Central nervous system manifestations of LRBA deficiency: case report of two siblings and literature review.

BACKGROUND: LPS-responsive beige-like anchor protein (LRBA) deficiency is a primary immunodeficiency disease (PID) characterized by a regulatory T cell defect resulting in immune dysregulation and autoimmunity. We present two siblings born to consanguineous parents of North African descent with LRBA deficiency and central nervous system (CNS) manifestations. As no concise overview of these manifestations is available in literature, we compared our patient's presentation with a reviewed synthesis of the available literature. CASE PRESENTATIONS: The younger brother presented with enteropathy at age 1.5 years, and subsequently developed Evans syndrome and diabetes mellitus. These autoimmune manifestations led to the genetic diagnosis of LRBA deficiency through whole exome sequencing with PID gene panel. At 11 years old, he had two tonic-clonic seizures. Brain MRI showed multiple FLAIR-hyperintense lesions and a T2-hyperintense lesion of the cervical medulla.  His sister presented with immune cytopenia at age 9 years, and developed diffuse lymphadenopathy and interstitial lung disease. Genetic testing confirmed the same mutation as her brother. At age 13 years, a brain MRI showed multiple T2-FLAIR-hyperintense lesions. She received an allogeneic hematopoietic stem cell transplantation (allo-HSCT) 3 months later. Follow-up MRI showed regression of these lesions. CONCLUSIONS: Neurological disease is documented in up to 25% of patients with LRBA deficiency. Manifestations range from cerebral granulomas to acute disseminating encephalomyelitis, but detailed descriptions of neurological and imaging phenotypes are lacking. LRBA deficiency amongst other PIDs should be part of the differential diagnosis in patients with inflammatory brain lesions. We strongly advocate for a more detailed description of CNS manifestations in patients with LRBA deficiency, when possible with MR imaging. This will aid clinical decision concerning both anti-infectious and anti-inflammatory therapy and in considering the indication for allo-HSCT.

Off-label drug use in paediatric haemato-oncology patients: financial implications and proposed solutions for Belgian patients.

Treatment of children with cancer requires access to and reimbursement of effective drugs. Children with haemato-oncological diseases are often treated according to established treatment recommendations or in the framework of late-phase clinical trials. These often involve the use of drugs authorised for adults but which, however, have been used for many years in paediatrics with no perspective of authorisation in children. In Belgium, medicines are predominantly reimbursed based on their authorised indication. As a consequence, many drugs used in paediatric haemato-oncology are used off-label, despite their status of 'standard of care'. As reimbursement is often not available, alternative ways for funding need to be explored, which causes a significant administrative burden for healthcare providers and emotional distress for the parents. Solutions to organise a systematic reimbursement of standard of care off-label used drugs are described.Conclusion: A number of structural solutions are proposed, and we hope that they might guide health authorities to provide a solution to the problem caused by the lack of reimbursement of some standard of care medicines for children with cancer. What is Known: • Off-label drug use is frequently observed in paediatric haemato-oncology and compromises-in some countries-reimbursement. What is New: • An estimation of the impact of non-reimbursed drugs in Belgium is provided. • Some solutions are presented to overcome this problem in Belgium.

Autophagy and phagocytosis-like cell cannibalism exert opposing effects on cellular survival during metabolic stress.

Understanding mechanisms controlling neuronal cell death and survival under conditions of altered energy supply (e.g., during stroke) is fundamentally important for the development of therapeutic strategies. The function of autophagy herein is unclear, as both its beneficial and detrimental roles have been described. We previously demonstrated that loss of AMP-activated protein kinase (AMPK), an evolutionarily conserved enzyme that maintains cellular energy balance, leads to activity-dependent degeneration in neuronal tissue. Here, we show that energy depletion in Drosophila AMPK mutants results in increased autophagy that convincingly promotes, rather than rescues, neurodegeneration. The generated excessive autophagic response is accompanied by increased TOR and S6K activity in the absence of an AMPK-mediated negative regulatory feedback loop. Moreover, energy-depleted neurons use a phagocytic-like process as a means to cellular survival at the expense of surrounding cells. Consequently, phagocytosis stimulation by expression of the scavenger receptor Croquemort significantly delays neurodegeneration. This study thus reveals a potentially novel strategy for cellular survival during conditions of extreme energy depletion, resembling xeno-cannibalistic events seen in metastatic tumors. We provide new insights into the roles of autophagy and phagocytosis in the neuronal metabolic stress response and open new avenues into understanding of human disease and development of therapeutic strategies.

