Association of HMGB1 polymorphisms with outcome after allogeneic hematopoietic cell transplantation

Association of High Mobility Group Box-Protein 1 and Platelet Microparticles in Patients After Hematopoietic Stem Cell Transplantation

Thrombotic complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT) significantly impact transplant outcomes. We focused on high mobility group box-protein (HMGB)1, one causative agent of thrombotic lesions in allo-HSCT, and investigated its association with platelets. We statistically analyzed available data from 172 patients with hematopoietic malignancies receiving allo-HSCT. A significant enhancement of monocyte-chemotactant protein-1, HMGB1, and platelet-derived microparticle (PDMP) levels was observed at day 0 after transplantation as compared to pre-transplantation. Multivariate analysis of the association among HMGB1 and 16 factors on day 0 revealed a significant correlation of HMGB1 levels with thrombin-antithrombin complex, interleukin-6, and PDMPs. High mobility group box-protein 1-induced procoagulant platelet induction and PDMP generation were performed in vitro using healthy platelets. High mobility group box-protein 1-induced PDMP generation was suppressed by toll-like receptor inhibitors and recombinant thrombomodulin. These results suggest that HMGB1 contributes to platelet activation in patients after allo-HSCT and is associated with PDMP-related thrombotic complications.

A Promising Insight: The Potential Influence and Therapeutic Value of the Gut Microbiota in GI GVHD

Allogeneic hematopoietic cell transplantation (allo-HSCT) is a reconstruction process of hematopoietic and immune functions that can be curative in patients with hematologic malignancies, but it carries risks of graft-versus-host disease (GVHD), thrombotic microangiopathy (TMA), Epstein–Barr virus (EBV) infection, cytomegalovirus infection, secondary hemophagocytic lymphohistiocytosis (sHLH), macrophage activation syndrome (MAS), bronchiolitis obliterans, and posterior reversible encephalopathy syndrome (PRES). Gastrointestinal graft-versus-host disease (GI GVHD), a common complication of allo-HSCT, is one of the leading causes of transplant-related death because of its high treatment difficulty, which is affected by preimplantation, antibiotic use, dietary changes, and intestinal inflammation. At present, human trials and animal studies have proven that a decrease in intestinal bacterial diversity is associated with the occurrence of GI GVHD. Metabolites produced by intestinal bacteria, such as lipopolysaccharides, short-chain fatty acids, and secondary bile acids, can affect the development of GVHD through direct or indirect interactions with immune cells. The targeted damage of GVHD on intestinal stem cells (ISCs) and Paneth cells results in intestinal dysbiosis or dysbacteriosis. Based on the effect of microbiota metabolites on the gastrointestinal tract, the clinical treatment of GI GVHD can be further optimized. In this review, we describe the mechanisms of GI GVHD and the damage it causes to intestinal cells and we summarize recent studies on the relationship between intestinal microbiota and GVHD in the gastrointestinal tract, highlighting the role of intestinal microbiota metabolites in GI GVHD. We hope to elucidate strategies for immunomodulatory combined microbiota targeting in the clinical treatment of GI GVHD.

Caspase-1 inhibition ameliorates murine acute graft versus host disease by modulating the Th1/Th17/Treg balance

Our previous studies have implicated Caspase-1 signaling in driving the proinflammatory state of acute graft versus host disease (aGVHD). Therefore, we aimed to elucidate the mechanism of Caspase-1 in in murine models of aGVHD through specific inhibition of its activity with the decoy peptide Ac-YVAD-CMK. We transplanted bone marrow from donor C57BL/6 (H-2b) mice into recipient BALB/c (H-2Kd) mice and randomized the recipients into the following treatment cohorts: (1) allogeneic hematopoietic stem cell transplantation and splenic cell infusion control (PBS group); (2) low dose Ac-YVAD-CMK (AC low group); (3) and high dose Ac-YVAD-CMK (AC high group). Indeed, we observed that Caspase-1 inhibition by Ac-YVAD-CMK ameliorated pathological damage and inflammation in the liver, lungs, and colon elicited by aGVHD. This was associated with reduced mortality secondary to aGVHD. Mechanistically, we found that Caspase-1 inhibition modulated donor T cell expansion, restored the balance of Th1/Th17/Treg subsets, and markedly decreased serum levels and aGVHD target organ mRNA expression of IL-1β, IL-18, and HMGB1. Thus, we demonstrate that inhibition of Caspase-1 by Ac-YVAD-CMK mitigates murine aGVHD by regulating Th1/Th17/Treg balance and attenuating its characteristic proinflammatory state.

Review of Genetic Variation as a Predictive Biomarker for Chronic Graft-Versus-Host-Disease After Allogeneic Stem Cell Transplantation

