Chronic VEGF Blockade Worsens Glomerular Injury in the Remnant Kidney Model

VEGF inhibition can promote renal vascular and parenchymal injury, causing proteinuria, hypertension and thrombotic microangiopathy. The mechanisms underlying these side effects are unclear. We investigated the renal effects of the administration, during 45 days, of sunitinib (Su), a VEGF receptor inhibitor, to rats with 5/6 renal ablation (Nx). Adult male Munich-Wistar rats were distributed among groups S+V, sham-operated rats receiving vehicle only; S+Su, S rats given Su, 4 mg/kg/day; Nx+V, Nx rats receiving V; and Nx+Su, Nx rats receiving Su. Su caused no change in Group S. Seven and 45 days after renal ablation, renal cortical interstitium was expanded, in association with rarefaction of peritubular capillaries. Su did not worsen hypertension, proteinuria or interstitial expansion, nor did it affect capillary rarefaction, suggesting little angiogenic activity in this model. Nx animals exhibited glomerulosclerosis (GS), which was aggravated by Su. This effect could not be explained by podocyte damage, nor could it be ascribed to tuft hypertrophy or hyperplasia. GS may have derived from organization of capillary microthrombi, frequently observed in Group Nx+Su. Treatment with Su did not reduce the fractional glomerular endothelial area, suggesting functional rather than structural cell injury. Chronic VEGF inhibition has little effect on normal rats, but can affect glomerular endothelium when renal damage is already present

Hypoxia Inducible Factor Signaling Modulates Susceptibility to Mycobacterial Infection via a Nitric Oxide Dependent Mechanism

Tuberculosis is a current major world-health problem, exacerbated by the causative pathogen, Mycobacterium tuberculosis (Mtb), becoming increasingly resistant to conventional antibiotic treatment. Mtb is able to counteract the bactericidal mechanisms of leukocytes to survive intracellularly and develop a niche permissive for proliferation and dissemination. Understanding of the pathogenesis of mycobacterial infections such as tuberculosis (TB) remains limited, especially for early infection and for reactivation of latent infection. Signaling via hypoxia inducible factor α (HIF-α) transcription factors has previously been implicated in leukocyte activation and host defence. We have previously shown that hypoxic signaling via stabilization of Hif-1α prolongs the functionality of leukocytes in the innate immune response to injury. We sought to manipulate Hif-α signaling in a well-established Mycobacterium marinum (Mm) zebrafish model of TB to investigate effects on the host's ability to combat mycobacterial infection. Stabilization of host Hif-1α, both pharmacologically and genetically, at early stages of Mm infection was able to reduce the bacterial burden of infected larvae. Increasing Hif-1α signaling enhanced levels of reactive nitrogen species (RNS) in neutrophils prior to infection and was able to reduce larval mycobacterial burden. Conversely, decreasing Hif-2α signaling enhanced RNS levels and reduced bacterial burden, demonstrating that Hif-1α and Hif-2α have opposing effects on host susceptibility to mycobacterial infection. The antimicrobial effect of Hif-1α stabilization, and Hif-2α reduction, were demonstrated to be dependent on inducible nitric oxide synthase (iNOS) signaling at early stages of infection. Our findings indicate that induction of leukocyte iNOS by stabilizing Hif-1α, or reducing Hif-2α, aids the host during early stages of Mm infection. Stabilization of Hif-1α therefore represents a potential target for therapeutic intervention against tuberculosis

Cytoprotective effect of glutaraldehyde erythropoietin on HEK293 kidney cells after silver nanoparticle exposure

Kanidta Sooklert,1,2 Supreecha Chattong,3 Krissanapong Manotham,3 Chawikan Boonwong,1 I-yanut Klaharn,1 Depicha Jindatip,4 Amornpun Sereemaspun1,4 1Nanobiomedicine Laboratory, Department of Anatomy, Faculty of Medicine, 2Inter-Department Program of Biomedical Sciences, Faculty of Graduate School, Chulalongkorn University, 3Renal Unit, Department of Medicine, Lerdsin General Hospital, 4Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, ThailandAbstract: The toxic effects from exposure to silver nanoparticles (AgNPs), which are broadly present in many consumer products, have long raised concerns. Many studies have focused on the mechanisms of nanosilver, which cause toxicity in human cells, but little is known about prevention of this type of injury. This study investigated the in vitro effects of glutaraldehyde erythropoietin (GEPO), a cytoprotective compound derived from erythropoietin, in terms of cell protection against AgNP-induced injury. HEK293 cells were pretreated with or without GEPO before administration of AgNPs. The protective effects of GEPO in this cell line were assessed by the percentage of viable cells, alterations of cell morphology, and the proliferative capability of the cells. In addition, we assessed the role of GEPO in lowering cellular oxidative stress and regulating expression of the anti-apoptotic protein Bcl2. The results showed rescue effects on the percentage of viable and proliferative cells among GEPO pretreated cells. Pretreatment with GEPO maintained the normal cell shape and ultrastructural morphology. Moreover, GEPO reduced the generation of reactive oxygen species in cells and activated expression of Bcl2, which are the major mechanisms in protection against cellular toxicity induced by AgNPs. In conclusion, our study showed that the cytotoxic effects from exposure to AgNPs can be prevented by GEPO. Keywords: glutaraldehyde erythropoietin, silver nanoparticles, cytoprotection, nanotoxicit

