Artemisinins are a family of sesquiterpene trioxane lactone anti-malarial agents originally derived from Artemisia annua L. The anti-malarial action of artemisinins involves the formation of free ...radicals via cleavage of the endoperoxide bond in its structure, which mediate eradication of the Plasmodium species. With its established safety record in millions of malarial patients, artemisinins are also being investigated in diseases like infections, cancers and inflammation. Artemisinins have been reported to possess robust inhibitory effects against viruses (e.g. Human cytomegalovirus), protozoa (e.g. Toxoplasma gondii), helminths (e.g. Schistosoma species and Fasciola hepatica) and fungi (e.g. Cryptococcus neoformans). Artemisinins have demonstrated cytotoxic effects against a variety of cancer cells by inducing cell cycle arrest, promoting apoptosis, preventing angiogenesis, and abrogating cancer invasion and metastasis. Artemisinins have been evaluated in animal models of autoimmune diseases, allergic disorders and septic inflammation. The anti-inflammatory effects of artemisinins have been attributed to the inhibition of Toll-like receptors, Syk tyrosine kinase, phospholipase Cγ, PI3K/Akt, MAPK, STAT-1/3/5, NF-κB, Sp1 and Nrf2/ARE signaling pathways. This review provides a comprehensive update on non-malarial use of artemisinins, modes of action of artemisinins in different disease conditions, and drug development of artemisinins beyond anti-malarial. With the concerted efforts in the novel synthesis of artemisinin analogs and clinical pharmacology of artemisinins, it is likely that artemisinin drugs will become a major armamentarium combating a variety of human diseases beyond malaria.
Background Respiratory virus infections are commonly associated with COPD exacerbations, but little is known about the mechanisms linking virus infection to exacerbations. Pathogenic mechanisms in ...stable COPD include oxidative and nitrosative stress and reduced activity of histone deacetylase-2 (HDAC2), but their roles in COPD exacerbations is unknown. We investigated oxidative and nitrosative stress (O&NS) and HDAC2 in COPD exacerbations using experimental rhinovirus infection. Methods Nine subjects with COPD (Global Initiative for Chronic Obstructive Lung Disease stage II), 10 smokers, and 11 nonsmokers were successfully infected with rhinovirus. Markers of O&NS-associated cellular damage, and inflammatory mediators and proteases were measured in sputum, and HDAC2 activity was measured in sputum and bronchoalveolar macrophages. In an in vitro model, monocyte-derived THP-1 cells were infected with rhinovirus and nitrosylation and activity of HDAC2 was measured. Results Rhinovirus infection induced significant increases in airways inflammation and markers of O&NS in subjects with COPD. O&NS markers correlated with virus load and inflammatory markers. Macrophage HDAC2 activity was reduced during exacerbation and correlated inversely with virus load, inflammatory markers, and nitrosative stress. Sputum macrophage HDAC2 activity pre-infection was inversely associated with sputum virus load and inflammatory markers during exacerbation. Rhinovirus infection of monocytes induced nitrosylation of HDAC2 and reduced HDAC2 activity; inhibition of O&NS inhibited rhinovirus-induced inflammatory cytokines. Conclusions O&NS, airways inflammation, and impaired HDAC2 may be important mechanisms of virus-induced COPD exacerbations. Therapies targeting these mechanisms offer potential new treatments for COPD exacerbations.
