N-acetylcysteine in the treatment of steroid-resistant acute graft-versus-host-disease: preliminary results. Gruppo Italiano Trapianto di Midollo Osseo (GITMO)

Oxidative stress indicators during the course of acute graft versus host disease

Aim: This prospective study aimed to observe the changes in oxidative stress indicators, including total anti-oxidant status (TAS), total oxidant status (TOS), paraoxanase-1 (PON1), total thiol (TT), native thiol (NT), disulphide (DS) and nitric oxide (NO) levels from sequential blood samples obtained during a de-novo episode of acute graft versus host disease (aGvHD) and evaluate their association with disease severity and the risk of steroid resistant disease. Material and Method: Sequential patients who underwent an allogeneic stem cell transplantation (ASCT) in our unit and subsequently developed a de-novo episode of aGvHD between January 2022 and May 2022 were included in case they gave informed consent. All patients were started high dose (2 mg/kg/day) methylprednisolone as institutional standard first-line treatment of aGvHD as soon as the clinical diagnosis is evident. All episodes were confirmed simultaneously with gastrointestinal (GI) endoscopy and/or skin biopsies. TAS, TOS, PON1, TT, NT, DS and NO were studied from blood samples collected on days 0, +3 and +7 of steroid treatment. Demographic characteristics, diagnoses, donor type, GvHD prophylaxis, stage and grade of aGvHD, performance status (PS), the presence of cytomegalovirus (CMV) reactivation and response to steroid therapy were also noted. Results: A total of 15 cases was included. The median age was 49 (23-77). Males constituted 60.0% (n=9). The most frequent diagnosis and donor type were acute leukemia (53.3%, n=8) and matched related donor (46.7%, n=7), respectively. High grade aGvHD with Glucksberg grading and International Bone Marrow Transplant Registry severity index (IBMTR-SI) included 53,3% (n=8) and 86.7% (n=10) of cases, respectively. Non-responders (20.0%, n=3) significantly had advanced stage GI involvement, higher grade of aGvHD with Glucksberg grading and IBMTR-SI, and lower PS (p=0.005, p=0.04, p=0.006, and p=0.02, respectively). The changes in TAS, TOS, PON1, TT, NT, DS and NO levels on days 0, +3 and +7 of steroid treatment were not significant. Median PON1 levels on days 0, +3 and +7 of steroid treatment were significantly lower among non-responders (p

Optimizing therapy for iron overload in the myelodysplastic syndromes: recent developments

The myelodysplastic syndromes (MDS) are characterized by cytopenias and risk of progression to acute myeloid leukaemia (AML). Most MDS patients eventually require transfusion of red blood cells for anaemia, placing them at risk of transfusional iron overload. In β-thalassaemia major, transfusional iron overload leads to organ dysfunction and death; however, with iron chelation therapy, organ function is improved, and survival improved to near normal and correlated with the degree of compliance with chelation. In lower-risk MDS, several nonrandomized studies suggest an adverse effect of iron overload on survival and that lowering iron with chelation may minimize this impact. Emerging data indicate that chelation may improve organ function, particularly hepatic function, and a minority of patients may have improvement in cell counts and decreased transfusion requirements. While guidelines for MDS generally recommend chelation in selected lower-risk patients, data from nonrandomized trials suggest iron overload may impact adversely on the outcome of higher-risk MDS and stem cell transplantation (SCT). This effect may be due to increased transplant-related mortality, infection and AML progression, and preliminary data suggest that lowering iron may be beneficial in this patient group. Other areas of active and future investigation include optimizing the monitoring of iron overload using imaging such as T2* MRI and measures of labile iron and oxidative stress; correlating new methods of measuring iron to clinical outcomes; clarifying the contribution of different cellular and extracellular iron pools to iron toxicity; optimizing chelation by using agents that access the appropriate iron pools to minimize the relevant clinical consequences in individual patients; and incorporating measures of quality of life and co-morbidities into clinical trials of chelation in MDS. It should be noted that chelation is costly and potentially toxic, and in MDS should be initiated after weighing potential risks and benefits for each patient until more definitive data are available. In this review, data on the impact of iron overload in MDS and SCT are discussed; for example, several noncontrolled studies show inferior survival in patients with iron overload in these clinical settings, including an increase in transplant-related mortality and infection risk. Possible mechanisms of iron toxicity include oxidative stress, which can damage cellular components, and the documented impact of lowering iron on organ function with measures such as iron chelation therapy includes an improvement in elevated liver transaminases. Lowering iron also appears to improve survival in both lower-risk MDS and SCT in nonrandomized studies. Selected aspects of iron metabolism, transport, storage and distribution that may be amenable to future intervention and improved removal of iron from important cellular sites are discussed, as are attempts to quantify quality of life and the importance of co-morbidities in measures to treat MDS, including chelation therapy.

