Skewed Dendritic Cell Differentiation of MyD88-Deficient Donor Bone Marrow Cells, Instead of Massive Expansion as Myeloid-Derived Suppressor Cells, Aggravates GVHD

Graft-versus-host disease (GVHD), a life-threatening complication after bone marrow transplantation (BMT), is induced by activation of alloreactive donor T cells. Our previous study demonstrated that transplantation of myeloid differentiation factor 88 (MyD88)-deficient knockout (KO) bone marrow (BM) resulted in aggravation of GVHD. Here, to understand the cellular mechanism, we performed longitudinal in vivo imaging and flow cytometric analyses followed by transcriptome and functional examination of donor MyD88-KO BM progenies in GVHD hosts, using a major histocompatibility complex-matched but minor histocompatibility antigen-mismatched C57BL/6→BALB.B model. In GVHD hosts with MyD88-KO BMT, donor BM-derived CD11b+Gr-1+ cells were found to undergo cell death, a fate significantly different from the explosive expansion shown by the wild type (WT) counterparts, and also from the moderate expansion of the WT or MyD88-KO BM-derived cells in non-GVHD hosts. It was also revealed that MyD88-KO CD11b+Gr-1+ cells preferred differentiation into CD11c+ dendritic cells (DCs) to expansion as myeloid-derived suppressor cells in GVHD hosts or in high inflammatory in vitro conditions. These CD11c+ DCs comprised the majority of MyD88-KO CD11b+Gr-1+ apoptotic cells in GVHD hosts. Their ability to cross-present alloantigens of host origin contributed to the enhancement of T cell alloreactivity, causing GVHD aggravation and eventually death through the killing function of activated T cells. These results provide insights into the roles of MyD88 in myelopoiesis of donor BM and the protective effects in GVHD hosts, helpful information for development of a strategy to control GVHD.

TLR/MyD88-mediated Innate Immunity in Intestinal Graft-versus-Host Disease

Graft-versus-host disease (GHVD) is a severe complication after allogeneic hematopoietic stem cell transplantation. The degree of inflammation in the gastrointestinal tract, a major GVHD target organ, correlates with the disease severity. Intestinal inflammation is initiated by epithelial damage caused by pre-conditioning irradiation. In combination with damages caused by donor-derived T cells, such damage disrupts the epithelial barrier and exposes innate immune cells to pathogenic and commensal intestinal bacteria, which release ligands for Toll-like receptors (TLRs). Dysbiosis of intestinal microbiota and signaling through the TLR/myeloid differentiation primary response gene 88 (MyD88) pathways contribute to the development of intestinal GVHD. Understanding the changes in the microbial flora and the roles of TLR signaling in intestinal GVHD will facilitate the development of preventative and therapeutic strategies.

Attenuation of Hepatic Graft-versus-host Disease in Allogeneic Recipients of MyD88-deficient Donor Bone Marrow

Acute graft-versus-host-disease (GVHD) is characterized by selective damage to the liver, the skin, and the gastrointestinal tract. Following allogeneic hematopoietic stem cell transplantation, donor bone marrow (BM) cells repopulate the immune system of the recipient. We previously demonstrated that the acute intestinal GVHD (iGVHD) mortality rate was higher in MyD88-deficient BM recipients than that in the control BM recipients. In the present study, the role of MyD88 (expressed by donor BM) in the pathophysiology of hepatic GVHD (hGVHD) was examined. Unlike iGVHD, transplantation with MyD88-deficient T-cell depleted (TCD) BM attenuated hGVHD severity and was associated with low infiltration of T cells into the liver of the recipients. Moreover, GVHD hosts, transplanted with MyD88-deficient TCD BM, exhibited markedly reduced expansion of CD11b(+)Gr-1(+) myeloid-derived suppressor cells (MDSC) in the liver. Adoptive injection of the MDSC from wild type mice, but not MyD88-deficient mice, enhanced hepatic T cell infiltration in the MyD88-deficient TCD BM recipients. Pre-treatment of BM donors with LPS increased MDSC levels in the liver of allogeneic wild type BM recipients. In conclusion, hGVHD and iGVHD may occur through various mechanisms based on the presence of MyD88 in the non-T cell compartment of the allograft.

