Haematopoietic stem cell transplantation and gene therapy in the fetus: ready for clinical use?

Allogeneic haematopoietic stem cell transplantation in utero has been successfully used for the prenatal treatment of severe combined immunodefiency syndrome. However, this treatment has not been successful in the therapy of other conditions in which the fetus is immunologically competent. The main obstacles to success are lack of competitive advantage of donor versus host stem cells, preventing stable engraftment and graft rejection. Several strategies are being explored to overcome these problems, and some of them have been successful in animal studies. Prenatal gene therapy, using ex-vivo transduced autologous haematopoietic cells or direct gene targeting in utero, is another potential approach in the treatment of immunocompetent fetal recipients. Although this has been shown to be feasible in animal models, safety concerns regarding transduction of fetal germ cells or maternal cells should be addressed in preclinical experiments prior to initiation of clinical trials.     

Autologous hemopoietic stem cell transplantation for multiple sclerosis: is it worthwile?

High-dose immunosuppressive chemotherapy or total body irradiation followed by autologous transplantation of hemopoietic stem cells (ASCT) was introduced in the treatment of active, progressing, and therapy-resistant multiple sclerosis (MS) in 1995. Since then, more than 300 patients have undergone this sort of treatment worldwide and the European Group for Blood and Marrow Transplantation (EBMT) published on two occasions, in 2002 and in 2006, the results of collective analyses performed in 85 and in 183 cases, respectively. In most communications the results were reported favorable with some cases showing spectacular recoveries and also probabilities of long-lasting disease stability, between 60 and 80% at three years after transplant. Of great interest was the fact that magnetic resonance imaging studies invariably showed that the inflammation in the central nervous system resolved and gadolinium-enhancing lesions were completely abolished or markedly reduced. These results appear superior to those yielded by standard therapies but this superiority needs to be demonstrated by comparative studies, such as the EBMT-launched ASTIMS trial. Moreover, ASCT is a rather toxic procedure associated with a mortality risk of 2-3%. Therefore, it is not a treatment for the general population of MS patients but only for selected cases that do not respond to standard therapies and worsen rapidly, i.e. in situations where benefits are expected to counterbalance morbidity and mortality risks. Nevertheless, certain issues seem to have cleared up: ASCT should be used early, during the inflammatory phase of the disease; very high-intensity pre-transplant conditioning regimens increase toxicity but do not seem to increase efficacy compared to intermediate-intensity regimens; the results are dramatic and life-saving in resistant, so-called "malignant" cases; ASCT does not only cause debulking of autoreactive clones but it also brings about qualitative immunological changes that might eventually establish immunologic self-tolerance; the progression of brain atrophy appears to slow down with time; with the implementation of proper patient-selection criteria, the risks of morbidity and mortality can be minimized.     

Liver transplantation: is it possible in HIV/HCV co-infected patients?

The prognosis of HIV infection has been modified by antiretroviral therapy. However, the morbidity and the mortality of HCV co-infection increase and may be a major problem of health service. Up to now co-infected patients are excluded of transplantation due to complexity, the ethical aspects, the immunodeficiency and the co-infection. This study tries to estimate the feasibility in this population. Between December 1999 and March 2002, seven patients were transplanted. The average of CD4 was 332/ml; the viral load was <50 copies/ml. Before transplantation, no patient had experienced opportunist infection and all patients received antiretroviral therapy adapted to their history. The average follow-up is of 14 months: one patient died 3 months after transplantation, the other one presented a candida in oesophagus, the average of CD4 was 280/ml, and viral load was <50 copies/ml in five patients. A relapse of HVC was observed in all patients. Interferon/rivabirine therapy was proposed for four patients. Every patient received tacrolimus and corticoids. HAART were modified four times for toxicity and one time for virological failure. We observed two cases of transient renal insufficiency, two cases of diabetes, two cases of pancreatitis, and abnormalities of the respiratory mitochondrial chain in four patients. Finally, liver transplantation in HIV-HCV co-infected patients seems to be feasible when strict criteria of selection are taken into account. This still experimental strategy requires a multidisciplinary partnership.     

