Mitochondrial-targeted curcumin inhibits T-cell activation via Nrf2 and inhibits graft-versus-host-disease in a mouse model.

Anti-inflammatory and immune suppressive agents are required to moderate hyper-activation of lymphocytes under disease conditions or organ transplantation. However, selective disruption of mitochondrial redox has not been evaluated as a therapeutic strategy for suppression of T-cell-mediated pathologies. Using mitochondrial targeted curcumin (MitoC), we studied the effect of mitochondrial redox modulation on T-cell responses by flow cytometry, transmission electron microscopy, transcriptomics, and proteomics, and the role of Nrf2 was studied using Nrf2- /- mice. MitoC decreased mitochondrial TrxR activity, enhanced mitochondrial ROS (mROS) production, depleted mitochondrial glutathione, and suppressed activation-induced increase in mitochondrial biomass. This led to suppression of T-cell responses and metabolic reprogramming towards Treg differentiation. MitoC induced nuclear translocation and DNA binding of Nrf2, leading to upregulation of Nrf2-dependent genes and proteins. MitoC-mediated changes in mitochondrial redox and modulation of T-cell responses are abolished in Nrf2- /- mice. Restoration of mitochondrial thiols abrogated inhibition of T-cell responses. MitoC suppressed alloantigen-induced lymphoblast formation, inflammatory cytokines, morbidity, and mortality in acute graft-versus-host disease mice. Disruption of mitochondrial thiols but not mROS increase inculcates an Nrf2-dependent immune-suppressive disposition in T cells for the propitious treatment of graft-versus-host disease.

T Helper Cell Lineage-Defining Transcription Factors: Potent Targets for Specific GVHD Therapy?

Allogenic hematopoietic stem cell transplantation (allo-HSCT) represents a potent and potentially curative treatment for many hematopoietic malignancies and hematologic disorders in adults and children. The donor-derived immunity, elicited by the stem cell transplant, can prevent disease relapse but is also responsible for the induction of graft-versus-host disease (GVHD). The pathophysiology of acute GVHD is not completely understood yet. In general, acute GVHD is driven by the inflammatory and cytotoxic effect of alloreactive donor T cells. Since several experimental approaches indicate that CD4 T cells play an important role in initiation and progression of acute GVHD, the contribution of the different CD4 T helper (Th) cell subtypes in the pathomechanism and regulation of the disease is a central point of current research. Th lineages derive from naïve CD4 T cell progenitors and lineage commitment is initiated by the surrounding cytokine milieu and subsequent changes in the transcription factor (TF) profile. Each T cell subtype has its own effector characteristics, immunologic function, and lineage specific cytokine profile, leading to the association with different immune responses and diseases. Acute GVHD is thought to be mainly driven by the Th1/Th17 axis, whereas Treg cells are attributed to attenuate GVHD effects. As the differentiation of each Th subset highly depends on the specific composition of activating and repressing TFs, these present a potent target to alter the Th cell landscape towards a GVHD-ameliorating direction, e.g. by inhibiting Th1 and Th17 differentiation. The finding, that targeting of Th1 and Th17 differentiation appears more effective for GVHD-prevention than a strategy to inhibit Th1 and Th17 cytokines supports this concept. In this review, we shed light on the current advances of potent TF inhibitors to alter Th cell differentiation and consecutively attenuate GVHD. We will focus especially on preclinical studies and outcomes of TF inhibition in murine GVHD models. Finally, we will point out the possible impact of a Th cell subset-specific immune modulation in context of GVHD.

Tyrosine supplement ameliorates murine aGVHD by modulation of gut microbiome and metabolome.

