The role of macrophages in vascular adaptation to pregnancy in mice

Macrophages are abundant in female reproductive tissues and play crucial roles in the establishment of murine pregnancy through actions in the ovary, and potentially in the uterus. Within the ovary, macrophages support the vascular integrity of the corpus luteum allowing progesterone (P4) production. These ovarian macrophages have been shown to be associated with endothelial cells in the corpora lutea and express the angiogenic marker Tie2. This supports an angiogenic role for ovarian macrophages at the outset of pregnancy. On the other hand, the role of uterine macrophages during murine pregnancy is not fully understood. It has been postulated that uterine macrophages contribute to immune tolerance and tissue remodelling for embryo implantation, trophoblast invasion, and decidualisation. In addition, some studies have suggested that macrophages are involved in uterine vascular remodelling through interactions with endothelial cells, trophoblast cells, and other immune cell subsets including uterine natural killer (uNK) cells and regulatory T (Treg) cells. Therefore, studies within this thesis sought to investigate the role of uterine macrophages in promoting vascular adaptations to pregnancy. Previous studies with macrophage-deficient mice or mice transiently depleted of macrophages during pregnancy have shown pregnancy failure (Pollard et al., 1991, Care et al., 2013). Whilst these studies demonstrate macrophages as being indispensable for pregnancy success, the specific physiological role of uterine macrophages has not been confirmed. Studies within this thesis utilised the CD11b-DTR transgenic mouse model to deplete CD11b-expressing cells via administration of diphtheria toxin (DT). Administration of 25 ng/g DT to CD11b-DTR mice elicited >90% depletion of macrophages from the uterus and other tissues 24 h post-DT administration. Importantly, administration of DT to wild type mice had no effect on pregnancy or macrophage numbers. Data from chapter three demonstrated that macrophage depletion resulted in pregnancy failure from day 7.5 pc, 48 h post-DT administration. Macrophage depletion impaired decidualisation and reduced trophoblast invasion on day 7.5 pc. In addition, vascular remodelling within the uterus was reduced post-macrophage depletion. Pregnancy failure on day 7.5 pc was in part attributable to defects in corpus luteum structure and reduced serum P4. However, hormone supplementation in macrophage-depleted mice failed to fully restore viable pregnancy. This implies a role for macrophages other than in ovarian P4 production and presumably within the uterus during the peri-implantation phase of murine pregnancy. Whilst near-complete macrophage depletion resulted in pregnancy failure, an attenuated dose of DT was investigated to explore the effect of less extensive macrophage loss. Moderate macrophage depletion during the peri-implantation phase allowed a greater proportion of pregnancies to survive. However, there was a reduced number of viable fetuses and reduced fetal growth measured at day 17.5 pc. Associated with fetal growth restriction was an impairment in the placental labyrinth zone which had reduced densities of fetal capillaries. In addition, uterine vascular remodelling was impaired during mid-gestation after moderate macrophage depletion, similar to what was observed at the higher DT dose. To further investigate the involvement of macrophages in uterine vascular remodelling, macrophage or P4 replacement procedures were conducted in DT-treated CD11b-DTR mice. Macrophage replacement improved viable pregnancy rates and restored serum P4, decidualisation, trophoblast invasion, and to an extent, uterine vascular remodelling. Whilst P4 supplementation restored decidualisation, P4 administration failed to improve uterine vascular remodelling and trophoblast invasion after macrophage depletion. In addition, macrophage depletion caused reduced abundance of uNK cells, while P4 or macrophage administration restored uNK cell abundance. In order to interrogate macrophage-derived products as mediators of uterine vascular remodelling during early to mid-gestation, RNA profiling was performed in the decidua and myometrium on day 7.5 pc. Macrophage depletion resulted in substantial gene expression changes. A majority of these dysregulated genes could be restored by either P4 or macrophage administration. Importantly, macrophage administration restored a larger proportion of the genes dysregulated by macrophage depletion than did P4 supplementation. Notably, C1q genes were downregulated after macrophage depletion, independent of P4 administration, but macrophage replacement restored C1q expression. C1q has been shown to be an important factor for placental development and fetal growth with some evidence to suggest that decidual vascular remodelling is impaired in C1q-deficient dams. To investigate C1Q function in murine pregnancy, C1Q-deficient dams were utilised in allogeneic pregnancy. At late gestation, fetuses were growth restricted and placentas were hypertrophic in C1Q-deficient dams. Importantly, C1Q deficiency caused impaired decidual vascular remodelling and reduced uNK cell abundance. Wild type macrophage administration to C1Q-deficient dams restored decidual vascular remodelling and uNK cells, highlighting that macrophage-derived C1Q can facilitate uterine vascular remodelling during early to mid-gestation. The data presented in this thesis shows that macrophages play an indispensable role during the peri-implantation phase of murine pregnancy through effects in the uterus, in addition to their known roles within the ovary. Furthermore, macrophage-derived C1Q appears to be a regulator of uterine vascular adaptation during early to mid-gestation and facilitates pregnancy success. This indicates that macrophages and C1Q are essential factors in promoting adequate placentation and fetal growth, and should be further investigated in the context of human pregnancy and gestational disorders.Thesis (Ph.D.) -- University of Adelaide, Adelaide Medical School, 202