Are we ready for genome editing in human embryos for clinical purposes?

Perhaps the two most significant pioneering biomedical discoveries with immediate clinical implications during the past forty years have been the advent of assisted reproductive technologies (ART) and the genetics revolution. ART, including in vitro fertilization (IVF), intracytoplasmic sperm injection and preimplantation genetic testing, has resulted in the birth of more than 8 million children, and the pioneer of IVF, Professor Bob Edwards, was awarded the 2010 Nobel Prize. The genetics revolution has resulted in our genomes being sequenced and many of the molecular mechanisms understood, and technologies for genomic editing have been developed. With the combination of nearly routine ART protocols for healthy conceptions together with almost error-free, inexpensive and simple methods for genetic modification, the question “Are we ready for genome editing in human embryos for clinical purposes?” was debated at the 5th congress on controversies in preconception, preimplantation and Prenatal Genetic Diagnosis, in collaboration with the Ovarian Club Meeting, in November 2018 in Paris. The co-authors each presented scientific, medical and bioethical backgrounds, and the debate was chaired by Professor Alan Handyside. In this paper, we consider whether genome editing is safe and ethical. We conclude that we are currently not ready for genome editing to be used in human embryos for clinical purposes, and we call for a global debate to determine if and when this technology could be used in ART. ‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬     

Torque teno virus load as marker of rejection and infection in solid organ transplantation – A systematic review and meta-analysis

Balancing immunosuppression to prevent rejection in solid organ transplant (SOT) recipients remains challenging. Torque teno virus (TTV), a commensal non-pathogenic virus, has been proposed as marker of functional immunity: higher loads correspond to over-immunosuppression, and lower loads to under-immunosuppression. This review offers an overview of the current evidence of the association between TTV-load and infection and rejection after SOT. A systematic literature search strategy, deposited in the PROSPERO registry, resulted in 548 records. After screening, 23 original and peer-reviewed articles were assessed investigating the association between TTV-load, infection and/or rejection in SOT. The Quality in Prognostic Studies (QUIPS)-tool was used to assess the risk of bias. Meta-analysis with random-effects was performed on results with similar outcomes and exposure measures. Most of the included studies involved retrospective cohorts in which the TTV-load was measured longitudinally, within the first 2 years post-transplantation. Infection outcomes differed between studies and included viral, bacterial, parasitic and fungal infections. Rejection was defined by biopsy confirmation or initiation of rejection treatment. Twelve out of 16 studies reported an association between high TTV-load and infections, whereas 13 out of 15 reported an association between low TTV-load and rejection. Meta-analysis showed an increased risk of infection (OR: 1.16, 95% CI: 1.03–1.32; HR: 1.05, 95% CI: 0.97–1.14) and a decreased risk of rejection (OR: 0.90, 95% CI: 0.87–0.94; HR: 0.74, 95% CI: 0.71–0.76) per 1 log TTV-load increase. The qualitative assessment showed varying risks of bias in the included studies. This systematic review and meta-analysis indicates that blood TTV-load measured within the first 2 years after SOT is associated with the risk of infection or allograft rejection, although substantial risk of bias in the studies included warrant cautious interpretation. The results in this review provide a rationale for larger, prospective, studies into TTV as marker of infection and rejection after SOT.     

Acquisition of human cytomegalovirus infection in infants via breast milk: natural immunization or cause for concern?

Since the recognition in the 1960s that human cytomegalovirus (HCMV) infections could be transmitted by breast milk, there has been relatively little attention paid to the potential medical consequences of such infections. Indeed, since HCMV infections acquired by healthy newborn infants appear to be largely asymptomatic in nature, there has been no real incentive to develop or implement strategies to prevent transmission by this route. However, recent studies have identified a significant risk for low-birth weight, premature infants for the development of HCMV disease following acquisition of infection via breast milk. Such infections may cause considerable short-term morbidity and, in some cases, severe, life-threatening illness. There is little consensus amongst neonatologists on the approach to prevention and management of such infections. This review summarises the epidemiology and natural history of HCMV infections acquired via breast milk, and outlines available strategies for prevention and management of such infections, as well as opportunities for future clinical research on this understudied topic.     

