Pituitary Adenylate Cyclase-Activating Polypeptide Reverses Ammonium Metavanadate-Induced Airway Hyperresponsiveness in Rats. Oxid Med Cell Longev. 2015;2015:787561. [PMID: 26199679 PMCID: PMC4496651 DOI: 10.1155/2015/787561]

Diagnostic and Prognostic Value of PACAP in Multiple Myeloma

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a multifunctional neuropeptide with well-known anti-inflammatory, antioxidant, antitumor, and immunomodulatory effects. PACAP regulates the production of various proinflammatory factors and may influence the complex cytokine network of the bone marrow microenvironment altered by plasma cells, affecting the progression of multiple myeloma (MM) and the development of end-organ damage. The aim of our study was to investigate the changes in PACAP-38 levels in patients with MM to explore its value as a potential biomarker in this disease. We compared the plasma PACAP-38 levels of MM patients with healthy individuals by ELISA method and examined its relationship with various MM-related clinical and laboratory parameters. Lower PACAP-38 levels were measured in MM patients compared with the healthy controls, however, this difference vanished if the patient achieved any response better than partial response. In addition, lower peptide levels were found in elderly patients. Significantly higher PACAP-38 levels were seen in patients with lower stage, lower plasma cell infiltration in bone marrow, lower markers of tumor burden in serum, lower total urinary and Bence-Jones protein levels, and in patients after lenalidomide therapy. Higher PACAP-38 levels in newly diagnosed MM patients predicted longer survival and a higher probability of complete response to treatment. Our findings confirm the hypothesis that PACAP plays an important role in the pathomechanism of MM. Furthermore, our results suggest that PACAP might be used as a valuable, non-invasive, complementary biomarker in diagnosis, and may be utilized for prognosis prediction and response monitoring.

Vanadium exposure exacerbates allergic airway inflammation and remodeling through triggering reactive oxidative stress

Background

Metal components of environmental PM2.5 are associated with the exacerbation of allergic diseases like asthma. In our recent hospital-based population study, exposure to vanadium is shown to pose a significant risk for current asthma, but the causal relationship and its underlying molecular mechanisms remain unclear.

Objective

We sought to determine whether vanadium co-exposure can aggravate house dust mite (HDM)-induced allergic airway inflammation and remodeling, as well as investigate its related mechanisms.

Methods

Asthma mouse model was generated by using either vanadium pentoxide (V₂O₅) or HDM alone or in combination, in which the airway inflammation and remodeling was investigated. The effect of V₂O₅ co-exposure on HDM-induced epithelial-derived cytokine release and oxidative stress (ROS) generation was also examined by in vitro analyses. The role of ROS in V₂O₅ co-exposure-induced cytokine release and airway inflammation and remodeling was examined by using inhibitors or antioxidant.

Results

Compared to HDM alone, V₂O₅ co-exposure exacerbated HDM-induced airway inflammation with increased infiltration of inflammatory cells and elevated levels of Th1/Th2/Th17 and epithelial-derived (IL-25, TSLP) cytokines in the bronchoalveolar lavage fluids (BALFs). Intriguingly, V₂O₅ co-exposure also potentiated HDM-induced airway remodeling. Increased cytokine release was further supported by in vitro analysis in human bronchial epithelial cells (HBECs). Mechanistically, ROS, particularly mitochondrial-derived ROS, was significantly enhanced in HBECs after V₂O₅ co-exposure as compared to HDM challenge alone. Inhibition of ROS with its inhibitor N-acetyl-L-cysteine (NAC) and mitochondrial-targeted antioxidant MitoTEMPO blocked the increased epithelial release caused by V₂O₅ co-exposure. Furthermore, vitamin D₃ as an antioxidant was found to inhibit V₂O₅ co-exposure-induced increased airway epithelial cytokine release and airway remodeling.

Conclusions

Our findings suggest that vanadium co-exposure exacerbates epithelial ROS generation that contribute to increased allergic airway inflammation and remodeling.

Vanadium exposure exacerbates allergic airway inflammation and remodeling through triggering reactive oxidative stress

Background

Metal components of environmental PM2.5 are associated with the exacerbation of allergic diseases like asthma. In our recent hospital-based population study, exposure to vanadium is shown to pose a significant risk for current asthma, but the causal relationship and its underlying molecular mechanisms remain unclear.