The burden of severe acute gastroenteritis and risk factors associated with poor outcome in a cohort of Sowetan children under five years of age

MSc (Med), Epidemiology and Biostatistics,University of the Witwatersrand, Faculty of Health SciencesIntroduction In developing countries, diarrhoea is a major cause of morbidity and mortality among children under five years of age. This study aimed to determine the effect of age and HIV infection status on incidence of acute gastroenteritis and to identify risk factors associated with death and prolonged hospitalisation. Methods A secondary data analysis was performed using an existing cohort of children enrolled on a pneumococcal vaccine efficacy study performed in 1998-2005 in Soweto. Results The incidence rate of acute gastroenteritis requiring hospitalisation was 10.13 (CI95% 9.68, 10.58) per 1000 person years. Incidence was highest in those under six months of age, decreased with increasing age, and was 5.42 times (CI95% 4.89, 6.01) higher in those infected with HIV compared to that in HIV-uninfected children. HIV-infected children were more likely to be malnourished, have severe dehydration and have a concomitant diagnosis of lower respiratory tract infection (LRTI). HIV-infected children were four times more likely to die in hospital (OR 3.99 CI95% 2.04, 7.81) and almost twice as likely to be hospitalized > 2 days (OR 1.81 CI95% 1.38, 2.38) compared to HIV-uninfected children. Presence of malnutrition, severe dehydration and a concomitant diagnosis of LRTI were also significant risk factors for death and prolonged hospitalisation. Conclusions Acute gastroenteritis is an important cause of hospitalisation in children under 2 years, especially among HIV-infected children. Prevention and management of severe dehydration, malnutrition, HIV infection and concomitant LRTI need to be targeted to decrease mortality and shorten the duration of hospitalisation in children admitted with acute gastroenteritis

Diagnostic testing practices for diarrhoeal cases in South African public hospitals

BACKGROUND : Stool samples submitted for diagnostic testing represent a proportion of diarrhoeal cases seeking healthcare, and an even smaller proportion of diarrhoeal cases in the community. Despite this, surveillance relies heavily on these laboratory results. This study described diarrhoeal diagnostic practices and aetiological agents of diarrhoea in patients admitted to three South African public hospitals in order to understand biases in surveillance data, and inform guidelines, diagnostic and laboratory practices to improve clinical management. METHODS : A doctors’ survey was conducted to determine sample submission, diarrhoeal treatment and barriers to submitting samples for testing. Results for all samples submitted for routine diagnostics were obtained from the NHLS Central Data Warehouse. An enhanced surveillance study enrolled patients with acute diarrhoea at the same hospitals over the same period. Differences between routine culture results and molecular testing from the surveillance study were described. RESULTS : Stool samples were seldom submitted for diagnostic testing (median of 10% of admitted cases). Current diagnostic guidelines were not useful, hence most doctors (75.1%) relied on their own clinical judgement or judgement of a senior clinician. Although most doctors (90.3%) agreed that diagnostics were helpful for clinical management, they reported patients being unwilling to provide samples and long laboratory turnaround times. Routine diagnostic data represent cases with chronic diarrhoea and dysentery since doctors are most likely to submit specimens for these cases. Pathogen yield (number of pathogens detected for samples tested for specific pathogens) was significantly higher in the surveillance study, which used molecular methods, than through routine diagnostic services (73.3% versus 8.2%, p < 0.001), including for viruses (48.9% versus 2.6%, p < 0.001), bacteria (40.1% versus 2.2%, p < 0.001) and parasites (16.2% versus 3.6%, p < 0.001). Despite viruses being commonly detected in the surveillance study, viral testing was seldom requested in routine diagnostic investigations. CONCLUSIONS : Comprehensive diagnostic and treatment guidelines are required for diarrhoeal diseases. These guidelines should be informed by local epidemiological data, where diagnostic testing is reserved for cases most likely to benefit from specific treatment. Optimisation of current diagnostic processes and methods are required for these cases, specifically in terms of minimising turnaround times while maximising diagnostic acumen.The ANDEMIA study was supported by the German Federal Ministry of Education and Research.http://www.biomedcentral.com/bmcinfectdisam2023Medical VirologyPaediatrics and Child Healt

