Immunomodulatory Therapy Reduces the Severity of Placental Lesions in Chronic Histiocytic Intervillositis

Virtual crossmatching reveals upregulation of placental HLA-Class II in chronic histiocytic intervillositis

Chronic histiocytic intervillositis (CHI) is a recurrent placental lesion where maternal macrophages infiltrate the intervillous space. Its cause is unknown, though due to similarities to rejected allografts one hypothesis is that CHI represents maternal-fetal rejection. Here, virtual crossmatching was applied to healthy pregnancies and those with a history of CHI. Anti-HLA antibodies, measured by Luminex, were present in slightly more controls than CHI (8/17 (47.1%) vs 5/14 (35.7%)), but there was no significant difference in levels of sensitisation or fetal specific antibodies. Quantification of immunohistochemical staining for HLA-Class II was increased in syncytiotrophoblast of placentas with CHI (Grade 0.44 [IQR 0.1-0.7]) compared to healthy controls (0.06 [IQR 0-0.2]) and subsequent pregnancies (0.13 [IQR 0-0.3]) (P = 0.0004). HLA-Class II expression was positively related both to the severity of CHI (r = 0.67) and C4d deposition (r = 0.48). There was no difference in overall C4d and HLA-Class I immunostaining. Though increased anti-HLA antibodies were not evident in CHI, increased expression of HLA-Class II at the maternal-fetal interface suggests that they may be relevant in its pathogenesis. Further investigation of antibodies immediately after diagnosis is warranted in a larger cohort of CHI cases to better understand the role of HLA in its pathophysiology.

Reproductive and treatment outcomes in chronic intervillositis of unknown etiology: A systematic review and meta-analysis

Chronic Intervillositis of Unknown Etiology (CIUE) is a rare idiopathic inflammatory disorder of the placenta. The evidence suggests an increased risk for poor obstetrical outcomes and a risk of recurrence as high as 100 %. This meta-analysis examined CIUE prevalence, recurrence, association with autoimmune disorders, reproductive outcomes, pregnancy complications, and the benefits of medical treatments. A systematic review, following PRISMA guidelines, involved a thorough search across multiple databases including Medline, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Evidence Based Medical Reviews, and Scopus. Out of 590 initially identified studies, 19 studies were included for both qualitative synthesis and meta-analysis after full-text review. Risk of bias was assessed using appropriate tools: The Risk Of Bias In Non-randomized Studies of Interventions tool was applied to twelve studies, while the Joanna Briggs Institute case series critical appraisal tool was used for seven studies. Our findings confirm that CIUE is a rare condition (0.7 %). CIUE is associated with decreased live birth rates (53 %), increased recurrent pregnancy loss (23 %), fetal loss beyond 22 weeks gestation (25 %), a higher prevalence of autoimmune diseases (14 %), and a recurrence rate of 30 % in subsequent pregnancies. Moreover, individuals with CIUE had higher rates of pregnancy complications, including gestational hypertension (19 %), intrauterine growth restriction (45 %), and preterm births (43 %). No significant improvement in live birth rate was observed among treated CIUE patients; however, caution is warranted when interpreting these findings due to the limited sample size. Future research in CIUE is crucial given its rarity and complexity.

Maternal Factors and Placental Pathologies Associated with a Diagnosis of Chronic Villitis

OBJECTIVE

 To evaluate maternal risk factors associated with chronic villitis of unknown etiology (VUE) and to describe cooccurring placental pathologies.

STUDY DESIGN

 A retrospective case-control study was conducted using placental pathology records from deliveries ≥ 20 weeks between 2010 and 2018. Cases were placentas with documented chronic villitis without infectious cause, hereafter called VUE. Controls were placentas without this diagnosis, matched to the cases 2:1. Maternal and neonatal demographic and clinical data were collected. Descriptive statistics are reported with Fisher's exact test or a chi-squared test, as appropriate, and multivariable conditional logistic regression was conducted.

RESULTS

 Our study included 352 cases with VUE and 657 controls. A diagnosis of gestational diabetes (p = 0.03) and gestational hypertension (p = 0.06) was 1.5 times more likely to occur in those with a VUE diagnosis. A trend was also seen for chronic hypertension (odds ratio [OR] = 1.7, p = 0.07) and preeclampsia (OR = 1.5, p = 0.09) compared with controls. Placentas with VUE, specifically high-grade VUE, were more likely to be small for gestational age (p = 0.01), and to be diagnosed with other placental findings including lymphoplasmacytic or chronic deciduitis (p < 0.01), maternal (p < 0.01) and fetal vascular malperfusion (p = 0.02), and chorionitis (acute or chronic; p < 0.01).

