Keratinocyte growth factor (KGF) gene therapy mediated by an attenuated form of Salmonella typhimurium ameliorates radiation induced pulmonary injury in rats

Phloretin is protective in a murine salmonella enterica serovar typhimurium infection model

Salmonella, an important zoonotic pathogen, causes significant morbidity and mortality in both humans and animals. Phloretin mainly isolated from strawberries and apples has the effects of treating inflammation and pathogenic bacteria, but its protective efficacy and mechanism of action against Salmonella spp. are less clear. In this study, we found that phloretin alleviated body weight loss, colon length shortening, and colonic pathological damage caused by S. Typhimurium. Phloretin also decreased S. Typhimurium translocation to the mesenteric lymph nodes (MLN) and spleen. Further mechanism studies showed that phloretin significantly inhibited inflammation and oxidative stress levels in the colonic tissue. Phloretin also prevented S. Typhimurium-mediated impairment in the colon epithelium barrier by the regulation ZO-1 and occludin levels. Interestingly, phloretin did not inhibit S. typhimurium growth in vitro, but reduced the internalization of S. Typhimurium into Caco-2 cells. Taken together, these findings indicated that phloretin may be a new dietary strategy to combat the disease.

Radiation-Induced Lung Injury (RILI)

Radiation pneumonitis (RP) and radiation fibrosis (RF) are two dose-limiting toxicities of radiotherapy (RT), especially for lung, and esophageal cancer. It occurs in 5-20% of patients and limits the maximum dose that can be delivered, reducing tumor control probability (TCP) and may lead to dyspnea, lung fibrosis, and impaired quality of life. Both physical and biological factors determine the normal tissue complication probability (NTCP) by Radiotherapy. A better understanding of the pathophysiological sequence of radiation-induced lung injury (RILI) and the intrinsic, environmental and treatment-related factors may aid in the prevention, and better management of radiation-induced lung damage. In this review, we summarize our current understanding of the pathological and molecular consequences of lung exposure to ionizing radiation, and pharmaceutical interventions that may be beneficial in the prevention or curtailment of RILI, and therefore enable a more durable therapeutic tumor response.

Cytokine gene therapy for treatment of ischemia and hypoxia stress induced gastrointestinal injury

Stress induced gastrointestinal ischemia and hypoxia injury is a common digestive system condition caused via complicated mechanisms. Although clinical treatments are diverse, their efficacy is still not satisfactory. Recently, many cytokines have been shown to be related to gastrointestinal ischemia and anoxia, such as hepatocyte growth factor, hypoxia inducible factor, and keratinocyte growth factor. The number of studies on cytokines for the treatment of gastrointestinal diseases is increasing. We have constructed a eukaryotic expression vector carrying cytokine genes to transfer cytokine genes to the local damage tissue to achieve the therapeutic purpose. Cytokine gene therapy may be a safe and effective new strategy for repairing gastrointestinal ischemia and hypoxia stress injury, which will offer a new tool for the mechanism research and treatment of hypoxic ischemic disease.

Attenuating endogenous Fgfr2b ligands during bleomycin-induced lung fibrosis does not compromise murine lung repair