Objective

We sought to determine whether vanadium co-exposure can aggravate house dust mite (HDM)-induced allergic airway inflammation and remodeling, as well as investigate its related mechanisms.

Methods

Asthma mouse model was generated by using either vanadium pentoxide (V2O5) or HDM alone or in combination, in which the airway inflammation and remodeling was investigated. The effect of V2O5 co-exposure on HDM-induced epithelial-derived cytokine release and oxidative stress (ROS) generation was also examined by in vitro analyses. The role of ROS in V2O5 co-exposure-induced cytokine release and airway inflammation and remodeling was examined by using inhibitors or antioxidant.

Results

Compared to HDM alone, V2O5 co-exposure exacerbated HDM-induced airway inflammation with increased infiltration of inflammatory cells and elevated levels of Th1/Th2/Th17 and epithelial-derived (IL-25, TSLP) cytokines in the bronchoalveolar lavage fluids (BALFs). Intriguingly, V2O5 co-exposure also potentiated HDM-induced airway remodeling. Increased cytokine release was further supported by in vitro analysis in human bronchial epithelial cells (HBECs). Mechanistically, ROS, particularly mitochondrial-derived ROS, was significantly enhanced in HBECs after V2O5 co-exposure as compared to HDM challenge alone. Inhibition of ROS with its inhibitor N-acetyl-L-cysteine (NAC) and mitochondrial-targeted antioxidant MitoTEMPO blocked the increased epithelial release caused by V2O5 co-exposure. Furthermore, vitamin D3 as an antioxidant was found to inhibit V2O5 co-exposure-induced increased airway epithelial cytokine release and airway remodeling.

Conclusions

Our findings suggest that vanadium co-exposure exacerbates epithelial ROS generation that contribute to increased allergic airway inflammation and remodeling.

Airway Redox Homeostasis and Inflammation Gone Awry: From Molecular Pathogenesis to Emerging Therapeutics in Respiratory Pathology

As aerobic organisms, we are continuously and throughout our lifetime subjected to an oxidizing atmosphere and, most often, to environmental threats. The lung is the internal organ most highly exposed to this milieu. Therefore, it has evolved to confront both oxidative stress induced by reactive oxygen species (ROS) and a variety of pollutants, pathogens, and allergens that promote inflammation and can harm the airways to different degrees. Indeed, an excess of ROS, generated intrinsically or from external sources, can imprint direct damage to key structural cell components (nucleic acids, sugars, lipids, and proteins) and indirectly perturb ROS-mediated signaling in lung epithelia, impairing its homeostasis. These early events complemented with efficient recognition of pathogen- or damage-associated recognition patterns by the airway resident cells alert the immune system, which mounts an inflammatory response to remove the hazards, including collateral dead cells and cellular debris, in an attempt to return to homeostatic conditions. Thus, any major or chronic dysregulation of the redox balance, the air-liquid interface, or defects in epithelial proteins impairing mucociliary clearance or other defense systems may lead to airway damage. Here, we review our understanding of the key role of oxidative stress and inflammation in respiratory pathology, and extensively report current and future trends in antioxidant and anti-inflammatory treatments focusing on the following major acute and chronic lung diseases: acute lung injury/respiratory distress syndrome, asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and cystic fibrosis.

Attenuation of relaxing response induced by pituitary adenylate cyclase-activating polypeptide in bronchial smooth muscle of experimental asthma

Bronchomotor tone is regulated by contraction and relaxation of airway smooth muscle (ASM). A weakened ASM relaxation might be a cause of airway hyperresponsiveness (AHR), a characteristic feature of bronchial asthma. Pituitary adenylyl cyclase-activating polypeptide (PACAP) is known as a mediator that causes ASM relaxation. To date, whether or not the PACAP responsiveness is changed in asthmatic ASM is unknown. The current study examined the hypothesis that relaxation induced by PACAP is reduced in bronchial smooth muscle (BSM) of allergic asthma. The ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Twenty-four hours after the last antigen challenge, the main bronchial smooth muscle (BSM) tissues were isolated. Tension study showed a BSM hyperresponsiveness to acetylcholine in the OA-challenged mice. Both quantitative RT-PCR and immunoblot analyses revealed a significant decrease in PAC₁ receptor expression in BSMs of the diseased mice. Accordingly, in the antigen-challenged group, the PACAP-induced PAC₁ receptor-mediated BSM relaxation was significantly attenuated, whereas the relaxation induced by vasoactive intestinal polypeptide was not changed. These findings suggest that the relaxation induced by PACAP is impaired in BSMs of experimental asthma due to a downregulation of its binding partner PAC₁ receptor. Impaired BSM responsiveness to PACAP might contribute to the AHR in asthma.