CONCLUSION

 Gestational diabetes and hypertension were associated with a diagnosis of VUE, and overall, VUE placentas have more abnormal placental findings compared with control. Understanding VUE risk factors may facilitate prenatal care strategies and counseling to achieve the best outcomes for pregnant patients and their neonates.

KEY POINTS

· VUE is a common inflammatory lesion of the placenta.. · Gestational diabetes and hypertension are associated with a VUE diagnosis.. · Findings of other placental pathologies increase in VUE..

Characterizing Histopathologic Features in Pregnancies With Chronic Histiocytic Intervillositis Using Computerized Image Analysis

CONTEXT.—

Chronic histiocytic intervillositis (CHI) is a rare condition characterized by maternal immune cell infiltration into the human placenta. CHI is strongly associated with fetal growth restriction, miscarriage, and stillbirth, and knowledge of its etiology, and consequently effective treatment, is limited. Currently, diagnosis is largely subjective and varies between centers, making comparison between studies challenging.

OBJECTIVE.—

To objectively quantify and interrelate inflammatory cells and fibrin in placentas with CHI compared with controls and determine how pathology may be altered in subsequent pregnancies following diagnosis. Macrophage phenotype was also investigated in untreated cases of CHI.

DESIGN.—

Computerized analysis was applied to immunohistochemically stained untreated (index) cases of CHI, subsequent pregnancies, and controls. Index placentas were additionally stained by immunofluorescence for M1 (CD80 and CD86) and M2 macrophage markers (CD163 and CD206).

RESULTS.—

Quantification revealed a median 32-fold increase in macrophage infiltration in index cases versus controls, with CHI recurring in 2 of 11 (18.2%) subsequent pregnancies. A total of 4 of 14 placentas (28.6%) with a diagnosis of CHI did not exhibit infiltration above controls. Macrophages in index pregnancies strongly expressed CD163. There was no significant difference in fibrin deposition between index cases and controls, although subsequent pregnancies displayed a 2-fold decrease compared with index pregnancies. CD3+ T cells were significantly elevated in index pregnancies; however, they returned to normal levels in subsequent pregnancies.

CONCLUSIONS.—

In CHI, intervillous macrophages expressed CD163, possibly representing an attempt to resolve inflammation. Computerized analysis of inflammation in CHI may be useful in determining how treatment affects recurrence, and alongside pathologist expertise in grading lesion severity.

Diagnostic value of neutrophil-to-lymphocyte and platelet-to-lymphocyte ratio to predict recurrent pregnancy loss and abortion; a systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the diagnostic value of the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in women with a history of abortion (missed and threatened) and recurrent pregnancy loss (RPL) in comparison with healthy pregnancies.

METHODS

Electronic databases including MEDLINE, Scopus, Web of Science, Embase, and Cochrane Library were searched for NLR and PLR in women who experienced early pregnancy loss up to January 1, 2023 with a combination of proper keywords. Meta-analysis was done for comparison with three or more studies and summary estimates were measured.

RESULTS

A total of 390 citations were retrieved initially, and after screening, 16 articles were deemed eligible for the final review. Among these, 14 studies underwent meta-analysis. The meta-analysis revealed that the standard mean of the NLR was significantly higher in abortion cases compared to the control group. However, there was no significant difference in the PLR between the pregnancy loss group and the control group.

CONCLUSION

NLR was significantly higher among RPL patients compared to the control group, according to these data, NLR may be capable of being used in the diagnosis of RPL as an easy, cheap, and accessible modality. Further studies, which take these variables into account, will need to be undertaken to determine the diagnostic value of NLR and PLR in early pregnancy loss.

Update on hydroxychloroquine use in pregnancy

It is well-known that hydroxychloroquine (HCQ) treats malaria, systemic lupus erythematosus, and rheumatoid arthritis in women for its immunomodulatory and anti-inflammatory action. Additionally, HCQ was used in cases with refractory antiphospholipid syndrome. HCQ safety was reinforced in pregnant women owing to insignificant reports of adverse pregnancy outcomes and major congenital malformation. Recently, HCQ was tested in cases with chronic placental inflammation with a promising result of increased life birth; however, its benefit needs further validation. We aimed to highlight the recent updates for HCQ use in various conditions in pregnancy.

C4d Staining Is Present in Normal Placentas From Pregnancies Prior to Pregnancy Loss Associated With Chronic Histiocytic Intervillositis and Is Reduced by Immunomodulatory Therapy in Subsequent Pregnancies

INTRODUCTION

Chronic histiocytic intervillositis (CHI) is associated with adverse pregnancy outcomes and high recurrence risk. Recent studies suggest that CHI may represent a host-vs-graft rejection, and that C4d immunostain can be used as a marker for complement activation and antibody-mediated rejection in the CHI.