Chronic graft-versus-host disease (cGvHD) is one of the major complications of allogeneic stem cell transplantation (HSCT). cGvHD is an autoimmune-like disorder affecting multiple organs and involves a dermatological rash, tissue inflammation and fibrosis. The incidence of cGvHD has been reported to be as high as 30% to 60% and there are currently no reliable tools for predicting the occurrence of cGvHD. There is therefore an important unmet clinical need for predictive biomarkers. The present review summarizes the state of the art for genetic variation as a predictive biomarker for cGvHD. We discuss three different modes of action for genetic variation in transplantation: genetic associations, genetic matching, and pharmacogenetics. The results indicate that currently, there are no genetic polymorphisms or genetic tools that can be reliably used as validated biomarkers for predicting cGvHD. A number of recommendations for future studies can be drawn. The majority of studies to date have been under-powered and included too few patients and genetic markers. Like in all complex multifactorial diseases, large collaborative genome-level studies are now needed to achieve reliable and unbiased results. Some of the candidate genes, in particular, CTLA4, HSPE, IL1R1, CCR6, FGFR1OP, and IL10, and some non-HLA variants in the HLA gene region have been replicated to be associated with cGvHD risk in independent studies. These associations should now be confirmed in large well-characterized cohorts with fine mapping. Some patients develop cGvHD despite very extensive immunosuppression and other treatments, indicating that the current therapeutic regimens may not always be effective enough. Hence, more studies on pharmacogenetics are also required. Moreover, all of these studies should be adjusted for diagnostic and clinical features of cGvHD. We conclude that future studies should focus on modern genome-level tools, such as machine learning, polygenic risk scores and genome-wide association study-transcription meta-analyses, instead of focusing on just single variants. The risk of cGvHD may be related to the summary level of immunogenetic differences, or whole genome histocompatibility between each donor-recipient pair. As the number of genome-wide analyses in HSCT is increasing, we are approaching an era where there will be sufficient data to incorporate these approaches in the near future.

Clinical markers combined with HMGB1 polymorphisms to predict efficacy of conventional DMARDs in rheumatoid arthritis patients

The efficacy of conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) for rheumatoid arthritis (RA) patients was limited. However, there were no predictive markers for poor csDMARDs outcome. Clinical information of RA patients was collected and the high-mobility group box 1 (HMGB1) polymorphisms (rs4145277, rs2249825, rs1412125 and rs1045411) were examined. Among the 252 patients, 31.0% had no response of csDMARDs. Anti-citrullinated protein antibody (ACPA)-positive, C-reactive protein (CRP) and Disease Activity Score (DAS) 28- erythrocyte sedimentation rate (ESR) were the associated factors, which (DAC:DAS 28 > 4.7 and ACPA-positive and CRP > 7.1 mg/L) was used to predict poor csDMARDs outcome, the sensitivity and specificity was 87.2% and 60.9%, respectively. Among those DAC patients, the refractory RA rate in the rs2249825 GG genotype patients was 83.3%, the specificity was 98.5%. The clinical markers (DAC) and rs2249825 GG genotype can be used to predict poor csDMARDs outcome.

High mobility group box 1 (HMGB1): a pivotal regulator of hematopoietic malignancies

High mobility group box 1 (HMGB1) is a nonhistone chromatin-associated protein that has been widely reported to play a pivotal role in the pathogenesis of hematopoietic malignancies. As a representative damage-associated molecular pattern (DAMP), HMGB1 normally exists inside cells but can be secreted into the extracellular environment through passive or active release. Extracellular HMGB1 binds with several different receptors and interactors to mediate the proliferation, differentiation, mobilization, and senescence of hematopoietic stem cells (HSCs). HMGB1 is also involved in the formation of the inflammatory bone marrow (BM) microenvironment by activating proinflammatory signaling pathways. Moreover, HMGB1-dependent autophagy induces chemotherapy resistance in leukemia and multiple myeloma. In this review, we systematically summarize the emerging roles of HMGB1 in carcinogenesis, progression, prognosis, and potential clinical applications in different hematopoietic malignancies. In summary, targeting the regulation of HMGB1 activity in HSCs and the BM microenvironment is highly beneficial in the diagnosis and treatment of various hematopoietic malignancies.

Effects of recombinant thrombomodulin on long-term prognosis after allogeneic hematopoietic stem cell transplantation

We investigated the effects of early recombinant thrombomodulin (rTM) treatment on long-term prognosis after hematopoietic stem cell transplantation (HSCT). Subjects included 300 patients who underwent allogeneic HSCT (131 in the rTM(+) group and 169 in the rTM(-) group). The control group received heparin or no anti-coagulation therapy. When we examined patients with confirmed complications (day 1-100), the frequencies of acute graft-versus-host disease (aGVHD) and thrombotic microangiopathy (TMA) were significantly lower in the rTM(+) group, while the frequencies of veno-occlusive disease did not show such differences. rTM administration was associated with significant differences in the cumulative incidence of aGVHD (any grade and II-IV grades) and TMA. The cumulative overall survival probability was significantly higher in the rTM(+) group (42.3% versus 26.2%, p = .037). Therefore, some causes of a poor prognosis included aGVHD and TMA. The present findings suggest that rTM plays a preventive role in transplant-related complications, such as aGVHD and TMA, after allogeneic HSCT.

Effects of recombinant thrombomodulin therapy and soluble human leukocyte antigen-G levels during hematopoietic stem cell transplantation

BACKGROUND

Conditioning chemotherapies for hematopoietic stem cell transplantation (HSCT), especially those that include total body irradiation, can result in serious complications such as graft-versus-host disease (GVHD). Human leukocyte antigen G (HLA-G) is a non-classical class I molecule with multiple immunoregulatory functions.

METHODS

We measured interleukin (IL)-10, transforming growth factor (TGF)β₁, and soluble HLA-G (sHLA-G) in HSCT patients and examined the relationship between sHLA-G levels and acute GVHD (aGVHD). Additionally, we investigated the effect of recombinant soluble thrombomodulin (rTM) therapy on sHLA-G levels. Our study cohort included 135 patients who underwent allogeneic HSCT at several institutions in Japan.

RESULTS

Serum levels of IL-10 and TGFβ₁ exhibited no significant changes following HSCT. In contrast, levels of sHLA-G were significantly increased at days 21 and 28 post-HSCT. For patients with confirmed complications, the frequency of aGVHD was significantly lower in those with a > 2.8-fold increase in sHLA-G levels at day 28 relative to day 7 post-HSCT. sHLA-G levels in patients who received rTM therapy were significantly higher at days 21 and 28 post-HSCT compared with those in patients who did not receive rTM therapy.

