Preventive azithromycin treatment reduces noninfectious lung injury and acute graft-versus-host disease in a murine model of allogeneic hematopoietic cell transplantation.

Noninfectious lung injury and acute graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT) are associated with significant morbidity and mortality. Azithromycin is widely used in allogeneic HCT recipients for pulmonary chronic GVHD, although current data appear controversial. We induced GVHD and noninfectious lung injury in lethally irradiated B6D2F1 mice by transplanting bone marrow and splenic T cells from allogeneic C57BL/6 mice. Experimental groups were treated with oral azithromycin starting on day 14 until the end of week 6 or week 14 after transplantation. Azithromycin treatment resulted in improved survival and decreased lung injury; the latter characterized by improved pulmonary function, reduced peribronchial and perivascular inflammatory cell infiltrates along with diminished collagen deposition, and a decrease in lung cytokine and chemokine expression. Azithromycin also improved intestinal GVHD but did not affect liver GVHD at week 6 early after transplantation. At week 14, azithromycin decreased liver GVHD but had no effect on intestinal GVHD. In vitro, allogeneic antigen-presenting cell (APC)- dependent T cell proliferation and cytokine production were suppressed by azithromycin and inversely correlated with relative regulatory T cell (Treg) expansion, whereas no effect was seen when T cell proliferation occurred APC independently through CD3/CD28-stimulation. Further, azithromycin reduced alloreactive T cell expansion but increased Treg expansion in vivo with corresponding downregulation of MHC II on CD11c(+) dendritic cells. These results demonstrate that preventive administration of azithromycin can reduce the severity of acute GVHD and noninfectious lung injury after allo-HCT, supporting further investigation in clinical trials.

Steroid treatment alters adhesion molecule and chemokine expression in experimental acute graft-vs.-host disease of the intestinal tract.

OBJECTIVE: Acute graft-vs.-host disease (aGVHD) is a major complication after allogeneic bone marrow transplantation (allo-BMT) that is characterized by high morbidity and mortality. Systemic treatment with steroids has been the mainstay of first-line therapy of aGVHD, although controlled experimental data in this context are limited. MATERIALS AND METHODS: Using a haploidentical murine BMT model, steroid effects on hepatic and intestinal inflammation during aGVHD have been investigated. Lethally irradiated B6D2F1 mice received bone marrow cells and splenocytes from either syngeneic (B6D2F1) or allogeneic (C57BL/6) donors. RESULTS: Intraperitoneal administration of prednisolone (2 mg/kg body weight every day) early after onset of GVHD from day +10 until day +42 resulted in reduced clinical GVHD severity and improved survival of allogeneic recipients. Although the liver was barely affected by prednisolone treatment, aGVHD-related histopathologic injury of the gastrointestinal tract was strongly reduced in association with diminished expression of interferon-γ, tumor necrosis factor, CXCL 9-11, CCL2-3, mucosal addressin cell adhesion molecule-1, and intercellular adhesion molecule-1. Prednisolone-induced reduction of adhesion molecule expression in the gut manifested earlier than seen for cytokines or chemokines. Interestingly, when starting steroid treatment on day +28, the course of GVHD was unchanged and no major differences in cyto- or chemokine expression in gastrointestinal tract or liver on day +42 were seen. CONCLUSIONS: When started early after GVHD onset, prednisolone-related beneficial effects can affect aGVHD target organs differently, involving divergent regulation of inflammation and leukocyte migration. Specifically, a change in adhesion properties between leukocytes and endothelial cells in the gastrointestinal tract may be one of the initial steps in a cascade of steroid-related aGVHD-attenuating events.

Preventive usage of broad spectrum chemokine inhibitor NR58-3.14.3 reduces the severity of pulmonary and hepatic graft-versus-host disease.

Pulmonary graft-versus-host disease (pGVHD) is a major complication after allogeneic bone marrow transplantation (BMT), which involves donor leukocyte migration into the lung along chemokine gradients, leading to pulmonary dysfunction and respiratory insufficiency. As broad spectrum chemokine inhibitor (BSCI) NR58-3.14.3 suppresses leukocyte migration in response to various chemokines, including CCL2, CCL3, CCL5, we investigated the effects of NR58-3.14.3 on the evolution of pGVHD. Lethally irradiated B6D2F1 mice received BMT from syngeneic (B6D2F1) or allogeneic (C57BL/6) donors, and animals were treated with either NR58-3.14.3 or vehicle control from day -1 to day +14. At week 6, in allogeneic recipients that received BSCI, inflammatory cell infiltrates in the lung were decreased, and reduced histopathologic changes translated into improved pulmonary function when compared to allo-controls. Acute GVHD of the liver was also diminished, whereas no differences were seen in the gut. Alloantigen-dependent splenic T cell expansion and systemic TNF-alpha and IFN-gamma levels were comparable in NR58-3.14.3-treated animals and allo-controls. No suppressive effect of NR58-3.14.3 on CTL cytotoxicity was found, and diminished cellular infiltrates in lung and liver were most likely due to decreased migration of mononuclear cells. Therefore, novel approaches involving BSCIs may provide a promising tool in the management of pGVHD.