Agonistic anti-DCIR antibody inhibits ITAM-mediated inflammatory signaling and promotes immune resolution.

DC inhibitory receptor (DCIR) is a C-type lectin receptor selectively expressed on myeloid cells, including monocytes, macrophages, DCs, and neutrophils. Its role in immune regulation has been implicated in murine models and human genome-wide association studies, suggesting defective DCIR function associates with increased susceptibility to autoimmune diseases such as rheumatoid arthritis, lupus, and Sjögren's syndrome. However, little is known about the mechanisms underlying DCIR activation to dampen inflammation. Here, we developed anti-DCIR agonistic antibodies that promote phosphorylation on DCIR's immunoreceptor tyrosine-based inhibitory motifs and recruitment of SH2 containing protein tyrosine phosphatase-2 for reducing inflammation. We also explored the inflammation resolution by depleting DCIR+ cells with antibodies. Utilizing a human DCIR-knock-in mouse model, we validated the antiinflammatory properties of the agonistic anti-DCIR antibody in experimental peritonitis and colitis. These findings provide critical evidence for targeting DCIR to develop transformative therapies for inflammatory diseases.

Generation and characterization of ABBV642, a dual variable domain immunoglobulin molecule (DVD-Ig) that potently neutralizes VEGF and PDGF-BB and is designed for the treatment of exudative age-related macular degeneration.

Exudative age-related macular degeneration (AMD) is the most common cause of moderate and severe vision loss in developed countries. Intraocular injections of vascular endothelial growth factor (VEGF or VEGF-A)-neutralizing proteins provide substantial benefit, but frequent, long-term injections are needed. In addition, many patients experience initial visual gains that are ultimately lost due to subretinal fibrosis. Preclinical studies and early phase clinical trials suggest that combined suppression of VEGF and platelet-derived growth factor-BB (PDGF-BB) provides better outcomes than suppression of VEGF alone, due to more frequent regression of neovascularization (NV) and suppression of subretinal fibrosis. We generated a dual variable domain immunoglobulin molecule, ABBV642 that specifically and potently binds and neutralizes VEGF and PDGF-BB. ABBV642 has been optimized for treatment of exudative AMD based on the following design characteristics: 1) high affinity binding to all VEGF-A isoforms and both soluble and extracellular matrix (ECM)-associated PDGF-BB; 2) potential for extended residence time in the vitreous cavity to decrease the frequency of intraocular injections; 3) rapid clearance from systemic circulation compared with molecules with wild type Fc region for normal FcRn binding, which may reduce the risk of systemic complications; and 4) low risk of potential effector function. The bispecificity of ABBV642 allows for a single injection of a single therapeutic agent, and thus a more streamlined development and regulatory path compared with combination products. In a mouse model of exudative AMD, ABBV642 was observed to be more effective than aflibercept. ABBV642 has potential to improve efficacy with reduced injection frequency in patients with exudative AMD, thereby reducing the enormous disease burden for patients and society.

Preferential germline usage and VH/VL pairing observed in human antibodies selected by mRNA display.

Since the invention of phage display, in vitro antibody display technologies have revolutionized the field of antibody discovery. In combination with antibody libraries constructed with sequences of human origin, such technologies enable accelerated therapeutic antibody discovery while bypassing the laborious animal immunization and hybridoma generation processes. Many in vitro display technologies developed since aim to differentiate from phage display by displaying full-length IgG proteins, utilizing eukaryotic translation system and codons, increasing library size or real-time kinetic selection by fluorescent activated cell sorting. We report here the development of an mRNA display technology and an accompanying HCDR3 size spectratyping monitor for human antibody discovery. Importantly, the mRNA display technology maintains a monovalent linkage between the mRNA (genotype) and display binding protein (phenotype), which minimizes avidity effect common in other display systems and allows for a stringent affinity and off-rate selection. The mRNA display technology successfully identified 100 human antibodies in 15 different selections against various targets from naïve human antibody libraries. These antibodies in general have high affinity and diversity. By analyzing the germline usage and combination of antibodies selected by the mRNA display technology, we identified trends and determined the productivity of each germline subgroup in the libraries that could serve as the knowledge base for constructing fully synthetic, next generation antibody libraries.

Effect of the light chain C-terminal serine residue on disulfide bond susceptibility of human immunoglobulin G1λ.

The light chain cysteine residue that forms an interchain disulfide bond with the cysteine residue in the heavy chain in IgG1κ is the last amino acid. The cysteine residue is followed by a serine residue in IgG1λ. Effect of the serine residue on the susceptibility of disulfide bonds to reduction was investigated in the current study using a method including reduction, differential alkylation using iodoacetic acid with either natural isotopes or enriched with carbon-13, and mass spectrometry analysis. This newly developed method allowed an accurate determination of the susceptibility of disulfide bonds in IgG antibodies. The effect of the serine residue on disulfide bond susceptibility was compared using three antibodies with differences only in the light chain last amino acid, which was either a serine residue, an alanine residue or deleted. The results demonstrated that the presence of the amino acid (serine or alanine) increased the susceptibility of the inter light and heavy chain disulfide bonds to reduction. On the other hand, susceptibility of the two inter heavy chain disulfide bonds and intrachain disulfide bonds was not changed significantly.

H2-mismatched transplantation with repetitive cell infusions and CD40 ligand antibody infusions without myeloablation.

Graft rejection and graft-versus-host disease are major problems in mismatched marrow transplants along with toxicity from standard myeloablative host treatments. We have established a tolerization model, using 1 Gy irradiation, which reduces stem cell capacity to < 10% of control while causing minimal myelosuppression, donor antigen pre-exposure (spleen cells), CD40-ligand antibody blockade and high levels of marrow (40 x 106 cells), which allows for stable long-term multilineage engraftment in H2-mismatched murine marrow transplants. We now show that the establishment of 'microchimaerism' (0.5-3.8%) sets the stage for macrochimaerism, with subsequent marrow infusions in H2-mismatched mice with CD40-ligand blockade only. Neither irradiation nor spleen cell exposure were necessary. When 40 x 106 bone marrow cells were infused on weeks 0, 12, 14 and 16, blood engraftment was about seven times the single 40 x 106 control. When marrow cells were given on weeks 0, 3, 4, 5 and 6, engraftment at 24 weeks post transplant was 17.9 +/- 1.2%, compared with 2.7 +/- 0.8% for the single 40 x 106 control (P = 0.009). We have shown stable, long-term multilineage chimaerism and established that the schedule of marrow administration, not the total cell dose, is critical for tolerization. This approach indicates that microchimaerism can tolerize for subsequent marrow infusions and produce macrochimaerism. This strategy could be applied in clinical human transplants.