BACKGROUND: Microbial communities and their metabolic components in the gut are of vital importance for immune homeostasis and have an influence on the susceptibility of the host to a number of immune-mediated diseases like acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, little is known about the functional connections between microbiome and metabolome in aGVHD due to the complexity of the gastrointestinal environment. METHOD: Initially, gut microbiota and fecal metabolic phenotype in aGVHD murine models were unleashed by performing 16S ribosomal DNA gene sequencing and ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS)-based metabolomics. FINDINGS: The group with aGVHD experienced a significant drop in Lachnospiraceae_unclassified but an increase in the relative abundance of Clostridium XI, Clostridium XIVa and Enterococcus. Meanwhile, a lower content of tyrosine was observed in the gut of aGVHD mice. The correlation analysis revealed that tyrosine-related metabolites were inversely correlated with Clostridium XIVa, besides, Blautia and Enterococcus also displayed the negative tendency in aGVHD condition. Apart from exploring the importance and function of tyrosine, different tyrosine diets were offered to mice during transplantation. Additional tyrosine supplements can improve overall survival, ameliorate symptoms at the early stage of aGVHD and change the structure and composition of gut microbiota and fecal metabolic phenotype. In addition, aGVHD mice deprived from tyrosine displayed worse manifestations than the vehicle diet group. INTERPRETATION: The results demonstrated the roles and mechanisms of gut microbiota, indispensable metabolites and tyrosine in the progression of aGVHD, which can be an underlying biomarker for aGVHD diagnosis and treatment. FUNDING: This research was funded by the International Cooperation and Exchange Program (81520108002), the National Key R&D Program of China, Stem Cell and Translation Research (2018YFA0109300), National Natural Science Foundation of China (81670169, 81670148, 81870080 and 91949115) and Natural Science Foundation of Zhejiang Province (LQ19H080006).

Carnitine Profile Changes in Pediatric Hematopoietic Stem Cell Transplant: New Role for Carnitine?

Carnitine is an essential cofactor for mitochondrial import and oxidation of fatty acids. High-dose chemotherapy and radiation, often required for hematopoietic stem cell transplant (HSCT), leads to tissue damage, mitochondrial dysfunction, and alterations in carnitine metabolism. The aim of this pilot cohort study was to describe plasma and urinary carnitine profiles during pediatric HSCT and their relationships with clinical outcomes. Plasma and urinary carnitine samples were collected from 22 pediatric patients before and through day 180 post-HSCT. Associations were observed between graft-versus-host disease and an elevated plasma total carnitine (P=0.019), and also increased plasma acyl:free carnitine ratio with veno-occlusive disease (P=0.016). Mortality was observed in those with their highest urinary total carnitine losses on day 0 (P=0.005), and in those with an abnormal day 28 plasma ratio either above or below the reference range (P=0.007). Changes in carnitine profiles were more reflective of metabolic stress and negative outcomes than of inadequate dietary intake. Associations observed direct larger studies to assess the validity of carnitine profiles as a prognostic indicator and also to assess whether prophylactic carnitine supplementation pre-HSCT could reduce mitochondrial injury and urinary losses and help mitigate inflammatory and metabolic comorbidities of HSCT.

The Green Tea Catechin Epigallocatechin Gallate Ameliorates Graft-versus-Host Disease.

Allogeneic hematopoetic stem cell transplantation (allo-HSCT) is a standard treatment for leukemia and other hematologic malignancies. The major complication of allo-HSCT is graft-versus-host-disease (GVHD), a progressive inflammatory illness characterized by donor immune cells attacking the organs of the recipient. Current GVHD prevention and treatment strategies use immune suppressive drugs and/or anti-T cell reagents these can lead to increased risk of infections and tumor relapse. Recent research demonstrated that epigallocatechin gallate (EGCG), a component found in green tea leaves at a level of 25-35% at dry weight, may be useful in the inhibition of GVHD due to its immune modulatory, anti-oxidative and anti-angiogenic capacities. In murine allo-HSCT recipients treated with EGCG, we found significantly reduced GVHD scores, reduced target organ GVHD and improved survival. EGCG treated allo-HSCT recipients had significantly higher numbers of regulatory T cells in GVHD target organs and in the blood. Furthermore, EGCG treatment resulted in diminished oxidative stress indicated by significant changes of glutathione blood levels as well as glutathione peroxidase in the colon. In summary, our study provides novel evidence demonstrating that EGCG ameliorates lethal GVHD and reduces GVHD-related target organ damage. Possible mechanisms are increased regulatory T cell numbers and reduced oxidative stress.

