Damage-associated molecular patterns (DAMPs) in preterm labor with intact membranes and preterm PROM: A study of the alarmin HMGB1

Perinatology Research Branch, NICHD/NIH/DHHS, Wayne State University/Hutzel Women’s Hospital, 3990 John R, Detroit, MI 48201, USA.
The journal of maternal-fetal & neonatal medicine: the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians (Impact Factor: 1.37). 09/2011; 24(12):1444-55. DOI: 10.3109/14767058.2011.591460
Source: PubMed


Preterm parturition is a syndrome caused by multiple etiologies. Although intra-amniotic infection is causally linked with intrauterine inflammation and the onset of preterm labor, other patients have preterm labor in the absence of demonstrable infection. It is now clear that inflammation may be elicited by activation of the Damage-Associated Molecular Patterns (DAMPs), which include pathogen-associated molecular patterns (PAMPs) as well as "alarmins" (endogenous molecules that signal tissue and cellular damage). A prototypic alarmin is high-mobility group box 1 (HMGB1) protein, capable of inducing inflammation and tissue repair when it reaches the extracellular environment. HMGB1 is a late mediator of sepsis, and blockade of HMGB1 activity reduces mortality in an animal model of endotoxemia, even if administered late during the course of the disorder. The objectives of this study were to: (1) determine whether intra-amniotic infection/inflammation (IAI) is associated with changes in amniotic fluid concentrations of HMGB1; and (2) localize immunoreactivity of HMGB1 in the fetal membranes and umbilical cord of patients with chorioamnionitis.
Amniotic fluid samples were collected from the following groups: (1) preterm labor with intact membranes (PTL) with (n=42) and without IAI (n=84); and (2) preterm prelabor rupture of membranes (PROM) with (n=38) and without IAI (n=35). IAI was defined as either a positive amniotic fluid culture or amniotic fluid concentration of interleukin-6 (IL-6) ≥ 2.6ng/mL. HMGB1 concentrations in amniotic fluid were determined by ELISA. Immunofluorescence staining for HMGB1 was performed in the fetal membranes and umbilical cord of pregnancies with acute chorioamnionitis.
(1) Amniotic fluid HMGB1 concentrations were higher in patients with IAI than in those without IAI in both the PTL and preterm PROM groups (PTL IAI: median 3.1 ng/mL vs. without IAI; median 0.98 ng/mL; p <0.001; and preterm PROM with IAI median 7.3 ng/mL vs. without IAI median 2.6 ng/mL; p=0.002); (2) patients with preterm PROM without IAI had a higher median amniotic fluid HMGB1 concentration than those with PTL and intact membranes without IAI (p <0.001); and (3) HMGB1 was immunolocalized to amnion epithelial cells and stromal cells in the Wharton's jelly (prominent in the nuclei and cytoplasm). Myofibroblasts and macrophages of the chorioamniotic connective tissue layer and infiltrating neutrophils showed diffuse cytoplasmic HMGB1 immunoreactivity.
(1) intra-amniotic infection/inflammation is associated with elevated amniotic fluid HMGB1 concentrations regardless of membrane status; (2) preterm PROM was associated with a higher amniotic fluid HMGB1 concentration than PTL with intact membranes, suggesting that rupture of membranes is associated with an elevation of alarmins; (3) immunoreactive HMGB1 was localized to amnion epithelial cells, Wharton's jelly and cells involved in the innate immune response; and (4) we propose that HMGB1 released from stress or injured cells into amniotic fluid may be responsible, in part, for intra-amniotic inflammation due to non-microbial insults.