Fibroblast growth factors (Fgfs) mediate organ repair. Lung epithelial cell overexpression of Fgf10 postbleomycin injury is both protective and therapeutic, characterized by increased survival and attenuated fibrosis. Exogenous administration of FGF7 (palifermin) also showed prophylactic survival benefits in mice. The role of endogenous Fgfr2b ligands on bleomycin-induced lung fibrosis is still elusive. This study reports the expression of endogenous Fgfr2b ligands, receptors, and signaling targets in wild-type mice following bleomycin lung injury. In addition, the impact of attenuating endogenous Fgfr2b-ligands following bleomycin-induced fibrosis was tested by using a doxycycline (dox)-based inducible, soluble, dominant-negative form of the Fgfr2b receptor. Double-transgenic (DTG) Rosa26(rtTA/+);tet(O)solFgfr2b mice were validated for the expression and activity of soluble Fgfr2b (failure to regenerate maxillary incisors, attenuated recombinant FGF7 signal in the lung). As previously reported, no defects in lung morphometry were detected in DTG (+dox) mice exposed from postnatal days (PN) 1 through PN105. Female single-transgenic (STG) and DTG mice were subjected to various levels of bleomycin injury (1.0, 2.0, and 3.0 U/kg). Fgfr2b ligands were attenuated either throughout injury (days 0-11; days 0-28) or during later stages (days 6-28 and 14-28). No significant changes in survival, weight, lung function, confluent areas of fibrosis, or hydroxyproline deposition were detected in DTG mice. These results indicate that endogenous Fgfr2b ligands do not significantly protect against bleomycin injury, nor do they expedite the resolution of bleomycin-induced lung injury in mice.

The expression of aquaporins 1 and 5 in rat lung after thoracic irradiation

Radiation-induced lung toxicity (RILT), leading to radiation pneumonia or fibrosis, is a primary problem of radiation therapy. The pathogenesis of RILT remains unclear. In this study, we used a rat model of RILT to examine the expression of aquaporins (AQPs) after radiation injury. Sprague Dawley rats were given a single dose of 17 Gy (dose rate of 3.0 Gy/min) of X-irradiation to the thorax. Rats that survived acute pneumonitis (at 1-4 weeks) were evaluated weekly for the expression of AQP1 and AQP5 in the lung by immunohistochemical and reverse transcription polymerase chain reaction (RT-PCR) analyses. Immunohistochemical analysis showed that AQP1 protein was expressed in the capillary endothelium, and its level was significantly decreased after irradiation. AQP5 protein was expressed in the alveolar epithelium, and its level was increased between Days 7 and 14 after irradiation but decreased at Day 28, compared with the sham group. The RT-PCR results were consistent with the immunohistochemical analysis results. In summary, this study provides the first report of AQP1 and AQP5 expression in a model of radiation-induced pulmonary inflammation and edema. Decreased levels of AQP1 and AQP5 after irradiation suggest that these proteins play a role in the pathogenesis of RILT.

Palifermin for the protection and regeneration of epithelial tissues following injury: new findings in basic research and pre-clinical models

Keratinocyte growth factor (KGF) is a paracrine-acting epithelial mitogen produced by cells of mesenchymal origin, that plays an important role in protecting and repairing epithelial tissues. Pre-clinical data initially demonstrated that a recombinant truncated KGF (palifermin) could reduce gastrointestinal injury and mortality resulting from a variety of toxic exposures. Furthermore, the use of palifermin in patients with hematological malignancies reduced the incidence and duration of severe oral mucositis experienced after intensive chemoradiotherapy. Based upon these findings, as well as the observation that KGF receptors are expressed in many, if not all, epithelial tissues, pre-clinical studies have been conducted to determine the efficacy of palifermin in protecting different epithelial tissues from toxic injury in an attempt to model various clinical situations in which it might prove to be of benefit in limiting tissue damage. In this article, we review these studies to provide the pre-clinical background for clinical trials that are described in the accompanying article and the rationale for additional clinical applications of palifermin.

Prevention of future incidents and investigational lines

All radiation devices in use nowadays are subject to cause serious incidents and accidents, with potential risks in exposed population groups. These risks may have immediate or long term health implications. The detection of radioactive incidents is a procedure that should be systematized in economically developed societies. International organizations may provide support to other states in the event of a radioactive incident. Prevention, mitigation and treatment of the radiation effects are done by anticipating the moment of exposure and by establishing new efforts for investigation of radioprotective products. In this article we will analyze the causes of radiological incidents, the means to detect them, and the current preventive and therapeutic procedures available, with special emphasis on new biodosimetry methods for triage and investigational radioprotective drugs. Finally, we will explore the most efficient measures, for future prevention.