CCL3 is a protein of the CC chemokine family known to be important for T cell recruitment in inflammatory diseases. The aim of the current study was to evaluate the effects and putative mechanism of action of evasin-1, a novel CCL3-binding protein, in the pathogenesis of acute graft-versus-host disease (GVHD). GVHD was induced by the transplantation of splenocytes from C57BL/6J to B6D2F1 mice. Treatment of recipient mice with evasin-1 prevented mortality associated with GVHD. This was correlated with reduced weight loss and clinical disease severity. Analysis of the small intestine showed that evasin-1 treatment reduced the histopathological score and decreased levels of IFN-γ and CCL5. Mechanistically, evasin-1 treatment reduced the number of CD4+ and CD8+ T cells infiltrating the small intestine, as assessed by immunohistochemistry, and the adhesion of leukocytes to intestinal venules of recipient mice, as assessed by intravital microscopy. Evasin-1 was also able to decrease liver damage, as seen by reduction of inflammatory infiltrate and IFN-γ levels. Treatment with evasin-1 did not interfere with graft-versus-leukemia. Altogether, our studies demonstrate that CCL3 plays a major role in mediating GVHD, but not graft-versus-leukemia in mice and suggest that blockade of CCL3 with evasin-1 has potential therapeutic application in patients undergoing bone marrow transplantation.

Rezende et al. report that the transplant of 5-lipoxygenase (5-LO)−deficient leukocytes protects mice from GVHD. Treatment with the 5-LO inhibitor zileuton or a LTB4 antagonist at the initial phase of the transplant achieves similar protective effects. 5-LO is a crucial contributor to tissue damage in GVHD.

PAF is a potent lipid mediator involved in several manifestations of acute inflammation, including leukocyte influx, leukocyte interaction with endothelium, and production of inflammatory cytokines. The present study evaluated the relevance of PAFR for the pathogenesis of acute GVHD using a model of adoptive transfer of splenocytes from WT or PAFR(-/-) C57BL/6J to B6D2F1 mice. Mice, which received PAFR(-/-) splenocytes or treatment with the PAFR antagonist, showed reduced clinical signs of disease and no mortality. In GVHD mice receiving PAFR(-/-) splenocytes, there was deceased bacterial translocation and tissue injury. Furthermore, production of proinflammatory cytokines and chemokines (TNF-α, IFN-γ, CCL2, CCL3, and CCL5) and accumulation of CD8(+) cells in intestine and liver were reduced in mice transplanted with the PAFR(-/-) splenocyte. Mechanistically, an absence or pharmacological blockade of PAFR was associated with decreased rolling and adhesion of leukocytes to the mesenteric microcirculation, as assessed by intravital microscopy. Despite decreased GVHD, there was maintained GVL activity when PAFR(-/-) leukocytes were transferred into WT mice. In conclusion, PAFR on donor leukocytes plays a critical role in GVHD by mediating leukocyte influx and cytokine production in target tissues. PAFR antagonist may potentially be useful in the treatment of GVHD in bone marrow-transplanted patients.

Lithothamnion muelleri (Hapalidiaceae) is a marine red alga, which is a member of a group of algae with anti-inflammatory, antitumor, and immunomodulatory properties. The present study evaluated the effects of treatment with Lithothamnion muelleri extract (LM) in a model of acute graft-versus-host disease (GVHD), using a model of adoptive splenocyte transfer from C57BL/6 donors into B6D2F1 recipient mice. Mice treated with LM showed reduced clinical signs of disease and mortality when compared with untreated mice. LM-treated mice had reduced tissue injury, less bacterial translocation, and decreased levels of proinflammatory cytokines and chemokines (interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), chemokine (C-C motif) ligand 2 (CCL2), chemokine (C-C motif) ligand 3 (CCL3) and chemokine (C-C motif) ligand 5 (CCL5)). The polysaccharide-rich fraction derived from LM could inhibit leukocyte rolling and adhesion in intestinal venules, as assessed by intravital microscopy. LM treatment did not impair the beneficial effects of graft-versus-leukaemia (GVL). Altogether, our studies suggest that treatment with Lithothamnion muelleri has a potential therapeutic application in GVHD treatment.

Acute exercise increases the amount of circulating inflammatory cells and cytokines to maintain physiological homeostasis. However, it remains unclear how physical training regulates exercise-induced inflammation and performance. Here, we demonstrate that acute high intensity exercise promotes an inflammatory profile characterized by increased blood IL-6 levels, neutrophil migratory capacity, and leukocyte recruitment to skeletal muscle vessels. Moreover, we found that physical training amplified leukocyte–endothelial cell interaction induced by acute exercise in skeletal muscle vessels and diminished exercise-induced inflammation in skeletal muscle tissue. Furthermore, we verified that disruption of the gp-91 subunit of NADPH-oxidase inhibited exercise-induced leukocyte recruitment on skeletal muscle after training with enhanced exercise time until fatigue. In conclusion, the training was related to physical improvement and immune adaptations. Moreover, reactive oxygen species (ROS) could be related to mechanisms to limit aerobic performance and its absence decreases the inflammatory response elicited by exercise after training.