MATERIALS AND METHODS

This retrospective cohort study focused on 5 fetal autopsy cases associated with CHI (5 index cases) from 5 women. We analyzed placentas from the index cases (fetal autopsy cases associated with CHI) and placentas from the women's previous and subsequent pregnancies. We assessed the presence and extent of CHI and C4d immunostaining in these placentas. We evaluated each available placenta and graded the severity of CHI as either <50% or ≥50%. Additionally, we conducted C4d immunostaining on one representative section from each placenta and graded the staining levels as follows: 0+ for staining <5%; 1+ for staining between 5% and <25%; 2+ for staining between 25% and <75%; and 3+ for staining ≥75%.

RESULTS

Three of the 5 women had pregnancies prior to their index cases (fetal autopsy cases associated with CHI). Despite the absence of CHI in their initial pregnancies, the placentas displayed positive C4d staining with grades of 1+, 3+, and 3+, respectively. These results suggest the presence of complement activation and antibody-mediated rejection in placentas from their prior pregnancies without CHI. Three of the 5 women received immunomodulatory therapy after experiencing pregnancy losses associated with CHI. After treatment, 2 of these women had live births at 35 and 37 gestational weeks, respectively, while the third had a stillbirth at 25 gestational weeks. The severity of CHI and the degree of C4d staining in the placentas decreased in all 3 cases following immunomodulatory therapies. Specifically, the level of C4d staining decreased from 3+ to 2+, 2+ to 0+, and 3+ to 1+ in these 3 cases, respectively.

DISCUSSION

In women with a history of recurrent pregnancy loss associated with CHI, C4d immunostaining was present in the placentas from their previous non-CHI pregnancies, suggesting activation of the classical complement pathway and antibody-mediated reaction in their prior non-CHI pregnancies before the development of CHI in subsequent pregnancies. Immunomodulatory therapy may improve pregnancy outcomes by reducing complement activation, as shown by the reduction of C4d immunopositivity in the placentas after immunomodulatory treatment. Although we believe that the study provides valuable insights, we acknowledge that there are limitations to the findings. Therefore, to further elucidate the pathogenesis of CHI, additional research efforts with a collaborative and multidisciplinary approach are necessary.

Identification of a unique intervillous cellular signature in chronic histiocytic intervillositis

INTRODUCTION

Chronic histiocytic intervillositis (CHI) is a rare histopathological lesion in the placenta characterized by an infiltrate of CD68⁺ cells in the intervillous space. CHI is associated with adverse pregnancy outcomes such as miscarriage, fetal growth restriction, and (late) intrauterine fetal death. The adverse pregnancy outcomes and a variable recurrence rate of 25-100% underline its clinical relevance. The pathophysiologic mechanism of CHI is unclear, but it appears to be immunologically driven. The aim of this study was to obtain a better understanding of the phenotype of the cellular infiltrate in CHI.

METHOD

We used imaging mass cytometry to achieve in-depth visualization of the intervillous maternal immune cells and investigated their spatial orientation in situ in relation to the fetal syncytiotrophoblast.

RESULTS

We found three phenotypically distinct CD68⁺HLA-DR⁺CD38⁺ cell clusters that were unique for CHI. Additionally, syncytiotrophoblast cells in the vicinity of these CD68⁺HLA-DR⁺CD38⁺ cells showed decreased expression of the immunosuppressive enzyme CD39.

DISCUSSION

The current results provide novel insight into the phenotype of CD68⁺ cells in CHI. The identification of unique CD68⁺ cell clusters will allow more detailed analysis of their function and could result in novel therapeutic targets for CHI.

Patterns of Interferon γ Expression and C4d Deposition in Chronic Intervillositis of Unknown Etiology

The pathogenesis of chronic intervillositis of unknown etiology (CIUE) may involve IFNγ overexpression. This study assesses the extent of IFNγ expression in CIUE by immunohistochemistry and compares it to spontaneous pregnancy losses. C4d deposition is also assessed to see whether IFNγ and C4d might represent separate diagnostic categories. Placenta from first to early second trimester with high grade CIUE (CHG; 17 cases) and low grade CIUE (CLG; 12 cases) is compared to euploid (SPLN; 18 cases), aneuploid spontaneous pregnancy losses (SPLA, 17 cases), normal placenta (NP, 13 cases). Protein level expression of IFNγ and C4d is assessed on whole tissue sections by immunohistochemistry. 35% of CHG and 42% of CLG show some level of IFNγ expression localized to the luminal surface of syncytiotrophoblast. 12% of SPLA and no SPLN or NP cases are IFNγ positive. C4d deposition is seen in 100% of CIUE, 88% of SPLA, 83% of SPLN, and 46% of NP samples. IFNγ overexpression occurs in approximately 40% of CIUE-related pregnancy losses. IFNγ expression restricted to a subgroup of CIUE implies that IFNγ may define a distinct disease process. The non-discriminatory pattern of C4d deposition suggests it is a non-specific phenomenon possibly related to placental damage.

