Monoclonal gammopathy of undetermined significance in systemic transthyretin amyloidosis (ATTR)

Objective: To identify the prevalence of monoclonal gammopathy of undetermined significance (MGUS) in patients with transthyretin (ATTR) amyloidosis.

Patients and methods: We performed a retrospective analysis of patients with biopsy-proven ATTRwt (wild-type transthyretin amyloid protein) and genopositive ATTR V122I (valine-to-isoleucine substitution at position 122 of the TTR gene) amyloidosis evaluated at the Amyloidosis Center at Boston University and Boston Medical Center between 1 January 2003 and 31 December 2016.

Results: There were a total of 226 patients with ATTRwt and ATTR V122I amyloidosis evaluated during the specified time frame with 155 and 71 patients in each cohort, respectively. Those with complete medical records, 140 patients with ATTRwt and 57 V1221 ATTRm subjects, were included in the analyses. Fifty-five patients (39%) in the ATTRwt cohort and 28 patients (49%) in the ATTR V122I cohort had an MGUS, as indicated by an abnormality in the serum-free light-chain ratio and/or serum immunofixation electrophoresis.

Conclusion: These data confirm the high prevalence of coexistent MGUS with ATTR amyloidosis in this patient population, with an MGUS rate that is higher than the general population. These findings also highlight the importance of a thorough diagnostic evaluation in patients with amyloidosis to determine the precursor protein, as the clinical course and treatment of AL (light-chain amyloid protein) and ATTR amyloidosis are distinct.     

Subcutaneous growth hormone-releasing hormone therapy in growth hormone-deficient children: first year of therapy.

The purpose of this study was to determine the efficacy and safety of GH-releasing Hormone [GHRH-(1-44)] therapy in GH-deficient children. Twenty previously untreated prepubertal children with GHRH deficiency were treated for 1 yr in a multicenter, open label, company-sponsored study with at least 20 micrograms/kg GHRH-(1-44), sc, half at bedtime and half upon awakening. The main effects were enhancement of linear growth, advancement in bone age, and alteration in general blood chemistries and hormonal values. The mean velocity of the entire group increased from 3.6 +/- 1.1 to 8.1 +/- 1.5 cm/yr (P < 10(-4)) at 1 yr of therapy. After 6 months of therapy, 16 were growing at a mean of 9.4 +/- 2.0 cm/yr and were continued on this dose. In 4 patients who were growing at a rate of 5.5 +/- 1.7 cm/yr, the dose was increased to 40 micrograms/kg daily for the second 6 months. The high dose group increased their mean linear growth velocity for the second 6 months while on the higher dose to 7.6 +/- 0.4 cm/yr (P < 10(-2)). This was equal to the mean velocity for the second 6 months of therapy of the 16 subjects who remained on the 20 micrograms/kg daily therapy (7.6 +/- 1.2 cm/yr). Mean advancement of bone age was 1.3 +/- 0.6 yr during the first year of therapy. No adverse changes in general biochemical, hormonal, or pituitary radiographic analyses were noted. No change in fasting glucose or insulin concentrations, or excessive generation of insulin-like growth factor-I concentrations occurred. We conclude that GHRH in a daily dose of 20-40 micrograms/kg for 1 yr was effective in increasing growth velocity in most GHRH-responsive GH-deficient patients. It was well tolerated without side-effects. Glucose intolerance was not noted.     

Granulocyte colony-stimulating factor administration to healthy volunteers: analysis of the immediate activating effects on circulating neutrophils

In four healthy volunteers, we analyzed in detail the immediate in vivo effects on circulating neutrophils of subcutaneous administration of 300 micrograms of granulocyte colony-stimulating factor (G-CSF). Neutrophil activation was assessed by measurement of degranulation. Mobilization of secretory vesicles was shown by a decrease in leukocyte alkaline phosphatase content of the circulating neutrophils. Furthermore, shortly postinjection, Fc gamma RIII was found to be upregulated from an intracellular pool that we identified by immunoelectron microscopy as secretory vesicles. Intravascular release of specific granules was shown by increased plasma levels of lactoferrin and by upregulation of the expression of CD66b and CD11b on circulating neutrophils. Moreover, measurement of fourfold elevated plasma levels of elastase, bound to its physiologic inhibitor alpha 1- antitrypsin, indicated mobilization of azurophil granules. However, no expression of CD63, a marker of azurophil granules, was observed on circulating neutrophils. G-CSF--induced mobilization of secretory vesicles and specific granules could be mimicked in whole blood cultures in vitro, in contrast to release of azurophil granules. Therefore, we postulate that the most activated neutrophils leave the circulation, as observed shortly postinjection, and undergo subsequent stimulation in the endothelial microenvironment, resulting in mobilization of azurophil granules. Our data demonstrate that G-CSF should be regarded as a potent immediate activator of neutrophils in vivo.     