Inhaled oligonucleotide is an emerging therapeutic modality for various common respiratory diseases, including obstructive airway diseases like asthma and chronic obstructive pulmonary disease (COPD) ...and restrictive airway diseases like idiopathic pulmonary fibrosis (IPF). The advantage of direct accessibility for oligonucleotide molecules to the lung target sites, bypassing systemic administration, makes this therapeutic approach promising with minimized potential systemic side effects. Asthma, COPD, and IPF are common chronic respiratory diseases, characterized by persistent airway inflammation and dysregulated tissue repair and remodeling, although each individual disease has its unique etiology. Corticosteroids have been widely prescribed for the treatment of asthma, COPD, and IPF. However, the effectiveness of corticosteroids as an anti-inflammatory drug is limited by steroid resistance in severe asthma, the majority of COPD cases, and pulmonary fibrosis. There is an urgent medical need to develop target-specific drugs for the treatment of these respiratory conditions. Oligonucleotide therapies, including antisense oligonucleotide (ASO), small interfering RNA (siRNA), and microRNA (miRNA) are now being evaluated both pre-clinically and clinically as potential therapeutics. The mechanisms of action of ASO and siRNA are highly target mRNA specific, ultimately leading to target protein knockdown. miRNA has both biomarker and therapeutic values, and its knockdown by a miRNA antagonist (antagomir) has a broader but potentially more non-specific biological outcome. This review will compile the current findings of oligonucleotide therapeutic targets, verified in various respiratory disease models and in clinical trials, and evaluate different chemical modification approaches to improve the stability and potency of oligonucleotides for the treatment of respiratory diseases.
Exposure to environmental allergens is a major risk factor for asthma development. Allergens possess proteolytic activity that is capable of disrupting the airway epithelium. Although there is ...increasing evidence pointing to asthma as an epithelial disease, the underlying mechanism that drives asthma has not been fully elucidated. In this study, we investigated the direct DNA damage potential of aeroallergens on human bronchial epithelial cells and elucidated the mechanisms mediating the damage. Human bronchial epithelial cells, BEAS-2B, directly exposed to house dust mites (HDM) resulted in enhanced DNA damage, as measured by the CometChip and the staining of DNA double-strand break marker, γH2AX. HDM stimulated cellular reactive oxygen species production, increased mitochondrial oxidative stress, and promoted nitrosative stress. Notably, expression of nuclear factor erythroid 2-related factor 2-dependent antioxidant genes was reduced immediately after HDM exposure, suggesting that HDM altered antioxidant responses. HDM exposure also reduced cell proliferation and induced cell death. Importantly, HDM-induced DNA damage can be prevented by the antioxidants glutathione and catalase, suggesting that HDM-induced reactive oxygen and nitrogen species can be neutralized by antioxidants. Mechanistic studies revealed that HDM-induced cellular injury is NADPH oxidase (NOX)-dependent, and apocynin, a NOX inhibitor, protected cells from double-strand breaks induced by HDM. Our results show that direct exposure of bronchial epithelial cells to HDM leads to the production of reactive oxygen and nitrogen species that damage DNA and induce cytotoxicity. Antioxidants and NOX inhibitors can prevent HDM-induced DNA damage, revealing a novel role for antioxidants and NOX inhibitors in mitigating allergic airway disease.
Background Asthma is related to airway inflammation and oxidative stress. High levels of reactive oxygen and nitrogen species can induce cytotoxic DNA damage. Nevertheless, little is known about the ...possible role of allergen-induced DNA damage and DNA repair as modulators of asthma-associated pathology. Objective We sought to study DNA damage and DNA damage responses induced by house dust mite (HDM) in vivo and in vitro. Methods We measured DNA double-strand breaks (DSBs), DNA repair proteins, and apoptosis in an HDM-induced allergic asthma model and in lung samples from asthmatic patients. To study DNA repair, we treated mice with the DSB repair inhibitor NU7441. To study the direct DNA-damaging effect of HDM on human bronchial epithelial cells, we exposed BEAS-2B cells to HDM and measured DNA damage and reactive oxygen species levels. Results HDM challenge increased lung levels of oxidative damage to proteins (3-nitrotyrosine), lipids (8-isoprostane), and nucleic acid (8-oxoguanine). Immunohistochemical evidence for HDM-induced DNA DSBs was revealed by increased levels of the DSB marker γ Histone 2AX (H2AX) foci in bronchial epithelium. BEAS-2B cells exposed to HDM showed enhanced DNA damage, as measured by using the comet assay and γH2AX staining. In lung tissue from human patients with asthma, we observed increased levels of DNA repair proteins and apoptosis, as shown by caspase-3 cleavage, caspase-activated DNase levels, and terminal deoxynucleotidyl transferase–mediated dUTP nick end-labeling staining. Notably, NU7441 augmented DNA damage and cytokine production in the bronchial epithelium and apoptosis in the allergic airway, implicating DSBs as an underlying driver of asthma pathophysiology. Conclusion This work calls attention to reactive oxygen and nitrogen species and HDM-induced cytotoxicity and to a potential role for DNA repair as a modulator of asthma-associated pathophysiology.