Psoralen and Ultraviolet A Light Treatment Directly Affects Phosphatidylinositol 3-Kinase Signal Transduction by Altering Plasma Membrane Packing.

Psoralen and ultraviolet A light (PUVA) are used to kill pathogens in blood products and as a treatment of aberrant cell proliferation in dermatitis, cutaneous T-cell lymphoma, and graft-versus-host disease. DNA damage is well described, but the direct effects of PUVA on cell signal transduction are poorly understood. Because platelets are anucleate and contain archetypal signal transduction machinery, they are ideally suited to address this. Lipidomics on platelet membrane extracts showed that psoralen forms adducts with unsaturated carbon bonds of fatty acyls in all major phospholipid classes after PUVA. Such adducts increased lipid packing as measured by a blue shift of an environment-sensitive fluorescent probe in model liposomes. Furthermore, the interaction of these liposomes with lipid order-sensitive proteins like amphipathic lipid-packing sensor and α-synuclein was inhibited by PUVA. In platelets, PUVA caused poor membrane binding of Akt and Bruton's tyrosine kinase effectors following activation of the collagen glycoprotein VI and thrombin protease-activated receptor (PAR) 1. This resulted in defective Akt phosphorylation despite unaltered phosphatidylinositol 3,4,5-trisphosphate levels. Downstream integrin activation was furthermore affected similarly by PUVA following PAR1 (effective half-maximal concentration (EC50), 8.4 ± 1.1 versus 4.3 ± 1.1 µm) and glycoprotein VI (EC50, 1.61 ± 0.85 versus 0.26 ± 0.21 µg/ml) but not PAR4 (EC50, 50 ± 1 versus 58 ± 1 µm) signal transduction. Our findings were confirmed in T-cells from graft-versus-host disease patients treated with extracorporeal photopheresis, a form of systemic PUVA. In conclusion, PUVA increases the order of lipid phases by covalent modification of phospholipids, thereby inhibiting membrane recruitment of effector kinases.

Endoscopic and Histological Findings Are Predicted by Fecal Calprotectin in Acute Intestinal Graft-Versus-Host-Disease.

BACKGROUND: Gastrointestinal graft-versus-host-disease (GI-GVHD) is a major cause of nonrelapse mortality after hematopoietic stem cell transplantation (HSCT) necessitating endoscopic examinations and biopsies for diagnosis. Fecal calprotectin (CPT) has been widely used in gastrointestinal inflammation, but comprehensive data in GI-GVHD are lacking. AIMS: We aimed to identify an association of CPT with endoscopic findings, mucosal damage and symptoms for diagnosing and monitoring acute GI-GVHD. METHODS: Symptoms were prospectively evaluated in 110 consecutive HSCT recipients by standardized questionnaires and Bristol Stool Scale (BSS). CPT was assayed by ELISA. Symptom assessment and CPT were performed weekly and with onset of first symptoms. GVHD was diagnosed according to the Glucksberg criteria and by endoscopic biopsies. Patients with GI-GVHD received standard high-dose corticosteroid therapy and follow-up CPT, and symptom evaluation was performed after 28 days. Patients not responding to steroid treatment were re-evaluated by colonoscopy. RESULTS: GI-GVHD was diagnosed in 40 patients. Twelve patients with GI symptoms and CMV colitis and 24 patients with isolated skin GVHD were included as control subjects. CPT was significantly higher in GI-GVHD compared to skin GVHD and CMV colitis. Endoscopic findings, histological grading, abdominal cramps, diarrhea, urgency and BSS correlated with CPT. At follow-up, CPT correlated with abdominal cramps, diarrhea, urgency and BSS. In steroid refractory patients, CPT level was still significantly associated with severity of mucosal damage. CONCLUSION: CPT predicts endoscopic and histological findings in GI-GVHD and correlates with lower GI symptoms. It enables to discriminate GVHD from CMV colitis and to monitor therapeutic success.

Thiol dependent NF-κB suppression and inhibition of T-cell mediated adaptive immune responses by a naturally occurring steroidal lactone Withaferin A.