Global respiratory syncytial virus-associated mortality in young children (RSV GOLD): a retrospective case series

Background: Respiratory syncytial virus (RSV) infection is an important cause of pneumonia mortality in young children. However, clinical data for fatal RSV infection are scarce. We aimed to identify clinical and socioeconomic characteristics of children aged younger than 5 years with RSV-related mortality using individual patient data. Methods: In this retrospective case series, we developed an online questionnaire to obtain individual patient data for clinical and socioeconomic characteristics of children aged younger than 5 years who died with community-acquired RSV infection between Jan 1, 1995, and Oct 31, 2015, through leading research groups for child pneumonia identified through a comprehensive literature search and existing research networks. For the literature search, we searched PubMed for articles published up to Feb 3, 2015, using the key terms “RSV”, “respiratory syncytial virus”, or “respiratory syncytial viral” combined with “mortality”, “fatality”, “death”, “died”, “deaths”, or “CFR” for articles published in English. We invited researchers and clinicians identified to participate between Nov 1, 2014, and Oct 31, 2015. We calculated descriptive statistics for all variables. Findings: We studied 358 children with RSV-related in-hospital death from 23 countries across the world, with data contributed from 31 research groups. 117 (33%) children were from low-income or lower middle-income countries, 77 (22%) were from upper middle-income countries, and 164 (46%) were from high-income countries. 190 (53%) were male. Data for comorbidities were missing for some children in low-income and middle-income countries. Available data showed that comorbidities were present in at least 33 (28%) children from low-income or lower middle-income countries, 36 (47%) from upper middle-income countries, and 114 (70%) from high-income countries. Median age for RSV-related deaths was 5·0 months (IQR 2·3–11·0) in low-income or lower middle-income countries, 4·0 months (2·0–10·0) in upper middle-income countries, and 7·0 months (3·6–16·8) in high-income countries. Interpretation: This study is the first large case series of children who died with community-acquired RSV infection. A substantial proportion of children with RSV-related death had comorbidities. Our results show that perinatal immunisation strategies for children aged younger than 6 months could have a substantial impact on RSV-related child mortality in low-income and middle-income countries

Identifying gaps in hand hygiene practice to support tailored target audience messaging in Soweto : a cross-sectional community survey

Effective risk communication is essential for outbreak mitigation, as recently highlighted during the coronavirus disease 2019 (COVID-19) pandemic. Hand hygiene is one of the proposed public health interventions to protect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) acquisition and transmission along with social distancing, improved ventilation, environmental cleaning, and wearing of masks. Improving hand hygiene practices in the community requires an understanding of the socio-behavioural context. This cross-sectional community survey in Soweto identified gaps in hand hygiene, which can inform appropriate messaging at the community level. Only 42% of survey respondents practiced adequate hand hygiene. Tailored educational messaging should be targeted at young adults in particular, and the importance of soap for hand hygiene must be emphasised for all age groups. Risk communication should expand to focus on preventing multiple infectious diseases during and beyond the COVID-19 pandemic.GlaxoSmithKline and the German Federal Ministry of Education and Research. The CHAMPS programme is funded by the Bill & Melinda Gates Foundation.https://sajid.co.za/index.php/sajiddm2022Medical Virolog

Epidemiology of human astroviruses among children younger than 5 years : prospective hospital‐based sentinel surveillance in South Africa, 2009‐2014

