Circulating Cytokines Associated with Poor Pregnancy Outcomes in Beninese Exposed to Infection with Plasmodium falciparum

Obesogenic Diet in Mice Leads to Inflammation and Oxidative Stress in the Mother in Association with Sex-Specific Changes in Fetal Development, Inflammatory Markers and Placental Transcriptome

BACKGROUND

Obesity during pregnancy is related to adverse maternal and neonatal outcomes. Factors involved in these outcomes may include increased maternal insulin resistance, inflammation, oxidative stress, and nutrient mishandling. The placenta is the primary determinant of fetal outcomes, and its function can be impacted by maternal obesity. The aim of this study on mice was to determine the effect of obesity on maternal lipid handling, inflammatory and redox state, and placental oxidative stress, inflammatory signaling, and gene expression relative to female and male fetal growth.

METHODS

Female mice were fed control or obesogenic high-fat/high-sugar diet (HFHS) from 9 weeks prior to, and during, pregnancy. On day 18.5 of pregnancy, maternal plasma, and liver, placenta, and fetal serum were collected to examine the immune and redox states. The placental labyrinth zone (Lz) was dissected for RNA-sequencing analysis of gene expression changes.

RESULTS

the HFHS diet induced, in the dams, hepatic steatosis, oxidative stress (reduced catalase, elevated protein oxidation) and the activation of pro-inflammatory pathways (p38-MAPK), along with imbalanced circulating cytokine concentrations (increased IL-6 and decreased IL-5 and IL-17A). HFHS fetuses were asymmetrically growth-restricted, showing sex-specific changes in circulating cytokines (GM-CSF, TNF-α, IL-6 and IFN-γ). The morphology of the placenta Lz was modified by an HFHS diet, in association with sex-specific alterations in the expression of genes and proteins implicated in oxidative stress, inflammation, and stress signaling. Placental gene expression changes were comparable to that seen in models of intrauterine inflammation and were related to a transcriptional network involving transcription factors, LYL1 and PLAG1.

CONCLUSION

This study shows that fetal growth restriction with maternal obesity is related to elevated oxidative stress, inflammatory pathways, and sex-specific placental changes. Our data are important, given the marked consequences and the rising rates of obesity worldwide.

Pathogenicity and virulence of malaria: Sticky problems and tricky solutions

Infections with Plasmodium falciparum and Plasmodium vivax cause over 600,000 deaths each year, concentrated in Africa and in young children, but much of the world's population remain at risk of infection. In this article, we review the latest developments in the immunogenicity and pathogenesis of malaria, with a particular focus on P. falciparum, the leading malaria killer. Pathogenic factors include parasite-derived toxins and variant surface antigens on infected erythrocytes that mediate sequestration in the deep vasculature. Host response to parasite toxins and to variant antigens is an important determinant of disease severity. Understanding how parasites sequester, and how antibody to variant antigens could prevent sequestration, may lead to new approaches to treat and prevent disease. Difficulties in malaria diagnosis, drug resistance, and specific challenges of treating P. vivax pose challenges to malaria elimination, but vaccines and other preventive strategies may offer improved disease control.

Interleukin-5 levels in relation to malaria severity: a systematic review

BACKGROUND

The role of cytokines such as interleukin-5 (IL-5) in the pathogenesis of malaria remains unclear. This systematic review sought to synthesize variations in IL-5 levels between severe and uncomplicated malaria, as well as between malaria and controls not afflicted with the disease.

METHODS

This systematic review was registered at the International Prospective Register of Systematic Reviews (PROSPERO; CRD42022368773). Searches for studies that reported IL-5 levels in patients with malaria (any severity) and/or uninfected individuals were performed in Web of Science, PubMed, EMBASE, Scopus, CENTRAL, and MEDLINE, between 1st and 10th October, 2022. The risk of bias among all included studies was minimized using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines for reporting observational studies. The differences in IL-5 levels between malaria and uninfected controls, and between severe and uncomplicated malaria were synthesized by narrative synthesis.

RESULTS

Among 1177 articles identified in the databases, 23 matched the eligibility criteria and were included in this systematic review. Qualitative syntheses showed the heterogeneity of IL-5 levels between different severities of clinical malaria and uninfected controls. The majority of the included studies (12/15 studies, 80%) found no change in IL-5 levels between malaria cases and uninfected controls. Similarly, most studies found no difference in IL-5 levels between severe (regardless of complications) and uncomplicated malaria (4/8 studies, 50%). The qualitative syntheses revealed that most studies found no difference in IL-5 levels between severe and non-severe malaria.

CONCLUSIONS

The comprehensive review suggests that IL-5 levels are unchanged in patients with different levels of clinical severity of malaria and uninfected controls. Given the limited number of published studies on IL-5 levels in malaria, there is a need for additional research to determine the function of this cytokine in the pathogenesis of malaria.

Do Antibodies to Malaria Surface Antigens Play a Role in Protecting Mothers From Maternal Anemia?

Pregnancy-associated malaria (PAM) caused by Plasmodium falciparum can result in detrimental outcomes for both mother and infant, including low infant birth weight, preterm birth, maternal anemia, spontaneous abortion, and maternal and/or infant mortality. Maternal anemia is a particularly complex outcome, as the body must both maintain erythropoiesis and tolerance of the growing fetus, while directing a Th1 response against the parasite. Underlying the pathogenesis of PAM is the expression of variant surface antigens (VSA_PAM) on the surface of infected red blood cells (iRBC) that mediate sequestration of the iRBC in the placenta. Naturally acquired antibodies to VSA_PAM can block sequestration and activate opsonic phagocytosis, both associated with improved pregnancy outcomes. In this review, we ask whether VSA_PAM antibodies can also protect mothers against malarial anemia. Studies were identified where VSA_PAM antibody titres and/or function were associated with higher maternal hemoglobin levels, thus supporting additional protective mechanisms for these antibodies against PAM. Yet these associations were not widely observed, and many studies reported no association between protection from maternal anemia and VSA_PAM antibodies. We discuss the epidemiological, biological and technical factors that may explain some of the variability among these studies. We appraise the current evidence of these complex interactions between PAM-specific immunity and maternal anemia, propose potential mechanisms, and discuss knowledge gaps.

COVID-19 in pregnancy: Placental and neonatal involvement

Since December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused over 12 million infections and more than 550 000 deaths.1 Morbidity and mortality appear partly due to host inflammatory response.2 Despite rapid, global research, the effect of SARS-CoV-2 on the developing fetus remains unclear. Case reports indicate that vertical transmission is uncommon; however, there is evidence that placental and fetal infection can occur.3-7 Placentas from infected patients show inflammatory, thrombotic, and vascular changes that have been found in other inflammatory conditions.8,9 This suggests that the inflammatory nature of SARS-CoV-2 infection during pregnancy could cause adverse obstetric and neonatal events. Exposure to intrauterine inflammation and placental changes could also potentially result in long-term, multisystemic defects in exposed infants. This review will summarize the known literature on the placenta in SARS-CoV-2 infection, evidence of vertical transmission, and possible outcomes of prenatal exposure to the virus.