Reticular dysgenesis SCID. Dr Stephanie Richards The Royal Children s Hospital, Melbourne

Transcription

1 Reticular dysgenesis SCID Dr Stephanie Richards The Royal Children s Hospital, Melbourne

2 Clinical presentation 36/40 male infant 2 nd child to non-consanguineous parents Noted to have temperature instability on d1 of life Treated for presumed sepsis FBE Hb 179g/L WCC 0.5x10^9/L Plts 329x10^9/L neuts 0.1x10^9/L lymphs 0.3x10^9/L CXR demonstrated absence of thymic shadow Transferred to RCH?SCID

3 Investigation Result FBE Hb 181g/L ( ) WCC 0.4x10^9/L ( ) Platelets 419X10^9/L ( ) Neutrophils 0.02x10^9/L ( ) Lymphocytes 0.32x10^9/L ( ) Immunoglobulins IgG 9.95g/L ( ) IgA <0.04 ( ) IgM <0.01 ( ) Lymphocyte subsets CD3+ 2% (28-76) CD x10^9/L ( ) CD19+ 70% (5-22) CD x10^9/L ( ) CD3-/CD16&56+ 22% (6-58) CD3-/CD16& x10^9/L ( ) Naïve T cells Unable to quantify due to marked T cell lymphopaenia T cell proliferation (PHA) WB patient unstim 0.4% (0.2%) WB patient PHA stimulated 2.2% (66.2%) WB patient EDU+ MFI 8.1% (46.8%) Bone marrow aspirate Markedly hypocellular bone marrow aspirate with agranulocytosis and marked reduction in lymphocytes and monocytes with relative sparing of erythropoiesis and normal megakaryopoiesis Occasional myeloblast and immature lymphocyte only Morphological appearance supports the clinical suspicion of RD

4 Management On transfer to RCH Barrier nursing in isolette Bactrim prophylaxis Fungal prophylaxis Pavilizumab Weekly virus screening (EBV/CMV/HHV6/Adenovirus/Enterovirus/Rotavirus/Norovirus) Confirmed sensorineural hearing loss Work-up for HSCT Investigations Normal echocardiogram Normal renal function (GFR study) Unremarkable CT chest Sibling not a HLA match Genetics Homozygous mutation in exon 1 of AK2 (c84_85inga pgly29argfs8)

5 HSCT 3mo age Donor source Apharesis MUD HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 match Mismatch at 1 DRB3 and 1 DPB1 allele Conditioning regimen Bu/Flu/ATG Immunosuppression CSA/MMF/Prednisolone Engrafted d+12 Complications VOD d+14 Treated with defibrotide and fluid restriction Engraftment syndrome d+14 Treated with methylprednisolone with improvement TPN for nutrition support

6 8 mo post-hsct evaluation Investigation Result FBE Hb 124/L ( ) WCC 6.0x10^9/L ( ) Platelets 206x10^9/L ( ) Neutrophils 1.56x10^9/L ( ) Lymphocytes 4.08x10^9/L ( ) Immunoglobulins Normal IgG/A/M (off immunoglobulin replacement) Lymphocyte subsets CD % (54-76) CD3+ 3.0^9/L ( ) CD3+/CD % (31-54) CD3+/CD4+ 2.2x10^9/L ( ) CD3+/CD % (12-28) CD3+/CD8+ 0.6x10^9/L ( ) CD % (15-39) CD x10^9/L (0.6-2.&) CD3-/CD16&56+ 3% (3-17) CD3-/CD16& x10^9/L ( ) Naïve T cells T cell proliferation (PHA) Normal naïve CD4+ and CD8+ T cells Not performed as yet Chimerism % (separated) donor

7 Reticular dysgenesis First described in 1959 by De Vaal and Seyneheve Histological findings highlighted the prominent reticular tissue framework First HSCT for RD in 1983 One of the rarer forms of severe combined immunodeficiency 1-3% of all cases of SCID Characterised by Granulocytopaenia Impaired lymphoid maturation Absent or very low T cells B cells normal or reduced Sensorineural deafness 1/3 rd infants pre-term Majority of patients present in first week of life High incidence of maternal engraftment (57%) Lack of innate and acquired immune function Extreme susceptibility to infections and early death Treatment Curative HSCT G-CSF not effective De Vaal OM et al Lancet 1959; Levinsky RJ et al Lancet 1983;

8 Reticular dysgenesis AK2 Gene defect identified in 2009 Mitochondrial adenylate kinase 2 (AK2) Proposed pathogenesis Mitochondrial oxidative phosphorylation (OXPHOS) supplies most of the cellular energy in the form of ATP Intracellular energy balance facilitated by multiple enzymes Facilitate transfer between ATP-generating sites and ATP-consuming sites AK2 is the primary ADP-generating enzyme Located in the mitochondrial intermembrane space Catalyses the reaction ATP + AMP <-> 2ADP ADP/ATP carriers transport ADP into the mitochondrial matrix and export ATP synthesised in the OXPHOS reaction out of the matrix into the cytosol ATP synthesis directly depends on the matrix concentration of ADP OXPHOS reaction therefore may fail in the absence of adenylate kinases Differentiation of haematopoietic stem cells requires high energy levels which are provided by the activation of oxidative phosphorylation (OXPHOS) in the mitochondria Deregulation of AK2 function could be involved in the alteration of mitochondrial metabolism Burkart A et al J Biol Chem 2011;296(6):

