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Updated: Apr 14, 2026
Analysis of Lymphocyte Extravasation Using an In Vitro Model of the Human Blood-brain Barrier
Published on: April 5, 2017
[Role of CD44 in monocyte transmigration across Cryptococcus neoformans-infected blood-brain barrier in vitro]
Li-Ke Zhang1, Jia-Wen Qiu, Xiao-Lu Liang
1Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou 510515, China.
Objective:
To explore the role of CD44 in monocyte adhesion to human brain microvascular endothelial cells (HBMECs) and monocyte migration across an in vitro model of blood-brain barrier (BBB) infected by Cryptococcus neoformans (Cn).
Methods:
An in vitro blood-brain barrier model was constructed using a transwell chamber covered with a HBMEC monolayer. The wild-type strain of Cn B4500FO2, TYCC645#32 strain with CPS1 gene deletion and PCIP strain with CPS1 complementation were chosen to infect the monolayer HBMECs. THP-1 cells were added to the upper chamber of transwell, and the relative migration rate was determined by counting the number of the cells entering the lower chambers. The inhibitory effects of anti-CD44 monoclonal antibody and the CD44 inhibitor bikunin were examined on THP-1 binding to and migration across HBMECs.
Results:
Cn infection of the HBMECs caused markedly enhanced THP-1 cell adhesion and migration across the monolyers (P<0.01) dependent on Cn concentration and exposure time. Addition of anti-CD44 monoclonal antibody and bikunin significantly lowered THP-1 adhesion and migration rates in the BBB model with Cn-infected HBMECs (P<0.01) with a dose dependence of the antibody (within 0-1 µg) and inhibitor (within 0-20 nmol/L). Both THP-1 adhesion rate and migration rate were lowered in the BBB model infected with CPS1 gene-deleted Cn but increased in the model infected with the complemented strain compared with those in the wild-type strain-infected model.
Conclusion:
In the in vitro BBB model, CD44 expressed on HBMECs may play an essential role in monocyte adhesion to and migration across the BBB. The capsular hyaluronic acid may mediate Cn-induced monocyte adhesion and migration.
Insights
CD44 on brain endothelial cells promotes monocyte adhesion and migration during Cryptococcus neoformans infection. Inhibiting CD44 reduces this process, suggesting a therapeutic target for fungal meningitis.
Area of Science:
- Neuroscience
- Immunology
- Microbiology
Background:
- The blood-brain barrier (BBB) protects the central nervous system but can be compromised during infection.
- Monocyte infiltration across the BBB is crucial for host defense but can also contribute to pathology.
- Cryptococcus neoformans (Cn) infection poses a significant threat, necessitating understanding of immune cell interactions at the BBB.
Purpose of the Study:
- To investigate the role of CD44 in monocyte adhesion to and migration across human brain microvascular endothelial cells (HBMECs).
- To determine the impact of Cryptococcus neoformans (Cn) infection on these interactions.
- To evaluate the potential of targeting CD44 as a therapeutic strategy.
Main Methods:
- An in vitro BBB model using HBMEC monolayers was established.
- HBMECs were infected with wild-type, CPS1-deleted, or complemented strains of Cn.
- THP-1 monocyte adhesion and transendothelial migration were quantified.
- The effects of anti-CD44 antibody and bikunin on monocyte interactions were assessed.
Main Results:
- Cn infection significantly increased THP-1 cell adhesion and migration across HBMECs in a dose- and time-dependent manner.
- Anti-CD44 antibody and bikunin treatment dose-dependently reduced THP-1 adhesion and migration.
- Monocyte migration was reduced with CPS1-deleted Cn but increased with the complemented strain, indicating the role of the fungal capsule.
Conclusions:
- CD44 expressed on HBMECs plays a critical role in mediating monocyte adhesion and migration across the BBB during Cn infection.
- The capsular hyaluronic acid of Cn appears to be a key mediator of this CD44-dependent process.
- Targeting CD44 may represent a viable therapeutic approach to control neuroinflammation in cryptococcal meningitis.