Withaferin A (WA), a steroidal lactone isolated from ayurvedic medicinal plant Withania somnifera, was shown to inhibit tumor growth by inducing oxidative stress and suppressing NF-κB pathway. However, its effect on T-cell mediated adaptive immune responses and the underlying mechanism has not been investigated. Since both T-cell responses and NF-κB pathway are known to be redox sensitive, the present study was undertaken to elucidate the effect of WA on adaptive immune responses in vitro and in vivo. WA inhibited mitogen induced T-cell and B-cell proliferation in vitro without inducing any cell death. It inhibited upregulation of T-cell (CD25, CD69, CD71 and CD54) and B-cell (CD80, CD86 and MHC-II) activation markers and secretion of Th1 and Th2 cytokines. WA induced oxidative stress by increasing the basal ROS levels and the immunosuppressive effects of WA were abrogated only by thiol anti-oxidants. The redox modulatory effects of WA in T-cells were attributed to its ability to directly interact with free thiols. WA inhibited NF-κB nuclear translocation in lymphocytes and prevented the direct binding of nuclear NF-κB to its consensus sequence. MALDI-TOF analysis using a synthetic NF-κB-p50 peptide containing Cys-62 residue suggested that WA can modify the cysteine residue of NF-κB. The pharmacokinetic studies for WA were also carried out and in vivo efficacy of WA was studied using mouse model of Graft-versus-host disease. In conclusion, WA is a potent inhibitor of T-cell responses and acts via a novel thiol dependent mechanism and inhibition of NF-κB pathway.

Prevention of acute GVHD in mice by treatment with Tripterygium hypoglaucum Hutch combined with cyclosporin A.

OBJECTIVE: To elucidate the protective roles and the underlying mechanism of Tripterygium hypoglaucum Hutch (THH) in mice graft-versus-host disease (GVHD). METHODS: BALB/c (H-2k(d)) mice were firstly treated with total body irradiation and infused with a mixture of bone marrow and spleen cells from C57BL/6. Then the severity of acute GVHD (aGVHD), chimeras of donor cells, inflammatory cytokines (IFN-γ, IL-4, and IL-10) of plasma, and regulatory T cells were evaluated to elucidate the different drug combinations and concentrations of cyclosporin A (CsA) and THH in preventing aGVHD. RESULTS: The control group treated with phosphate buffer solution displayed more obvious ruffled hair, hunched posture, diarrhea, reduced weight and more lymphocytes infiltration into the spleen and intestine than these treated with CsA, THH or low-dosed CsA combined with THH, especially those treated with low-dosed CsA combined with THH. No significant differences were observed in the chimeras of donor cells and survival rate among the CsA, THH, or CsA combined with THH-treated groups. Further studies implied that THH might reduce the aGVHD by increasing IL-10, decreasing IL-4, activating Treg cell, and maintaining a relatively high Foxp3 mRNA level. CONCLUSION: THH decreased the occurrence of mouse aGVHD and prolonged the survival time by increasing the levels of CD(4)(+)/CD(25)(+) T cells, regulating the cytokine secretion and promoting the expression of Foxp3.

Significance of heat shock proteins in the skin upon UV exposure.

The expression of heat shock proteins (Hsp) expression is induced in all cells by exposure to heat and other environmental stress and Hsp can protect cells from damage through further exposure. Hsp are highly conserved and it is likely that they are essential for survival in a potentially harmful environment. Most Hsp are molecular chaperones sensing unfolded proteins and mediating their re-folding, transport, and interaction. In human epidermis Hsp are associated with differentiation, photoprotection, and skin disease. Recent research has mainly focused on the 27kD and 72kD Hsp that are constitutively expressed in keratinocytes. Cell death induced by ultraviolet radiation (UV) can be inhibited by previous heat shock and UV itself can induce Hsp experimentally. Regulation of Hsp can be pharmacologically modified and topical and systemic inducers and inhibitors of Hsp expression are under development. Whether phototherapy exerts its clinical efficacy by modulation of Hsp has not been sufficiently studied. The UV-wavelength ranges, -intensities and -doses that are required to interfere with the heat shock response in the skin still remain to be elucidated.

