Comprehensive interrogation of a minimalist synthetic CDR-H3 library and its ability to generate antibodies with therapeutic potential.

We have generated large libraries of single-chain Fv antibody fragments (>10(10) transformants) containing unbiased amino acid diversity that is restricted to the central combining site of the stable, well-expressed DP47 and DPK22 germline V-genes. Library WySH2A was constructed to examine the potential for synthetic complementarity-determining region (CDR)-H3 diversity to act as the lone source of binding specificity. Library WySH2B was constructed to assess the necessity for diversification in both the H3 and L3. Both libraries provided diverse, specific antibodies, yielding a total of 243 unique hits against 7 different targets, but WySH2B produced fewer hits than WySH2A when selected in parallel. WySH2A also consistently produced hits of similar quality to WySH2B, demonstrating that the diversification of the CDR-L3 reduces library fitness. Despite the absence of deliberate bias in the library design, CDR length was strongly associated with the number of hits produced, leading to a functional loop length distribution profile that mimics the biases observed in the natural repertoire. A similar trend was also observed for the CDR-L3. After target selections, several key amino acids were enriched in the CDR-H3 (e.g., small and aromatic residues) while others were reduced (e.g., strongly charged residues) in a manner that was specific to position, preferentially occurred in CDR-H3 stem positions, and tended towards residues associated with loop stabilization. As proof of principle for the WySH2 libraries to produce viable lead candidate antibodies, 114 unique hits were produced against Delta-like ligand 4 (DLL4). Leads exhibited nanomolar binding affinities, highly specific staining of DLL4+ cells, and biochemical neutralization of DLL4-NOTCH1 interaction.

Clinical amelioration of murine lupus by a peptide based on the complementarity determining region-1 of an autoantibody and by cyclophosphamide: similarities and differences in the mechanisms of action.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibodies and systemic clinical manifestations. In this study we investigated the beneficial effects on murine lupus accomplished by a peptide based on the sequence of the complementarity-determining region 1 of an anti-DNA autoantibody (hCDR1) when given alone or in combination with cyclophosphamide (CYC), and determined the mechanisms underlying those effects. SLE-afflicted (NZB x NZW) F(1) mice were treated for 12 weeks with injections of hCDR1, CYC or a combination of both drugs. We found that hCDR1 and CYC ameliorated serological and renal manifestations of the diseased mice, down-regulated interferon-gamma and interleukin-10, and up-regulated transforming growth factor-beta. These effects were associated with an increment of naive CD4(+) cells at the expense of the number of CD4(+) cells with the memory/activated phenotype. Further, the number of CD8(+) cells in the diseased mice was increased by the two drugs, resulting in a significant decrease in the CD4 : CD8 ratio. However, whereas the frequency and activity of CD4(+) CD25(+) CD45RB(low) regulatory T cells and the expression of cytotoxic T-lymphocyte antigen 4 (CTLA-4) in CD4(+) cells were up-regulated by hCDR1 treatment, they were minimally affected following treatment with CYC. CTLA-4 played an important role in the activity of the hCDR1-induced CD4(+) CD25(+) cells as manifested by down-regulation of CD28 expression, decrease of activation-induced apoptosis, and modulation of the cytokine profile in CD4(+) CD25(-) cells derived from SLE-afflicted mice. Thus, although the two drugs have similar ameliorative effects, hCDR1 but not CYC elicits regulatory pathways that are of importance for tolerance induction in SLE.

The therapeutic potential of TREM-1 modulation in the treatment of sepsis and beyond.

The triggering receptor expressed on myeloid cells (TREM)-1 is a recently identified molecule that is involved in monocytic activation and the inflammatory response. It belongs to a family related to natural killer cell receptors, and is expressed on neutrophils, mature monocytes and macrophages. The engagement of TREM-1 synergizes with the activation of several toll-like receptors in amplifying the inflammatory response mediated by microbial components. The modulation of the TREM-1 signaling pathway, by the use of small synthetic peptides derived from its extracellular domain, confers interesting survival advantages during experimental murine septic shock, even when administered late after the onset of sepsis.

