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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-AAV2 NAb titer measured over time in the serum of subjects receiving a single course of rituximab. Serum samples were collected at baseline (pre-rituximab administration), and 4, 16 and 24 weeks thereafter. Y axis, log of the reciprocal dilution at which the neutralizing activity of the test serum is lower than 50%. The circles indicate subjects that show a drop in NAb titer after rituximab administration compared to baseline NAb titer. Baseline samples from subjects 4 and 20 and week 5 sample from subject 20 were not tested. For each time point, the NAb titer was obtained by testing each serum dilution in triplicate.
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fig4: Anti-AAV2 NAb titer measured over time in the serum of subjects receiving a single course of rituximab. Serum samples were collected at baseline (pre-rituximab administration), and 4, 16 and 24 weeks thereafter. Y axis, log of the reciprocal dilution at which the neutralizing activity of the test serum is lower than 50%. The circles indicate subjects that show a drop in NAb titer after rituximab administration compared to baseline NAb titer. Baseline samples from subjects 4 and 20 and week 5 sample from subject 20 were not tested. For each time point, the NAb titer was obtained by testing each serum dilution in triplicate.

Mentions: Despite the observed decrease in anti-AAV IgG in most of the subjects following rituximab administration, measurement of anti-AAV2 NAb in the cohort of 28 subjects at baseline, weeks 4, 16 and 24 showed that only subjects with starting NAb titers equal to or below 1:1000 achieved a lower serum-neutralizing activity following rituximab administration (Figure 4), while high-titer NAb did not change. Out of 28 subjects, 9 had a half-log drop in NAb titer, and in two subjects (2 and 31; Figure 4), the NAb titer decreased below 1:3.16 in the serum.


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-AAV2 NAb titer measured over time in the serum of subjects receiving a single course of rituximab. Serum samples were collected at baseline (pre-rituximab administration), and 4, 16 and 24 weeks thereafter. Y axis, log of the reciprocal dilution at which the neutralizing activity of the test serum is lower than 50%. The circles indicate subjects that show a drop in NAb titer after rituximab administration compared to baseline NAb titer. Baseline samples from subjects 4 and 20 and week 5 sample from subject 20 were not tested. For each time point, the NAb titer was obtained by testing each serum dilution in triplicate.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig4: Anti-AAV2 NAb titer measured over time in the serum of subjects receiving a single course of rituximab. Serum samples were collected at baseline (pre-rituximab administration), and 4, 16 and 24 weeks thereafter. Y axis, log of the reciprocal dilution at which the neutralizing activity of the test serum is lower than 50%. The circles indicate subjects that show a drop in NAb titer after rituximab administration compared to baseline NAb titer. Baseline samples from subjects 4 and 20 and week 5 sample from subject 20 were not tested. For each time point, the NAb titer was obtained by testing each serum dilution in triplicate.
Mentions: Despite the observed decrease in anti-AAV IgG in most of the subjects following rituximab administration, measurement of anti-AAV2 NAb in the cohort of 28 subjects at baseline, weeks 4, 16 and 24 showed that only subjects with starting NAb titers equal to or below 1:1000 achieved a lower serum-neutralizing activity following rituximab administration (Figure 4), while high-titer NAb did not change. Out of 28 subjects, 9 had a half-log drop in NAb titer, and in two subjects (2 and 31; Figure 4), the NAb titer decreased below 1:3.16 in the serum.

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