HPLC--how necessary is it for haemoglobinopathy diagnosis in India?

Cation exchange high performance liquid chromatography (HPLC) is emerging as the method of choice for the initial screening of thalassemias and haemoglobinopathies and quantification of Haemoglobins (Hbs) like HbA, HbA2 and HbF. Since it is expensive, the present study was conducted to evaluate the need for HPLC in Indian laboratories and identify situations where it would be imperative. Eighty three patients suspected to have thalassemia and haemoglobinopathies were analysed. Both HPLC and alkaline gel electrophoresis detected 14 cases of HbE syndrome and 14 cases of HbS syndrome. However of the 14 cases diagnosed as HbD syndrome by alkaline electrophoresis, eight cases were diagnosed as Hb Q India, 1 case as HbD Iran and 5 cases of HbD Punjab on HPLC. Thirty-one cases were detected to have beta heterozygous thalassemia based on the high HbA2 levels (>3.9%) and eight cases were diagnosed as beta homozygous thalassemia by both HPLC and gel electrophoresis. One of them had an unknown Hb migrating in F-A region. Her mother also had same unknown Hb variant. In view of electrophoretic migration and retention time (RT) on HPLC, possibility of HbG-San Jose was considered. HPLC being an automated instrument is highly sensitive and specific, has high resolution and helps in quantification of various haemoglobins. However in a developing country like India where economical factors play a major role in planning for management of patients, the role of HPLC is limited.     

HIV-1 infection: is it time to reconsider our concepts?

The long asymptomatic phase of HIV infection is critical in the progression to AIDS. It probably reflects an ancestral relationship with lentiviruses stemming from the primate-simian immunodeficiency virus evolutionary pathway leading to an idiosyncratic immune tolerance, which needs to be understood if effective vaccines are to be rationally designed. The majority of CD4+ T cells that die due to HIV-1 in the asymptomatic phase are not infected with the virus. Transmission of the predominant HIV-1 R5 variants to T cells is mediated by infected monocyte-derived macrophages. The two cell populations come into intimate contact mainly in the lymph nodes during antigen presentation where there is also active viral replication. We propose that HIV exploits antigen presentation to access target T cells and evade immune surveillance. This is achieved at the assembly point of an immunological synapse between an antigen presenting, HIV-1-infected macrophage and a responding effector/memory CD4+ T cell. Viral envelope gp120 glycoproteins proximal to MHC II molecules cross-link with T cell CD4 molecules, thus establishing a supra molecular immuno-viral synapse. The interaction results in conformational changes of gp120 exposing its V3 domain. Ionic interaction of this domain with the synapse-recruited chemokine receptor CCR5 dimerizes the receptor triggering intracellular signals that contribute to T cell receptor transactivation pathways and subsequent enhancement of T cell activation. HIV-downregulated MHC II gives weak immune complexes. Disruption of the immuno-viral synapse before completion of cell entry is a frequent outcome condemning the responding T cell to a premature activation-induced T cell death. Information on the assembly, mechanistic and functional interactions at the immuno-viral synapses may well assist in elucidating new strategies to combat HIV infection.     

Disturbances in placental immunology: ready for therapeutic interventions?

Recent studies have provided new insight into aberrations in the immunological interplay between mother and fetus and their potential role in the development of recurrent fetal loss and preeclampsia. The action of anti-phospholipid antibodies in recurrent fetal loss is now proposed to involve the complement system, neutrophil activation and the production of TNFα by immune bystander cells. A clear involvement of the immune system is emerging in preeclampsia, involving mainly the innate arm, especially neutrophils. The activation of peripheral neutrophils by placentally released inflammatory debris triggers the induction of neutrophil extracellular traps (NETs), which may lead to an occlusion of the intervillous space, thereby further promoting a condition of placental hypoxia. It has, hence, been suggested that new therapeutic strategies be developed, including the possible use of TNFα antagonists in cases of recurrent miscarriage. These strategies need to be addressed with caution due to the possible induction of fetal congenital abnormalities.     

Complex sleep apnea syndrome: is it a unique clinical syndrome?