Amelioration of SLE-like manifestations in (NZBxNZW)F1 mice following treatment with a peptide based on the complementarity determining region 1 of an autoantibody is associated with a down-regulation of apoptosis and of the pro-apoptotic factor JNK kinase.

Treatment with peptides based on the complementarity determining regions (CDR) of murine and human monoclonal anti-DNA antibodies that bear the common idiotype, 16/6 Id, ameliorates disease manifestations of mice with either induced or spontaneous SLE. Aberrant expression and function of the p21Ras/MAP kinase pathway are associated with active SLE. Therefore, we examined the effect of treatment with a CDR1-based peptide of a human autoantibody (hCDR1) on the p21Ras pathway and SLE manifestations of SLE-prone (NZBxNZW)F1 mice. Untreated SLE-afflicted mice demonstrated increased expression of p21Ras and the phosphorylated active form of its down-stream element JNK kinase in conjunction with reduced hSOS and unchanged p120GAP, as compared to healthy controls. Amelioration of SLE manifestations following treatment with hCDR1 was associated with a diminished expression of phosphorylated JNK kinase, mainly in the T cell population that also exhibited reduced rates of apoptosis. Thus, hCDR1 therapy ameliorates SLE, at least in part, via down-regulation of the activity of the pro-apoptotic JNK kinase.

A peptide based on the complementarity determining region 1 of a human monoclonal autoantibody ameliorates spontaneous and induced lupus manifestations in correlation with cytokine immunomodulation.

A peptide based on the sequence of the complementarity determining region (CDR) 1 of a human monoclonal anti-DNA autoantibody that bears the 16/6 idiotype (16/6Id) was synthesized as a potential candidate for the treatment of SLE patients. The peptide, designated hCDR1, did not induce experimental SLE upon active immunization of mice. The ability of the peptide to treat an already established lupus that was either induced in BALB/c mice or developed spontaneously in (NZB x NZW)F1 mice was tested. Ten weekly injections of hCDR1 (200, 50 microg/mouse) given subcutaneously mitigated disease manifestations (e.g., leukopenia, proteinuria and kidney damage) and resulted in a prominent reduction in the dsDNA specific antibody titers. Furthermore, treatment with hCDR1 resulted in reduced secretion and expression of the "pathogenic" cytokines [i.e., INFgamma, IL-1beta, TNFalpha (in the induced model) and IL-10], whereas the immunosuppressive cytokine TGFbeta was up-regulated. Thus, the significant ameliorating effects of hCDR1 are manifested at least partially via the immunomodulation of the cytokine profile. These results suggest that hCDR1 is a potential candidate for a novel treatment of SLE patients.

Treatment of induced murine SLE with a peptide based on the CDR3 of an anti-DNA antibody reverses the pattern of pathogenic cytokines.

A peptide based on the complementarity determining region (CDR) 3 of a pathogenic anti-DNA monoclonal antibody that bears the 16/6 idiotype (Id) was shown previously to be a dominant T-cell epitope in experimental SLE, and to be capable of inhibiting SLE-associated responses. When injected, concomitant with active immunization with the pathogenic human anti-DNA, 16/6 Id+ mAb, pCDR3 inhibited the proliferation of LN-derived T cells stimulated in vitro with the 16/6 Id mAb. The inhibition of the specific proliferative responses could be reversed by the addition of exogenous IL-2 to the cultures. Analysis of secreted cytokine profile in supernatants of these cultures demonstrated that pCDR3 treatment reduced significantly the levels of both IL-2 and IFN-gamma that were elevated further in cells of the 16/6 Id-immunized mice. The CDR3-based peptide was shown here to immunomodulate in vivo experimental SLE, induced by the human anti-DNA 16/6 Id+ antibody. The beneficial effects of pCDR3 on the clinical manifestations of SLE were associated with downregulation of the Th1-type (IL-2, IFN-gamma) and proinflammatory (TNF-alpha) cytokines, whereas the immunosuppressive cytokine TGF-beta was up regulated.