R707, a fully human antibody directed against CC-chemokine receptor 7, attenuates xenogeneic acute graft-versus-host disease.

Acute graft-versus-host disease (aGVHD) remains a barrier to the success of allogeneic hematopoietic stem cell transplantation (HSCT). Previously, we demonstrated that CC-chemokine receptor 7 (CCR7) is critical for aGVHD pathogenesis but dispensable for beneficial graft-versus-leukemia responses. As a result, we evaluated a fully human anti-CCR7-blocking antibody as a new approach to prevent aGVHD in preclinical models. Here we report that antibody R707 is able to block human CCR7 signaling and function in vitro in response to its 2 natural ligands. The antibody was less active against the murine orthologue, however, and failed to substantially limit aGVHD in a standard murine allogeneic HSCT model. Nevertheless, R707 significantly reduced xenogeneic aGVHD induced by human peripheral blood mononuclear cells (PBMCs). R707 limited CD4+ and in particular CD8+ T cell expansion during the period of antibody administration. These effects were transient, however, and T cell numbers recovered after antibody cessation. R707 did not substantially impair the antitumor potential of the PBMC inoculum as antibody-treated mice retained their capacity to reject a human acute myeloid leukemia cell line. Collectively, these data indicate for the first time that an antibody directed against CCR7 might represent a viable new approach for aGVHD prevention.

The Ex Vivo Treatment of Donor T Cells with Cosalane, an HIV Therapeutic and Small-Molecule Antagonist of CC-Chemokine Receptor 7, Separates Acute Graft-versus-Host Disease from Graft-versus-Leukemia Responses in Murine Hematopoietic Stem Cell Transplantation Models.

Despite recent advances in therapy, allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative option for a range of high-risk hematologic malignancies. However, acute graft-versus-host disease (aGVHD) continues to limit the long-term success of HSCT, and new therapies are still needed. We previously demonstrated that aGVHD depends on the ability of donor conventional T cells (Tcons) to express the lymph node trafficking receptor, CC-Chemokine Receptor 7 (CCR7). Consequently, we examined the ability of cosalane, a recently identified CCR7 small-molecule antagonist, to attenuate aGVHD in mouse HSCT model systems. Here we show that the systemic administration of cosalane to transplant recipients after allogeneic HSCT did not prevent aGVHD. However, we were able to significantly reduce aGVHD by briefly incubating donor Tcons with cosalane ex vivo before transplantation. Cosalane did not result in Tcon toxicity and did not affect their activation or expansion. Instead, cosalane prevented donor Tcon trafficking into host secondary lymphoid tissues very early after transplantation and limited their subsequent accumulation within the liver and colon. Cosalane did not appear to impair the intrinsic ability of donor Tcons to produce inflammatory cytokines. Furthermore, cosalane-treated Tcons retained their graft-versus-leukemia (GVL) potential and rejected a murine P815 inoculum after transplantation. Collectively, our data indicate that a brief application of cosalane to donor Tcons before HSCT significantly reduces aGVHD in relevant preclinical models while generally sparing beneficial GVL effects, and that cosalane might represent a viable new approach for aGVHD prophylaxis.

Impaired bone marrow B-cell development in mice with a bronchiolitis obliterans model of cGVHD.

Chronic graft-versus-host disease (cGVHD) causes significant morbidity and mortality in patients after allogeneic bone marrow (BM) or stem cell transplantation (allo-SCT). Recent work has indicated that both T and B lymphocytes play an important role in the pathophysiology of cGVHD. Previously, our group showed a critical role for the germinal center response in the function of B cells using a bronchiolitis obliterans (BO) model of cGVHD. Here, we demonstrated for the first time that cGVHD is associated with severe defects in the generation of BM B lymphoid and uncommitted common lymphoid progenitor cells. We found an increase in the number of donor CD4+ T cells in the BM of mice with cGVHD that was negatively correlated with B-cell development and the frequency of osteoblasts and Prrx-1-expressing perivascular stromal cells, which are present in the B-cell niche. Use of anti-DR3 monoclonal antibodies to enhance the number of donor regulatory T cells (Tregs) in the donor T-cell inoculum ameliorated the pathology associated with BO in this model. This correlated with an increased number of endosteal osteoblastic cells and significantly improved the generation of B-cell precursors in the BM after allo-SCT. Our work indicates that donor Tregs play a critical role in preserving the generation of B-cell precursors in the BM after allo-SCT. Approaches to enhance the number and/or function of donor Tregs that do not enhance conventional T-cell activity may be important to decrease the incidence and severity of cGVHD in part through normal B-cell lymphopoiesis.