CONCLUSION

These data suggest that HLA-G/sHLA-G participate in prevention of GVHD, and that rTM may prevent aGVHD following HSCT by promoting elevation of sHLA-G.

Replication and validation of genetic polymorphisms associated with survival after allogeneic blood or marrow transplant

Multiple candidate gene-association studies of non-HLA single-nucleotide polymorphisms (SNPs) and outcomes after blood or marrow transplant (BMT) have been conducted. We identified 70 publications reporting 45 SNPs in 36 genes significantly associated with disease-related mortality, progression-free survival, transplant-related mortality, and/or overall survival after BMT. Replication and validation of these SNP associations were performed using DISCOVeRY-BMT (Determining the Influence of Susceptibility COnveying Variants Related to one-Year mortality after BMT), a well-powered genome-wide association study consisting of 2 cohorts, totaling 2888 BMT recipients with acute myeloid leukemia, acute lymphoblastic leukemia, or myelodysplastic syndrome, and their HLA-matched unrelated donors, reported to the Center for International Blood and Marrow Transplant Research. Gene-based tests were used to assess the aggregate effect of SNPs on outcome. None of the previously reported significant SNPs replicated at P < .05 in DISCOVeRY-BMT. Validation analyses showed association with one previously reported donor SNP at P < .05 and survival; more associations would be anticipated by chance alone. No gene-based tests were significant at P < .05. Functional annotation with publicly available data shows these candidate SNPs most likely do not have biochemical function; only 13% of candidate SNPs correlate with gene expression or are predicted to impact transcription factor binding. Of these, half do not impact the candidate gene of interest; the other half correlate with expression of multiple genes. These findings emphasize the peril of pursing candidate approaches and the importance of adequately powered tests of unbiased genome-wide associations with BMT clinical outcomes given the ultimate goal of improving patient outcomes.

Associations between acute GVHD-related biomarkers and endothelial cell activation after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) can cause serious transplant-related complications such as graft-versus-host disease (GVHD). Acute GVHD (aGVHD) has been diagnosed by clinical manifestations, laboratory data and pathological effects until now, but recently the discovery of specific biomarkers such as suppression of tumorigenicity 2 (ST2), elafin and regenerating islet-derived 3α (REG3α) is challenging this approach.

METHODS

We investigated the expression of aGVHD-related markers (regulated on activation normal T-cell expressed and secretes: RANTES, elafin, REG3α and ST2) and endothelial cell activation markers (soluble vascular cell adhesion molecule: sVCAM-1 and plasminogen activator inhibitor: PAI-1) in patients undergoing allogeneic HSCT. Additionally, we studied the effects of recombinant soluble thrombomodulin (rTM) on the expression of these markers. Our study cohort included 225 patients who underwent allogeneic HSCT at several institutions in Japan.

RESULTS

RANTES, sVCAM-1, PAI-1, elafin, REG3α and ST2 exhibited significant increases in patients not receiving rTM after HSCT. When we examined patients with confirmed complications, the frequencies of aGVHD and VOD were significantly lower in the rTM-treated group. In addition, aGVHD-related biomarkers such as elafin, REG3α, and ST2 were elevated significantly in patients with aGVHD.

CONCLUSION

Our findings suggest that endothelial cell activation might be linked to aGVHD, and that rTM might act to prevent aGVHD, at least in part, through its effect on endothelial cells.

Impact of High-Mobility Group Box 1 Polymorphism on Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND OBJECTIVE

The high-mobility group box 1 (HMGB1) protein is a eukaryotic, ubiquitously expressed protein that serves as a biomarker for various diseases and is involved in the promotion of a proinflammatory response to cell injury. In aneurysmal subarachnoid hemorrhage (aSAH), increased HMGB1 levels have been linked to poor outcome and an increased risk for cerebral vasospasm. The role of HMGB1 polymorphisms in aSAH has not been previously investigated.

METHODS

Patients with aSAH and controls enrolled in the prospective, 2-center CARAS (Cerebral Aneurysm Renin Angiotensin System) study were evaluated. The 3814 C/G HMGB1 single nucleotide polymorphism (SNP) rs2249825 was detected using 5'exonuclease (Taqman) genotyping assays from blood samples from patients with aSAH and controls. Associations between aSAH and its clinical sequelae with the HMGB1 SNP were assessed.

RESULTS

Samples from 149 patients with aSAH and 50 controls were available for analysis. No increased risk for aSAH associated with the SNP was found compared with the control group. Delayed cerebral ischemia (DCI) was defined as a cerebral infarction at the time of discharge from the intensive care unit and identified in 21.2% of patients with aSAH. In multivariable logistic regression analysis, the G allele of rs2249825 was independently associated with DCI (odds ratio, 5.695; 95% confidence interval, 1.804-17.975; P = 0.003).

CONCLUSIONS

The minor allele G of rs2249825 was associated with an increased risk for DCI, or cerebral infarction, after aSAH. This finding may be attributable to an increased HMGB1 protein expression in these patients.

Alarmins and Their Receptors as Modulators and Indicators of Alloimmune Responses

Cell damage and death releases alarmins, self-derived immunomodulatory molecules that recruit and activate the immune system. Unfortunately, numerous processes critical to the transplantation of allogeneic materials result in the destruction of donor and recipient cells and may trigger alarmin release. Alarmins, often described as damage-associated molecular patterns, together with exogenous pathogen-associated molecular patterns, are potent orchestrators of immune responses; however, the precise role that alarmins play in alloimmune responses remains relatively undefined. We examined evolving concepts regarding how alarmins affect solid organ and allogeneic hematopoietic cell transplantation outcomes and the mechanisms by which self molecules are released. We describe how, once released, alarmins may act alone or in conjunction with nonself materials to contribute to cytokine networks controlling alloimmune responses and their intensity. It is becoming recognized that this class of molecules has pleotropic functions, and certain alarmins can promote both inflammatory and regulatory responses in transplant models. Emerging evidence indicates that alarmins and their receptors may be promising transplantation biomarkers. Developing the therapeutic ability to support alarmin regulatory mechanisms and the predictive value of alarmin pathway biomarkers for early intervention may provide opportunities to benefit graft recipients.

