Nitric oxide, inducible nitric oxide synthase and inflammation in veterinary medicine

Involvement of shedding induced by ADAM17 on the nitric oxide pathway in hypertension

A Disintegrin and Metalloprotease 17 (ADAM17), also called tumor necrosis factor-ɑ (TNF-ɑ) convertase (TACE), is a well-known protease involved in the sheddase of growth factors, chemokines and cytokines. ADAM17 is also enrolled in hypertension, especially by shedding of angiotensin converting enzyme type 2 (ACE2) leading to impairment of angiotensin 1–7 [Ang-(1–7)] production and injury in vasodilation, induction of renal damage and cardiac hypertrophy. Activation of Mas receptor (MasR) by binding of Ang-(1–7) induces an increase in the nitric oxide (NO) gaseous molecule, which is an essential factor of vascular homeostasis and blood pressure control. On the other hand, TNF-ɑ has demonstrated to stimulate a decrease in nitric oxide bioavailability, triggering a disrupt in endothelium-dependent vasorelaxation. In spite of the previous studies, little knowledge is available about the involvement of the metalloprotease 17 and the NO pathways. Here we will provide an overview of the role of ADAM17 and Its mechanisms implicated with the NO formation.

Influence and Implications of the Molecular Paradigm of Nitric Oxide Underlying Inflammatory Reactions of the Gastrointestinal Tract of Dog: A Major Hallmark of Inflammatory Bowel Disease

Nitric oxide (NO), a pleiotropic free radical messenger molecule, is responsible for the various cellular function of the gastrointestinal mucosa. It plays a major role in the maintenance of perfusion, regulation of microvascular, epithelial permeability, and immune functions. Nitric oxide exerts its beneficial effect on the initiation and maintenance of inflammation in human inflammatory bowel disease (IBD). But the accelerated production of NO triggers activation of the inducible form of the NO synthase enzyme (iNOS) that leads to damages of the intestinal membrane. Nitric oxide synthase enzyme is responsible for the higher production of NO from l-arginine and causes an inflammatory condition in the intestinal epithelium. Nitric oxide induces nitrative DNA damage and oxidative DNA damage in the cellular system. Accelerated production of NO enhances iNOS activity that is associated with cytotoxicity and apoptosis of gastrointestinal epithelial cells in the dog. Chronic inflammation leads to angiogenesis that is modulated by the immune system in IBD. Chronic inflammation is a major risk factor for the development of gastrointestinal malignancies. Nitric oxide participates in mucosal inflammation in the intestine through invigoration of NO synthase enzyme. The intrinsic complex mechanism is correlated with the inflammation in the gastrointestinal tract and is also correlated with the expression of iNOS, enzymatic activity and NO production. Nitric oxide employs a significant role in modulating epithelial permeability with accelerated immune response in acute colitis. But the enormous generation of NO causes adverse effects on the mucosal cell during the inflammatory process in IBD. In this review, a complex episode of NO generation with altered biochemical pathways was assessed for the regulation of mucosal inflammation in inflammatory bowel disease of dogs. This review is a unique compilation of the role of NO in the pathogenesis of inflammatory bowel disease of dogs. Nitric oxide plays a key role in modulating cancer in the gastrointestinal tract. This review seeks to explore the characteristics of NO as a major hallmark of canine inflammatory bowel diseases.

Nitric Oxide as a Central Molecule in Hypertension: Focus on the Vasorelaxant Activity of New Nitric Oxide Donors

Cardiovascular diseases include all types of disorders related to the heart or blood vessels. High blood pressure is an important risk factor for cardiac complications and pathological disorders. An increase in circulating angiotensin-II is a potent stimulus for the expression of reactive oxygen species and pro-inflammatory cytokines that activate oxidative stress, perpetuating a deleterious effect in hypertension. Studies demonstrate the capacity of NO to prevent platelet or leukocyte activation and adhesion and inhibition of proliferation, as well as to modulate inflammatory or anti-inflammatory reactions and migration of vascular smooth muscle cells. However, in conditions of low availability of NO, such as during hypertension, these processes are impaired. Currently, there is great interest in the development of compounds capable of releasing NO in a modulated and stable way. Accordingly, compounds containing metal ions coupled to NO are being investigated and are widely recognized as having great relevance in the treatment of different diseases. Therefore, the exogenous administration of NO is an attractive and pharmacological alternative in the study and treatment of hypertension. The present review summarizes the role of nitric oxide in hypertension, focusing on the role of new NO donors, particularly the metal-based drugs and their protagonist activity in vascular function.

