Robust immunity to influenza vaccination in haematopoietic stem cell transplant recipients following reconstitution of humoral and adaptive immunity.

Objectives: Influenza causes significant morbidity and mortality, especially in high-risk populations. Although current vaccination regimens are the best method to combat annual influenza disease, vaccine efficacy can be low in high-risk groups, such as haematopoietic stem cell transplant (HSCT) recipients. Methods: We comprehensively assessed humoral immunity, antibody landscapes, systems serology and influenza-specific B-cell responses, together with their phenotypes and isotypes, to the inactivated influenza vaccine (IIV) in HSCT recipients in comparison to healthy controls. Results: Inactivated influenza vaccine significantly increased haemagglutination inhibition (HAI) titres in HSCT recipients, similar to healthy controls. Systems serology revealed increased IgG1 and IgG3 antibody levels towards the haemagglutinin (HA) head, but not to neuraminidase, nucleoprotein or HA stem. IIV also increased frequencies of total, IgG class-switched and CD21loCD27+ influenza-specific B cells, determined by HA probes and flow cytometry. Strikingly, 40% of HSCT recipients had markedly higher antibody responses towards A/H3N2 vaccine strain than healthy controls and showed cross-reactivity to antigenically drifted A/H3N2 strains by antibody landscape analysis. These superior humoral responses were associated with a greater time interval after HSCT, while multivariant analyses revealed the importance of pre-existing immune memory. Conversely, in HSCT recipients who did not respond to the first dose, the second IIV dose did not greatly improve their humoral response, although 50% of second-dose patients reached a seroprotective HAI titre for at least one of vaccine strains. Conclusions: Our study demonstrates efficient, although time-dependent, immune responses to IIV in HSCT recipients, and provides insights into influenza vaccination strategies targeted to immunocompromised high-risk groups.

A high-dimensional cytometry atlas of peripheral blood over the human life span.

Age can profoundly affect susceptibility to a broad range of human diseases. Children are more susceptible to some infectious diseases such as diphtheria and pertussis, while in others, such as coronavirus disease 2019 and hepatitis A, they are more protected compared with adults. One explanation is that the composition of the immune system is a major contributing factor to disease susceptibility and severity. While most studies of the human immune system have focused on adults, how the immune system changes after birth remains poorly understood. Here, using high-dimensional spectral flow cytometry and computational methods for data integration, we analyzed more than 50 populations of immune cells in the peripheral blood, generating an immune cell atlas that defines the healthy human immune system from birth up to 75 years of age. We focused our efforts on children under 18 years old, revealing major changes in immune cell populations after birth and in children of schooling age. Specifically, CD4+ T effector memory cells, Vδ2+ gamma delta (γδ)T cells, memory B cells, plasmablasts, CD11c+ B cells and CD16+ CD56bright natural killer (NK) cells peaked in children aged 5-9 years old, whereas frequencies of T helper 1, T helper 17, dendritic cells and CD16+ CD57+ CD56dim NK cells were highest in older children (10-18 years old). The frequency of mucosal-associated invariant T cells was low in the first several years of life and highest in adults between 19 and 30 years old. Late adulthood was associated with fewer mucosal-associated invariant T cells and Vδ2+ γδ T cells but with increased frequencies of memory subsets of B cells, CD4+ and CD8+ T cells and CD57+ NK cells. This human immune cell atlas provides a critical resource to understand changes to the immune system during life and provides a reference for investigating the immune system in the context of human disease. This work may also help guide future therapies that target specific populations of immune cells to protect at-risk populations.

Opposing Effects of Prior Infection versus Prior Vaccination on Vaccine Immunogenicity against Influenza A(H3N2) Viruses.