Sensing danger: toll-like receptors and outcome in allogeneic hematopoietic stem cell transplantation

Pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) play key roles in initiating innate and adaptive immune responses. Based mainly on animal studies there is growing evidence to suggest that TLRs are involved in the development of chemotherapy-induced mucositis and in the propagation of graft versus host reactions as well as graft versus tumor effects in allogeneic hematopoietic stem cell transplantation (HSCT). In this review we discuss these findings along with the emerging, although still preliminary, clinical evidence, that points to a role of PRRs in determining the outcome of HSCT and new therapeutic perspectives that may be related to this development.

Association of single-nucleotide polymorphisms of high-mobility group box 1 with susceptibility and clinicopathological characteristics of uterine cervical neoplasia in Taiwanese women

To date, no study associated the genetic polymorphisms of high-mobility group box 1 protein (HMGB1) with the development of uterine cervical cancer. We therefore conducted this study to investigate the associations of HMGB1 single-nucleotide polymorphisms (SNPs) with cervical carcinogenesis and clinicopathological characteristics of cancer patients. Five hundred two women, including 112 with invasive cancer, 85 with precancerous lesions of the uterine cervix, and 305 normal controls, were consecutively enrolled into this study. Analysis of HMGB1 SNPs was done by real-time polymerase chain reaction and genotyping. Our results found that the risk of susceptibility to cervical invasive cancer was 1.85 (95 % CI 1.12-3.04; p = 0.016) in women with TC and 1.99 (95 % CI 1.24-3.23; p = 0.005) in women with TC/CC after adjusting for age, using TT as a comparison reference in HMGB1 SNP rs1412125. In rs2249825, the increased risk was also seen for the development of cervical invasive cancer in women with CG [adjusted odds ratio (AOR) 2.04, 95 % CI 1.22-3.40; p = 0.006] or CG/GG (AOR 2.02, 95 % CI 1.22-3.32; p = 0.006) using CC as a comparison reference. An additional integrated in silico analysis confirmed that rs2249825 creates a binding site for v-Myb, which may affect HMGB1 expression. In conclusion, Taiwanese women with TC or TC/CC in HMGB1 SNP rs1412125 as well as CG or CG/GG in rs2249825 were susceptible to the development of cervical invasive cancer.

Danger Signals and Graft-versus-host Disease: Current Understanding and Future Perspectives

Graft-versus-host response after allogeneic hematopoietic stem cell transplantation (allo-HCT) represents one of the most intense inflammatory responses observed in humans. Host conditioning facilitates engraftment of donor cells, but the tissue injury caused from it primes the critical first steps in the development of acute graft-versus-host disease (GVHD). Tissue injuries release pro-inflammatory cytokines (such as TNF-α, IL-1β, and IL-6) through widespread stimulation of pattern recognition receptors (PRRs) by the release of danger stimuli, such as damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs). DAMPs and PAMPs function as potent stimulators for host and donor-derived antigen presenting cells (APCs) that in turn activate and amplify the responses of alloreactive donor T cells. Emerging data also point towards a role for suppression of DAMP induced inflammation by the APCs and donor T cells in mitigating GVHD severity. In this review, we summarize the current understanding on the role of danger stimuli, such as the DAMPs and PAMPs, in GVHD.

The role of danger signals and ectonucleotidases in acute graft-versus-host disease

Allogeneic hematopoietic cell transplantation (allo-HCT) represents the only curative treatment approach for many patients with benign or malignant diseases of the hematopoietic system. However, post-transplant morbidity and mortality are significantly increased by the development of acute graft-versus-host disease (GvHD). While alloreactive T cells act as the main cellular mediator of the GvH reaction, recent evidence suggests a critical role of the innate immune system in the early stages of GvHD initiation. Danger-associated molecular patterns released from the intracellular space as well as from the extracellular matrix activate antigen-presenting cells and set pro-inflammatory pathways in motion. This review gives an overview about danger signals representing therapeutic targets with a clinical perspective with a particular focus on extracellular nucleotides and ectonucleotidases.

Relationship between HMGB1 and PAI-1 after allogeneic hematopoietic stem cell transplantation

Background

Conditioning regimens including total body irradiation (TBI) or cyclophosphamide can mobilize high-mobility group box 1 (HMGB1) to peripheral blood. Additionally, increased plasminogen activator inhibitor (PAI)-1 levels are associated with post-allogeneic hematopoietic stem cell transplantation (aHSCT). However, changes to circulating levels of HMGB1 after aHSCT are poorly understood.

Materials and methods

The study cohort included 289 patients who underwent aHSCT at one of 25 institutions in Japan. We have investigated the relationship between HMGB1 and PAI-1 following aHSCT. A significant increase in HMGB1 levels occurred after conditioning treatment. Additionally, levels of HMGB1 at day 0 were significantly increased in TBI+ patients and cyclophosphamide/TBI patients.

Conclusion

Our data revealed that an increased level of HMGB1 at day 0 following aHSCT correlates with increased PAI-1 after aHSCT, which is consistent with previous reports. Increased HMGB1 at day 0 after a conditioning regimen may play a role in transplantation-associated coagulopathy following aHSCT, because PAI-1 can accelerate procoagulant activity.