Protective Effects of PACAP in Peripheral Organs

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide widely distributed in the nervous system, where it exerts strong neuroprotective effects. PACAP is also expressed in peripheral organs but its peripheral protective effects have not been summarized so far. Therefore, the aim of the present paper is to review the existing literature regarding the cytoprotective effects of PACAP in non-neuronal cell types, peripheral tissues, and organs. Among others, PACAP has widespread expression in the digestive system, where it shows protective effects in various intestinal pathologies, such as duodenal ulcer, small bowel ischemia, and intestinal inflammation. PACAP is present in both the exocrine and endocrine pancreas as well as liver where it reduces inflammation and steatosis by interfering with hepatic pathology related to obesity. It is found in several exocrine glands and also in urinary organs, where, with its protective effects being mainly published regarding renal pathologies, PACAP is protective in numerous conditions. PACAP displays anti-inflammatory effects in upper and lower airways of the respiratory system. In the skin, it is involved in the development of inflammatory pathology such as psoriasis and also has anti-allergic effects in a model of contact dermatitis. In the non-neuronal part of the visual system, PACAP showed protective effects in pathological conditions of the cornea and retinal pigment epithelial cells. The positive role of PACAP has been demonstrated on the formation and healing processes of cartilage and bone where it also prevents osteoarthritis and rheumatoid arthritis development. The protective role of PACAP was also demonstrated in the cardiovascular system in different pathological processes including hyperglycaemia-induced endothelial dysfunction and age-related vascular changes. In the heart, PACAP protects against ischemia, oxidative stress, and cardiomyopathies. PACAP is also involved in the protection against the development of pre-senile systemic amyloidosis, which is presented in various peripheral organs in PACAP-deficient mice. The studies summarized here provide strong evidence for the cytoprotective effects of the peptide. The survival-promoting effects of PACAP depend on a number of factors which are also shortly discussed in the present review.

PACAP38 improves airway epithelial barrier destruction induced by house dust mites allergen

PURPOSE

This study aimed to investigate the mechanism of PACAP38 on house dust mite (HDM)-induced asthmatic airway epithelial barrier destruction.

METHODS

The HDM-induced asthma mice model and 16HBE cell model was established respectively. The enzyme linked immunosorbent assay (ELSIA), cell count and immunohistochemical assay were performed on mice in control group, HDM group and PACAP38 + HDM group.The cAMP/PKA activity, p-CREB and total CREB expression, TEER and the FITC-DX were investigated on cells in control-16HBE group, HDM-16HBE group and PACAP38 + HDM-16HBE group.

RESULTS

The levels of IL-4 and IL-5 in the HDM group were significantly higher than those in the control group (P < 0.05), while the above indexes in the PACAP38 + HDM group were lower than those in the HDM group (P < 0.05). E-cadherin, β-catenin, ZO-1 and occludin in the control group were highly immunoreactive in airway epithelial cells, whereas connexin staining was attenuated after HDM induction. The TEER level, cAMP levels and PKA activity were decreased, while FITC-DX transmittance was increased in HDM-16HBE group (P < 0.05) compared with the control-16HBE group.

CONCLUSION

PACAP38 could reduce the airway inflammation, weaken the AJC protein heterotopia and activate cAMP/PKA signaling pathway in HDM-induced asthma, which indicate that PACAP38 may be an important contributor in HDM-induced asthma.

Oral administration of ammonium metavanadate and potassium dichromate distorts the inflammatory reaction induced by turpentine oil injection in male rats

