Adenovirus-mediated in vivo silencing of anaphylatoxin receptor C5aR

RNAi therapeutic strategies for acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS), replacing the clinical term acute lung injury, involves serious pathophysiological lung changes that arise from a variety of pulmonary and nonpulmonary injuries and currently has no pharmacological therapeutics. RNA interference (RNAi) has the potential to generate therapeutic effects that would increase patient survival rates from this condition. It is the purpose of this review to discuss potential targets in treating ARDS with RNAi strategies, as well as to outline the challenges of oligonucleotide delivery to the lung and tactics to circumvent these delivery barriers.

C5a/C5aR Pathway Plays a Vital Role in Brain Inflammatory Injury via Initiating Fgl-2 in Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a serious emergency with high mortality and morbidity. Up to date, a limited understanding of ICH pathogenesis is difficult to implement effective therapeutic strategy. Much evidence demonstrates that the complement cascade is activated after experimental ICH. However, the exact mechanism has not been well studied in ICH. In the current study, C57BL/6J mice were injected with autologous whole blood. C5a/C5aR levels, microglia infiltration, inflammatory cytokine, and fibrinogen-like protein 2 (Fgl-2) expression in the perihematomal region were analyzed following ICH. In addition, brain water content and neurological dysfunction were detected following ICH. Our data demonstrated that ICH induced complement activation, along with an increase of C5a/C5aR levels, microglia infiltration, and inflammatory cytokine levels. However, C5aR^-/- mice exhibited significant attenuation of inflammatory reaction, accompanied by a remarkable reduction of Fgl-2, brain water content, and neurological dysfunction. Furthermore, inhibiting extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 efficiently inhibited C5a-mediated Fgl-2 production following ICH. Taken together, these data suggest that C5a/C5aR plays a vital role in the ICH-induced inflammatory damage via Fgl-2, and ERK1/2 and p38 pathways also are involved in the pathogenesis of ICH. Therefore, inhibition of C5a/C5aR activation might enlarge our insights in ICH therapy.

Prospective of colon cancer treatments and scope for combinatorial approach to enhanced cancer cell apoptosis

Colorectal cancer is the leading cause of cancer-related mortality in the western world. It is also the third most common cancer diagnosed in both men and women in the United States with a recent estimate for new cases of colorectal cancer in the year 2012 being around 103,170. Various risk factors for colorectal cancer include life-style, diet, age, personal and family history, and racial and ethnic background. While a few cancers are certainly preventable but this does not hold true for colon cancer as it is often detected in its advanced stage and generally not diagnosed until symptoms become apparent. Despite the fact that several options are available for treating this cancer through surgery, chemotherapy, radiation therapy, immunotherapy, and nutritional-supplement therapy, but the success rates are not very encouraging when used alone where secondary complications appear in almost all these therapies. To maximize the therapeutic-effects in patients, combinatorial approaches are essential. In this review we have discussed the therapies previously and currently available to patients diagnosed with colorectal-cancer, focus on some recent developments in basic research that has shaded lights on new therapeutic-concepts utilizing macrophages/dendritic cells, natural killer cells, gene delivery, siRNA-, and microRNA-technology, and specific-targeting of tyrosine kinases that are either mutated or over-expressed in the cancerous cell to treat these cancer. Potential strategies are discussed where these concepts could be applied to the existing therapies under a comprehensive approach to enhance the therapeutic effects.

Human colonic epithelial cells detect and respond to C5a via apically expressed C5aR through the ERK pathway

Intestinal epithelial cells (IECs) exhibit numerous adaptations to maintain barrier function as well as play sentinel roles by expressing receptors for microbial products and antimicrobial peptides. The complement system is another important innate sensing and defense mechanism of the host against bacteria and increasing evidence shows that complement plays a role in colitis. The split component C5a is a potent proinflammatory molecule, and the C5a receptor (C5aR) CD88 has been reported on multiple cell types. Here, we examined the question of whether human colonic cell lines can detect activated complement via C5aR and what signaling pathway is critical in the subsequent responses. T84, HT29, and Caco2 cell lines all possessed mRNA and protein for C5aR and the decoy receptor C5L2. Polarized cells expressed the proteins on the apical cell membrane. C5a binding to the C5aR on human IECs activates the ERK pathway, which proved critical for a subsequent upregulation of IL-8 mRNA, increased permeability of monolayers, and enhanced proliferation of the cells. The fact that human IECs are capable of detecting complement activation in the lumen via this anaphylatoxin receptor highlights the potential for IECs to detect pathogens indirectly through complement activation and be primed to amplify the host response through heightened inflammatory mediator expression to further recruit immune cells.

