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Anti-aβ oligomer IgG and surface sialic acid in intravenous immunoglobulin: measurement and correlation with clinical outcomes in Alzheimer's disease treatment.

Kwon H, Crisostomo AC, Smalls HM, Finke JM - PLoS ONE (2015)

Bottom Line: The fraction of IgG antibodies with anti-oligomeric Aβ affinity and surface sialic acid was compared between Octagam and Gammagard intravenous immunoglobulin (IVIG) using two complementary surface plasmon resonance methods.The fraction and location of surface-accessible sialic acid in the Fab domain was found to be similar between Gammagard and Octagam.These findings indicate that anti-oligomeric Aβ IgG and total surface sialic acid alone cannot account for reported clinical differences in the two IVIG products.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicinal Chemistry, University of Washington, Seattle, Washington, United States of America.

ABSTRACT
The fraction of IgG antibodies with anti-oligomeric Aβ affinity and surface sialic acid was compared between Octagam and Gammagard intravenous immunoglobulin (IVIG) using two complementary surface plasmon resonance methods. These comparisons were performed to identify if an elevated fraction existed in Gammagard, which reported small putative benefits in a recent Phase III clinical trial for Alzheimer's Disease. The fraction of anti-oligomeric Aβ IgG was found to be higher in Octagam, for which no cognitive benefits were reported. The fraction and location of surface-accessible sialic acid in the Fab domain was found to be similar between Gammagard and Octagam. These findings indicate that anti-oligomeric Aβ IgG and total surface sialic acid alone cannot account for reported clinical differences in the two IVIG products. A combined analysis of sialic acid in anti-oligomeric Aβ IgG did reveal a notable finding that this subgroup exhibited a high degree of surface sialic acid lacking the conventional α2,6 linkage. These results demonstrate that the IVIG antibodies used to engage oligomeric Aβ in both Gammagard and Octagam clinical trials did not possess α2,6-linked surface sialic acid at the time of administration. Anti-oligomeric Aβ IgG with α2,6 linkages remains untested as an AD treatment.

No MeSH data available.


Related in: MedlinePlus

4G8 is IgL sialylated, 6E10 is Fc sialylated, and IVIG exhibits both Fc and IgL sialylation.(A) SDS-PAGE gel of Octagam IVIG (OCT), Gammagard IVIG (GG), 4G8, and 6E10. (B) SNA lectin blot of Octagam IVIG (OCT), Gammagard IVIG (GG), 4G8, and 6E10. Diffuse dark staining in the SNA lectin blot is evident immediately above both light chain (IgL) and heavy chain (IgH) bands of IVIG (black rectangles), in the upper of two IgL bands of 4G8 (circle), and in the single IgH band of 6E10 (square). (C,D) SDS-PAGE gel of 6E10 and 4G8 (C) and OCT and GG (D), all treated with and without PNGase F. PNGase F-treated samples contained one of two surfactants, 10% Triton X-100 or 15% NEB. For comparison, samples without PNGase F contained 10% Triton X-100. Bands migrating as indicated by “P” are the PNGase F enzyme (36 kD). Arrows in non-PNGase F lanes indicate IgG bands that are absent after PNGase F treatment.
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pone.0120420.g006: 4G8 is IgL sialylated, 6E10 is Fc sialylated, and IVIG exhibits both Fc and IgL sialylation.(A) SDS-PAGE gel of Octagam IVIG (OCT), Gammagard IVIG (GG), 4G8, and 6E10. (B) SNA lectin blot of Octagam IVIG (OCT), Gammagard IVIG (GG), 4G8, and 6E10. Diffuse dark staining in the SNA lectin blot is evident immediately above both light chain (IgL) and heavy chain (IgH) bands of IVIG (black rectangles), in the upper of two IgL bands of 4G8 (circle), and in the single IgH band of 6E10 (square). (C,D) SDS-PAGE gel of 6E10 and 4G8 (C) and OCT and GG (D), all treated with and without PNGase F. PNGase F-treated samples contained one of two surfactants, 10% Triton X-100 or 15% NEB. For comparison, samples without PNGase F contained 10% Triton X-100. Bands migrating as indicated by “P” are the PNGase F enzyme (36 kD). Arrows in non-PNGase F lanes indicate IgG bands that are absent after PNGase F treatment.

Mentions: To determine if Octagam and Gammagard differ in sialic acid location, SDS-PAGE and lectin blots were used initially (Fig 6). SDS-PAGE in Fig 6A shows that Octagam and Gammagard are comprised of light (IgGL) and heavy (IgGH) chain bands near the expected masses of 25 and 50 kD respectively. However, a clear picture of IgGL and IgGH states in IVIG is complicated by diffuse primary IgGL and IgGH bands and also many higher molecular weight bands. The bands of mAbs 4G8 and 6E10 were much simpler than those of IVIG. While simpler than IVIG, 4G8 does exhibit two well-resolved bands for both IgGL and IgGH. By contrast, 6E10 shows only a single discernible band for both IgGL and IgGH. One explanation for additional IgGL and IgGH bands in Fig 6A is the presence of glycans bound in the respective VL and VH regions of these chains [29,39].