Small molecule inhibitors and stimulators of inducible nitric oxide synthase in cancer cells from natural origin (phytochemicals, marine compounds, antibiotics)

Nitric oxide synthases (NOS) are a family of isoforms, which generate nitric oxide (NO). NO is one of the smallest molecules in nature and acts mainly as a potent vasodilator. It participates in various biological processes ranging from physiological to pathological conditions. Inducible NOS (iNOS, NOS2) is a calcium-independent and inducible isoform. Despite high iNOS expression in many tumors, the role of iNOS is still unclear and complex with both enhancing and prohibiting actions in tumorigenesis. Nature presents a broad variety of natural stimulators and inhibitors, which may either promote or inhibit iNOS response. In the present review, we give an overview of iNOS-modulating agents with a special focus on both natural and synthetic molecules and their effects in related biological processes. The role of iNOS in physiological and pathological conditions is also discussed.

Molecular mechanism of action responsible for carrageenan-induced inflammatory response

Carrageenan-induced inflammation has long been used as an in vivo model of local inflammation. We developed an in vitro model of inflammation using primary blood cells to characterize gene induction following carrageenan (λ-CGN) stimulation and identify the signal transduction pathway(s) through which λ-CGN worked, using swine whole blood cultures from Yorkshire barrows. Blood samples were divided into stimulated and unstimulated groups. Unstimulated blood was a control for λ-CGN treated cultures to delineate treatment effects from time-in-culture effects. All cultures were collected and separated into two fractions; supernatant for ELISA analyses and white blood cells for mRNA expression. Lambda (λ)-CGN induced MCP-1 at the proteomic and the genomic levels. Lambda-CGN increased IL-8 protein production but had no impact on serum amyloid A protein levels. Alveolar Macrophage-Derived Neutrophil Chemotactic Factor-II (AMCF-II), a swine-specific member of the IL8/GRO family, showed increased gene expression. TNF-α and IL-6 protein levels were not induced by λ-CGN stimulation. Stimulation of HEK-293 cells co-transfected with a single pattern recognition receptor and the secreted embryonic alkaline phosphatase (SEAP) read-out system demonstrated that λ-CGN signals through the TLR-2 and TLR-4 signal transduction pathways. Using silencing RNA to inhibit TLR6 expression in TLR2 transfected HEK-293 cells indicated that λ-CGN works through the TLR2/6 pathway. Silencing TLR6 expression in TLR4 transfected HEK-293 cells showed that λ-CGN stimulation of this cell line worked through a TLR4/6 heterodimer, as lipopolysaccharide (LPS) induced SEAP production through a TLR4 homodimer. These results demonstrate that although carrageenan can stimulate through TLR4 signaling pathways, it initiates an inflammatory response in these cells that differs from a typical endotoxin effect such as LPS stimulation, in terms of the pathways and gene products altered, suggesting that activation of TLR2/6 and TLR4/6 are the predominant pathways through which carrageenan induces inflammatory responses.

Inducible nitric oxide synthase: Good or bad?

Nitric oxide synthases (NOS) are a family of isoforms responsible for the synthesis of the potent dilator nitric oxide (NO). Expression of inducible NOS (iNOS) occurs in conditions of inflammation, and produces large amounts of NO. In pathological conditions iNOS is regarded as a harmful enzyme and is proposed to be a major contributor to diseases of the cardiovascular system such as atherosclerosis. In this review, we address the notion that iNOS is a detrimental enzyme in disease and discuss its potentially beneficial roles. Additionally, we describe other molecules associated with iNOS in diseases such as atherosclerosis, and current research on therapeutic inhibitors tested to reduced pathology associated with cardiovascular diseases (CVD).

Topical treatment with probiotic Lactobacillus brevis CD2 inhibits experimental periodontal inflammation and bone loss

BACKGROUND AND OBJECTIVE

An increasing body of evidence suggests that the use of probiotic bacteria is a promising intervention approach for the treatment of inflammatory diseases with a polymicrobial etiology. The objective of this study was to determine whether Lactobacillus brevis CD2 could inhibit periodontal inflammation and bone loss in experimental periodontitis.