Non-HLA genomics: does it have a role in predicting haematopoietic stem cell transplantation outcome?

Haematopoietic stem cell transplantation (HSCT) remains the only cure for many haematological neoplasms; however, the mortality rate remains high, at around 30-80%. Complications after HSCT include relapse, graft-versus-host disease, graft rejection and infection. High-resolution HLA matching has improved survival in HSCT over recent years; however, GVHD still remains a serious complication. Single nucleotide polymorphisms (SNPS) within genes that are involved with an individual's capability to mount an immune response to infectious pathogens, residual leukaemia, alloantigens or genes involved in drug metabolism have been studied for their association with HSCT outcome. Indeed, over the last 15 years, several groups, including ourselves, have demonstrated that non-HLA gene polymorphisms can be predictive of HSCT outcome. Can genetic characteristics of the patient and donor be used in the future to tailor HSCT protocols and determine GVHD prophylaxis? This review summarizes some of the recent SNP association studies in HSCT and highlights some of the disparities therein, discussing the integral problems of performing genetic association studies on diseases with complex outcomes using heterogeneous cohorts. The review will comment on recent genomewide association studies (GWAS) and discuss their relevance in this field, and it will also comment on recent meta-analysis combining GWAS studies with other studies such as gene expression micro array data in the field of autoimmune disease and solid organ transplantation. It will mention possible novel candidate gene polymorphisms, for example SNPS in microRNAs. In addition, it will discuss some of the inherent problems associated with gene association studies including the GRIPs (genetic risk prediction studies) recommendations. In summary, this review will assess the usefulness of non-HLA genomic studies in HSCT with regard to predicting outcome and modifying therapy.

The Free Radical Scavenger NecroX-7 Attenuates Acute Graft-versus-Host Disease via Reciprocal Regulation of Th1/Regulatory T Cells and Inhibition of HMGB1 Release

Graft-versus-host disease (GVHD) is a major complication associated with allogeneic hematopoietic stem cell transplantation. Despite the prominent role of the adaptive immune system, the importance of controlling the innate immune system in the pathogenesis of GVHD has recently been rediscovered. High-mobility group box 1 (HMGB1) is a crucial damage-associated molecular pattern signal that functions as a potent innate immune mediator in GVHD. In the present study, we investigated treatment of experimental GVHD through HMGB1 blockade using the compound cyclopentylamino carboxymethylthiazolylindole (NecroX)-7. Treated animals significantly attenuated GVHD-related mortality and inhibited severe tissue damage. These protective effects correlated with the decrease in HMGB1 expression and lower levels of reactive oxidative stress. Additionally, NecroX-7 inhibited the HMGB1-induced release of TNF and IL-6, as well as the expression of TLR-4 and receptor for advanced glycation end products. We also observed increased regulatory T cell numbers, which may be associated with regulation of differentiation signals independent of HMGB1. Taken together, these data indicate that NecroX-7 protects mice against lethal GVHD by reciprocal regulation of regulatory T/Th1 cells, attenuating systemic HMGB1 accumulation and inhibiting HMGB1-mediated inflammatory response. Our results indicate the possibility of a new use for a clinical drug that is effective for the treatment of GVHD.

Innate immune activation by tissue injury and cell death in the setting of hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) with donor lymphocyte infusion is the mainstay of treatment for many types of hematological malignancies, but the therapeutic effect and prevention of relapse is complicated by donor T-cell recognition and attack of host tissue in a process known as graft-versus-host disease (GvHD). Cytotoxic myeloablative conditioning regimens used prior to Allo-HSCT result in the release of endogenous innate immune activators that are increasingly recognized for their role in creating a pro-inflammatory milieu. This increased inflammatory state promotes allogeneic T-cell activation and the induction and perpetuation of GvHD. Here, we review the processes of cellular response to injury and cell death that are relevant following Allo-HSCT and present the current evidence for a causative role of a variety of endogenous innate immune activators in the mediation of sterile inflammation following Allo-HSCT. Finally, we discuss the potential therapeutic strategies that target the endogenous pathways of innate immune activation to decrease the incidence and severity of GvHD following Allo-HSCT.

HMGB1 genetic polymorphisms in oral squamous cell carcinoma and oral lichen planus patients

OBJECTIVES

This study examined the single nucleotide polymorphisms (SNPs) in high-mobility group box 1 (HMGB1) gene in patients with oral squamous cell carcinoma (OSCC) and oral lichen planus (OLP).

MATERIALS AND METHODS

The study was conducted on 93 patients with OSCC, 53 patients with OLP, and 100 controls, all Caucasians of the same ethnicity, matched by age. HMGB1 genotypes for 4 SNPs, 2262G/A (rs1045411), 1177G/C (rs3742305), 3814C/G (rs2249825), and rs4540927, were assessed using TaqMan SNP Genotyping Assays, Applied Biosystems.

RESULTS

The HMGB1 1177GG genotype was associated with lymph-node metastasis and tumor stage in OSCCs (P = 0.016 and P = 0.030, respectively). Genotype 1177GG resulted in poorer recurrence-free survival (RFS), P = 0.000. The 1177G/C polymorphism was an independent predictor of RFS compared to GG genotype, P = 0.001. The three polymorphisms were in linkage disequilibrium (LD). The AGC and GGC haplotypes were associated with an increased oral cancer risk, determined over the haplotype odds ratios (HOR = 13.316, P = 0.015, and HOR = 5.769, P = 0.029, respectively). The AGC haplotype was related to erosive OLP progression to OSCC (HOR = 12.179, P = 0.001).