Prior vaccination can alternately enhance or attenuate influenza vaccine immunogenicity and effectiveness. Analogously, we found that vaccine immunogenicity was enhanced by prior A(H3N2) virus infection among participants of the Ha Nam Cohort, Viet Nam, but was attenuated by prior vaccination among Australian Health Care Workers (HCWs) vaccinated in the same year. Here, we combined these studies to directly compare antibody titers against 35 A(H3N2) viruses spanning 1968-2018. Participants received licensed inactivated vaccines containing A/HongKong/4801/2014 (H3N2). The analysis was limited to participants aged 18-65 Y, and compared those exposed to A(H3N2) viruses circulating since 2009 by infection (Ha Nam) or vaccination (HCWs) to a reference group who had no recent A(H3N2) infection or vaccination (Ha Nam). Antibody responses were compared by fitting titer/titer-rise landscapes across strains, and by estimating titer ratios to the reference group of 2009-2018 viruses. Pre-vaccination, titers were lowest against 2009-2014 viruses among the reference (no recent exposure) group. Post-vaccination, titers were, on average, two-fold higher among participants with prior infection and two-fold lower among participants with 3-5 prior vaccinations compared to the reference group. Titer rise was negligible among participants with 3-5 prior vaccinations, poor among participants with 1-2 prior vaccinations, and equivalent or better among those with prior infection compared to the reference group. The enhancing effect of prior infection versus the incrementally attenuating effect of prior vaccinations suggests that these exposures may alternately promote and constrain the generation of memory that can be recalled by a new vaccine strain.

Influenza virus infection history shapes antibody responses to influenza vaccination.

Studies of successive vaccination suggest that immunological memory against past influenza viruses may limit responses to vaccines containing current strains. The impact of memory induced by prior infection is rarely considered and is difficult to ascertain, because infections are often subclinical. This study investigated influenza vaccination among adults from the Ha Nam cohort (Vietnam), who were purposefully selected to include 72 with and 28 without documented influenza A(H3N2) infection during the preceding 9 years (Australian New Zealand Clinical Trials Registry 12621000110886). The primary outcome was the effect of prior influenza A(H3N2) infection on hemagglutinin-inhibiting antibody responses induced by a locally available influenza vaccine administered in November 2016. Baseline and postvaccination sera were titrated against 40 influenza A(H3N2) strains spanning 1968-2018. At each time point (baseline, day 14 and day 280), geometric mean antibody titers against 2008-2018 strains were higher among participants with recent infection (34 (29-40), 187 (154-227) and 86 (72-103)) than among participants without recent infection (19 (17-22), 91 (64-130) and 38 (30-49)). On days 14 and 280, mean titer rises against 2014-2018 strains were 6.1-fold (5.0- to 7.4-fold) and 2.6-fold (2.2- to 3.1-fold) for participants with recent infection versus 4.8-fold (3.5- to 6.7-fold) and 1.9-fold (1.5- to 2.3-fold) for those without. One of 72 vaccinees with recent infection versus 4 of 28 without developed symptomatic A(H3N2) infection in the season after vaccination (P = 0.021). The range of A(H3N2) viruses recognized by vaccine-induced antibodies was associated with the prior infection strain. These results suggest that recall of immunological memory induced by prior infection enhances antibody responses to inactivated influenza vaccine and is important to attain protective antibody titers.

Robust and prototypical immune responses toward influenza vaccines in the high-risk group of Indigenous Australians.

Morbidity and mortality rates from seasonal and pandemic influenza occur disproportionately in high-risk groups, including Indigenous people globally. Although vaccination against influenza is recommended for those most at risk, studies on immune responses elicited by seasonal vaccines in Indigenous populations are largely missing, with no data available for Indigenous Australians and only one report published on antibody responses in Indigenous Canadians. We recruited 78 Indigenous and 84 non-Indigenous Australians vaccinated with the quadrivalent influenza vaccine into the Looking into InFluenza T cell immunity - Vaccination cohort study and collected blood to define baseline, early (day 7), and memory (day 28) immune responses. We performed in-depth analyses of T and B cell activation, formation of memory B cells, and antibody profiles and investigated host factors that could contribute to vaccine responses. We found activation profiles of circulating T follicular helper type-1 cells at the early stage correlated strongly with the total change in antibody titers induced by vaccination. Formation of influenza-specific hemagglutinin-binding memory B cells was significantly higher in seroconverters compared with nonseroconverters. In-depth antibody characterization revealed a reduction in immunoglobulin G3 before and after vaccination in the Indigenous Australian population, potentially linked to the increased frequency of the G3m21* allotype. Overall, our data provide evidence that Indigenous populations elicit robust, broad, and prototypical immune responses following immunization with seasonal inactivated influenza vaccines. Our work strongly supports the recommendation of influenza vaccination to protect Indigenous populations from severe seasonal influenza virus infections and their subsequent complications.

Immune cellular networks underlying recovery from influenza virus infection in acute hospitalized patients.