STUDY OBJECTIVES: Some patients with apparent obstructive sleep apnea hypopnea syndrome (OSAHS) have elimination of obstructive events but emergence of problematic central apneas or Cheyne-Stokes breathing pattern. Patients with this sleep-disordered breathing problem, which for the sake of study we call the "complex sleep apnea syndrome," are not well characterized. We sought to determine the prevalence of complex sleep apnea syndrome and hypothesized that the clinical characteristics of patients with complex sleep apnea syndrome would more nearly resemble those of patients with central sleep apnea syndrome (CSA) than with those of patients with OSAHS. DESIGN: Retrospective review SETTING: Sleep disorders center. PATIENTS OR PARTICIPANTS: Two hundred twenty-three adults consecutively referred over 1 month plus 20 consecutive patients diagnosed with CSA. INTERVENTIONS: NA. MEASUREMENTS AND RESULTS: Prevalence of complex sleep apnea syndrome, OSAHS, and CSA in the 1-month sample was 15%, 84%, and 0.4%, respectively. Patients with complex sleep apnea syndrome differed in gender from patients with OSAHS (81% vs 60% men, p < .05) but were otherwise similar in sleep and cardiovascular history. Patients with complex sleep apnea syndrome had fewer maintenance-insomnia complaints (32% vs 79%; p < .05) than patients with CSA but were otherwise not significantly different clinically. Diagnostic apnea-hypopnea index for patients with complex sleep apnea syndrome, OSAHS, and CSA was 32.3 +/- 26.8, 20.6 +/- 23.7, and 38.3 +/- 36.2, respectively (p = .005). Continuous positive airway pressure suppressed obstructive breathing, but residual apnea-hypopnea index, mostly from central apneas, remained high in patients with complex sleep apnea syndrome and CSA (21.7 +/- 18.6 in complex sleep apnea syndrome, 32.9 +/- 30.8 in CSA vs 2.14 +/- 3.14 in OSAHS; p < .001). CONCLUSIONS: Patients with complex sleep apnea syndrome are mostly similar to those with OSAHS until one applies continuous positive airway pressure. They are left with very disrupted breathing and sleep on continuous positive airway pressure. Clinical risk factors don't predict the emergence of complex sleep apnea syndrome, and best treatment is not known.     

Current developmental surveillance: is it time for change?

Developmental screening tools are an integral part of child health surveillance, but only few valid and reliable tests are currently in use in the community. Early detection and referral of children with developmental delay is critical for long term outcomes. Developmental screening, using standardised tests, is increasingly important. The public health nurses in the Midlands currently use a modified version of Denver Development Screening Tool (DDST) for screening infants at 9 months of age. The DDST however fails to identify a high proportion of children developmentally at risk, because of its poor sensitivity, an outcome of which is a high proportion of under-referrals. The low sensitivity of the test is a source of potentially misleading information and may be responsible for many at-risk children remaining undetected. Sensitive and specific screening questionnaires need to be introduced in community child health screening surveillance to minimise the risk of missing children with developmental delay.     

Constitutive deficiency in DNA mismatch repair: is it time for Lynch III?

Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome types I and II, and the related subtypes Turcot and Muir-Torre syndrome, have all been associated with inheritance of germ line mutations in the DNA mismatch repair (MMR) genes. Fifty individuals have recently been identified with an early onset of a different spectrum of cancers associated with inheritance of two MMR mutations--resulting either in a constitutive loss of MMR function, or greatly impaired MMR function. In contrast to Lynch I and II individuals, individuals with inheritance of homozygous or compound heterozygous mutations in the MMR genes that result in a complete lack of protein, present with hematological and brain malignancies in the first decade of life. Biallelic mutations with compromised but residual protein function present with a broader spectrum of cancers (brain, hematological or gastrointestinal) in the second to fourth decades of life. We propose that inheritance of two MMR mutations in an individual and the unique tumor spectrum that occurs with an early onset should be defined separately from Lynch syndrome I and II, or the subtypes Turcot and Muir-Torre. We suggest Lynch III as an appropriate name for identifying individuals with constitutively compromised MMR associated with biallelic mutations.