Chronic Inflammatory Placental Disorders Associated With Recurrent Adverse Pregnancy Outcome

Chronic inflammatory placental disorders are a group of rare but devastating gestational syndromes associated with adverse pregnancy outcome. This review focuses on three related conditions: villitis of unknown etiology (VUE), chronic histiocytic intervillositis (CHI) and massive perivillous fibrin deposition (MPFD). The hallmark of these disorders is infiltration of the placental architecture by maternal immune cells and disruption of the intervillous space, where gas exchange between the mother and fetus occurs. Currently, they can only be detected through histopathological examination of the placenta after a pregnancy has ended. All three are associated with a significant risk of recurrence in subsequent pregnancies. Villitis of unknown etiology is characterised by a destructive infiltrate of maternal CD8+ T lymphocytes invading into the chorionic villi, combined with activation of fetal villous macrophages. The diagnosis can only be made when an infectious aetiology has been excluded. VUE becomes more common as pregnancy progresses and is frequently seen with normal pregnancy outcome. However, severe early-onset villitis is usually associated with fetal growth restriction and recurrent pregnancy loss. Chronic histiocytic intervillositis is characterised by excessive accumulation of maternal CD68+ histiocytes in the intervillous space. It is associated with a wide spectrum of adverse pregnancy outcomes including high rates of first-trimester miscarriage, severe fetal growth restriction and late intrauterine fetal death. Intervillous histiocytes can also accumulate due to infection, including SARS-CoV-2, although this infection-induced intervillositis does not appear to recur. As with VUE, the diagnosis of CHI requires exclusion of an infectious cause. Women with recurrent CHI and their families are predisposed to autoimmune diseases, suggesting CHI may have an alloimmune pathology. This observation has driven attempts to prevent CHI with a wide range of maternal immunosuppression. Massive perivillous fibrin deposition is diagnosed when >25% of the intervillous space is occupied by fibrin, and is associated with fetal growth restriction and late intrauterine fetal death. Although not an inflammatory disorder per se, MPFD is frequently seen in association with both VUE and CHI. This review summarises current understanding of the prevalence, diagnostic features, clinical consequences, immune pathology and potential prophylaxis against recurrence in these three chronic inflammatory placental syndromes.

Chronic histiocytic intervillositis (CHI): current treatments and perinatal outcomes, a systematic review and a meta-analysis

BACKGROUND

Chronic histiocytic intervillositis (CHI) is a rare placental lesion with a high recurrence rate and poor perinatal outcomes. There are currently limited guidelines regarding the diagnosis of this condition in the index pregnancy and treatment where recurrence is suspected.

OBJECTIVE

The primary objective of this systematic review and meta-analysis was to determine the perinatal outcomes of pregnancies affected by chronic histiocytic intervillositis and to what extent they can be improved with treatment. The secondary objective was to assess the relationship between CHI lesion severity and pregnancy loss.

METHODS

A systematic search of Ovid Embase, Web of Science, Science Direct, PubMed, Ovid Medline, Google Scholar and CINAHL was carried out. Case reports, cohort, case-control and randomised controlled trials (RCT) detailing the perinatal outcomes of CHI pregnancies, both treated and untreated, were included.

RESULTS

No RCTs were identified. However, in a review population of 659 pregnancies, with additional 7 in case reports, CHI treatments included aspirin, prednisone, prednisolone, low molecular weight heparin (LMWH), hydroxychloroquine and adalimumab. A descriptive synthesis of data found mixed results for treatments in relation to live birth, miscarriage and fetal growth restriction outcomes. Furthermore, quantitative synthesis of 38 pregnancies revealed a non-significant improvement in live birth rate with CHI targeted treatment (OR 1.79 [95% CI 0.33-9.61] (p=0.50), while meta-analysis of CHI severity in line with pregnancy loss, in a sample of 231 pregnancies, revealed lower odds of pregnancy loss with less severe lesions (OR: 0.17 [0.03-0.80], p=0.03).

CONCLUSIONS

This systematic review and meta-analysis reinforce notions surrounding the insufficient evidence for CHI treatment. It also strengthens previous hypotheses detailing the positive association between CHI lesion severity and odds of pregnancy loss. Aspirin, LMWH, prednisolone, hydroxychloroquine and adalimumab are candidates with varying levels of weak to moderate evidence supporting their use. Further prospective research is required to obtain robust evidence pertaining to treatment safety and efficacy and optimal drug regimes.

SYSTEMATIC REVIEW REGISTRATION

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