Incidence of small-for-gestational-age infant birthweight following early intertwin fetal growth discordance in dichorionic and monochorionic twin pregnancies

BACKGROUND

Serial growth scans are routinely recommended for twin pregnancies to identify fetal growth restriction (defined as an estimated fetal weight of <10th percentile), which can result in increased perinatal morbidity and mortality. However, the clinical significance of early intertwin growth discordance in the absence of fetal growth restriction remains unclear.

OBJECTIVE

This study aimed to compare the rates of small-for-gestational-age infants among twin pregnancies with intertwin growth discordance in the absence of fetal growth restriction with that among twin pregnancies with concordant, normal growth identified by ultrasound between 24 0/7 and 31 6/7 weeks' gestation.

STUDY DESIGN

This was a retrospective cohort study of twin deliveries at a single hospital from 2010 to 2019. Pregnancies without fetal growth restriction were categorized as discordant or concordant using the earliest prenatal growth ultrasound between 24 0/7 and 31 6/7 weeks' gestation. Discordance was defined as an estimated fetal weight difference of ≥18% between twins. Pregnancies with major fetal anomalies, no growth ultrasound between 24 0/7 and 31 6/7 weeks' gestation, or twin-twin transfusion syndrome were excluded. The cohort was stratified by chorionicity. Our primary outcome was small-for-gestational-age defined as <10th percentile per the Fenton growth curve at delivery. Secondary outcomes included gestational age at delivery, mode of delivery, neonatal intensive care unit admission, length of stay, and neonatal complications and placental pathology.

RESULTS

Of the 707 twin pregnancies that met the inclusion criteria, 558 (79%) were dichorionic and 149 (21%) were monochorionic. Most pregnancies were concordant on ultrasound between 24 0/7 and 31 6/7 weeks' gestation (dichorionic, 93%; monochorionic, 87%). Regardless of chorionicity, twin pregnancies with discordance at ultrasound, were more likely to have a small-for-gestational-age infant than concordant twin pregnancies (dichorionic: 51% vs 29%; P=.002; monochorionic: 65% vs 24%; P<.001). Furthermore, women with twin pregnancies with discordance were delivered at an earlier gestational age (dichorionic: 36 weeks [interquartile range, 33-36] vs 34 weeks [interquartile range, 34-38]; P<.001; monochorionic: 34 weeks [interquartile range, 32-34] vs 36 weeks [interquartile range, 34-37]; P=.003). Pregnancies with growth discordance were more likely to be delivered by cesarean delivery (dichorionic: 90% vs 72%; P=.01; monochorionic: 65% vs 60%; P=.70), although this was only statistically significant for dichorionic twin pregnancies. Neonates of pregnancies with growth discordance had a higher incidence of respiratory distress syndrome (dichorionic: 54% vs 37%; P=.04; monochorionic: 70% vs 45%; P=.04) and neonatal intensive care unit admission (dichorionic: 71% vs 50%; P=.01; monochorionic: 90% vs 65%; P=.03). Furthermore, dichorionic infants had longer neonatal intensive care unit stays (30 [interquartile range, 18-61] vs 18 [interquartile range, 10-35] days; P=.02).

CONCLUSION

Regardless of chorionicity, twin pregnancies with discordance without fetal growth restriction identified on growth ultrasound between 24 0/7 and 31 6/7 weeks' gestation were nearly twice as likely to develop small-for-gestational-age neonates, deliver earlier in gestation, and experience greater neonatal morbidity than twin pregnancies without discordance. Patients with pregnancies complicated by isolated intertwin discordance between 24 0/7 and 31 6/7 weeks' gestation will need counseling regarding adverse perinatal outcomes.

