Immunosuppression in two cases of indeterminate hepatitis

Background

Pediatric acute liver failure (PALF) is a potentially lethal and rapidly progressive clinical syndrome, with a large proportion of cases remaining indeterminate despite extensive investigations.

Patients and Results

In this case report, we describe two male children with indeterminate PALF and a family history of autoimmune disease, both of whom were lymphopenic with necrosis, inflammation, and lymphocytic infiltrates on their liver biopsies. One of these patients subsequently developed hepatitis-associated aplastic anemia. Notably, in addition to receiving standard liver failure care, both patients were successfully treated off-label with anti-thymocyte globulin (ATG), as well as a more prolonged course of cyclosporine and corticosteroids.

Conclusions

The fact that these medications all suppress T lymphocytes further supports the theory that T-cell activation plays a prominent role in the pathophysiology of indeterminate hepatitis. Further research should examine the short-term and long-term effects of ATG in this population, as well as the necessary duration of treatment with immune-suppressing agents.

Further evidence supporting the role of DUT gene in diabetes with bone marrow failure syndrome

In 2017, a homozygous DUT mutation was reported to cause a syndrome of diabetes and bone marrow failure. However, no further patient with this combination has been reported and the phenotype of heterozygous DUT mutation is unknown. We describe the genotype, phenotype, and post bone marrow transplantation (BMT) data of two unrelated families with this rare syndrome. Whole-exome and/or direct sequencing of the DUT gene were performed in all family members. Each family has two children presented within the first 10 years of life with thrombocytopenia, macrocytosis, with or without anemia, followed by non-autoimmune diabetes. The same homozygous missense DUT mutation, reported in 2017 (c.425A>G p.(Tyr142Cys), was detected in all affected children. The heterozygous carriers have no BM failure, one developed type 2 diabetes, and the rest have normal fasting glucose, insulin, HbA1c, and c-peptide. Multiple nevi were detected in homozygous and heterozygous mutation carriers. Allogenic BMT normalized BM aplasia without impact on diabetes. Post BMT follow-up revealed normal puberty and school performance; but three have height <2.5 SDS. We add two families with this syndrome supporting a role of DUT in bone marrow and β-cell function. The heterozygous carriers of this DUT mutation appear to be healthy.

Bone marrow aplasia following donor lymphocyte infusion in 4-year-old patient with chronic granulomatous disease after allogeneic stem cell transplantation: case report

Donor lymphocyte infusion (DLI) is typically used in 3 clinical situations: therapeutically for proven relapse of malignancy, prophylactically in patients with high-risk of relapse, and in case of mixed chimerism. Mixed chimerism, which occur after transplantation can be a sign of possible rejection. In case of increased mixed chimerism, immunotherapy with donor lymphocyte infusions could reverse this process. After DLI, both acute and chronic graft-versus-host disease and marrow aplasia are well-known toxicities. In this paper, we present a case report of young patient with chronic granulomatous disease (CGD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), with successful immunotherapy following mixed chimerism, which was complicated by bone marrow aplasia that required a second stem cell infusion. DLI seems to be an effective and highly promising treatment method of transplant rejection in patients with CGD but can induce bone marrow aplasia and may require a second stem cell infusion.

The NAD-Booster Nicotinamide Riboside Potently Stimulates Hematopoiesis through Increased Mitochondrial Clearance

It has been recently shown that increased oxidative phosphorylation, as reflected by increased mitochondrial activity, together with impairment of the mitochondrial stress response, can severely compromise hematopoietic stem cell (HSC) regeneration. Here we show that the NAD⁺-boosting agent nicotinamide riboside (NR) reduces mitochondrial activity within HSCs through increased mitochondrial clearance, leading to increased asymmetric HSC divisions. NR dietary supplementation results in a significantly enlarged pool of progenitors, without concurrent HSC exhaustion, improves survival by 80%, and accelerates blood recovery after murine lethal irradiation and limiting-HSC transplantation. In immune-deficient mice, NR increased the production of human leucocytes from hCD34+ progenitors. Our work demonstrates for the first time a positive effect of NAD⁺-boosting strategies on the most primitive blood stem cells, establishing a link between HSC mitochondrial stress, mitophagy, and stem-cell fate decision, and unveiling the potential of NR to improve recovery of patients suffering from hematological failure including post chemo- and radiotherapy.

Heterozygous loss of Srp72 in mice is not associated with major hematological phenotypes

OBJECTIVES

Familial cases of hematological malignancies are associated with germline mutations. In particular, heterozygous mutations of SRP72 correlate with the development of myelodysplasia and bone marrow aplasia in two families. The signal recognition particle 72 kDa protein (SRP72) is part of the SRP complex, responsible for targeting of proteins to the endoplasmic reticulum. The main objective of this study is to investigate the role of SRP72 in the hematopoietic system, thus explaining why a reduced dose could increase susceptibility to hematological malignancies.

METHODS

We developed an Srp72 null mouse model and characterized its hematopoietic system using flow cytometry, bone marrow transplantations, and gene expression analysis.

RESULTS

Heterozygous loss of Srp72 in mice is not associated with major changes in hematopoiesis, although causes mild reductions in blood and BM cellularity and minor changes within the stem/progenitor compartment. We did not observe any hematological disorder. Interestingly, gene expression analysis demonstrated that genes encoding secreted factors, including cytokines and receptors, were transcriptionally down-regulated in Srp72^+/- animals.

CONCLUSIONS

The Srp72^+/- mouse model only partially recapitulates the phenotype observed in families with inherited SRP72 lesions. Nonetheless, these results can provide mechanistic insights into why SRP72 mutations are associated with aplasia and myelodysplasia in humans.

A new model of busulphan-induced chronic bone marrow aplasia in the female BALB/c mouse

Aplastic anaemia (AA) is characterized by hypocellular marrow, pancytopenia, and risk of severe anaemia, haemorrhage and infection. AA is often idiopathic, but frequently occurs after exposure to drugs/chemicals. However, the pathogenesis of AA is not clearly understood, and there are no convenient animal models of drug-induced AA. We have evaluated regimens of busulphan (BU) administration in the mouse to produce a model of chronic bone marrow aplasia showing features of human AA. Mice were given 8 doses of BU at 0, 5.25 and 10.50 mg/kg over 23 days; marrow and blood samples were examined at 1, 19, 49, 91 and 112 days after dosing. At day 1 post dosing, in mice treated at 10.50 mg/kg, nucleated marrow cells, CFU-GM and Erythroid-CFU were reduced. Similarly, peripheral blood erythrocytes, leucocytes, platelets and reticulocytes were reduced. At day 19 and 49 post dosing, there was a trend for parameters to return towards normal. However, at day 91 and 112 post dosing, values remained significantly depressed, with a stabilized chronic bone marrow aplasia. At day 91 and 112 post dosing, marrow cell counts, CFU-GM and Erythroid-CFU were decreased; marrow nucleated cell apoptosis and c-kit+ cell apoptosis were increased; peripheral blood erythrocyte, leucocyte, and platelet counts were reduced. We conclude that this is a model of chronic bone marrow aplasia which has many interesting features of AA. The model is convenient to use and has potential in several areas, particularly for investigations on mechanisms of AA pathogenesis in man.