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Prevalence and pharmacological modulation of humoral immunity to AAV vectors in gene transfer to synovial tissue.

Mingozzi F, Chen Y, Edmonson SC, Zhou S, Thurlings RM, Tak PP, High KA, Vervoordeldonk MJ - Gene Ther. (2012)

Bottom Line: This difference was more evident for AAV2, against which higher titers were measured.A drop of NAb titer was observed in a subset of those subjects carrying NAb titers ≤1:1000; however, only in a minority of subjects titers dropped below 1:5.This work provides insights into strategies to overcome the limitation of pre-existing humoral immunity to AAV vectors.

View Article: PubMed Central - PubMed

Affiliation: Center of Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. mingozzi@email.chop.edu

ABSTRACT
Antibodies against adeno-associated viral (AAV) vectors are highly prevalent in humans. Both preclinical and clinical studies showed that antibodies against AAV block transduction even at low titers, particularly when the vector is introduced into the bloodstream. Here we measured the neutralizing antibody (NAb) titer against AAV serotypes 2, 5, 6 and 8 in the serum and matched synovial fluid (SF) from rheumatoid arthritis patients. The titer in the SF was lower than that in the matched plasma samples, indicating a difference in distribution of NAb to AAV depending on the body fluid compartment. This difference was more evident for AAV2, against which higher titers were measured. Of all serotypes, anti-AAV5 antibodies were the least prevalent in both the serum and SF. We next evaluated the impact of B-cell depletion on anti-AAV antibodies in rheumatoid arthritis patients who received one or two courses of the anti-CD20 antibody rituximab as part of their disease management. A drop of NAb titer was observed in a subset of those subjects carrying NAb titers ≤1:1000; however, only in a minority of subjects titers dropped below 1:5. This work provides insights into strategies to overcome the limitation of pre-existing humoral immunity to AAV vectors.

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Related in: MedlinePlus

Anti-AAV IgG titers before and after a single course of rituximab. Anti-AAV IgGs were measured in the serum at baseline and 24 weeks after rituximab administration. (a) Anti-AAV2 IgG (ng ml−1) and (b) anti-AAV5 IgG (ng ml−1). For each sample, the average of a duplicate reading is reported. AVG, average±standard deviation of all individual measurements.
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fig3: Anti-AAV IgG titers before and after a single course of rituximab. Anti-AAV IgGs were measured in the serum at baseline and 24 weeks after rituximab administration. (a) Anti-AAV2 IgG (ng ml−1) and (b) anti-AAV5 IgG (ng ml−1). For each sample, the average of a duplicate reading is reported. AVG, average±standard deviation of all individual measurements.

Mentions: To test the efficacy of B-cell depletion with the anti-CD20 antibody rituximab, a series of 28 RA subjects receiving two intravenous infusions of 1000 mg of the drug 2 weeks apart were selected. All subjects were also stable on methothrexate, a cytotoxic drug with known antiproliferative effects on both B and T cells. Following rituximab administration, B cells (monitored in peripheral blood by staining for CD19) disappeared from the circulation for several weeks and began reappearing around week 24 post-rituximab infusion.22 Serum samples were analyzed for both non-NAb and NAb to AAV; no matched SF was available from these subjects. However, anti-AAV antibody titer determination in matched serum and SF samples suggests that NAb titer in the serum is representative of that in the SF (vide supra). Total anti-capsid IgG to both AAV2 and AAV5 were measured in a subset of subjects (n=15) before rituximab administration and 24 weeks after the course was given in these patients, a time point when maximum therapeutic benefit (that is, disease activity score reduction) was observed.22 For both serotypes, a drop in total IgG was observed in most of the subjects tested (Figures 3a and b), which was statistically significant in the case of anti-AAV-2 IgG (P=0.0371, paired t-test), but not for anti-AAV-5 IgG (P=0.5020, paired t-test). Both for AAV2 and AAV5 IgG, a drop in titer was not observed in all subjects, and the magnitude of the changes measured was variable. This is in agreement with the observed variability in the clinical response to rituximab administration in this cohort of subjects.22


Prevalence and pharmacological modulation of humoral immunity to AAV vectors in gene transfer to synovial tissue.