Silencing of C5a receptor gene with siRNA for protection from Gram-negative bacterial lipopolysaccharide-induced vascular permeability

Endothelial barrier dysfunction leading to increased permeability and vascular leakage is an underlying cause of several pathological conditions. Whereas these changes have been shown to be associated with activation of the complement system, leading to the release of C5a and interaction of C5a-C5a receptor (C5aR), the role of C5aR in endothelial cells remain(s) ill-defined. Here, we report an essential role of C5aR in endothelial cell injury and vascular permeability through silencing of the C5aR gene using siRNA. In the cultured mouse dermal microvascular endothelial cells (MEMECs) monolayer transfected with C5aR-siRNA, endotoxin-induced cell injury by evaluated as transendothelial flux, cell detachment, and cytoskeletal disorganization was inhibited. Upregulation of vascular cell adhesion molecule-1 (VCAM-1) was also suppressed. Studies exploring the underlying mechanism of siRNA-mediated suppression in VCAM-1 expression were related to reduction of NF-kappaB activation and nuclear localization of both p50 and p65. The effect was associated with inhibition in activation of protein kinase Cdelta(PKC-delta) and induction of PKC-mediated mitogen-activated protein kinase phosphatases-1 (MKP-1) leading to the increased activity of p42/p44 mitogen-activated protein (MAP) kinase cascade. In the model of mice administrated with C5aR-siRNA, endotoxin-induced plasma leakage was inhibited in local abdominal skin. Systemic administration of endotoxin to mice resulted in increased microvascular permeability in multiple organs was reduced. These studies demonstrate that the C5aR responsible for vascular endothelial cell injury and plasma permeability is an important factor, and that blockade of C5aR may be useful therapeutic targets for the prevention of vascular permeability in pathogenic condition.

APM2 is a novel mediator of cisplatin resistance in a variety of cancer cell types regardless of p53 or MMR status

Cisplatin is one of the most widely used chemotherapeutics in the world today. Unfortunately, chemoresistance often develops hindering the effectiveness of the drug. Mismatch-repair (MMR) and p53 have previously been shown to be important determinants of cisplatin resistance and can contribute to cisplatin resistance clinically. Here, we have used cDNA microarray to identify several genes as up or downregulated in a previously described, cisplatin resistant, clone of the HCT116 cell line (HCT116-K). On follow-up, one gene, APM2, was found to promote cisplatin resistance when overexpressed in sensitive HCT116 clones. Furthermore, silencing APM2 in a panel of cell lines encompassing all combinations of p53 status and MMR proficiency (HCT116-K, HCT116, SW620, MCF7, PC-3 and OV2008) resulted in sensitization regardless of these 2 factors. In addition, silencing APM2 stably using shRNA also resulted in the sensitization of cells to cisplatin. More importantly, cisplatin inhibited the growth of APM2 silenced tumor xenografts (HCT116-K or OV2008 cells) significantly better than it inhibited the growth of xenografts carrying nontargeting control shRNAs. These findings represent a novel strategy that could be exploited to overcome cisplatin resistance in patients regardless of p53 status or ability to perform MMR.

Attenuation of IgG immune complex-induced acute lung injury by silencing C5aR in lung epithelial cells

Acute lung injury (ALI) in mouse lung occurs after distal airway deposition of IgG immune complexes (IgGICs), resulting in a breakdown of the vascular-airway barrier, causing intrapulmonary edema, hemorrhage, and accumulation of neutrophils [polymorphonuclear leukocytes (PMNs)] in the alveolar compartment, these changes being complement (C5a) and C5a receptor (C5aR) dependent. In this ALI model, C5aR expression (protein) was found to occur on upper (bronchial) and lower (alveolar) airway epithelial cells. An adenovirus construct (siRNA) was used to silence mRNA for C5aR in the lung. Under such conditions, C5aR protein was markedly reduced on lung epithelial cells, resulting in much reduced leakage of albumin into the lung, diminished buildup of PMNs, and lower levels of proinflammatory mediators in bronchoalveolar lavage fluids. These studies indicate that bronchial and alveolar epithelial cell C5aR is up-regulated and greatly contributes to inflammation and injury in the lung. The use of siRNA administered into the airways avoids systemic suppression of C5aR, which might compromise innate immunity. It is possible that such an intervention might be employed in humans with ALI or acute respiratory distress syndrome as well as in upper-airway inflammatory diseases, such as chronic obstructive pulmonary disease and asthma, where there is evidence for complement activation and buildup of PMNs.

RNA interference as a potential therapeutic treatment for inflammation associated lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) remain important sources of morbidity for patients in the ICUs in the developed world. However, imagine having as a therapeutic tool, the ability to regulate, in a tissue specific manner, the expression of a given gene. RNA interference, as potentially such a method of selectively suppressing protein expression, has evolved as an important tool in the study of gene specific function and targeted therapeutics. Significant progress has been made in identifying potential gene targets integral to the pathways leading to the development of inflammation-associated lung injury. This review will discuss the progress, thus far, in the application of in vivo RNA interference-based gene therapy in the investigation of inflammation-associated lung injury.