Expanding the mutational spectrum of LZTR1 in schwannomatosis

Schwannomatosis is characterized by the development of multiple non-vestibular, non-intradermal schwannomas. Constitutional inactivating variants in two genes, SMARCB1 and, very recently, LZTR1, have been reported. We performed exome sequencing of 13 schwannomatosis patients from 11 families without SMARCB1 deleterious variants. We identified four individuals with heterozygous loss-of-function variants in LZTR1. Sequencing of the germline of 60 additional patients identified 18 additional heterozygous variants in LZTR1. We identified LZTR1 variants in 43% and 30% of familial (three of the seven families) and sporadic patients, respectively. In addition, we tested LZTR1 protein immunostaining in 22 tumors from nine unrelated patients with and without LZTR1 deleterious variants. Tumors from individuals with LZTR1 variants lost the protein expression in at least a subset of tumor cells, consistent with a tumor suppressor mechanism. In conclusion, our study demonstrates that molecular analysis of LZTR1 may contribute to the molecular characterization of schwannomatosis patients, in addition to NF2 mutational analysis and the detection of chromosome 22 losses in tumor tissue. It will be especially useful in differentiating schwannomatosis from mosaic Neurofibromatosis type 2 (NF2). However, the role of LZTR1 in the pathogenesis of schwannomatosis needs further elucidation.     

Changing patterns of presentations of patients with HIV-related disease at a tertiary referral centre and its implications for physician training

Highly active antiretroviral therapy (HAART) has been shown to be highly effective in controlling HIV-related disease progression. Our objective was to determine whether HAART had altered the spectrum of HIV-related disease presentations at a tertiary medical referral centre and if a change in the clinical presentations of HIV-infected individuals to the hospital had impacted on physicians' training. A retrospective study which examined all admissions of HIV-infected patients identified between 1 October 1996 to 30 September 1998 using a hospital-designed computer database was undertaken at the Beth Israel Deaconess Medical Center (BIDMC) tertiary medical referral centre. All medical residents were surveyed in order to assess their knowledge of HIV-associated admissions and their confidence treating HIV-infected patients. There were significant changes in the admitting diagnosis for HIV-related illness between 1996 and 1998. Admissions for opportunistic infections (OIs) declined whereas admissions with bacterial infections increased significantly. Use of HAART remained stable between the 2 years of the study. Physicians' overestimated the use of HAART and only 8% of residents felt very comfortable taking care of an HIV-infected patient. In conclusion, the spectrum of presentations with HIV-related disease to a tertiary referral centre continues to change in the HAART era and impacts on physicians' experience of the management of HIV disease.     

Anti-factor VIII antibodies of hemophiliac patients are frequently directed towards nonfunctional determinants and do not exhibit isotypic restriction

A significant proportion of hemophilia A patients receiving transfusions of factor VIII (FVIII) develop a specific antibody response towards FVIII. These antibodies are usually detected by assays in which they inhibit the function of the molecule, such as the Bethesda clotting test. We have prepared anti-FVIII antibodies by specific immunoadsorption from the plasma of four hemophiliacs with stable inhibitor levels. The isotypic distribution of such antibodies was determined and their capacity to bind to insolubilized FVIII was compared with their inhibitory activity in two functional assays, namely, the Bethesda assay and a chromogenic assay. In addition, the FVIII epitope specificity was determined by competition with monoclonal antibodies for the binding to insolubilized FVIII. We show here that (1) anti-FVIII antibodies are not isotypically restricted; thus, a significant proportion of specific IgG2 was found; (2) antibodies are frequently directed towards epitopes of FVIII that are not directly involved in the function of the molecule and therefore escape detection in the Bethesda method or chromogenic assay; and (3) each patient shows a unique pattern of FVIII epitope recognition. We conclude that evaluation of anti-FVIII antibodies by a functional method does not provide an accurate evaluation of the specific antibody response. These findings have important implications for the comparison of the immunogenicity of FVIII molecules produced by different technologies and for the development of methods to control anti-FVIII antibody production.     