Anti-aβ oligomer IgG and surface sialic acid in intravenous immunoglobulin: measurement and correlation with clinical outcomes in Alzheimer's disease treatment.

Kwon H, Crisostomo AC, Smalls HM, Finke JM - PLoS ONE (2015)

4G8 is IgL sialylated, 6E10 is Fc sialylated, and IVIG exhibits both Fc and IgL sialylation.(A) SDS-PAGE gel of Octagam IVIG (OCT), Gammagard IVIG (GG), 4G8, and 6E10. (B) SNA lectin blot of Octagam IVIG (OCT), Gammagard IVIG (GG), 4G8, and 6E10. Diffuse dark staining in the SNA lectin blot is evident immediately above both light chain (IgL) and heavy chain (IgH) bands of IVIG (black rectangles), in the upper of two IgL bands of 4G8 (circle), and in the single IgH band of 6E10 (square). (C,D) SDS-PAGE gel of 6E10 and 4G8 (C) and OCT and GG (D), all treated with and without PNGase F. PNGase F-treated samples contained one of two surfactants, 10% Triton X-100 or 15% NEB. For comparison, samples without PNGase F contained 10% Triton X-100. Bands migrating as indicated by “P” are the PNGase F enzyme (36 kD). Arrows in non-PNGase F lanes indicate IgG bands that are absent after PNGase F treatment.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380445&req=5

pone.0120420.g006: 4G8 is IgL sialylated, 6E10 is Fc sialylated, and IVIG exhibits both Fc and IgL sialylation.(A) SDS-PAGE gel of Octagam IVIG (OCT), Gammagard IVIG (GG), 4G8, and 6E10. (B) SNA lectin blot of Octagam IVIG (OCT), Gammagard IVIG (GG), 4G8, and 6E10. Diffuse dark staining in the SNA lectin blot is evident immediately above both light chain (IgL) and heavy chain (IgH) bands of IVIG (black rectangles), in the upper of two IgL bands of 4G8 (circle), and in the single IgH band of 6E10 (square). (C,D) SDS-PAGE gel of 6E10 and 4G8 (C) and OCT and GG (D), all treated with and without PNGase F. PNGase F-treated samples contained one of two surfactants, 10% Triton X-100 or 15% NEB. For comparison, samples without PNGase F contained 10% Triton X-100. Bands migrating as indicated by “P” are the PNGase F enzyme (36 kD). Arrows in non-PNGase F lanes indicate IgG bands that are absent after PNGase F treatment.
Mentions: To determine if Octagam and Gammagard differ in sialic acid location, SDS-PAGE and lectin blots were used initially (Fig 6). SDS-PAGE in Fig 6A shows that Octagam and Gammagard are comprised of light (IgGL) and heavy (IgGH) chain bands near the expected masses of 25 and 50 kD respectively. However, a clear picture of IgGL and IgGH states in IVIG is complicated by diffuse primary IgGL and IgGH bands and also many higher molecular weight bands. The bands of mAbs 4G8 and 6E10 were much simpler than those of IVIG. While simpler than IVIG, 4G8 does exhibit two well-resolved bands for both IgGL and IgGH. By contrast, 6E10 shows only a single discernible band for both IgGL and IgGH. One explanation for additional IgGL and IgGH bands in Fig 6A is the presence of glycans bound in the respective VL and VH regions of these chains [29,39].

Bottom Line: The fraction of IgG antibodies with anti-oligomeric Aβ affinity and surface sialic acid was compared between Octagam and Gammagard intravenous immunoglobulin (IVIG) using two complementary surface plasmon resonance methods.The fraction and location of surface-accessible sialic acid in the Fab domain was found to be similar between Gammagard and Octagam.These findings indicate that anti-oligomeric Aβ IgG and total surface sialic acid alone cannot account for reported clinical differences in the two IVIG products.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicinal Chemistry, University of Washington, Seattle, Washington, United States of America.

ABSTRACT
The fraction of IgG antibodies with anti-oligomeric Aβ affinity and surface sialic acid was compared between Octagam and Gammagard intravenous immunoglobulin (IVIG) using two complementary surface plasmon resonance methods. These comparisons were performed to identify if an elevated fraction existed in Gammagard, which reported small putative benefits in a recent Phase III clinical trial for Alzheimer's Disease. The fraction of anti-oligomeric Aβ IgG was found to be higher in Octagam, for which no cognitive benefits were reported. The fraction and location of surface-accessible sialic acid in the Fab domain was found to be similar between Gammagard and Octagam. These findings indicate that anti-oligomeric Aβ IgG and total surface sialic acid alone cannot account for reported clinical differences in the two IVIG products. A combined analysis of sialic acid in anti-oligomeric Aβ IgG did reveal a notable finding that this subgroup exhibited a high degree of surface sialic acid lacking the conventional α2,6 linkage. These results demonstrate that the IVIG antibodies used to engage oligomeric Aβ in both Gammagard and Octagam clinical trials did not possess α2,6-linked surface sialic acid at the time of administration. Anti-oligomeric Aβ IgG with α2,6 linkages remains untested as an AD treatment.

No MeSH data available.


Related in: MedlinePlus