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Available from: Tinnakorn Chaiworapongsa, Feb 10, 2014
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    • "Unlike most cytokines, IL-1β is a leaderless protein, posttranslational proteolytic cleavage of which is required for the release of its mature 17 kDa form (Perregaux and Gabel, 1994) and in monocytes occurs rapidly on inflammasomes. The latter in pregnancy has been little studied to date but some observations, for example, raised levels of the DAMP, high mobility group box-1, HMGB-1 (Romero et al., 2011) point tentatively to inflammasome involvement. Amniotic fluid caspase-1 levels have also been shown to be highest in women with sPTB with confirmed intrauterine infection compared with women throughout pregnancy without infection (Gotsch et al., 2008) while monosodium urate (a DAMP linked with the lysosmal damage pathway of NLRP3) causes increased IL-1β production in trophoblasts (Mulla et al., 2011). "
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    ABSTRACT: Distinguishing between fetal and maternal inflammatory responses is necessary for understanding the immune interplay either side of the placenta. Fetal immunity reaches maturity during extrauterine life and while basic inflammatory responses afford a certain degree of protection, fetuses are vulnerable to infection. With the discovery of inflammasomes-intracellular scaffolds that facilitate the elaboration of reactions resulting in the release of mature interleukin-1β (IL-1β)-it is necessary to consider how inflammatory stimuli are processed. The purinergic P2X7 receptor located on haematopoietic cells is a key intermediary in signal transduction initiated at Toll-like receptors (TLR) terminating in release of the mature IL-1β product. We demonstrate herein that IL-1β release from fetal membranes and mononuclear cells isolated from cord, placental, and maternal blood, obtained at term, is P2X7- and caspase-1 dependent. The P2X7-dependent release of the cytokine, which was highest from choriodecidua, was attenuated by progesterone (P4), prolactin and an NFkB inhibitor. The NLRP3 inflammasome appears necessary for the processing of IL-1β in gestational tissues and leukocytes.
    Full-text · Article · Jun 2015 · Frontiers in Physiology
    • "Microbial invasion of the amniotic cavity (MIAC) was defined according to the results of AF culture and polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) (Ibis ® Technology – Athogen, Carlsbad, CA) [24] [25] [26] [27]. Intra-amniotic inflammation was diagnosed when the AF IL-6 concentration was ≥ 2.6 ng/mL [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38]. Based on the results of AF cultures, PCR/ESI-MS and AF concentrations of IL-6, patients with clinical chorioamnionitis at term were classified as having: 1) no intra-amniotic inflammation, or 2) microbial-associated intraamniotic inflammation (combination of MIAC and intra-amniotic inflammation), or 3) intra-amniotic inflammation without detectable bacteria (an elevated AF IL-6 concentration without evidence of bacteria using both cultivation and molecular methods). "
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    ABSTRACT: Recent studies indicate that clinical chorioamnionitis is a heterogeneous condition and only approximately one-half of the patients have bacteria in the amniotic cavity, which is often associated with intra-amniotic inflammation. The objective of this study is to characterize the nature of the inflammatory response within the amniotic cavity in patients with clinical chorioamnionitis at term according to the presence or absence of 1) bacteria in the amniotic cavity and 2) intra-amniotic inflammation. A retrospective cross-sectional case-control study was conducted to examine cytokine and chemokine concentrations in the amniotic fluid (AF). Cases consisted of women with clinical chorioamnionitis at term (n=45). Controls were women with uncomplicated pregnancies at term who did not have intra-amniotic inflammation and were in labor (n=24). Women with clinical chorioamnionitis were classified according to the results of AF cultures, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry, and AF concentration of interleukin-6 (IL-6) into those: 1) without intra-amniotic inflammation, 2) with microbial-associated intra-amniotic inflammation, and 3) with intra-amniotic inflammation without detectable bacteria. The AF concentrations of 29 cytokines/chemokines were determined using sensitive and specific V-PLEX immunoassays. 1) The AF concentrations of pro- and anti-inflammatory cytokines/chemokines such as interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin-4 (IL-4), macrophage inflammatory protein-1 beta (MIP-1β), and interleukin-8 (IL-8) (except Eotaxin-3) were significantly higher in women with clinical chorioamnionitis at term than in controls (term labor without intra-amniotic inflammation); 2) patients with microbial-associated intra-amniotic inflammation, and those with intra-amniotic inflammation without detectable bacteria, had a dramatic differential expression of cytokines and chemokines in AF compared to patients with spontaneous labor without intra-amniotic inflammation. However, no difference could be detected in the pattern of the intra-amniotic inflammatory response between patients with intra-amniotic inflammation with and without detectable bacteria; and 3) in patients with clinical chorioamnionitis at term but without intra-amniotic inflammation, the behavior of cytokines and chemokines in the AF was similar to those in spontaneous labor at term. Patients with clinical chorioamnionitis who had microbial-associated intra-amniotic inflammation or intra-amniotic inflammation without detectable bacteria had a dramatic upregulation of the intra-amniotic inflammatory response assessed by amniotic fluid concentrations of cytokines. A subset of patients with term clinical chorioamnionitis does not have intra-amniotic infection/inflammation, as demonstrated by elevated AF concentrations of inflammation-related proteins, when compared to women in term labor with uncomplicated pregnancies, suggesting over-diagnosis. These observations constitute the first characterization of the cytokine/chemokine network in the amniotic cavity of patients with clinical chorioamnionitis at term.
    No preview · Article · May 2015 · Journal of Perinatal Medicine
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    • "HMGB1, is released later than other proinflammatory cytokines, and serves as a “late mediator” of sepsis [12]. Blocking HMGB1 activity reduces mortality in an animal endotoxemia model, even when administered late during the course of the disorder [35]. Up to now, the emerging evidence suggests the pivotal role of HMGB1 in the development of the LPS-induced ALI [13]–[16]. "
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    Full-text · Article · Jul 2013 · PLoS ONE
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