Biomedical subjects

Marc R Kok

Publications and source records attributed to Marc R Kok.

7 recordsLinked to original sources

PubMed2005

Immune responses following salivary gland administration of recombinant adeno-associated virus serotype 2 vectors.

BACKGROUND: Gene transfer to salivary glands (SGs) can be accomplished in a minimally invasive manner, resulting in stable, long-term secretion of the transgene product. Therefore, SGs provide a novel target site for several potentially useful clinical gene therapeutics applications. Previous studies have indicated that intravenous, intramuscular and intranasal administration of recombinant adeno-associated virus serotype 2 (rAAV2) vectors induce host immune responses. There are no reported studies on immune responsiveness of rAAV2 vector administration to SGs. MATERIAL AND METHODS: Vectors were administered by retrograde infusion to the SGs of Balb/c mice in various combinations. Thereafter, transgene expression was determined, and evaluations of host innate and adaptive immune responsiveness performed over a 56-day period. RESULTS: Histological examination of SGs from vector-treated mice showed no significant changes in appearance from controls, including the frequency of activated macrophage detection. There were also no differences in salivary flow rates among experimental groups. In vitro stimulation of splenocytes from mice administered rAAV2 showed elevated interferon-gamma levels in culture media. Significant titers of neutralizing antibodies to rAAV2 were detected in serum of mice following rAAV2 vector administration. While SGs could be transduced with low doses of vector it was not possible to repeat the administration and detect transduction with the same serotype at low doses. However, repeat administration was possible with an alternative serotype (rAAV4). CONCLUSIONS: Following a single administration of rAAV2 vectors to SGs there is no significant innate immune response. However, rAAV2 vector administration to SGs results in both cellular and humoral immune responses. The latter may interfere with the efficacy of repeated rAAV2 vector administration.

Animals↗

PubMed2005

Salivary glands as a potential gene transfer target for gene therapeutics of some monogenetic endocrine disorders.

Salivary glands (SGs) exhibit several important features which are also common to endocrine glands: self-containment due to a surrounding capsule, highly efficient protein production and the ability to secrete proteins into the bloodstream. We have hypothesized that SGs are potentially useful as gene transfer targets for the correction of inherited monogenetic endocrine disorders. In the present communication, we extend our studies and attempt to test our hypothesis by comparing the efficacy of two commonly used viral vectors and the resulting serum and salivary distribution of transgene encoded hormones. A low dose (5 x10(9) particles) of either an adenoviral serotype 5 (Ad5) vector encoding the human erythropoietin (hEPO) cDNA or an adeno-associated virus sero-type 2 (AAV2) vector encoding either the hEPO or human growth hormone (hGH) cDNA was administered to individual submandibular SGs of Balb/c mice. Serum and salivary hEPO and hGH levels were determined at defined time points. Two additional recombinant viruses encoding enhanced green fluorescence protein (GFP) were also used (AdGFP and AAVGFP) in order to perform immunohistochemical analyses of transgenic protein localization in SG sections post-administration. AAV2 vectors led to stable gene transfer unlike the results with the Ad5 vectors. Indeed, in one mouse we observed hEPO production for a period of two years after administration of AAVhEPO to SGs. hEPO, which is a constitutive pathway secretory protein, was readily secreted into the bloodstream from the SGs, yielding therapeutically adequate serum levels. Conversely, hGH, a regulated secretory pathway protein, was preferentially secreted into saliva. SGs may be an attractive candidate target tissue for gene therapeutics of some monogenetic endocrine deficiency disorders. At present, AAV2 vectors seem particularly useful for such applications, and transgenes encoding constitutive secretory pathway hormones are more suitable for this application with SGs than those encoding regulated secretory pathway hormones.

Adenoviridae↗

PubMed2004

Pilot clinical trial of dehydroepiandrosterone (DHEA) versus placebo for Sjögren's syndrome.

OBJECTIVE: To screen for potential efficacy and assess feasibility and safety of dehydroepiandrosterone (DHEA) as a treatment for Sjögren's syndrome (SS). METHODS: A 24-week randomized, double-blinded, pilot trial of oral DHEA (200 mg/day) versus placebo was conducted. The primary comparison was to a hypothesized 20% placebo response rate. If 14 consecutive subjects on DHEA did not respond, a Phase III trial would be considered futile. A placebo group of 14 subjects was planned to verify placebo response rate and estimate sample size required for a definitive trial. Response criteria required 20% improvement in at least 2 of 3 domains. Analysis of covariance was used to adjust for baseline differences and for stratified randomization. Outcome measures included visual analog scale questionnaires for dry eye and dry mouth symptoms, lissamine green ocular dye staining and Schirmer I tests, stimulated salivary flow, IgG, and erythrocyte sedimentation rate (ESR). RESULTS: Randomization resulted in 14 DHEA and 14 placebo group subjects. At baseline, mean +/- SD for DHEA versus placebo groups were Schirmer I tests 4.5 +/- 4.5 versus 5.4 +/- 6.1 mm/5 minutes; Van Bijsterveld score 5.3 +/- 2.1 versus 5.5 +/- 2.2; unstimulated saliva 0.03 +/- 0.05 versus 0.04 +/- 0.10 ml/minute; IgG 1,699 +/- 749 versus 1,712 +/- 621 g/dl; and ESR 40 +/- 31 versus 44 +/- 28 mm/hour. Apart from changes over the trial in dry mouth symptoms, no significant differences were noted between the DHEA and placebo groups for dry eye symptoms, objective measures of ocular dryness, stimulated salivary flow; IgG, or ESR. Four DHEA and one placebo group patient dropped out because of adverse effects. Although 7 subjects met response criteria in the DHEA group, 5 met the criteria in the placebo group, and there was no significant difference between groups. CONCLUSION: DHEA showed no evidence of efficacy in SS. Without evidence for efficacy, patients with SS should avoid using unregulated DHEA supplements, since long-term adverse consequences of exposure to this hormone are unknown.