Vitamin D possesses immunomodulatory functions and vitamin D deficiency has been associated with the rise in chronic inflammatory diseases, including asthma (Litonjua and Weiss, 2007). Vitamin D ...supplementation studies do not provide insight into the molecular genetic mechanisms of vitamin D-mediated immunoregulation. Here, we provide evidence for vitamin D regulation of two human chromosomal loci, Chr17q12-21.1 and Chr17q21.2, reliably associated with autoimmune and chronic inflammatory diseases. We demonstrate increased vitamin D receptor (
) expression in mouse lung CD4+ Th2 cells, differential expression of Chr17q12-21.1 and Chr17q21.2 genes in Th2 cells based on vitamin D status and identify the IL-2/Stat5 pathway as a target of vitamin D signaling. Vitamin D deficiency caused severe lung inflammation after allergen challenge in mice that was prevented by long-term prenatal vitamin D supplementation. Mechanistically, vitamin D induced the expression of the
-encoded protein Aiolos to suppress IL-2 signaling and ameliorate cytokine production in Th2 cells. These translational findings demonstrate mechanisms for the immune protective effect of vitamin D in allergic lung inflammation with a strong molecular genetic link to the regulation of both Chr17q12-21.1 and Chr17q21.2 genes and suggest further functional studies and interventional strategies for long-term prevention of asthma and other autoimmune disorders.
The average respiration rate for an adult is 12–20 breaths per minute, which constantly exposes the lungs to allergens and harmful particles. As a result, respiratory diseases, which includes asthma, ...chronic obstructive pulmonary disease (COPD) and acute lower respiratory tract infections (LTRI), are a major cause of death worldwide. Although asthma, COPD and LTRI are distinctly different diseases with separate mechanisms of disease progression, they do share a common feature – airway inflammation with intense recruitment and activation of granulocytes and mast cells. Neutrophils, eosinophils, basophils, and mast cells are crucial players in host defense against pathogens and maintenance of lung homeostasis. Upon contact with harmful particles, part of the pulmonary defense mechanism is to recruit these cells into the airways. Despite their protective nature, overactivation or accumulation of granulocytes and mast cells in the lungs results in unwanted chronic airway inflammation and damage. As such, understanding the bright and the dark side of these leukocytes in lung physiology paves the way for the development of therapies targeting this important mechanism of disease. Here we discuss the role of granulocytes in respiratory diseases and summarize therapeutic strategies focused on granulocyte recruitment and activation in the lungs.
A disintegrin and metalloproteinase domain-15 (ADAM15) is expressed by cells implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD), but its contributions to COPD are unknown. ...To address this gap, ADAM15 levels were measured in samples from cigarette smoke (CS)-versus air-exposed wild-type (WT) mice. CS-induced COPD-like disease was compared in CS-exposed WT, Adam15
, and Adam15 bone marrow chimeric mice. CS exposure increased Adam15 expression in lung macrophages and CD8
T cells and to a lesser extent in airway epithelial cells in WT mice. CS-exposed Adam15
mice had greater emphysema, small airway fibrosis, and lung inflammation (macrophages and CD8
T cells) than WT mice. Adam15 bone marrow chimera studies revealed that Adam15 deficiency in leukocytes led to exaggerated pulmonary inflammation and COPD-like disease in mice. Adam15 deficiency in CD8
T cells was required for the exaggerated pulmonary inflammation and COPD-like disease in CS-exposed Adam15
mice (as assessed by genetically deleting CD8
T cells in Adam15
mice). Adam15 deficiency increased pulmonary inflammation by rendering CD8
T cells and macrophages resistant to CS-induced activation of the mitochondrial apoptosis pathway by preserving mTOR signaling and intracellular Mcl-1 levels in these cells. These results strongly link ADAM15 deficiency to the pathogenesis of COPD.
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