Therapeutic potential of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion injury-induced acute renal failure in rats

This study was designed to investigate the role of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion (I/R)-induced acute renal failure in rats. Acute renal failure was induced in rats by administration of a single dose of cisplatin (CP) (6 mg/kg, intraperitoneally on day 6) and occlusion of the left renal artery for 45 min (I) and opened for the next 24 h (R). The drug samples of 7,8-dimethoxycoumarin (DMC, 50, 75, and 100 mg/kg) and cyclosporin A (50 μM/kg) were administered orally for six consecutive days. Administration of a single dose of cisplatin and I/R event has significantly raised blood urea nitrogen and creatinine, N-acetyl beta-D: -glucosaminidase, and thiobarbituric acid reactive substances but decreased FrNa, creatinine clearance, reduced glutathione (GSH), mitochondrial cytochrome c oxidase, and adenosine triphosphate levels. Further, pretreatment of DMC (50, 75, and 100 mg/kg, p.o., for six consecutive days) has ameliorated the CP- and I/R-induced biochemical and histopathological changes in a dose-dependent manner. Furthermore, 75 and 100 mg/kg of 7,8-dimethoxycoumarin has shown to possess the significant renoprotective effect similar to that of the cyclosporin A-treated group which served as positive control. Based on the results of the present study, it has been concluded that 7,8-dimethoxycoumarin protects the kidney against the CP and I/R injury via antioxidant, anti-inflammatory, and inactivation of mitochondrial permeability transition pore opening.     

Novel Approaches to Oral Immunization for Hepatitis B

Hepatitis B is a necroinflammatory liver disease manifested with subacute to acute symptoms, liver cirrhosis, and mortality. Parenteral alum-adsorbed hepatitis B surface antigenic (HBsAg) vaccination, although available, poses serious concerns regarding inability to induce both cell-mediated and mucosal immune response. In this context, oral delivery may be a prospective solution to the issues associated with conventional vaccination. However, the strategy is detrimental to the antigenic substances, suffers various physical/chemical barriers, and impedes poor transcytosis via mucosal route. Therefore, surface-engineered novel carrier-based approaches are reportedly promising for effective HBsAg oral vaccine delivery. This review focuses on the efforts for developing oral mucosal vaccine against hepatitis B, with considerable attention on novel drug delivery systems for spatial distribution of antigenic substance to the immune effector cells and organs.     

Fever as the only manifestation of hypersensitivity reactions associated with oxaliplatin in a patient with colorectal cancer Oxaliplatin-induced hypersensitivity reaction

Hypersensitivity reactions (HSR) to oxaliplatin in patients with colorectal cancer include facial ushing, erythema, pruritis, fever, tachycardia, dyspnea, tongue swelling, rash/hives, headache, chills, weakness, vomiting, burning sensations, dizziness, and edema. We report a patient with fever as the sole manifestation of initial HSR, review the literature and discuss the management of HSR. A 57-year-old female with T3N2M0 rectal adenocarcinoma received modified FOLFOX-6. She tolerated the first 8 cycles without any toxicities except grade 1 peripheral neuropathy and nausea. During 9th and 10th infusions, she developed fever to a maximum of 38.3℃ with stable hemodynamic status despite medications. During 11th infusion, she developed grade 3 HSR consisting of symptomatic bronchospasm, hypotension, nausea, vomiting, cough, and fever. On examination, she was pale, cyanotic, with a temperature of 38.8℃, BP dropped to 95/43 mm Hg, pulse of 116/min and O2 saturation of 88%-91%. She was hospitalized for management and recovered in 24 h. Fever alone is not a usual symptom of oxaliplatin HSR. It may be indicative that the patient may develop serious reactions subsequently, as did our patient who developed hypotension with the third challenge. Treatment and prevention consists of slowing the infusion rate, use of steroids and antagonists of Type 1 and 2 histamine receptor antagonists, whereas desensitization could help to provide the small number of patients who experience severe HSR with the ability to further receive an effective therapy for their colorectal cancer.     