Adjuvants, Immunologic↗

PubMed2004

Reengineered salivary glands are stable endogenous bioreactors for systemic gene therapeutics.

The use of critical-for-life organs (e.g., liver or lung) for systemic gene therapeutics can lead to serious safety concerns. To circumvent such issues, we have considered salivary glands (SGs) as an alternative gene therapeutics target tissue. Given the high secretory abilities of SGs, we hypothesized that administration of low doses of recombinant adeno-associated virus (AAV) vectors would allow for therapeutic levels of transgene-encoded secretory proteins in the bloodstream. We administered 10(9) particles of an AAV vector encoding human erythropoietin (hEPO) directly to individual mouse submandibular SGs. Serum hEPO reached maximum levels 8-12 weeks after gene delivery and remained relatively stable for 54 weeks (longest time studied). Hematocrit levels were similarly increased. Moreover, these effects proved to be vector dose-dependent, and even a dosage as low as 10(8) particles per animal led to significant increases in hEPO and hematocrit levels. Vector DNA was detected only within the targeted SGs, and levels of AAV copies within SGs were highly correlated with serum hEPO levels (r = 0.98). These results show that SGs appear to be promising targets with potential clinical applicability for systemic gene therapeutics.

Animals↗

PubMed2004

Etanercept in Sjögren's syndrome: a twelve-week randomized, double-blind, placebo-controlled pilot clinical trial.

OBJECTIVE: To assess the safety and potential efficacy of etanercept in the treatment of Sjögren's syndrome (SS). METHODS: This pilot study was a 12-week randomized, double-blind, placebo-controlled trial of etanercept, with 14 subjects in each group. Patients received 25 mg of etanercept or placebo (vehicle) by twice-weekly subcutaneous injection. Patients met the American-European Consensus Group criteria for SS. The primary outcome required at least 20% improvement from baseline values for at least 2 of the following 3 domains: subjective or objective measures of dry mouth, subjective or objective measures of dry eyes, and IgG level or erythrocyte sedimentation rate (ESR). RESULTS: Of the 14 patients taking etanercept, 11 had primary SS and 3 had SS secondary to rheumatoid arthritis. Baseline measures did not differ between the 2 groups. Three etanercept-treated patients and 1 placebo-treated patient did not complete the trial. Five etanercept-treated patients and 3 placebo-treated patients showed improvement from baseline in the primary outcome variable at 12 weeks, but the difference was not statistically significant. There were no significant differences between the groups for changes in subjective measures of oral or ocular symptoms (by visual analog scale), the IgG level, Schirmer I test result, van Bijsterveld score, or salivary flow. At 12 weeks, the ESR had decreased in the etanercept group compared with baseline (P = 0.004); however, the mean reduction was only 18.6%. CONCLUSION: We found no evidence to suggest that treatment with etanercept at a dosage of 25 mg twice weekly for 12 weeks was clinically efficacious in SS. A larger trial will be necessary to definitively address the efficacy of etanercept in the treatment of SS.

Arthritis, Rheumatoid↗

PubMed2003

Advances in vector-mediated gene transfer.

Clinical applications of gene transfer technology initially targeted the treatment of inherited monogenetic disorders and cancers refractory to conventional therapies. Today, gene transfer approaches are being developed for most tissues and for multiple disorders including those affecting quality of life. The focus herein is eventual application of gene transfer technology for the management of organ-directed autoimmunity. A specific example is presented: Sjögren's syndrome and localized salivary gland gene transfer. The status of relevant pre-clinical gene transfer studies is reviewed, with an emphasis on use of adenoviral and adeno-associated viral vectors. Current limitations of effective organ-directed gene transfer are also discussed.

Adenoviridae↗

PubMed2003

Local adeno-associated virus-mediated interleukin 10 gene transfer has disease-modifying effects in a murine model of Sjögren's syndrome.

Female nonobese diabetic (NOD) mice develop spontaneous autoimmune sialadenitis and loss of salivary flow, and are a widely used model of Sjögren's syndrome. We examined the feasibility of local salivary gland immunomodulatory gene delivery to alter these sequelae in NOD mice. We constructed recombinant adeno-associated virus (rAAV) vectors encoding either human interleukin 10 (rAAVhIL-10) or beta-galactosidase (rAAVLacZ, control vector). Mice received rAAVhIL-10 or rAAVLacZ by retrograde submandibular ductal instillation either at age 8 weeks (early, before onset of sialadenitis), or at 16 weeks (late, after onset of sialadenitis). As a systemic treatment control, separate mice received intramuscular delivery of rAAVhIL-10 at each time point. Both submandibular and intramuscular delivery of vector led to low circulating levels of hIL-10. After submandibular administration of rAAVhIL-10, salivary flow rates at 20 weeks for both the early and late treatment groups were significantly higher than for both rAAVLacZ-administered and untreated mice. Systemic delivery of rAAVhIL-10 led to improved salivary flow in the late treatment group. Inflammatory infiltrates in submandibular glands, however, were significantly reduced only in mice receiving rAAVhIL-10 locally in the salivary gland compared with mice receiving this vector intramuscularly, or rAAVLacZ or no treatment. In addition, after submandibular rAAVhIL-10 delivery, NOD mice exhibited significantly lower blood glucose, and higher serum insulin, levels than all other groups, indicating some systemic benefit of this treatment. These studies show that expression of hIL-10 by rAAV vectors can have disease-modifying effects in the salivary glands of NOD mice, and suggest that local immunomodulatory gene transfer may be useful for managing the salivary gland pathology in Sjögren's syndrome.

Animals↗