9 Restore differentiation and possible association with sensorineural hearing loss Lagresle-Peyrou et al Nat Genet 2009;41:

10 Differential expression of AK2 Suggests that leukocytes may be susceptible to defects caused by lack of AK2 as they do not express AK1 in sufficient amounts to compensate for AK2 functional defects Adenylate kinases in fibroblasts, thrombocytes, erythrocytes and FACS-sorted PBCs All nucleated cell populations from PB contained detectable AK2 but little or no AK1 protein Tissue distribution of adenylate kinases Co-expression of AK1 and AK2 in most tissues Pannicke U et al Nat Genet ;1:

11 AK2 deficiency affects granulocyte but not monocyte differentiation Neutrophils Monocytes Six E et al Cell Death and Disease 2015;6:1-11

12 AK2 required for neutrophil differentiation but CKMT1 also required for monocyte differentiation Monocytes Neutrophils Tanimura A et al PLOS One 2014;9(2):e89916

13 Reference No of RD cases Conditioning HLA match and source Outcome DeSantes KB et al Bone Marrow Transplant 1996;17: n = 1 ATG; n = 1 ATG, cyclophosphamide and busulfan, cyclophosphamide, ATG T-depleted haploidentical Failed engraftment until after TBI with or without other agents Calle-Martin O et al Clin Exp Immunol 1997;110: No conditioning 1 st HSCT Busulfan and cyclophosphamide 2 nd HSCT HLA-identical sibling Partial immune reconstitution ongoing granulocytopaenia Autoimmunity Haddad E et al Blood 1998;91: Variable HLA-nonidentical related donor (parents with 1 HLA antigen to full haplotype mismatch) 4 alive with donor T cell engraftment at 6mo BMT; 2 alive at last follow-up (median 6yr) Knutsen AP and Wall DA J Clin Immunol 2001;20: Busulfan, cyclophosphamide 1 st HSCT BI/cyclophosphamide/ATG 2 nd HSCT Unrelated cord blood x2 Alive and well Bertrand Y et al Bone Marrow Transplant 2002;29: Busulfan and cyclophosphamide or cyclophosphamide and ATG Nonidentical (15 HSCTs; 10 = maternal, 3 = paternal, 1 =both parents) 3/10 survivors; only patients receiving busulfan and cyclophosphamide survived Bhattacharya A et al Bone Marrow Transplant 2005;36: Alemtuzumab, busulfan, cyclophosphamide 10/10 cord blood 100% donor chimerism; mean follow-up 2yr Reubsaet LL et al Bone Marrow Transplantation 2007;39: First Treosulfan/fludarabine Second busulfan/cyclophosphamide/atg 6/6 cord blood followed by 5/6 matched unrelated cord blood Well 1yr after second transplant Heltzer M et al J Allergy Clin Immunol 2007;120(4): Busulfan, cyclophosphamide and ATG T-depleted halploidentical (mother) Alive at 20mo post-hsct Needed boost 7mo post-hsct for neutropaenia Patel N et al J Allergy Clin Immunol 2009;124(5): Busulfan, Cyclophosphamide, arac, ATG or C-1H, CsA/Prednisolone 6/6 MUD Alive at 1.75yr post-hsct Enterocolitis and AIHA Nevan B et al Blood 2009;23(113): Variable unknown specifically for RD 2 patients had repeat HSCT for MDS with busulfan and cyclophosphamide T-depleted haploidentical (mother) for both repeat HSCT 2 MDS patients RIP 1 yr post-hsct repeat and 5yrs post-hsct (highgrade brain glioma) Other 2 RD unknown Henderson et al J Allergy Clin Immunol 2013;131(4): (Omenn syndrome) Busulfan, cyclophosphamide and ATG 9/10 HLA-A mismatched unrelated donor Cardiomyopathy post-hsct with multi-organ failure; RIP d+31 Al-Zahrani et al J Allergy Clin Immunol 2013;132(4): Busulfan and cyclophosphamide HLA identical sibling Clinically well 4.4yrs post-hsct

14 ?antioxidant therapy in AK2 deficiency - AKs also contribute to modulating the AMP-mediated response to stress signals in cells - Demonstrated in zebrafish that AK2 deficiency results in ROS production Rissone A et al J Exp Med 2015;

15 Acknowledgements Dr Theresa Cole Dr Sharon Choo Dr Kate Nicholls Dr Andrew Gennery

16 Thank you! Questions?

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