Characterizing Histopathologic Features in Pregnancies With Chronic Histiocytic Intervillositis Using Computerized...

Area of Science:

• Reproductive immunology
• Pathology
• Perinatal medicine

Background:

• Chronic histiocytic intervillositis (CHI) is a rare placental condition linked to adverse pregnancy outcomes like fetal growth restriction and stillbirth.
• Current diagnostic methods for CHI are subjective, hindering research and treatment development.
• The etiology and effective treatments for CHI remain poorly understood.

Purpose of the Study:

• To objectively quantify inflammatory cells and fibrin in placentas affected by CHI compared to controls.
• To investigate changes in placental pathology in subsequent pregnancies after a CHI diagnosis.
• To characterize the phenotype of macrophages in untreated CHI cases.

Main Methods:

• Computerized analysis of immunohistochemically stained placental tissues from untreated CHI cases, subsequent pregnancies, and controls.
• Immunofluorescence staining was used to identify M1 (CD80, CD86) and M2 (CD163, CD206) macrophage markers in CHI placentas.
• Quantification of macrophage infiltration and fibrin deposition was performed.

Main Results:

• A median 32-fold increase in macrophage infiltration was observed in CHI placentas compared to controls.
• CHI recurred in 18.2% of subsequent pregnancies; however, 28.6% of diagnosed CHI cases did not show elevated infiltration.
• Macrophages in CHI placentas predominantly expressed CD163, suggesting an anti-inflammatory role, while CD3+ T cells were elevated but normalized in subsequent pregnancies.

Conclusions:

• Intervillous macrophages in CHI expressing CD163 may indicate an attempt to resolve inflammation.
• Computerized analysis of placental inflammation can aid in assessing treatment efficacy and grading lesion severity in CHI.
• Objective quantification of placental pathology is crucial for understanding CHI and its recurrence.