Enhancement of T-helper type I immune responses against hepatitis B surface antigen by LPS derivatives adjuvanted liposomes delivery system

Currently, there is a clinical need for more effective vaccine for hepatitis B that induces robust cell-mediated immune response capable of viral clearance in chronic hepatitis B infection. In the present study, hepatitis B vaccines formulations were designed by loading the hepatitis B surface antigen into liposomes adjuvanted with rough lipopolysaccharide (Re-LPS) and lpxL1 LPS using conventional rotatory evaporation method and were characterized for various parameters, such as vesicle shape and surface morphology, size and size distribution, entrapment efficiency, turbidity, and in vitro release pattern. The immunoreactivity in mice was evaluated by measuring anti-HBs IgG titer and compared with alum-adsorbed HBsAg solution, plain HBsAg, and liposomal HBsAg formulations. The formulations were also evaluated for cell-mediated immune response by HBsAg specific proliferation of spleenocytes after secondary immunization and re-stimulation in vitro with the same antigen. Simultaneous estimation of cytokines (IL-4, IFN-γ) was also carried out. Ex vivo cellular uptake study was performed by fluorescence microscopy. Results indicate that the serum IgG titer obtained after i.m administration of Re-LPS- and lpxL1 LPS-adjuvanted liposomal HBsAg formulation was equivalent to alum-adsorbed HBsAg formulation but was more responsive, sustained, and significantly higher than the corresponding liposomal HBsAg and plain HBsAg formulations. Incorporation of lpxL1 LPS into the liposomal HBsAg increased the stimulation index (SI) 6–10 times as compared with plain HBsAg. Re-LPS- and lpxL1 LPS-adjuvanted liposomal HBsAg formulations induced stronger cellular immune response with a predominant Interferon-gamma (IFN-γ) level than those induced by free HBsAg alone, alum-adsorbed HBsAg, and non-adjuvanted liposomal HBsAg. Probably, the possible mechanism for the enhancement of cellular immunity in addition to humoral immunity by LPS-adjuvanted liposomal HBsAg formulation is due to marked enhancement of immunological presentation and recruitment of antigen via macrophage and antigen-presenting cells (APCs).     

Wolbachia endosymbiont of Brugia malayi elicits a T helper type 17-mediated pro-inflammatory immune response through Wolbachia surface protein

Wolbachia is an endosymbiotic bacterium of the filarial nematode Brugia malayi. The symbiotic relationship between Wolbachia and its filarial host is dependent on interactions between the proteins of both organisms. However, little is known about Wolbachia proteins that are involved in the inflammatory pathology of the host during lymphatic filariasis. In the present study, we cloned, expressed and purified Wolbachia surface protein (r-wsp) from Wolbachia and administered it to mice, either alone or in combination with infective larvae of B. malayi (Bm-L3) and monitored the developing immune response in infected animals. Our results show that spleens and mesenteric lymph nodes of mice immunized with either r-wsp or infected with Bm-L3 show increased percentages of CD4⁺ T helper type 17 (Th17) cells and Th1 cytokines like interferon-γ and interleukin-2 (IL-2) along with decreased percentages of regulatory T cells, Th2 cytokines like IL-4 and IL-10 and transforming growth factor β (TGF-β) levels in culture supernatants of splenocytes. These observations were stronger in mice immunized with r-wsp alone. Interestingly, when mice were first immunized with r-wsp and subsequently infected with Bm-L3, percentages of CD4⁺ Th17 cells and Th1 cytokines increased even further while that of regulatory T cells, Th2 cytokines and TGF-β levels decreased. These results for the first time show that r-wsp acts synergistically with Bm-L3 in promoting a pro-inflammatory response by increasing Th17 cells and at the same time diminishes host immunological tolerance by decreasing regulatory T cells and TGF-β secretion.     

Cellular immune response of Mastomys and gerbils in experimental filariasis

Summary
objective  To determine mitogenic and antigen-specific cellular immune responses of two species of rodents, viz . Meriones unguiculatus and Mastomys coucha to assess the usefulness of the A. viteae/Mastomys model for cellular immune studies in experimental filariasis.
methods  Lymphocyte blast transformation test (LTT) using spleen cells of normal and A. viteae infected animals.
results  The proliferative response of gerbils was much higher than that of Mastomys to both ConA and filarial antigens. Cells of both species of rodents did not respond to microfilarial (mf) antigen, however, their mitogenic response differed during infection. Some degree of nonspecific suppression was observed in gerbils during prepatent and patent stages of infection, while Mastomys revealed highest proliferation during patent microfilaraemia. Mastomys cells did not respond to adult or mf antigen,while adult-specific proliferation was detected in the case of gerbils.
conclusion  The A. viteae /gerbil model shows more similarity to human filarial infection regarding cellular immune response. Markedly low responsiveness of a high percentage of Mastomys and wide variations in the cellular response to nonspecific mitogen limit the usefulness of Mastomys coucha in immunological studies, especially cellular immunity.     

