Accelerated structural decrements in the aging female rhesus macaque lung compared with males.

Aging is associated with morphometric changes in the lung that lead to decreased lung function. The nonhuman primate lung has been shown to have similar architectural, morphological, and developmental patterns to that of humans. We hypothesized that the lungs of rhesus monkeys age in a pattern similar to human lungs. Thirty-four rhesus monkeys from the California National Primate Research Center were euthanized, necropsied, and the whole lungs sampled. Stereological analysis was performed to assess the morphological changes associated with age. The number of alveoli declined significantly from age 9 to 33 yr with a greater decline in females compared with males. Lungs of females contained roughly 20% more alveoli at age 9 yr than males, but by ∼30 yr of age, females had 30% fewer alveoli than males. The volume of alveolar air also showed a significant linear decrease in females relative to age, while males did not. The number-weighted mean volume of alveoli showed a significant positive correlation with age in females but not in males. The volume of alveolar duct showed a significant positive correlation with age in females, but not in males. Structural decrements due to aging in the lung were increased in the female compared with male rhesus monkey.

Pharmacological properties of N-(3,5-diamino-6-chloropyrazine-2-carbonyl)-N'-4-[4-(2,3-dihydroxypropoxy)phenyl]butyl-guanidine methanesulfonate (552-02), a novel epithelial sodium channel blocker with potential clinical efficacy for cystic fibrosis lung disease.

Amiloride improves mucociliary clearance (MC) by blocking airway epithelial sodium channels (ENaC) and expanding airway surface liquid (ASL). However, the low potency and rapid absorption of amiloride by airway epithelia translated into a short duration of efficacy as an aerosolized therapy for cystic fibrosis (CF) patients. To improve ENaC blocker CF pharmacotherapy, a more potent and durable ENaC blocker tailored for aerosol delivery was synthesized. Parion compound N-(3,5-diamino-6-chloropyrazine-2-carbonyl)-N'-4-[4-(2,3-dihydroxypropoxy)phenyl]butyl-guanidine methanesulfonate (552-02) was tested for potency and reversibility of ENaC block, epithelial absorption and biotransformation, selectivity, durability of ASL expansion under isotonic and hypertonic conditions in canine and human CF bronchial epithelial cells, and drug dissociation on ENaC in Xenopus oocytes. Short-circuit current assessed compound potency and reversibility, patch-clamp recordings of ENaC current assessed drug off-rate (k(off)), a gravimetric method and confocal microscopy measured mucosal water retention and ASL height, and drug absorption and biotransformation were assessed using liquid chromatography-mass spectrometry. Amiloride and 552-02 were tested in vivo for MC activity in sheep immediately and 4 to 6 h after aerosol dosing. Compared with amiloride, compound 552-02 was 60 to 100-fold more potent, it was 2 to 5-fold less reversible, it was slower at crossing the epithelium, and it exhibited a 170-fold slower k(off) value. 552-02 exhibited greater ASL expansion over 8 h in vitro, and it was more effective than amiloride at increasing MC immediately and 4 to 6 h after dosing. When combining hypertonic saline and 552-02, a synergistic effect on ASL expansion was measured in canine or CF bronchial epithelia. In summary, the preclinical data support the clinical use of 552-02 +/- hypertonic saline for CF lung disease.

Preclinical safety and biodistribution of adenovirus-based cancer vaccines after intradermal delivery.

The recombinant adenoviral (Ad) vector is being considered as a cancer vaccine platform because it efficiently induces immune responses to tumor antigens by intradermal immunization. The aims of this study were to evaluate the potential toxicities and biodistribution after a single dose or six weekly intradermal doses of Ad2/gp100v2 and Ad2/MART-1v2, which encode tumor-associated antigens gp100 and MelanA/MART-1, respectively. The only dose-related toxicities associated with intradermal administration of these Ad vectors were inflammatory cell infiltrates in the draining lymph nodes and injection sites that persisted 83 days after administration. The biodistribution of Ad DNA as detected by real-time polymerase chain reaction was largely confined to the injection sites and draining lymph nodes of mice treated with either a single dose or multiple doses of Ad vector and in the spleens of mice treated with multiple doses of Ad vector. Adenoviral DNA was transiently detected in the bone marrow, lung, or blood of only one animal for each site and was below the limit of assay quantification (<10 copies/microg DNA). The vector persisted in the skin and lymph nodes as long as 92 days after the last dose. We conclude that Ad vectors delivered by intradermal administration provide a safe, genetic vaccine delivery platform that induces desirable immune responses at the immunization sites and the lymph nodes that, ultimately, result in immune responses specific to the tumor antigens.

Enhanced efficacy of melanoma vaccines in the absence of B lymphocytes.

Provoking a specific cellular immune response against tumor-associated antigens is a promising therapeutic strategy to treat cancers with defined antigens such as melanoma. In recent clinical trials, however, immune responses against melanoma antigens have been elicited without consistent clinical responses, suggesting the need for approaches that potentiate the specific cellular immune response. Since B lymphocytes have been reported to exert a negative effect on the cellular arm of the immune response in certain model systems, the authors compared the protective immunity elicited by melanoma antigens in B cell-deficient microMT mice to that obtained in fully immunocompetent C57BL/6 mice. Immunization with melanoma-associated antigens was accomplished using recombinant adenovirus (Ad) vectors encoding human gp100 (Ad2/gp100) or murine TRP-2 (Ad2/mTRP-2). A single dose of Ad2/gp100 or Ad2/mTRP-2 inhibited the growth of established subcutaneous B16 melanoma tumors in B cell-deficient but not wild-type C57BL/6 mice. The enhanced tumor protection observed in B cell-deficient mice appeared to be associated with potentiation of the magnitude and longevity of the specific cellular immune response. Natural killer (NK) cells were also found to be essential to the protective immune response in microMT mice because NK cell depletion with anti-asialo-GM1 antibody resulted in both the loss of tumor growth suppression and attenuation of the specific cellular immune response. The authors conclude that the protective cell-mediated immunity provoked by Ad-based cancer vaccines is enhanced in the absence of B cells, suggesting that a therapeutic regimen that includes depletion of B lymphocytes may be beneficial to cancer vaccine therapy.

Soluble transforming growth factor-beta type III receptor gene transfection inhibits fibrous airway obliteration in a rat model of Bronchiolitis obliterans.

Post-transplant bronchiolitis obliterans (BO) is characterized by fibroproliferation and fibrous obliteration of distal airways in chronically rejected lungs. In this study, using a rat heterotopic allogeneic tracheal transplant model of BO, we evaluated the expression of transforming growth factor-beta (TGFbeta) during the development of airway fibrous obliteration. Immunohistochemical analysis revealed TGFbeta staining in infiltrating mononuclear cells at Days 2 and 7, and in the fibrous tissues until Day 21. Soluble TGFbeta receptor type III (TGFBIIIR), by blocking TGFbeta binding to its membrane receptors, functions as a TGFbeta antagonist. To study the role of TGFbeta in the development of BO, adenoviral-mediated soluble TGFBIIIR gene transfection (5 x 10(9) particles) was performed topically at the site of transplant on Day 5 after transplantation, which leads to inhibition of fibrous airway obliteration. In contrast, empty vector gene delivered through intramuscular injection, or given locally at Days 0 or 10 after tracheal transplantation had no significant effect. These results suggest that TGFbeta expressed in the allografts plays a pivotal role in the pathogenesis of BO. Soluble TGFBIIIR may competitively inhibit TGFbeta activity locally. Adenoviral-mediated soluble TGFBIIIR gene transfection should be further explored as a potential therapeutic modality for BO and other conditions involving chronic fibrosis.