MATERIAL AND METHODS

Periodontitis was induced by placing a silk ligature around the second maxillary molar of mice treated with L. brevis CD2 (8 × 10(5)  CFU in 1 mm(2) lyopatch) or placebo, which were placed between the gingiva and the buccal mucosa near the ligated teeth. The mice were killed after 5 d and bone loss was measured morphometrically, gingival expression of proinflammatory cytokines was determined by quantitative real-time polymerase chain reaction, and CFU counts of periodontitis-associated bacteria were determined after aerobic and anaerobic culture. To determine the role of arginine deiminase released by L. brevis CD2, soluble extracts with or without formamidine (arginine deiminase inhibitor) were tested in in vitro cellular activation assays.

RESULTS

Mice topically treated with L. brevis CD2 displayed significantly decreased bone loss and lower expression of tumor necrosis factor, and interleukin-1β, -6 and -17A as compared to placebo-treated mice. Moreover, L. brevis CD2-treated mice displayed lower counts of anaerobic bacteria but higher counts of aerobic bacteria than placebo-treated mice. In in vitro assays, the anti-inflammatory effects of soluble L. brevis CD2 extracts were heavily dependent on the presence of functional arginine deiminase, an enzyme that can inhibit nitric oxide synthesis.

CONCLUSION

These data provide proof-of-concept that the probiotic L. brevis CD2 can inhibit periodontitis through modulatory effects on the host response and the periodontal microbiota.

Theoretical Studies of Substitutionally Doped Single-Walled Nanotubes

The rich chemistry of single-walled carbon nanotubes (SWCNTs) is enhanced by substitutional doping, a process in which a single atom of the nanotube sidewall is replaced by a heteroatom. These so-called heteroatom-substituted SWCNTs (HSWCNTs) exhibit unique chemical and physical properties not observed in their corresponding undoped congeners. Herein, we present theoretical studies of both main group element and transition metal-doped HSWCNTs. Within density functional theory (DFT), we discuss mechanistic details of their proposed synthesis from vacancy-defected SWCNTs and describe their geometric and electronic properties. Additionally, we propose applications for these nanomaterials in nanosensing, nanoelectronics, and nanocatalysis.

Fluctuations in the occurrence of Escherichia coli O157:H7 on a Norwegian farm*

AIM

To describe the distribution of Escherichia coli O157:H7 on a sporadically positive dairy farm and on possible contact farms over a one-year period.

METHODS AND RESULTS

Environmental and faecal samples from all animals at the farm, and faecal samples from animals at contact farms were analysed for E. coli O157:H7 by immunomagnetic separation methods or VIDAS. Confirmed isolates were tested for cytotoxicity in the Vero cell assay and typed by PFGE. Escherichia coli O157:H7 (stx2 and eae) of the same PFGE type were isolated from cattle, sheep, hens and environmental samples at variable levels during summer and fall 2002, but were not detected in 2003.

CONCLUSIONS

Escherichia coli O157:H7 had a widespread distribution on the farm investigated, but the original source of contamination could not be identified. The occurrence of this bacterium on the farm did not result in any detectable increase in gastrointestinal disease in the associated population.

SIGNIFICANCE AND IMPACT OF THE STUDY

Despite a low endemic level of E. coli O157:H7 in the Norwegian cattle population, the growth and spread of this potentially important bacterium may occur.

Distribution of Escherichia coli O157:H7 within and among cattle operations in pasture-based agricultural areas

OBJECTIVE

To determine the distribution of Escherichia coli O157:H7 in pasture-based cattle production areas.

SAMPLE POPULATION

Two 100-km2 agricultural areas consisting of 207 pasture, 14 beef-confinement, and 3 dairy locations within 24 cattle operations.

PROCEDURE

13,726 samples from cattle, wildlife, and water sources were obtained during an 11-month period. Escherichia coli O157:H7 was identified by use of culture and polymerase chain reaction assays and characterized by pulsed-field gel electrophoresis (PFGE).