B cell-intrinsic and -extrinsic regulation of antibody responses by PARP14, an intracellular (ADP-ribosyl)transferase

The capacity to achieve sufficient concentrations of Ag-specific Ab of the appropriate isotypes is a critical component of immunity that requires efficient differentiation and interactions of Ag-specific B and Th cells along with dendritic cells. Numerous bacterial toxins catalyze mono(ADP-ribosyl)ation of mammalian proteins to influence cell physiology and adaptive immunity. However, little is known about biological functions of intracellular mammalian mono(ADP-ribosyl)transferases, such as any ability to regulate Ab responses. poly-(ADP-ribose) polymerase 14 (PARP14), an intracellular protein highly expressed in lymphoid cells, binds to STAT6 and encodes a catalytic domain with mammalian mono(ADP-ribosyl)transferase activity. In this article, we show that recall IgA as well as the STAT6-dependent IgE Ab responses are impaired in PARP14-deficient mice. Whereas PARP14 regulation of IgE involved a B cell-intrinsic process, the predominant impact on IgA was B cell extrinsic. Of note, PARP14 deficiency reduced the levels of Th17 cells and CD103⁺ DCs, which are implicated in IgA regulation. PARP14 enhanced the expression of RORα, Runx1, and Smad3 after T cell activation, and, importantly, its catalytic activity of PARP14 promoted Th17 differentiation. Collectively, the findings show that PARP14 influences the class distribution, affinity repertoire, and recall capacity of Ab responses in mice, as well as provide direct evidence of the requirement for protein mono-ADP-ribosylation in Th cell differentiation.

PARP-14 mediates B cell memory response through the regulation of energy metabolism and gene transcription (61.5)

Immunological memory, including both persistent and recall antibody (Ab) responses, enables more efficient and effective protection against recurrent or chronic infection. Although many basic features of memory responses are understood, key molecular mechanisms regulating emergence and persistence of memory B cells and plasma cells remain unknown. Recent evidence suggests that the regulation of energy metabolism might mediate memory T cell differentiation and function. PARP-14, a Stat6-interacting protein is highly expressed in lymphoid organs, influences B cell subset ratios as well as the initial IgA response to antigen, and has intrinsic ADP-ribosyltransferase activity. We now show that PARP-14 is essential for the regulation of energy metabolism in B cells and has been significant role in the increased Ag-specific Ab levels that follow booster immunization. Investigation of the mechanism(s) revealed that PARP-14 mediates at least in part to the formation of long-lived plasma cell formation and regulates IL-4 induction of PRDM1 (Blimp-1), a master regulator of plasma cell differentiation. These results reveal a novel function of a mammalian ADP-ribosyltransferase in memory of B lineage cells and may shed a light on a new target for vaccine development.

Differential contribution of IL-18 receptor beta to protective immunity and immunopathology during infection with intracellular bacteria (134.18)

IL-18 has been shown to play a critical role in cytokine-induced organ failure during endotoxic shock. Human monocytotropic ehrlichiosis (HME) is a tick-borne infectious disease caused by E. chaffeenesis. HME is modeled in B6 mice using Ehrlichia muris (EM) that cause mild disease, and Ixodes ovatus Ehrlichia (IOE) that cause fatal shock-like syndrome. As Ehrlichia-induced septic shock and tissue injury is associated with increased IL-18 production, we examined the effect of blocking IL-18 signaling via IL-18Rβ on host defense & immune responses following sublethal (EM) and lethal (IOE) infection. Compared to IOE-infected isotype controls, in vivo IL-18Rβ neutralization in IOE-infected mice decreased bacterial burden, increased frequency of IFN-γ producing NK and NKT cells and enhanced production of TNF-α by T and non T cells on day 2 post-infection. On day 7 post-infection, blocking IL-18Rβ in lethally infected mice did not significantly influence the acquired pathogenic immune responses compared to lethally-infected isotype controls. Interestingly, blocking IL-18Rβ in the EM-infected mice increased bacterial burden, which was associated with suppressed early production of TNF-α and IFN-γ by different cell subsets compared to EM-infected isotype controls. These data suggest that IL-18Rβ may play dual protective and pathogenic roles in sublethal and lethal ehrlichial infection, respectively, through regulation of IFN-γ and TNF-α production by different innate cell subsets.