Heavy metal pollution is rapidly increasing in the environment. It has been shown that exposure to vanadium and chromium is able to alter the immune response. Nevertheless, the mechanisms by which these metal pollutants mediate their immunomodulatory effects are not completely understood. Herein, we examined the effect of ammonium metavanadate and potassium dichromate on the development of an inflammatory response caused by subcutaneous injection of turpentine oil. We demonstrated that pretreatment of rats with ammonium metavanadate and potassium dichromate for two weeks prior to initiation of the inflammatory response resulted in a wider zone of necrosis surrounding the site of inflammation. The acute inflammatory process in the combined model was characterized by elevated serum levels of IL-10 and decreased serum levels of IL-6 as compared to rats not treated with ammonium metavanadate and potassium dichromate. Ammonium metavanadate and potassium dichromate administration induced a decrease in the proportion of splenic His48^HighCD11b/c⁺ myeloid cells accompanied by a reduced infiltration of the wound with neutrophils. Further analysis showed decreased proportions of CD3⁺CD4⁺IFNγ⁺ and CD3⁺CD4⁺IL-4⁺ T cells in the rats with combined model as compared to inflamed rats not treated with ammonium metavanadate and potassium dichromate. The data suggest that consumption of vanadium and chromium compounds disrupts the inflammatory response through an altered balance of pro- and anti-inflammatory cytokines and inhibition of effector T cell activation and neutrophil expansion.

Pituitary adenylate cyclase-activating polypeptide ameliorates vascular dysfunction induced by hyperglycaemia

BACKGROUND

Short-lasting hyperglycaemia occurs frequently in prediabetes and poorly controlled diabetes mellitus leading to vascular damage. Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to play a protective role in vascular complications of diabetes; moreover, antioxidant effects of PACAP were also described. Therefore, we hypothesized that PACAP exerts protective effects in short-term hyperglycaemia-induced vascular dysfunctions.

METHODS

After short-term hyperglycaemia, acetylcholine-induced and sodium nitroprusside-induced vascular relaxation of mouse carotid arteries were tested with a myograph with or without the presence of PACAP or superoxide dismutase. Potential direct antioxidant superoxide-scavenging action of pituitary adenylate cyclase-activating peptide was tested with pyrogallol autoxidation assay; furthermore, the effect of pituitary adenylate cyclase-activating peptide or superoxide dismutase was investigated on hyperglycaemia-associated vascular markers.

RESULTS

PACAP administration resulted in reduced endothelial dysfunction after a 1-h hyperglycaemic episode. PACAP was able to restore acetylcholine-induced relaxation of the vessels and improved sodium nitroprusside-induced relaxation. This effect was comparable to the protective effect of superoxide dismutase, but PACAP was unable to directly scavenge superoxide produced by autoxidation of pyrogallol. Endothelial dysfunction was associated with elevated levels of fibroblast growth factor basic, matrix metalloproteinase 9 and nephroblastoma overexpressed gene proteins. Their release was reduced by PACAP administration.

CONCLUSION

These results suggest a strong protective role of PACAP in the vascular complications of diabetes.

Advance of antioxidants in asthma treatment

Asthma is an allergic disease, characterized as a recurrent airflow limitation, airway hyperreactivity, and chronic inflammation, involving a variety of cells and cytokines. Reactive oxygen species have been proven to play an important role in asthma. The pathogenesis of oxidative stress in asthma involves an imbalance between oxidant and antioxidant systems that is caused by environment pollutants or endogenous reactive oxygen species from inflammation cells. There is growing evidence that antioxidant treatments that include vitamins and food supplements have been shown to ameliorate this oxidative stress while improving the symptoms and decreasing the severity of asthma. In this review, we summarize recent studies that are related to the mechanisms and biomarkers of oxidative stress, antioxidant treatments in asthma.

The pituitary adenylate cyclase-activating polypeptide (PACAP) protects adrenal function in septic rats administered etomidate

BACKGROUND

Both hyperinflammation during sepsis and etomidate can suppress adrenal function. In this study, we explored whether treatment with pituitary adenylate cyclase-activating polypeptide (PACAP) relieves adrenal suppression in cecal ligation and puncture (CLP)-induced septic rats.

MATERIALS AND METHODS

Female Sprague-Dawley rats were randomly divided into five groups (n=7 per group), including the sham group, sepsis group (CLP group), sepsis and etomidate group (CLP+ETO group), PACAP group, and etomidate alone group (ETO group). Rats were sacrificed on the third day of sepsis, and blood and adrenal gland samples were obtained for further testing.

RESULTS

The PACAP reduced the apoptosis rate of adrenal cells and peripheral lymphocytes, improving adrenal function, inhibiting the secretion of interferon gamma (IFN-γ) from peripheral lymphocytes, and slightly relieving the suppression of the adrenal function induced by the injection of etomidate in sepsis.

CONCLUSION

In septic conditions, the PACAP protects the adrenal gland by regulating peripheral inflammation, which slightly relieves the toxic effects of etomidate on adrenal function.