Cloning and analysis of the mouse Fanconi anemia group A cDNA and an overlapping penta zinc finger cDNA.

Despite the cloning of four disease-associated genes for Fanconi anemia (FA), the molecular pathogenesis of FA remains largely unknown. To study FA complementation group A using the mouse as a model system, we cloned and characterized the mouse homolog of the human FANCA cDNA. The mouse cDNA (Fanca) encodes a 161-kDa protein that shares 65% amino acid sequence identity with human FANCA. Fanca is located at the distal region of mouse chromosome 8 and has a ubiquitous pattern of expression in embryonic and adult tissues. Expression of the mouse cDNA in human FA-A cells restores the cellular drug sensitivity to normal levels. Thus, the expression pattern, protein structure, chromosomal location, and function of FANCA are conserved in the mouse. We also isolated a novel zinc finger protein, Zfp276, which has five C(2)H(2) domains. Interestingly, Zfp276 is situated in the Fanca locus, and the 3'UTR of its cDNA overlaps with the last four exons of Fanca in a tail-to-tail manner. Zfp276 is expressed in the same tissues as Fanca, but does not complement the mitomycin C (MMC)-sensitive phenotype of FA-A cells. The overlapping genomic organization between Zfp276 and Fanca may have relevance to the disease phenotype of FA.

Receptors that induce erythroid differentiation of Ba/F3 cells: structural requirements and effect on STAT5 binding.

Ectopic expression of the erythropoietin receptor (EpoR) in the interleukin-3 (IL-3)-dependent cell line Ba/F3 results in growth and partial erythroid differentiation in Epo. In contrast, introduction and activation of the interleukin-5 receptor (IL-5R) or of the granulocyte-macrophage colony-stimulating factor receptor (GM-CSFR) results in proliferation only. As this effect is specific to the EpoR, the role of its extracellular or cytoplasmic domain in differentiation was tested after construction of two chimeric receptors. One receptor contained the extracellular domain of EpoR fused to the endodomain of IL-3R beta-chain (E/beta), while the other contained the EpoR cytoplasmic region fused to the extracellular domain of GM-CSFR alpha-chain (GMER). Surprisingly, both receptors induced differentiation ruling out a strict specificity of the extracellular or cytoplasmic region of EpoR in this process. Instead the ability to signal differentiation correlated with structural features shared by the EpoR, GMER, and E/beta receptors. Dimerization of all three receptors results in the pairing of two signal transducing chains in the cytoplasm, in contrast to the mitogenic receptors IL-3R, IL-5R, GM-CSFR, which assemble as alphabeta heterodimers. Two new chimeric receptors that fulfilled the structural requirement exemplified by EpoR, but lacked any part of EpoR, were designed to consolidate this model. They consisted of the ectodomains of the GMR-alpha and IL-5R alpha, respectively, fused to the endodomain of IL-3R beta-chain. Both receptors were as effective as EpoR in signaling differentiation in response to their cognate ligand. Another property of receptors fulfilling these structural requirements is that they cause a marked delay in signal transducers and activators of transcription 5 (STAT5) activation on ligand stimulation. Taken together our studies show that structural assembly of receptors dictates their potential to signal erythroid differentiation in Ba/F3 cells, that differentiation can take place in the absence of Epo and that a delay in STAT5 activation is highly predictive of this process.

The gelatinase inhibitory activity of tetracyclines and chemically modified tetracycline analogues as measured by a novel microtiter assay for inhibitors.

A quantitative nonisotopic solution assay for gelatinases and inhibitors was developed using biotinylated gelatin as enzyme substrate. In this assay, residual biotinylated substrate is sandwiched between avidin-coated plates and streptavidin-peroxidase and is quantified by the peroxidase reaction. This assay was useful for measuring gelatinase activities and defining the activities of gelatinase inhibitors. When 23 tetracycline analogues were compared, significant differences in gelatinase B inhibition were found between various compounds. 4-epioxytetracycline base, 4-epichlortetracycline, meclocyclinesulfosalicylate, and unmodified metacycline and minocycline proved to be the most potent gelatinase B (EC 3.4.24.35) inhibitors. The gelatinase B inhibitory activity of tetracyclines was clearly dissociated from their antimicrobial activity. The effect of high-molecular-weight inhibitors, such as monoclonal antibodies, was also demonstrable in the microtiter plate assay. In view of the pathophysiological function of gelatinases, the definition of gelatinase inhibitors with known efficacy, safety, and side effects is crucial for the treatment of diseases such as rheumatoid arthritis and multiple sclerosis. Particular tetracyclines fulfil these criteria and the described assay is useful for defining other gelatinase-inhibiting lead compounds.