CONCLUSIONS

HMGB1 polymorphism 1177G/C could be associated with tumor progression and recurrence-free survival in patients with OSCC. The haplotypes of HMGB1 gene might be associated with susceptibility to OSCC and OLP progression to OSCC.

Toll-like receptor polymorphisms in allogeneic hematopoietic cell transplantation

To assess the impact of the genetic variation in toll-like receptors (TLRs) on outcome after allogeneic myeloablative conditioning hematopoietic cell transplantation (HCT), we investigated 29 single nucleotide polymorphisms across 10 TLRs in 816 patients and donors. Only donor genotype of TLR8 rs3764879, which is located on the X chromosome, was significantly associated with outcome at the Bonferroni-corrected level P ≤ .001. Male hemizygosity and female homozygosity for the minor allele were significantly associated with disease-free survival (hazard ratio [HR], 1.47 [95% confidence interval {CI}, 1.16 to 1.85]; P = .001). Further analysis stratified by donor sex due to confounding by sex was suggestive for associations with overall survival (male donor: HR, 1.41 [95% CI, 1.09 to 1.83], P = .010; female donor: HR, 2.78 [95% CI, 1.43 to 5.41], P = .003), disease-free survival (male donor: HR, 1.45 [95% CI, 1.12 to 1.87], P = .005; female donor: HR, 2.34 [95% CI, 1.18 to 4.65], P = .015), and treatment-related mortality (male donor: HR, 1.49 [95% CI, 1.09 to 2.04], P = .012; female donor: HR, 3.12 [95% CI, 1.44 to 6.74], P = .004). In conclusion, our findings suggest that the minor allele of TLR8 rs3764879 of the donor is associated with outcome after myeloablative conditioned allogeneic HCT.

National Institutes of Health Consensus Development Project on Criteria for Clinical Trials in Chronic Graft-versus-Host Disease: III. The 2014 Biomarker Working Group Report

Biology-based markers to confirm or aid in the diagnosis or prognosis of chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation or monitor its progression are critically needed to facilitate evaluation of new therapies. Biomarkers have been defined as any characteristic that is objectively measured and evaluated as an indicator of a normal biological or pathogenic process, or of a pharmacologic response to a therapeutic intervention. Applications of biomarkers in chronic GVHD clinical trials or patient management include the following: (1) diagnosis and assessment of chronic GVHD disease activity, including distinguishing irreversible damage from continued disease activity; (2) prognostic risk to develop chronic GVHD; and (3) prediction of response to therapy. Sample collection for chronic GVHD biomarkers studies should be well documented following established quality control guidelines for sample acquisition, processing, preservation, and testing, at intervals that are both calendar and event driven. The consistent therapeutic treatment of subjects and standardized documentation needed to support biomarker studies are most likely to be provided in prospective clinical trials. To date, no chronic GVHD biomarkers have been qualified for use in clinical applications. Since our previous chronic GVHD Biomarkers Working Group report in 2005, an increasing number of chronic GVHD candidate biomarkers are available for further investigation. This paper provides a 4-part framework for biomarker investigations: identification, verification, qualification, and application with terminology based on Food and Drug Administration and European Medicines Agency guidelines.

Various forms of tissue damage and danger signals following hematopoietic stem-cell transplantation

Hematopoietic stem-cell transplantation (HSCT) is the most potent curative therapy for many malignant and non-malignant disorders. Unfortunately, a major complication of HSCT is graft-versus-host disease (GVHD), which is mediated by tissue damage resulting from the conditioning regimens before the transplantation and the alloreaction of dual immune components (activated donor T-cells and recipient’s antigen-presenting cells). This tissue damage leads to the release of alarmins and the triggering of pathogen-recognition receptors that activate the innate immune system and subsequently the adaptive immune system. Alarmins, which are of endogenous origin, together with the exogenous pathogen-associated molecular patterns (PAMPs) elicit similar responses of danger signals and represent the group of damage-associated molecular patterns (DAMPs). Effector cells of innate and adaptive immunity that are activated by PAMPs or alarmins can secrete other alarmins and amplify the immune responses. These complex interactions and loops between alarmins and PAMPs are particularly potent at inducing and then aggravating the GVHD reaction. In this review, we highlight the role of these tissue damaging molecules and their signaling pathways. Interestingly, some DAMPs and PAMPs are organ specific and GVHD-induced and have been shown to be interesting biomarkers. Some of these molecules may represent potential targets for novel therapeutic approaches.

Association of HMGB1 and HMGB2 genetic polymorphisms with lung cancer chemotherapy response

The aim of the present study was to investigate the association of genetic polymorphisms in high mobility group box 1 and 2 (HMGB1 and HMGB2, respectively) with platinum-based chemotherapy responses in Chinese lung cancer patients. In total, 338 Chinese lung cancer patients (154 responders and 184 non-responders) were recruited to the study. All patients received at least two cycles of first-line platinum-based chemotherapy. Three tagging single nucleotide polymorphisms (SNPs) of HMGB1 and two tagging SNPs of HMGB2 were detected in patients. We found that rs1412125 and rs2249825 of HMGB1 were significantly associated with the platinum-based chemotherapy response in both recessive and genotypic models. In addition, rs1412125 showed significant association with platinum-based chemotherapy response for the subgroup of patients aged >55 years in additive, recessive and genotypic models. No significant associations were detected between other SNPs and the platinum-based chemotherapy response. The HMGB1 SNPs (rs1412125 and rs2249825) were associated with platinum-based chemotherapy responses in Chinese lung cancer patients. In conclusion, HMGB1 SNPs may serve as potential biomarkers for predicting the efficacy of platinum-based chemotherapy.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

HMGB1 gene polymorphism is associated with hypertension in Han Chinese population

BACKGROUND

High-mobility group box 1 protein (HMGB1) acts as a proinflammatory cytokine by activating pattern recognition receptors (PRRs), including Toll-like receptor 4 (TLR4) and the receptor of AGE (AGER) with oxidative injury. Animal study proved that HMGB1 contributed to the pathogenesis of experimental pulmonary hypertension (HT) via activation of TLR4. The aim of this study is to test whether HMGB1 harbor genetic susceptibility to HT in a Chinese population.