18F-3'-Deoxy-3'-Fluorothymidine Positron Emission Tomography Imaging for the Prediction of Acute Graft-Versus-Host Disease in Mouse Hematopoietic Stem Cell Transplant Models.

Acute graft-versus-host disease (aGVHD) remains a barrier to the success of allogeneic hematopoietic stem cell transplantation. In mice, studies have demonstrated that donor conventional T cells traffic into host secondary lymphoid tissues early after transplant, and that this process is critical for the development of disease. As a result, the measurement of cellular proliferation within lymphoid sites early after transplant might be a useful approach for predicting aGVHD in humans. 18F-3'-deoxy-3'-fluorothymidine (FLT) positron emission tomography (PET) imaging has recently emerged as a functional imaging modality in oncology patients. FLT, a thymidine analog, is incorporated into replicating DNA and is thus an indirect marker of cellular proliferation. Here we report that FLT PET imaging can differentiate mice receiving alloreactive T cells and destined to develop lethal aGVHD from control mice. Mice receiving allogeneic T cells demonstrated a stronger FLT signal within the peripheral lymph nodes compared with control mice at all time points after transplant. In addition, allogeneic T cell recipients transiently demonstrated stronger FLT uptake within the spleen. Importantly, these differences were apparent before the development of clinical disease. In contrast, the FLT signal within the host bowel, an important aGVHD target organ, was more variable after transplant and was not consistently different between aGVHD mice and control mice. Collectively, these findings suggest that the imaging of patient lymphoid sites using existing FLT PET technology might be useful for predicting aGVHD in the clinical setting.

Targeting the Canonical Nuclear Factor-κB Pathway with a High-Potency IKK2 Inhibitor Improves Outcomes in a Mouse Model of Idiopathic Pneumonia Syndrome.

Idiopathic pneumonia syndrome (IPS) is a noninfectious inflammatory disorder of the lungs that occurs most often after fully myeloablative allogeneic hematopoietic stem cell transplantation (HSCT). IPS can be severe and is associated with high 1-year mortality rates despite existing therapies. The canonical nuclear factor-(NF) κB signaling pathway has previously been linked to several inflammatory disorders of the lung, including asthma and lung allograft rejection. It has never been specifically targeted as a novel IPS treatment approach, however. Here, we report that the IκB kinase 2 (IKK2) antagonist BAY 65-5811 or "compound A," a highly potent and specific inhibitor of the NF-κB pathway, was able to improve median survival times and recipient oxygenation in a well-described mouse model of IPS. Compound A impaired the production of the proinflammatory chemokines CCL2 and CCL5 within the host lung after transplantation. This resulted in significantly lower numbers of donor lung infiltrating CD4+ and CD8+ T cells and reduced pulmonary inflammatory cytokine production after allograft. Compound A's beneficial effects appeared to be specific for limiting pulmonary injury, as the drug was unable to improve outcomes in a B6 into B6D2 haplotype-matched murine HSCT model in which recipient mice succumb to lethal acute graft-versus-host disease of the gastrointestinal tract. Collectively, our data suggest that the targeting of the canonical NF-κB pathway with a small molecule IKK2 antagonist may represent an effective and novel therapy for the specific management of acute lung injury that can occur after allogeneic HSCT.

An apolipoprotein E-mimetic stimulates axonal regeneration and remyelination after peripheral nerve injury.

Elevated apolipoprotein E (apoE) synthesis within crushed sciatic nerves advocates that apoE could benefit axonal repair and reconstruction of axonal and myelin membranes. We created an apoE-mimetic peptide, COG112 (acetyl-RQIKIWFQNRRMKWKKCLRVRLASHLRKLRKRLL-amide), and found that postinjury treatment with COG112 significantly improved recovery of motor and sensory function following sciatic nerve crush in C57BL/6 mice. Morphometric analysis of injured sciatic nerves revealed that COG112 promoted axonal regrowth after 2 weeks of treatment. More strikingly, the thickness of myelin sheaths was increased by COG112 treatment. Consistent with these histological findings, COG112 potently elevated growth associated protein 43 (GAP-43) and peripheral myelin protein zero (P0), which are markers of axon regeneration and remyelination, respectively. Electron microscopic examination further suggested that the apoE-mimetic COG112 may increase clearance of myelin debris. Schwann cell uptake of cholesterol-containing low-density lipoprotein particles was selectively enhanced by COG112 treatment in a Schwann cell line S16. Moreover, COG112 significantly promoted axon elongation in primary dorsal root ganglion cultures from rat pups. Considering that cholesterol and lipids are needed for reconstructing myelin sheaths and axon extension, these data support a hypothesis where supplementation with exogenous apoE-mimetics such as COG112 may be a promising strategy for restoring lost functional and structural elements following nerve injury.