The oxidative status of blood cells in a murine model of graft-versus-host disease

We studied the oxidative status of red and white blood cells during the development of graft vs host disease (GVHD) as well as the effects of treatment with antioxidants, both in vitro and in vivo. (BALB/c X C57BL/6) F1 mice were conditioned by total body radiation and, 1 day later, transplanted with semi-allogeneic C57BL/6 spleen cells. GVHD was followed by its clinical manifestations. Oxidative stress in red blood cells (RBC), neutrophils, and lymphocytes was assessed by measuring generation of reactive oxygen species and the content of reduced glutathione by flow cytometry after gating of the specific populations. Oxidative stress was noticed 3 weeks after transplantation. It was higher in mice receiving allogeneic spleen cells as compared with mice transplanted with syngeneic cells, suggesting that it was associated with GVHD. The results also demonstrated that treatment with the antioxidants N-acetylcysteine and a derivative of vitamin E (tocopherol succinate, propofol), both in vitro and in vivo, reduced the oxidative stress. The results indicate that various blood cells, including RBC, neutrophils, and lymphocytes, are under oxidative stress and that treatment with antioxidants reduced the stress and, thus, may be useful in ameliorating the severe consequences of GVHD.

N-acetylcysteine mildly inhibits the graft-vs.-leukemia effect but not the lymphokine activated cells (LAK) activity

N-acetylcysteine (NAC) is a known antioxidant and induces modulation of glutathione cellular content effects. It has been suggested that in the context of stem cell transplantation (SCT), NAC can prevent and treat graft-vs.-host disease, veno-occlusive disease and idiopathic pneumonia syndrome. We investigated the possible effect of NAC on graft-vs.-leukemia effect (GVL) and lymphokine activated cells (LAK) activity in murine models. After 10 days of NAC treatment, the cytotoxic activity of the LAK cells did not significantly differ from LAK activity generated from spleen cells obtained from untreated controls. However, NAC mildly suppressed GVL (appearance of leukemia in 8/36 animals treated with NAC as compared to 0/20 in the SCT control group, p=0.023). In spite of this mild suppression of GVL, no negative effect on achievement of donor chimerism was seen. We conclude that NAC usage in SCT may be relatively safe with regard to the GVL effect, yet further clinical studies are warranted.

Rust and corrosion in hematopoietic stem cell transplantation: the problem of iron and oxidative stress

Iron overload is a common acute and long-term event associated with autologous and allogeneic hematopoietic stem cell transplantation (HSCT). In a state of iron excess, free iron becomes available to catalyze the conversion of reactive oxygen species (ROS) intermediates such as superoxide anion (O2*-) and hydrogen peroxide (H2O2) to highly toxic free radicals such as hydroxyl radical (OH*). ROS may help to promote chronic liver disease, sinusoidal obstruction syndrome, idiopathic pneumonia syndrome and bacterial, fungal and other opportunistic infections. Phlebotomy has been effectively and safely used to deplete excess iron stores post-HSCT in thalassemic and other iron-overloaded patients. Intracellular iron levels may also be decreased through pharmacologic chelating agents, while antioxidants such as N-acetylcysteine, glutamine (glutathione precursor) and captopril have been shown to replenish glutathione redox potential and scavenge free radicals. A better understanding of the mechanisms involved in the iron-generated pro-oxidant state associated with HSCT will likely lead to reduced toxicity and improved patient outcomes.

Genes highly expressed in the early phase of murine graft-versus-host reaction

Graft-versus-host reaction (GVHR) is a complex process initiated upon allorecognition. For detection of early molecular events in GVHR, we first assessed time courses with respect to symptoms and serum interferon (IFN)-gamma levels and then used the differential display method to compare gene transcript patterns during the early phase between acute lethal GVHR mice and syngeneic controls. In the GVHR mice, high expression levels of seven genes encoding the following molecules were detected: TGTP/Mg21 (an IFN-gamma-related signaling molecule), vitronectin, Nedd5 (a mammalian septin), manganese superoxide dismutase, activin betaC subunit, PRCC (a papillary renal cell carcinoma-associated molecule), and an uncharacterized gene corresponding to a mouse expressed sequence tag (EST). The expression levels of most genes peaked before the symptomatological onset and the peak of IFN-gamma levels. Thus, gene expression monitoring may characterize the inductive process of GVHR and aid in the development of gene-based diagnostics and therapies.