METHODS

A case-control study comprising 2012 HT cases and 2210 controls was used to evaluate the association of three tagging single nucleotide polymorphism (tagSNPs) in HMGB1 gene with HT and blood pressure. Logistic regression model was used to adjust confounding factor for HT and general linear model (GLM) was applied to compare blood pressure levels between genotypes in cases and controls.

RESULTS

Single locus analysis showed that there was no statistical association of three tagSNPs with HT after adjustment for the covariates. Further stratification analysis found that rs2249825 was significantly associated with HT in ≥55 years groups, ORs (95% CI) of additive model and dominant model were 1.208 (1.029-1.417) and 1.212 (1.020-1.441), and p values were 0.021 and 0.029, respectively. Quantitative trait analysis indicated that DBP had a linear decrease with the variations of rs2249825 in both untreated HT group (p=0.002) and control group (p=0.034) respectively.

CONCLUSIONS

Our finding suggests that rs2249825 of HMGB1 genetic polymorphisms are significantly associated with HT and diastolic blood pressure, and the genetic effect on HT is modulated by age.

Siglec-G-CD24 axis controls the severity of graft-versus-host disease in mice

Activation of sialic-acid-binding immunoglobulin-like lectin-G (Siglec-G) by noninfectious damage-associated molecular patterns controls innate immune responses. However, whether it also regulates T-cell-mediated adaptive immune responses is not known. Graft-versus-host reaction is a robust adaptive immune response caused by allogeneic hematopoietic cell transplantation that have been activated by antigen-presenting cells (APCs) in the context of damaged host tissues following allogeneic hematopoietic cell transplantation. The role of infectious and noninfectious pattern recognition receptor-mediated activation in the induction and aggravation of graft-versus-host disease (GVHD) is being increasingly appreciated. But the role of pathways that control innate immune responses to noninfectious stimuli in modulating GVHD has heretofore not been recognized. We report that Siglec-G expression on host APCs, specifically on hematopoietic cells, negatively regulates GVHD in multiple clinically relevant murine models. Mechanistic studies with various relevant Siglec-G and CD24 knockout mice and chimeric animals, along with rescue experiments with novel CD24 fusion protein demonstrate that enhancing the interaction between Siglec-G on host APCs with CD24 on donor T cells attenuates GVHD. Taken together, our data demonstrate that Siglec-G-CD24 axis, controls the severity of GVHD and suggest that enhancing this interaction may represent a novel strategy for mitigating GVHD.

Pathogenesis of graft-versus-host disease: innate immunity amplifying acute alloimmune responses

In addition to reduced-intensity conditioning, which has expanded the eligibility for hematopoietic cell transplantation (HCT) to older patients, increased availability of alternative donors, including HLA-mismatched unrelated donors, has increased access to allogeneic HCT for more patients. However, acute graft-versus-host disease (GVHD) remains a lethal complication, even in HLA-matched donor-recipient pairs. The pathophysiology of GVHD depends on aspects of adaptive immunity and interactions between donor T-cells and host dendritic cells (DCs). Recent work has revealed that the role of other immune cells and endothelial cells and components of the innate immune response are also important. Tissue damage caused by the conditioning regimen leads to the release of exogenous and endogenous "danger signals". Exogenous danger signals called pathogen-associated molecular patterns and endogenous noninfectious molecules known as damage-associated molecular patterns (DAMPs) are responsible for initiating or amplifying acute GVHD by enhancing DC maturation and alloreactive T-cell responses. A significant association of innate immune receptor polymorphisms with outcomes, including GVHD severity, was observed in patients receiving allogeneic HCT. Understanding of the role of innate immunity in acute GVHD might offer new therapeutic approaches.

HMGB1 gene polymorphisms in patients with chronic hepatitis B virus infection

AIM: To characterize high mobility group box chromosomal protein 1 (HMGB1) polymorphisms in patients infected with hepatitis B virus (HBV) and determine the different patterns in patient subgroups.

METHODS: A total of 1495 unrelated Han Chinese HBV carriers were recruited in this hospital-based case-control study. The HMGB1 1176 G/C polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism assay.

RESULTS: A significant association was observed between HMGB1 1176 G/C polymorphism and outcome of HBV infection. The subjects bearing 1176G/G genotype had an increased risk of susceptibility to chronic hepatitis B, liver cirrhosis and severe hepatitis B when compared with those bearing at least one 1176C allele.

CONCLUSION: Patients with 1176G/G genotype of HMGB1 gene are more likely to have a progressive status in HBV infection.

Role of non-HLA gene polymorphisms in graft-versus-host disease

A large number of reports have associated various non-HLA gene polymorphisms with the risk and severity of graft-versus-host disease (GVHD). To date, candidate gene studies and genome-wide association studies have been performed to investigate such non-HLA gene polymorphisms in relation to GVHD. Candidate gene studies are hypothesis-driven and cost-effective, whereas genome-wide association studies have the potential to discover new gene polymorphisms, including possible biomarkers and therapeutic targets. Some gene polymorphisms have the potential to affect protein function or gene expression, or to encode minor histocompatibility antigens. Non-HLA genotyping for genes influencing GVHD prior to transplantation should provide useful information that will facilitate choosing the donor, type of graft, conditioning treatment, and GVHD prophylaxis. However, attention should be paid to the need for validation studies and ethical issues.