Altered functional status of the hypothalamic dopaminergic tone in patients with chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation: a pilot study.

We compared the functional status of the hypothalamic dopaminergic tone in patients given an allogeneic hematopoietic stem cell transplantation (allo-HSCT) with chronic graft-versus-host disease (GVHD) with that observed in patients with allo-HSCT without chronic GVHD and in healthy controls. The effect of acute dopaminergic blockade with intravenous metoclopramide on serum prolactin (PRL) concentrations was evaluated. Twenty volunteers, 20 to 52 years of age, seronegative for both hepatitis C virus and the human immunodeficiency virus, were studied: (1) 10 clinically healthy men (group 1), and (2) 9 patients with leukemia, and 1 patient with refractory aplastic anemia who underwent allo-HSCT, 5 of whom (3 men and 2 women) developed chronic GVHD (group 2), and 5 (3 men and 2 women) who did not develop chronic GVHD (group 3). Serum PRL concentrations were measured both fasting and after intravenous administration of metoclopramide (10-mg bolus). The area under the PRL curve was calculated. Patients in group 2 were older than those in groups 1 and 3 (P<.018), but their body mass index was similar. Fasting serum PRL concentrations were similar among the 3 groups; however, group 2 had higher PRL concentrations throughout the test (P<.001) and a greater area under the PRL curve than groups 1 and 3 (P<.001), without differences between the last 2 groups. The differences remained significant after adjustment for age (P<.01). Our results in a small group of patients with chronic GVHD after allo-HSCT suggest the existence of an increased functional level of their hypothalamic dopamine tone, which would favor a tendency toward a diminished endogenous production, release of pituitary PRL, or both. This could represent an adaptive mechanism aiming to maintain circulating PRL concentrations within a physiological range.

Effects of immunosuppressive agents on magnesium metabolism early after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: The calcineurin inhibitors, cyclosporine A (CSA) and tacrolimus, cause hypomagnesemia by suppressing reabsorption of magnesium (Mg) from renal tubules. To assess whether the effect on Mg metabolism after allogeneic hematopoietic stem cell transplantation (HSCT) differs among calcineurin inhibitors, we prospectively evaluated the Mg metabolism in recipients of allogeneic HSCT who received CSA or tacrolimus METHODS: Patients who underwent allogeneic HSCT were enrolled. CSA and tacrolimus were given by continuous infusion starting from day -1. Serum Mg and the total amount of urinary Mg excretion were measured once before starting of CSA or tacrolimus, and once weekly after HSCT for 4 weeks. Mg was supplemented with magnesium l-aspartate by continuous infusion to maintain the serum Mg level >1.4 mEq/L. RESULTS: Thirty-six patients were evaluated (12 in the CSA group, 24 in the tacrolimus group). The serum Mg level began to decrease in both groups at the first week after HSCT, and the mean serum Mg levels were significantly lower in the tacrolimus group than in the CSA group from the first to the third week. The total amount of urinary Mg excretion and Mg supplementation began to increase in both groups at the second week after HSCT, and the amounts in the tacrolimus group were significantly higher than those in the CSA group. CONCLUSIONS: Although both calcineurin inhibitors increased urinary Mg excretion and caused hypomagnesemia shortly after HSCT, the effect was more significant with tacrolimus than with CSA. This observation may explain the higher incidence of renal impairment and encephalopathy in patients receiving tacrolimus.

The IL-12 role in donor cell engraftment in a murine model of semiallogenic GVH disease with signs of autoimmune disease.