RESULTS

Odds of recovering E coli O157:H7 from feeder-aged cattle were > 4 times the odds for cow-calf or dairy cattle. There was no difference in prevalence for pastured versus confined cattle after controlling for production age group. Number of samples collected (37 to 4,829), samples that yielded E coli O157:H7 (0 to 53), and PFGE subtypes (0 to 48) for each operation varied and were highly correlated. Although most PFGE subtypes were only detected once, 17 subtypes were detected on more than 1 operation. Ten of 12 operations at which E coli O157:H7 was detected had at least 1 subtype that also was detected on another operation. We did not detect differences in the probability of having the same subtype for adjacent operations, nonadjacent operations in the same study area, or operations in the other study area.

CONCLUSIONS AND CLINICAL RELEVANCE

Strategies aimed at controlling E coli O157:H7 and specific subtypes should account for the widespread distribution and higher prevalence in feeder-aged cattle regardless of production environment and the fact that adjacent and distant cattle operations can have similar subtypes.

Relationship between inducible nitric oxide synthase expression and angiogenesis in primary gallbladder carcinoma tissue

AIM: To explore the relationship between angiogenesis and biological behaviors of primary gallbladder carcinoma (PGBC), the relationship between the expression of inducible nitric oxide synthase (iNOS) and biological behaviors of PGBC and its relationship with the expression of iNOS and angiogenesis of PGBC.

METHODS: The expression of iNOS and micro-vessel density (MVD) were assessed by immunohistochemical method and image analysis system in 40 specimens of PGBC and in 8 specimens of normal gallbladder. The immunostaining results and related clinicopathologic materials were analyzed by statistical methods.

RESULTS: MVD in PGBC was significantly higher than that in normal gallbladder tissue (46 ± 14 vs 14 ± 6, P < 0.05), and was not related with age, gender, tumor size and histological type. MVD of poorly and undifferentiated tumor tissues was higher than that of moderately-differentiated and well-differentiated tumor tissues (52 ± 9 vs 43 ± 9 vs 33 ± 6, P < 0.01). MVD of Nevin IV and V stages was higher than that of Nevin I, II and III stages (52 ± 8 vs 37 ± 13, P < 0.01). MVD of cases with lymphatic or liver metastasis was significantly higher than that without liver metastasis (55 ± 6 vs 42 ± 10, P < 0.05) or lymphatic metastasis (53 ± 8 vs 38 ± 8, P < 0.01). The positive level index (PLI) of iNOS in PGBC was 0.435 ± 0.134, and was not related with age, gender, tumor size, histological type, differentiation and clinical stage of PGBC. The PLI of iNOS in cases with lymphatic metastasis was higher than that without lymphatic metastasis (0.573 ± 0.078 vs 0.367 ± 0.064, P < 0.01). The PLI of iNOS in cases with liver metastasis was higher than that without liver metastasis (0.533 ± 0.067 vs 0.424 ± 0.084, P < 0.05). There was a significant correlation between PLI of iNOS and MVD in PGBC (P < 0.05).

CONCLUSION: Angiogenesis of PGBC is significantly related to the biological behaviors of PGBC. The expression of iNOS is related to the biological behaviors of PGBC. The detection of MVD and the expression of iNOS in PGBC can be used as parameters to determine the degree of malignancy and prognosis.

Titanium implants enhance pulmonary nitric oxide production and lung injury in rats exposed to endotoxin

An increase in levels of elemental Ti in the blood and lung of rats with a Ti alloy implant has been demonstrated. However, the pathophysiological role of the elevated elemental Ti level in the circulation remains unclear. Rats were implanted with Ti alloy discs for 4 weeks. The levels of elemental Ti in the blood and lung were especially increased compared with other tissues. The Ti alloy implant enhanced lung injury related to endotoxin from Gram-negative bacteria (lipopolysaccharide, LPS), which was characterized by lung edema and other histological changes such as recruitment of neutrophils, interstitial edema, and alveolar hemorrhage in the lung. In the presence of endotoxin, an increase of nitrite production was shown in the plasma and bronchoalveolar lavage fluid of rats implanted with a Ti alloy. Moreover, the Ti alloy implant further enhanced the induction of inducible nitric oxide (NO) synthase (iNOS) protein expression induced by LPS in the lung. These endotoxin-related responses in the presence or absence of the Ti alloy implant could be inhibited by aminoguanidine (an iNOS inhibitor). These results provide the first experimental evidence that circulating Ti released from Ti alloy implants has an ability to affect pulmonary iNOS protein expression, and enhance the pathogenesis of acute lung injury during endotoxemia.