Human gelatinase B, a marker enzyme in rheumatoid arthritis, is inhibited by D-penicillamine: anti-rheumatic activity by protease inhibition.

The direct and indirect inhibitory potential of D-penicillamine toward human neutrophil and synovial fluid gelatinase B, a marker enzyme for disease severity in RA, was investigated. Gelatinase and plasminogen activator activities were assessed by SDS-polyacrylamide gel electrophoresis zymography. D-penicillamine significantly inhibits purified and synovial fluid gelatinase B in vitro at concentrations attainable in vivo and also blocks in vitro plasminogen activation. Protease inhibition may be a mechanism of action for D-penicillamine as DMARD.

Prevention of acute autoimmune encephalomyelitis and abrogation of relapses in murine models of multiple sclerosis by the protease inhibitor D-penicillamine.

The in vitro activity of gelatinase B, an enzyme whose appearance in the cerebrospinal fluid is associated with inflammatory diseases of the central nervous system, was dose-dependently inhibited by the antirheumatic D-penicillamine. Inhibition of gelatinase B in electrophoretically pure preparations and in cell culture supernatants and human body fluids was obtained at dosages reached in the circulation of patients treated with a peroral dosis of 750 mg D-penicillamine per day. In mice, developing acute demyelination, D-penicillamine significantly reduced the mortality and morbidity rates of experimental allergic encephalomyelitis (EAE). In chronic relapsing EAE in Biozzi AB/H mice, an animal model for relapses in multiple sclerosis (MS), it attenuated the exacerbations, even when the treatment was started after the primary full-blown disease had developed. We infer protease inhibition as the mechanism of action of D-penicillamine and suggest that its use may be effective as peroral treatment for MS.

Multiple transcription start sites and 5' alternate splicing of murine IL-3 receptor beta-chain transcripts.

The murine interleukin-3 receptor beta-chain genes, IL-3R beta IL-3 and IL-3R beta c, encode the signal transducing chains of the high affinity receptors for IL-3 and IL-3, GM-CSF and IL-5 respectively. Little is known about the regulation of their expression. To enable the study of the promotors of IL-3R beta IL-3 and IL-3R beta c, we have characterized their respective 5' untranslated regions using a modified 5' RACE protocol. Four classes of alternatively spliced transcripts were isolated that initiate in a 400 nt region upstream from a previously reported start site(1). The initially reported partial IL-3R beta IL-3 clone belongs to the first class of transcripts(2). The second class starts in the middle of an intron as defined by the first class. The 3rd and 4th class establish 2 novel splice donor sites. These results were confirmed by RNAse-protection assay. The complex organization as evident from our data establishes an experimental framework for future experiments aimed at the study of the promoters for the murine IL-3R beta genes.

The cytokine-protease connection: identification of a 96-kD THP-1 gelatinase and regulation by interleukin-1 and cytokine inducers.

The induction of proteolytic enzymes is an important mechanism in the migration of monocytes into tissues and body fluids. The monocytic cell line THP-1 was used as a model system to study the production of a particular gelatinase. Upon stimulation with phorbol myristate acetate (PMA) the cells differentiated to the adherent phenotype and produced significant amounts of a 96-kD gelatinase in a dose-dependent way. The secretion rate was maximal between 12 and 24 h after induction. Study of gelatinase mRNA steady state levels showed that the synthesis of THP-1 gelatinase is regulated by PMA at transcriptional or posttranscriptional levels. Stimulation of signal transduction pathways with other substances, including calcium ionophore A 23187, dibutyryl cyclic AMP, and dexamethasone, were ineffective in inducing gelatinase mRNA or enzyme activity. However, THP-1 cells were responsive to the cytokine interleukin (IL)-1 beta, to bacterial lipopolysaccharide (LPS), and the lectin concanavalin A (Con A), the kinetics of gelatinase induction being similar to those of induction by PMA. The THP-1 cells did not synthesize and/or secrete detectable levels of IL-6 after stimulation with PMA, Con A, LPS, or IL-1 beta. The 96-kD monocytic THP-1 gelatinase was shown to be a neutral metalloproteinase that cross-reacted with hepatoma-derived and neutrophil gelatinases in immunoprecipitation experiments. The active enzyme produced by THP-1 cells consistently showed, however, a molecular mass different from that of normal granulocyte-, monocyte-, and tumor cell-derived gelatinases.(ABSTRACT TRUNCATED AT 250 WORDS)