Human studies and animal models were collated separately.

Results

Thirteen studies of HBOT in Crohn's disease and 6 studies in ulcerative colitis were identified. In all studies, participants had severe disease refractory to standard medical treatments, including corticosteroids, immunomodulators and anti-inflammatory medications. In patients with Crohn's disease, 31/40 (78%) had clinical improvements with HBOT, while all 39 patients with ulcerative colitis improved. One study in Crohn's disease reported a significant decrease in proinflammatory cytokines (IL-1, IL-6 and TNF-alpha) and one study in ulcerative colitis reported a decrease in IL-6 with HBOT. Adverse events were minimal. Twelve publications reported using HBOT in animal models of experimentally-induced IBD, including several studies reporting decreased markers of inflammation or immune dysregulation, including TNF-alpha (3 studies), IL-1beta (2 studies), neopterin (1 study) and myeloperoxidase activity (5 studies). HBOT also decreased oxidative stress markers including malondialdehyde (3 studies) and plasma carbonyl content (2 studies), except for one study that reported increased plasma carbonyl content. Several studies reported HBOT lowered nitric oxide (3 studies) and nitric oxide synthase (3 studies) and one study reported a decrease in prostaglandin E₂ levels. Four animal studies reported decreased edema or colonic tissue weight with HBOT, and 8 studies reported microscopic improvements on histopathological examination. Although most publications reported improvements with HBOT, some studies suffered from limitations, including possible publication and referral biases, the lack of a control group, the retrospective nature and a small number of participants.

Conclusions

HBOT lowered markers of inflammation and oxidative stress and ameliorated IBD in both human and animal studies. Most treated patients were refractory to standard medical treatments. Additional studies are warranted to investigate the effects of HBOT on biomarkers of oxidative stress and inflammation as well as clinical outcomes in individuals with IBD.