Biologic markers of chronic GVHD

Biologic markers of chronic GVHD may provide insight into the pathogenesis of the syndrome, identify molecular targets for novel interventions, and facilitate advances in clinical management. Despite extensive work performed to date largely focused on prediction and diagnosis of the syndrome, little synthesis of findings and validation of promising candidate markers in independent populations has been performed. Studies suggest that risk for subsequent chronic GVHD development may be associated with donor-recipient genetic polymorphism, deficiency in regulatory immune cell populations (NK, Treg, DC2), and variation in inflammatory and immunoregulatory mediators post-HCT (increased TNFα, IL-10 and BAFF, and decreased TGFβ and IL-15). Established chronic GVHD is associated with alteration in immune cell populations (increased CD3(+) T cells, Th17, CD4(+) and CD8(+) effector memory cells, monocytes, CD86 expression, BAFF/B cell ratio, and deficiency of Treg, NK cells, and naïve CD8(+) T cells). Inflammatory and immunomodulatory factors (TNFα, IL-6, IL-1β, IL-8, sIL-2R, and IL-1Ra, BAFF, anti-dsDNA, sIL-2Rα, and sCD13) are also perturbed. Little is known about biologic markers of chronic GVHD phenotype and severity, response to therapy, and prognosis.

Evaluation of published single nucleotide polymorphisms associated with acute GVHD

Candidate genetic associations with acute GVHD (aGVHD) were evaluated with the use of genotyped and imputed single-nucleotide polymorphism data from genome-wide scans of 1298 allogeneic hematopoietic cell transplantation (HCT) donors and recipients. Of 40 previously reported candidate SNPs, 6 were successfully genotyped, and 10 were imputed and passed criteria for analysis. Patient and donor genotypes were assessed for association with grades IIb-IV and III-IV aGVHD, stratified by donor type, in univariate and multivariate allelic, recessive and dominant models. Use of imputed genotypes to replicate previous IL10 associations was validated. Similar to previous publications, the IL6 donor genotype for rs1800795 was associated with a 20%-50% increased risk for grade IIb-IV aGVHD after unrelated HCT in the allelic (adjusted P = .011) and recessive (adjusted P = .0013) models. The donor genotype was associated with a 60% increase in risk for grade III-IV aGVHD after related HCT (adjusted P = .028). Other associations were found for IL2, CTLA4, HPSE, and MTHFR but were inconsistent with original publications. These results illustrate the advantages of using imputed single-nucleotide polymorphism data in genetic analyses and demonstrate the importance of validation in genetic association studies.

Clinical relevance of single nucleotide polymorphisms of the high mobility group box 1 protein gene in patients with major trauma in southwest China

BACKGROUND

High-mobility group box protein 1 (HMGB1) is a pivotal late mediator involved in the development of sepsis and multiple organ dysfunction syndrome (MODS) in critically ill patients. While several single nucleotide polymorphisms (SNPs) have been demonstrated to be critical determinants for outcome of critically ill patients, little is known about the clinical relevance of SNPs of the HMGB1 gene up to date.

METHODS

A total of 3 tag SNPs of the HMGB1 gene were selected using HapMap database and linkage disequilibrium analysis. The tag SNPs were genotyped using a pyrosequencing methodology in 556 unrelated patients with major trauma. Peripheral whole blood samples obtained immediately after admission were determined for HMGB1 production in response to ex vivo lipopolysaccharide (LPS) stimulation.

RESULTS

The rs2249825 SNP and the haplotype TCG were significantly associated with LPS-induced HMGB1 production by peripheral blood leukocytes. There were also significant differences in sepsis morbidity rate and MOD scores among patients with different genotypes of the rs2249825. In addition, the patients with the wild-type haplotype TCG had a lesser sepsis morbidity rate and MOD scores than those without the TCG haplotype.

CONCLUSION

A total of 3 SNPs might act as tag SNPs for the entire HMGB1 gene. The rs2249825 and the haplotype TCG might be used as relevant risk estimate for the development of sepsis and MODS in patients with major trauma.

Biomarkers in chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD ) is a leading cause of allogeneic hematopoietic stem-cell transplantation-related mortality and morbidity. It is an immune-mediated disorder that can target almost any organ in the body, often with devastating consequences. The immune-suppressive medications currently used to treat it are equally toxic and are often not very effective. At this time, our understanding of its pathophysiology is limited. The discovery of potential biomarkers offers new possibilities in the clinical management of cGVHD. They could potentially be used for diagnosing cGVHD, for predicting or evaluating response to therapy and for unique insights into the pathophysiology underlying the clinical manifestations of cGVHD. Understanding the biological origins of these biomarkers can help us construct a more comprehensive and clinically relevant model for the pathogenesis of this disease. In this article, we review existing evidence for candidate biomarkers that have been identified in the framework of how they may contribute to the pathophysiology of cGVHD. Issues regarding the discovery and application of biomarkers are discussed.

High-mobility group box 1 (HMGB1) as a master regulator of innate immunity

Damage-associated molecular patterns (DAMPs) comprise intracellular molecules characterized by the ability to reach the extracellular environment, where they prompt inflammation and tissue repair. The high-mobility box group 1 (HMGB1) protein is a prototypic DAMP and is highly conserved in evolution. HMGB1 is released upon cell and tissue necrosis and is actively produced by immune cells. Evidence suggests that HMGB1 acts as a key molecule of innate immunity, downstream of persistent tissue injury, orchestrating inflammation, stem cell recruitment/activation, and eventual tissue remodeling.