How innate and adaptive immune responses work in concert to resolve influenza disease is yet to be fully investigated in one single study. Here, we utilize longitudinal samples from patients hospitalized with acute influenza to understand these immune responses. We report the dynamics of 18 important immune parameters, related to clinical, genetic and virological factors, in influenza patients across different severity levels. Influenza disease correlates with increases in IL-6/IL-8/MIP-1α/ß cytokines and lower antibody responses. Robust activation of circulating T follicular helper cells correlates with peak antibody-secreting cells and influenza heamaglutinin-specific memory B-cell numbers, which phenotypically differs from vaccination-induced B-cell responses. Numbers of influenza-specific CD8+ or CD4+ T cells increase early in disease and retain an activated phenotype during patient recovery. We report the characterisation of immune cellular networks underlying recovery from influenza infection which are highly relevant to other infectious diseases.

Distinguishing naive- from memory-derived human B cells during acute responses.

OBJECTIVES: A fundamental question in influenza research is whether antibody titre decline upon successive exposure to variant strains is consequent to recall of cross-reactive memory B cells that competitively inhibit naive B-cell responses. In connection, it is not clear whether naive and memory B cells remain phenotypically distinct acutely after activation such that they may be distinguished ex vivo. METHODS: Here, we first compared the capacity of anti-Ig and Toll-like-receptor (TLR) 7/8 and TLR9 agonists (R848 and CpG) to augment human B-cell differentiation induced by IL-21 and sCD40L. The conditions that induced optimal differentiation were then used to compare the post-activation phenotype of sort-purified naive and memory B-cell subsets by FACS and antibody-secreting cell (ASC) ELISPOT. RESULTS: Sort-purified naive and memory B cells underwent robust plasmablast and ASC formation when stimulated with R848, but not CpG, and co-cultured with monocytes. This coincided with increased IL-1ß and IL-6 production when B cells were co-cultured with monocytes and stimulated with R848, but not CpG. Naive B cells underwent equivalent ASC generation, but exhibited less class-switch and modulation of CD27, CD38 and CD20 expression than memory B cells after stimulation with R848 and monocytes for 6 days. CONCLUSION: Stimulation with R848, IL-21 and sCD40L in the presence of monocytes induces robust differentiation and ASC generation from both naive and memory B-cells. However, naive and memory B cells retain key phenotypic differences after activation that may facilitate ex vivo discrimination and better characterisation of acute responses to variant antigens.

Recalling the Future: Immunological Memory Toward Unpredictable Influenza Viruses.

Persistent and durable immunological memory forms the basis of any successful vaccination protocol. Generation of pre-existing memory B cell and T cell pools is thus the key for maintaining protective immunity to seasonal, pandemic and avian influenza viruses. Long-lived antibody secreting cells (ASCs) are responsible for maintaining antibody levels in peripheral blood. Generated with CD4+ T help after naïve B cell precursors encounter their cognate antigen, the linked processes of differentiation (including Ig class switching) and proliferation also give rise to memory B cells, which then can change rapidly to ASC status after subsequent influenza encounters. Given that influenza viruses evolve rapidly as a consequence of antibody-driven mutational change (antigenic drift), the current influenza vaccines need to be reformulated frequently and annual vaccination is recommended. Without that process of regular renewal, they provide little protection against "drifted" (particularly H3N2) variants and are mainly ineffective when a novel pandemic (2009 A/H1N1 "swine" flu) strain suddenly emerges. Such limitation of antibody-mediated protection might be circumvented, at least in part, by adding a novel vaccine component that promotes cross-reactive CD8+ T cells specific for conserved viral peptides, presented by widely distributed HLA types. Such "memory" cytotoxic T lymphocytes (CTLs) can rapidly be recalled to CTL effector status. Here, we review how B cells and follicular T cells are elicited following influenza vaccination and how they survive into a long-term memory. We describe how CD8+ CTL memory is established following influenza virus infection, and how a robust CTL recall response can lead to more rapid virus elimination by destroying virus-infected cells, and recovery. Exploiting long-term, cross-reactive CTL against the continuously evolving and unpredictable influenza viruses provides a possible mechanism for preventing a disastrous pandemic comparable to the 1918-1919 H1N1 "Spanish flu," which killed more than 50 million people worldwide.

Thyroid nodules on chest CT of patients with tuberous sclerosis complex.