We analyzed the IL-12 effect in an autoimmune disease induced in a semiallogenic murine model of graft-vs-host disease (GVHD) Balb/c semiallogenic lymphoid cells i.v. infected in hybrid mice (Balb/c x A/J) F1 (CAF). IL-12 was administered 1 h before cell transplantation following two different protocols: (a) injecting 2 microg of mrIL-12 (murine recombinant IL-12) per mouse before the first semiallogenic cell injection; or (b) injecting the 2 microg of mrIL-12 fractionated in 5 days. ATh1 response was produced but an acute GVHD did not appear although differences in class I and II major histocompatibility complex (MHC) antigens were present. Four days after the semiallogenic cell transfer, IL-12 treated mice showed a marked reduction in the percent of spleen B cells compared with CAF1 control and CAF1 + Balb/c GVHD mice. After 5-6 months of follow-up, the donor cell chimerism increased significantly in spleen (70 +/- 31 vs. 43 +/- 31%) and in thymus. Flow cytometry of spleen lymphocytes demonstrated that donor chimerism was made up of TCD4, TCD8 and B lymphocytes and was higher in animals injected with IL-12. Moreover, CD8 T lymphocytes were 100% donor origin in the IL-12-injected group of GVHD animals and 50% origin in the IL-12-non-injected CAF1 + Balb/c group of animals. This paper shows that: (1) IL- 12 may play a role in the mechanisms of donor cell engraftment, probably produced by a CTL donor anti-host mechanism; (2) no acute GVHD was induced in spite of class I and II MHC differences; (3) IL-12 did not show any effect on the AR-like clinical signs of disease developed in this model of GVHD although histological subclinical signs were less frequent, and no glomerulonephritis was detected in the IL-12-treated GVHD mice.

Prevention of CD40-triggered dendritic cell maturation and induction of T-cell hyporeactivity by targeting of Janus kinase 3.

Pharmacological targeting of Janus kinase 3 (JAK3) has been employed successfully to control allograft rejection and graft-vs.-host disease (GVHD). Recent evidence suggests that in addition to its involvement in common-gamma chain (cgamma) signaling of cytokine receptors, JAK3 is also engaged in the CD40 signaling pathway of peripheral blood monocytes. In this study, we assessed the consequences of JAK3 inhibition during CD40-induced maturation of myeloid dendritic cells (DCs), and tested the impact thereof on the induction of T-cell alloreactivity. Dendritic cells triggering through CD40 induced JAK3 activity, the expression of costimulatory molecules, production of IL-12, and potent allogeneic stimulatory capacity. In contrast, JAK3 inhibition with the rationally designed JAK3 inhibitor WHI-P-154 prevented these effects arresting the DCs at an immature level. Interestingly, DCs exposed to the JAK3-inhibitor during CD40-ligation induced a state of hyporeactivity in alloreactive T cells that was reversible upon exogenous IL-2 supplementation to secondary cultures. These results suggest that immunosuppressive therapies targeting the tyrosine kinase JAK3 may also affect the function of myeloid cells. This property of JAK3 inhibitors therefore represents a further level of interference, which together with the well-established suppression of cgamma signaling could be responsible for their clinical efficacy.

Dietary fish oil supplementation alters LTB4:LTB5 ratios but does not affect the expression of acute graft versus host disease in mice.

One of the mechanisms by which corticosteroids may modify acute graft vs host disease (GvHD) is via inhibition of arachidonic acid (AA) metabolism. Leukotriene B4 (LTB4) is a product of that pathway which may take part in the pathogenesis of GvHD through the stimulation of T-lymphopoiesis and T-lymphocyte activation. LTB4 is a metabolite of AA (20:4n-6). Alternate dietary sources of polyunsaturated fatty acids (PUFA), specifically eicosapenteinoic acid (20:5n-3) (EPA) and docosahexaenoic acid (22:6n-3) (DHA), shift the LTs formed with a decrease in LTB4 an increase in LTB5. LTB5 is a less potent agonist than LTB4 and this results in a theoretical decrease of LTB4 mediated events. Supplementation of in vitro bone marrow cultures with EPA or DHA had no detrimental effect on myeloid colony formation. Dietary EPA/DHA supplementation in mice with induced GvHD appeared to be safe and well tolerated. The LTB4:LTB5 ratio shifted from 7.65 +/- 1.75 in control-fed animals to 1.03 +/- 0.18. Fish-oil-supplementation did not compromise engraftment or stem cell content. Alone, this therapy was unable to modify GvHD.