Gel core liposomes: An advanced carrier for improved vaccine delivery

Abstract

Many sub-unit vaccines are successful in preventing the occurrence of disease, but their use is largely restrained due to low immunogenicity. Novel carrier-based vaccine could serve as a vaccine adjuvant to overcome low immunogenicity of sub-unit vaccines. The use of liposomes as a delivery system for antigen is well recognized but they are unstable and release of antigen from them cannot be controlled over a prolonged period of time. To overcome the limitation of liposomes, this study has developed gel core liposomes in which a core of polymer was incorporated inside the liposomal vesicles, which serve the function of skeleton and provide mechanical strength to vesicles. In the present investigation BSA-loaded gel core liposomes were prepared by reverse phase evaporation method and characterized for vesicles size, shape, entrapment efficiency, in vitro release and stability studies. The in vivo studies to evaluate antigen presenting potential of the gel-core liposomes was performed in Balb/c mice by measuring the immune response elicited by intramuscular administration of BSA-loaded gel core liposomes and compared with intramuscularly administered BSA-loaded conventional liposomes, alum adsorbed BSA and plain antigen. Results indicate that intramuscular immunization with gel core liposomes induces efficient systemic antibody responses against BSA as compared to other formulations. The gel core liposomal formulation provides good entrapment efficiency, enhanced in vitro stability, prolonged antigen release and effective immunoadjuvant property, justifying its potential for improved vaccine delivery.     

Molecular Characterization of an rsmD-Like rRNA Methyltransferase from the Wolbachia Endosymbiont of Brugia malayi and Antifilarial Activity of Specific Inhibitors of the Enzyme

The endosymbiotic organism Wolbachia is an attractive antifilarial drug target. Here we report on the cloning and expression of an rsmD-like rRNA methyltransferase from the Wolbachia endosymbiont of Brugia malayi, its molecular properties, and assays for specific inhibitors. The gene was found to be expressed in all the major life stages of B. malayi. The purified enzyme expressed in Escherichia coli was found to be in monomer form in its native state. The activities of the specific inhibitors (heteroaryl compounds) against the enzyme were tested with B. malayi adult and microfilariae for 7 days in vitro at various concentrations, and NSC-659390 proved to be the most potent compound (50% inhibitory concentration [IC₅₀], 0.32 μM), followed by NSC-658343 (IC₅₀, 4.13 μM) and NSC-657589 (IC₅₀, 7.5 μM). On intraperitoneal administration at 5 mg/kg of body weight for 7 days to adult jirds into which B. malayi had been transplanted intraperitoneally, all the compounds killed a significant proportion of the implanted worms. A very similar result was observed in infected mastomys when inhibitors were administered. Docking studies of enzyme and inhibitors and an in vitro tryptophan quenching experiment were also performed to understand the binding mode and affinity. The specific inhibitors of the enzyme showed a higher affinity for the catalytic site of the enzyme than the nonspecific inhibitors and were found to be potent enough to kill the worm (both adults and microfilariae) in vitro as well as in vivo in a matter of days at micromolar concentrations. The findings suggest that these compounds be evaluated against other pathogens possessing a methyltransferase with a DPPY motif and warrant the design and synthesis of more such inhibitors.     

Role of 7,8-dimethoxycoumarin in anti-secretary and anti-inflammatory action on pyloric ligation-induced gastritis in rats

The present study was designed to investigate the effect of 7,8-dimethoxycoumarin (DMC) isolated from ethyl acetate extract of Citrus decumana peels on gastritis in rats. Isolation of 7,8-DMC from ethyl acetate extract of C. decumana peels was done by column and preparative thin layer chromatography using different solvents on polarity basis. Furthermore, effect of 7,8-DMC (50, 75, and 100 mg/kg, i.p.) in pyloric ligation-induced gastritis was studied in rats. The highest dose of 7,8-DMC showed significant decrease in the gastric volume, total acidity, ulcerative index, thiobarbituric acid reactive species levels, and myeloperoxidase activity, whereas there was an increase in the glutathione level. However, the lowest and medium doses did not produce significant results as compared to omeprazole and N-acetyl cysteine-treated groups. Compound 7,8-DMC (100 mg/kg) showed ameliorative effect on gastric inflammation and may be used as a therapeutic agent in the treatment of gastritis.