A few cases of thyroid disease have been reported in tuberous sclerosis complex (TSC); however, studies on prevalence and characterization of lesions have not been done. Patients with TSC are routinely screened using chest CT for assessment of lung disease. Incidental thyroid findings on chest CT have been reported in large studies of the general population. The purpose of this study is to evaluate the frequency and type of thyroid anomalies in a cohort of TSC patients. We performed a retrospective review of 93 patients with a definite diagnosis of TSC, who had a chest CT. Images of the thyroid gland and final radiological report were reviewed. Reports of additional thyroid studies performed in some patients were also reviewed. Thyroid abnormalities were present in 19 of 93 (20.4%) patients. They consisted mainly of hypodense lesions categorized as nodules. Multiple nodules were found in 10 patients (52.6%). There was one papillary carcinoma. Thyroid gland lesions may be part of the clinical spectrum of TSC. They are usually asymptomatic. As some cases of thyroid carcinoma have been described in TSC, ultrasound exams are recommended, given that CT is not the gold standard technique for thyroid evaluation.

Arachnoid cysts in tuberous sclerosis complex.

OBJECTIVE: Some clinical findings in tuberous sclerosis complex (TSC), such as hypomelanotic macules or angiofibromas are related to problems in development of the neural crest, which is also the origin of cranial leptomeninges. Arachnoid cysts have been reported in two TSC patients to date. The purpose of this study was to assess the prevalence and characteristics of arachnoid cysts in a large cohort of TSC. MATERIALS AND METHOD: We performed a review of brain MRIs of 220 TSC patients searching for arachnoid cysts. RESULTS: Arachnoid cysts were found in 12 (5.5%) (general population: 0.5%), including ten males (83.3%). Four patients (33.3%) had also autosomal dominant polycystic kidney disease (ADPKD) due to a contiguous deletion of the TSC2-PKD1 genes. Three patients (25%) had two or more arachnoid cysts, of whom two also had ADPKD. One patient with an arachnoid cyst did not have tubers, subependymal nodules or white matter migration lines. CONCLUSION: Our study suggests that arachnoid cysts are part of the clinical spectrum of TSC and may be also present in TSC patients without other typical TSC brain lesions.

Intracranial arteriopathy in tuberous sclerosis complex.

Arterial aneurysms, mostly aortic and intracranial, have been occasionally reported in patients with tuberous sclerosis complex. Brain magnetic resonance imaging reports of 404 patients with definite and 16 patients with either probable or possible tuberous sclerosis complex were revised for intracranial aneurysms. Among these patients, brain images of 220 patients with definite and 16 with probable or possible tuberous sclerosis complex were reviewed. Intracranial aneurysms were reported in 3 of 404 patients with a definite diagnosis (0.74%) (general population: 0.35%), including 2 children. A fourth intracranial aneurysm was found in a patient with probable tuberous sclerosis complex, who did not have tubers or subependymal nodules but had clinical manifestations related to neural crest derivatives, including lymphangioleiomyomatosis and extrarenal angiomyolipomas. The authors hypothesize that neural crest dysfunction can have a major role in intracranial arteriopathy in tuberous sclerosis complex, as smooth muscle cells in the forebrain vessels are of neural crest origin.

[Risk factors associated with non-alcoholic fatty liver disease: a case-control study]. / Factores de riesgo asociados a la presencia de hígado graso no alcohólico: un estudio de casos y controles.

BACKGROUND AND OBJECTIVES: To establish the factors associated with the presence of non-alcoholic fatty liver disease (NAFLD) and evaluate the influence of each component constituting the metabolic syndrome (MS) and the risk of developing NAFLD. PATIENTS AND METHODS: We performed a multicenter, population-based, observational, analytical study of cases and controls. A case was defined as any patient fulfilling the inclusion criteria and presenting NAFLD by abdominal echography for any reason. A control was randomly selected for each case, from the same health center and of the same age and sex. All the cases underwent anamnesis, physical examination, complete biochemical analyses and determination of MS according to the National Cholesterol Education Program-Adult Treatment Panel III criteria. All the controls also underwent an abdominal echography. RESULTS: We included 327 cases and 377 controls with a mean age of 56 ± 12 years for the cases and of 55 ± 13 years for the controls (range: 17 and 80 years); 52.0% of the cases were males and 49.1% of males were controls. The risk factors associated with NAFLD were obesity (odds ratio [OR] 3.82, 95% confidence interval [95% CI] 2.19-6.66), MS (OR 1.73, 95% CI 1.09-2.75), insulin resistance (OR 3.65, 95% CI 2.18-6.12), and an increase in alanine aminotransferase (ALT) (OR 4.72, 95% CI 2.58-8.61) and gamma glutamyl transferase values (GGT) (OR 1.95, 95% CI 1.14-3.34). The components of the MS best predicting NAFLD were hyperglycemia (OR 1.65, 95% CI1.06-2.56) and triglyceride values (OR 1.75, 95% CI1.13-2.72). CONCLUSIONS: The independent variables associated with NAFLD were obesity, insulin resistance and elevated ALT and GGT. The components of MS best predicting NAFLD were hyperglycemia and an increase in triglyceride values.