Doxorubicin-conjugated dexamethasone induced MCF-7 apoptosis without entering the nucleus and able to overcome MDR-1-induced resistance

Kamontip Chaikomon,1,2 Supreecha Chattong,1,3 Theerasak Chaiya,1 Danai Tiwawech,4 Yongsak Sritana-Anant,5 Amornpun Sereemaspun,6 Krissanapong Manotham1 1Molecular and Cellular Biology Unit, Department of Medicine, Lerdsin General Hospital, Bangkok, Thailand; 2Medical Sciences Program, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; 3EST Laboratory, SS Manufacturing, Nonthaburi, Thailand; 4Research Division, National Cancer Institute, Bangkok, Thailand; 5Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand; 6Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand Background: Doxorubicin (DOX) is the most widely used chemotherapeutic agent that has multimodal cytotoxicity. The main cytotoxic actions of DOX occur in the nucleus. The emergence of drug-resistant cancer cells that have the ability to actively efflux DOX out of the nucleus, and the cytoplasm has led to the search for a more effective derivative of this drug. Materials and methods: We created a new derivative of DOX that was derived via simple conjugation of the 3' amino group of DOX to the dexamethasone molecule. Results: Despite having a lower cytotoxic activity in MCF-7 cells, the conjugated product, DexDOX, exerted its actions in a manner that was different to that of DOX. DexDOX rapidly induced MCF-7 cell apoptosis without entering the nucleus. Further analysis showed that DexDOX increased cytosolic oxidative stress and did not interfere with the cell cycle. In addition, the conjugated product retained its cytotoxicity in multidrug resistance-1-overexpressing MCF-7 cells that had an approximately 16-fold higher resistance to DOX. Conclusion: We have synthesized a new derivative of DOX, which has the ability to overcome multidrug resistance-1-induced resistance. This molecule may have potential as a future chemotherapeutic agent. Keywords: doxorubicin, dexamethasone, drug-resistant tumor, bioconjugation, multidrug resistance, reactive oxygen specie

Angiogenesis Induction using Dental Pulp Stem Cells, A Collagen Scaffold Seeded in Pulp Chamber of Endodontically Treated Teeth and Subcutaneously Transplanted into Immunocompromised Mice

Background: Angiogenesis is an essential mechanism for repairing any damaged target tissues or organs in cell therapy because the process can provide the supplements of nutrients, oxygen, and other repair factors. Many studies have revealed the ability of stem cells to induce angiogenesis of vessels in various organs. According to previous studies, We postulated that dental pulp stem cells (DPSCs) may improve angiogenesis for dental tissue repair and hence the outcome of regeneration. Objective: We would like to evaluate the potential of DPSCs to induce an angiogenesis for dental tissue repair and regeneration. Methods: In this study we employed endodontically treated teeth as a model to evaluate the angiogenesis properties of dental pulp stem cells. DPSCs were isolated from human third molar impacted tooth samples and reconstituted in basement membrane matrix scaffold (Matri-Gel 3D) and injected in the pulp chamber of the prepared endodontically treated teeth. Transplantation of experimental and control teeth was performed subcutaneously in the dorsum of immunocompromised mice (NOD-SCID). Results: The vascular numbers in subcutaneous connective tissues of 4 week experimental mice, DPSCs and Matri-Gel scaffolds appeared visibly greater than those in the control group with Matri-Gel transplantation alone. Similar appearance was also found in the section of H-E stain of soft tissues of experimental teeth. Conclusions: This may suggest that DPSCs can induce the regeneration of vascular dependent tissues such as dental pulp regeneration in necrotic pulp from diseases and may have implications in the regeneration of revital tooth