Heme-binding-mediated negative regulation of the tryptophan metabolic enzyme indoleamine 2,3-dioxygenase 1 (IDO1) by IDO2

Indoleamine 2,3-dioxygenases (IDOs) are tryptophan-catabolizing enzymes with immunomodulatory functions. However, the biological role of IDO2 and its relationship with IDO1 are unknown. To assess the relationship between IDO2 and IDO1, we investigated the effects of co-expression of human (h) IDO2 on hIDO1 activity. Cells co-expressing hIDO1 and hIDO2 showed reduced tryptophan metabolic activity compared with those expressing hIDO1 only. In a proteomic analysis, hIDO1-expressing cells exhibited enhanced expression of proteins related to the cell cycle and amino acid metabolism, and decreased expression of proteins related to cell survival. However, cells co-expressing hIDO1 and hIDO2 showed enhanced expression of negative regulators of cell apoptosis compared with those expressing hIDO1 only. Co-expression of hIDO1 and hIDO2 rescued the cell death induced by tryptophan-depletion through hIDO1 activity. Cells expressing only hIDO2 exhibited no marked differences in proteome profiles or cell growth compared with mock-transfectants. Cellular tryptophan metabolic activity and cell death were restored by co-expressing the hIDO2 mutant substituting the histidine 360 residue for alanine. These results demonstrate that hIDO2 plays a novel role as a negative regulator of hIDO1 by competing for heme-binding with hIDO1, and provide information useful for development of therapeutic strategies to control cancer and immunological disorders that target IDO molecules.

Operative Treatment of Unstable Pelvic Ring Injury

PURPOSE: To analyze the clinical and radiological results of the different fixation methods according to the type and displacement of unstable pelvic ring injuries. MATERIALS AND METHODS: Twenty-three patients with unstable pelvic ring injuries from January 2005 to December 2009 were classified according to the AO/OTA classification system. When patients had been diagnosed with unstable pelvic ring injuries with partial instability, they were treated by anterior fixation with a plate and posterior percutaneous iliosacral screw fixation. When patients had been diagnosed with unstable pelvic ring injuries with complete instability, they were treated by open reduction and anterior to posterior fixation with a plate through the ilioinguinal approach. The radiological results were evaluated using Matta and Saucedo's method, and the clinical results were evaluated using Rommens and Hessmann's method. RESULTS: The outcomes from the radiological evaluation were that the displacement of the posterior pelvic ring were improved by about 6.65 mm in unstable pelvic ring injuries with partial instability. The displacement of the posterior pelvic ring were improved by about 7.8 mm in unstable pelvic ring injuries with complete instability. The clinical results were excellent in 13 cases and good in 6 cases on latest follow-up. CONCLUSION: Good results can be achieved by selecting the treatment method according to the type of unstable pelvic ring injurie and displacement.

The Relationship between Stud Morphology and 5th Metatarsal Proximal Stress Fractures on Soccer Players / 대한스포츠의학회지

This research sets out to define the relationship between stud morphology of soccer shoes and 5th metatarsal proximal stress fractures on soccer players by comparison and analysis. After the pre-survey of 132 soccer players in Gwangju, 107 players who seem to have a 5th metatarsal fracture were selected. We investigated the shape of the studs and asked whether they had ever had a 5th metatarsal proximal stress fracture. We also asked them some questions on factors, which cause stress fracture, such as what position they play, how long they have been playing soccer as athletes and average playing time. And we analyzed correlation between these several factors and whether they had ever had stress fracture using chi-square (x2) test and Logistic regression analysis. We concluded that soccer players who wore bar type studs shoes had a much greater possibility of stress fracture than soccer players who wore the round type. Also we learned that soccer players who play mid-fielder have a much greater possibility of stress fracture than soccer players who play other positions. And the result of logistic regression analysis of relevance between soccer shoes stud morphology and stress fracture shows a statistically significant odd ratio, 6.840. It has been suggested that the morphology of the soccer shoes stud has relevance to the occurrence of stress fracture. Therefore, according to the result of this study, soccer shoes with the round shape are more helpful in preventing 5th metatarsal proximal stress fracture than soccer shoes with the bar shape.

Delayed Operative Treatment of Long Bone Fractures in Patients with Brain Injury

PURPOSE: To evaluate the postoperative progress and outcomes of bone injured patients with long bone fracture showing callus formation and deformity due to delayed surgical treatment. MATERIALS AND METHODS: 10 cases with more than 1 year follow up were chosen from 12 patients with long bone fracture whose surgical treatment was delayed due to brain injury. Exuberant callus formation and deformations were observed. Average delayed period was 6.7 weeks (4~10 weeks). Preoperative callus formation, shortening and angulation were evaluated using plain radiographs. Total operation time and transfusion amount were compared with that from operations done within 2 weeks following accident. Postoperative bone union was checked. RESULTS: In all cases, preformed angulation and hypertrophic ossification made reduction difficult and this increased total operation time and transfusion amount but had no statistical importance. In patients with humerus and femur fractures accompanying brain injury, massive hypertrophic ossification was observed both in preoperative period and in postoperative period. Average bone union period was 13.5 weeks in humerus fractures, 17.9 weeks in femur fractures. The bone union period was shorter in subject group but had no statistical importance. CONCLUSION: Early surgical treatment is essential to patients with long bone fracture accompanying brain injury but if early surgical treatment can not be done, proper immobilization to fracture site should be done.