Mingozzi F, Chen Y, Edmonson SC, Zhou S, Thurlings RM, Tak PP, High KA, Vervoordeldonk MJ - Gene Ther. (2012)

Anti-AAV IgG titers before and after a single course of rituximab. Anti-AAV IgGs were measured in the serum at baseline and 24 weeks after rituximab administration. (a) Anti-AAV2 IgG (ng ml−1) and (b) anti-AAV5 IgG (ng ml−1). For each sample, the average of a duplicate reading is reported. AVG, average±standard deviation of all individual measurements.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3473155&req=5

fig3: Anti-AAV IgG titers before and after a single course of rituximab. Anti-AAV IgGs were measured in the serum at baseline and 24 weeks after rituximab administration. (a) Anti-AAV2 IgG (ng ml−1) and (b) anti-AAV5 IgG (ng ml−1). For each sample, the average of a duplicate reading is reported. AVG, average±standard deviation of all individual measurements.
Mentions: To test the efficacy of B-cell depletion with the anti-CD20 antibody rituximab, a series of 28 RA subjects receiving two intravenous infusions of 1000 mg of the drug 2 weeks apart were selected. All subjects were also stable on methothrexate, a cytotoxic drug with known antiproliferative effects on both B and T cells. Following rituximab administration, B cells (monitored in peripheral blood by staining for CD19) disappeared from the circulation for several weeks and began reappearing around week 24 post-rituximab infusion.22 Serum samples were analyzed for both non-NAb and NAb to AAV; no matched SF was available from these subjects. However, anti-AAV antibody titer determination in matched serum and SF samples suggests that NAb titer in the serum is representative of that in the SF (vide supra). Total anti-capsid IgG to both AAV2 and AAV5 were measured in a subset of subjects (n=15) before rituximab administration and 24 weeks after the course was given in these patients, a time point when maximum therapeutic benefit (that is, disease activity score reduction) was observed.22 For both serotypes, a drop in total IgG was observed in most of the subjects tested (Figures 3a and b), which was statistically significant in the case of anti-AAV-2 IgG (P=0.0371, paired t-test), but not for anti-AAV-5 IgG (P=0.5020, paired t-test). Both for AAV2 and AAV5 IgG, a drop in titer was not observed in all subjects, and the magnitude of the changes measured was variable. This is in agreement with the observed variability in the clinical response to rituximab administration in this cohort of subjects.22

Bottom Line: This difference was more evident for AAV2, against which higher titers were measured.A drop of NAb titer was observed in a subset of those subjects carrying NAb titers ≤1:1000; however, only in a minority of subjects titers dropped below 1:5.This work provides insights into strategies to overcome the limitation of pre-existing humoral immunity to AAV vectors.

View Article: PubMed Central - PubMed

Affiliation: Center of Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. mingozzi@email.chop.edu

ABSTRACT
Antibodies against adeno-associated viral (AAV) vectors are highly prevalent in humans. Both preclinical and clinical studies showed that antibodies against AAV block transduction even at low titers, particularly when the vector is introduced into the bloodstream. Here we measured the neutralizing antibody (NAb) titer against AAV serotypes 2, 5, 6 and 8 in the serum and matched synovial fluid (SF) from rheumatoid arthritis patients. The titer in the SF was lower than that in the matched plasma samples, indicating a difference in distribution of NAb to AAV depending on the body fluid compartment. This difference was more evident for AAV2, against which higher titers were measured. Of all serotypes, anti-AAV5 antibodies were the least prevalent in both the serum and SF. We next evaluated the impact of B-cell depletion on anti-AAV antibodies in rheumatoid arthritis patients who received one or two courses of the anti-CD20 antibody rituximab as part of their disease management. A drop of NAb titer was observed in a subset of those subjects carrying NAb titers ≤1:1000; however, only in a minority of subjects titers dropped below 1:5. This work provides insights into strategies to overcome the limitation of pre-existing humoral immunity to AAV vectors.

Show MeSH
Related in: MedlinePlus