Metabolic syndrome and nonalcoholic fatty liver disease in a Spanish population: influence of the diagnostic criteria used.

OBJECTIVE: Nonalcoholic fatty liver disease (NAFLD) is highly prevalent and it is considered the hepatic component of the metabolic syndrome (MetS). The WHO, the National Cholesterol Education Program (NCEP) and the International Diabetes Federation (IDF) have different criteria to define MetS. The aim of this study was to analyze the association between NAFLD and MetS using the three existing criteria. METHODS: Cross-sectional, descriptive population-based study derived from a previous study on the prevalence and factors associated with NAFLD in Spain. RESULTS: A total of 696 individuals [mean age 53 ± 14 years (range 17-83 years)] were included, 59% of whom were women. The prevalence of MetS was 34.2% according to the IDF, 17.7% according to the NCEP and 15.5% according to the WHO. Concordance among the different criteria was between 76 and 87%, with kappa indexes between 0.39 and 0.54. NAFLD was present in 184 individuals according to echographic criteria (prevalence 26.4%). The prevalence of NAFLD among patients with MetS was 43% (IDF), 53% (NCEP) and 64% (WHO). The odds ratio (95% confidence interval) for a logistic regression using NAFLD as a dependent variable varied from 3.44 (2.42-4.88) for IDF to 7.28 (4.68-11.3) for WHO, being 4.28 (2.84-6.43) for NCEP. CONCLUSION: The MetS is quite frequent in the general population, although its prevalence varies considerably according to the criteria used for its definition. The MetS is associated with NAFLD, with the WHO definition being the best to determine its presence, probably because of the inclusion of insulin resistance as a main component. Unification of criteria is needed to adequately compare the prevalence of MetS and its relationship with NAFLD in different population groups.

Prevalence and factors associated with the presence of nonalcoholic fatty liver disease in an adult population in Spain.

BACKGROUND/AIMS: The prevalence of nonalcoholic fatty liver disease (NAFLD) is unknown in Spain. The purpose of detecting NAFLD patients is to determine the associated factors and prevent its evolution to more severe forms. The aim of this study is to determine the prevalence and factors associated with NAFLD. METHODS: This is a multicentre, cross-sectional, populational study. Individuals between 15 and 85 years of age were randomly selected from 25 primary healthcare centres in the province of Barcelona, Spain. Clinical histories were reviewed, and anamnesis, physical examination, blood analysis and hepatic echography were performed. Individuals with an alcohol intake greater than 30 g/day in men and greater than 20 g/day in women or with known liver disease were excluded. RESULTS: Seven hundred and sixty-six individuals with a mean age of 53+/-14 years (range 17-83, 42.2% men) were included in the study. One hundred and ninety-eight individuals presented NAFLD with echographic criteria (prevalence 25.8, 33.4% men and 20.3% women P<0.001). On multivariate analysis, the following were associated with NAFLD: male sex [odds ratio (OR): 2.34, 95% confidence interval (95% CI): 1.57-3.49], age (OR: 1.04 per year, 95% CI: 1.02-1.05), metabolic syndrome (OR: 2.19, 95% CI: 1.29-3.72), insulin resistance (OR: 6.00, 95% CI: 3.43-10.5) and alanine aminotransferase (OR: 4.21, 95% CI: 2.23-7.95). Of the individuals who consumed alcohol, 29.4% consumed alcohol within the inclusion criteria, with a mean of 9.17+/-6.75 standard beverage units per week. Moderate alcohol intake was not related to NAFLD, although a possible protector effect was found with the quantity consumed among the drinkers who did not consume excessive amounts of alcohol (OR: 0.93 per standard beverage units, 95% CI: 0.88-0.98). CONCLUSION: NAFLD prevalence in our population is very high. Male sex, age, metabolic syndrome, insulin resistance and alanine aminotransferase are the factors associated with NAFLD. Furthermore, studies should be carried out with respect to the controversial effect of alcohol on NAFLD.