Suppression of apoptosis in hematopoietic factor-dependent progenitor cell lines by expression of the FAC gene

Fanconi anemia (FA) is a genetically heterogeneous, inherited blood disorder characterized by bone marrow failure, congenital malformations, and a predisposition to leukemias. Because FA cells are hypersensitive to DNA cross-linking agents and have chromosomal instability, FA has been viewed as a disorder of DNA repair. However, the exact cellular defect in FA cells has not been identified. Sequence analysis of the gene defective in group C patients (FAC) has shown no significant homologies to other known genes. The FAC protein has been localized to the cytoplasm, indicating that FAC may either play an indirect role in DNA repair or is involved in a different cellular pathway. Recent evidence has indicated that FA cells may be predisposed to apoptosis, especially after treatment with DNA cross-linking agents. The demonstration that genes can suppress apoptosis has been accomplished by overexpression of such genes in growth factor-dependent cell lines that die by apoptosis after factor withdrawal. Using retroviral-mediated gene transfer, we present evidence that expression of FAC in the hematopoietic factor-dependent progenitor cell lines 32D and MO7e can suppress apoptosis induced by growth factor withdrawal. Flow cytometry and morphologic analysis of propidium iodide stained cells showed significantly lower levels of apoptosis in FAC-retroviral transduced cells after growth factor deprivation. Expression of FAC in both cell lines promoted increased viability rather than proliferation, which is consistent with other apoptosis-inhibiting genes such as Bcl- 2. These findings imply that FAC may act as a mediator of an apoptotic pathway initiated by growth factor withdrawal. Furthermore, the congenital malformations and hematologic abnormalities characterizing FA may be related to an increased predisposition of FA progenitor cells to undergo apoptosis, particularly in the absence of extracellular signals.     

T-cell death by apoptosis in vertically human immunodeficiency virus- infected children coincides with expansion of CD8+/interleukin-2 receptor-/HLA-DR+ T cells: sign of a possible role for herpes viruses as cofactors?

One mechanism proposed to play a role in T-cell depletion in human immunodeficiency virus (HIV) infection is apoptosis (activation-induced cell death). We assessed whether apoptosis is related to activation of T cells in vivo and its possible triggers. DNA was extracted from peripheral blood mononuclear cells (PBMC) taken from 16 vertically HIV- infected children and 9 HIV-negative children born to HIV-positive mothers (controls) and tested by agarose gel electrophoresis for the presence of DNA fragments specific for apoptosis. Signs of apoptosis were found on in vitro culture of PBMC from 12 of 16 HIV-infected children, but not in PBMC from the nine controls. Eleven of the 12 HIV- infected children with apoptosis showed an elevated (> 15%) proportion of CD3+/HLA-DR+ cells. This was due to an increased proportion of CD8+/HLA-DR+ cells, as shown in 7 of 7 further tested patients. In none of the probands an increased (> 5%) proportion of IL-2 receptor expressing CD3+ cells was found. T cells undergoing apoptosis were preferentially of the CD8+ phenotype. Expansion of circulating CD8+/interleukin-2 receptor (IL-2R)-/HLA-DR+ T cells is known to occur during active infection with herpes viruses. To investigate the possible role of herpes viral coinfections for apoptosis in HIV infection, we focused on Epstein-Barr virus (EBV) as an example for a herpes virus usually acquired during childhood. In 10 of 12 patients with apoptosis, we found increased levels of EBV genome in PBMC and/or tissues, indicating active EBV replication. By contrast, no increased burden of EBV was found in the four HIV-infected patients without apoptosis or in the controls. Our data indicate that in children the occurrence of apoptosis in HIV infection is closely related to activation of CD8+ T cells. Furthermore, primoinfection with or reactivation of herpes viruses, such as EBV, may substantially contribute to such T-cell activation and the ensuing apoptosis. Additional studies are warranted to evaluate the contribution of herpes virus-triggered apoptosis to the T-cell loss leading to the acquired immunodeficiency syndrome.