BACKGROUND : The epidemiology of human astroviruses (HAstVs) in hospitalised patients less than 5 years of age from selected sites in South Africa was investigated. Diarrheagenic stool specimens collected from April 2009 to May 2014 were screened retrospectively for selected viruses, bacteria and parasites. METHOD : Patient data were analysed to identify epidemiologic factors most frequently detected with HAstV infections. The following case‐comparisons were investigated; HAstV‐positive and HAstV‐negative children, human immunodeficiency virus (HIV)‐infected and HIV‐uninfected (HAstV‐positive) children and HIV‐exposed and unexposed (HAstV‐positive HIV‐uninfected) children. RESULTS : Astrovirus was identified in 7.0% (234/3340) of cases and most frequently in ages 7 to 12 months (9.2%; 90/975) compared with 5.8% to 6.6% in other 6‐month age groups. No seasonal trends were observed. More HAstVs were detected in children from homes that used outdoor water sources (7.6%) compared to indoor sources [5.7%; adjusted odds ratio (aOR), 1.5; 95% CI, 1.1‐2.1; P = 0.009]. Astroviruses were detected in 8.4% (67/799) of HIV‐uninfected patients that were exposed to HIV compared with 5.9% (74/1257) of HIV‐unexposed patients ( P = 0.032). CONCLUSION : Astroviruses were most prevalent in children aged 7 to 12 months and were detected throughout the study period. The study was limited as only hospitalised patients were investigated and no comparisons were made to diarrhoea‐free control groups. Future HAstV surveillance should include community‐based studies and children presenting at outpatient facilities.The Rotavirus Sentinel Surveillance Program was funded by GlaxoSmithKline (E‐Track 200238). Research was supported by a National Health Laboratory Service Research (004_94494) (SN) and the Poliomyelitis Research Foundation (15/22) (NAP).http://wileyonlinelibrary.com/journal/jmv2020-02-01hj2018Medical Virolog

Case-control vaccine effectiveness studies: Data collection, analysis and reporting results

The case-control methodology is frequently used to evaluate vaccine effectiveness post-licensure. The results of such studies provide important insight into the level of protection afforded by vaccines in a \u27real world\u27 context, and are commonly used to guide vaccine policy decisions. However, the potential for bias and confounding are important limitations to this method, and the results of a poorly conducted or incorrectly interpreted case-control study can mislead policies. In 2012, a group of experts met to review recent experience with case-control studies evaluating vaccine effectiveness; we summarize the recommendations of that group regarding best practices for data collection, analysis, and presentation of the results of case-control vaccine effectiveness studies. Vaccination status is the primary exposure of interest, but can be challenging to assess accurately and with minimal bias. Investigators should understand factors associated with vaccination as well as the availability of documented vaccination status in the study context; case-control studies may not be a valid method for evaluating vaccine effectiveness in settings where many children lack a documented immunization history. To avoid bias, it is essential to use the same methods and effort gathering vaccination data from cases and controls. Variables that may confound the association between illness and vaccination are also important to capture as completely as possible, and where relevant, adjust for in the analysis according to the analytic plan. In presenting results from case-control vaccine effectiveness studies, investigators should describe enrollment among eligible cases and controls as well as the proportion with no documented vaccine history. Emphasis should be placed on confidence intervals, rather than point estimates, of vaccine effectiveness. Case-control studies are a useful approach for evaluating vaccine effectiveness; however careful attention must be paid to the collection, analysis and presentation of the data in order to best inform evidence-based vaccine policies

Case-control vaccine effectiveness studies: Preparation, design, and enrollment of cases and control

Case-control studies are commonly used to evaluate effectiveness of licensed vaccines after deployment in public health programs. Such studies can provide policy-relevant data on vaccine performance under \u27real world\u27 conditions, contributing to the evidence base to support and sustain introduction of new vaccines. However, case-control studies do not measure the impact of vaccine introduction on disease at a population level, and are subject to bias and confounding, which may lead to inaccurate results that can misinform policy decisions. In 2012, a group of experts met to review recent experience with case-control studies evaluating the effectiveness of several vaccines; here we summarize the recommendations of that group regarding best practices for planning, design and enrollment of cases and controls. Rigorous planning and preparation should focus on understanding the study context including healthcare-seeking and vaccination practices. Case-control vaccine effectiveness studies are best carried out soon after vaccine introduction because high coverage creates strong potential for confounding. Endpoints specific to the vaccine target are preferable to non-specific clinical syndromes since the proportion of non-specific outcomes preventable through vaccination may vary over time and place, leading to potentially confusing results. Controls should be representative of the source population from which cases arise, and are generally recruited from the community or health facilities where cases are enrolled. Matching of controls to cases for potential confounding factors is commonly used, although should be reserved for a limited number of key variables believed to be linked to both vaccination and disease. Case-control vaccine effectiveness studies can provide information useful to guide policy decisions and vaccine development, however rigorous preparation and design is essential

Corrigendum: The intersection of age, sex, race and socio-economic status in COVID-19 hospital admissions and deaths in South Africa

The following terminology was erroneously reported: “non-white race” should be “people of colour”, or “black African, coloured and people of Indian descent”