Related Experiment Video
Updated: Jun 15, 2025
A Non-invasive Way to Isolate and Phenotype Cells from the Conjunctiva
Published on: July 5, 2017
Complement Component C5a and Fungal Pathogen Induce Diverse Responses through Crosstalk between Transient Receptor
Loreena Rech1, Tina Dietrich-Ntoukas1, Peter S Reinach2
1Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany.
Abstract:
The conjunctiva has immune-responsive properties to protect the eye from infections. Its innate immune system reacts against external pathogens, such as fungi. The complement factor C5a is an important contributor to the initial immune response. It is known that activation of transient-receptor-potential-vanilloid 1 (TRPV1) and TRP-melastatin 8 (TRPM8) channels is involved in different immune reactions and inflammation in the human body. The aim of this study was to determine if C5a and mucor racemosus e voluminae cellulae (MR) modulate Ca2+-signaling through changes in TRPs activity in human conjunctival epithelial cells (HCjECs). Furthermore, crosstalk was examined between C5a and MR in mediating calcium regulation. Intracellular Ca2+-concentration ([Ca2+]i) was measured by fluorescence calcium imaging, and whole-cell currents were recorded using the planar-patch-clamp technique. MR was used as a purified extract. Application of C5a (0.05-50 ng/mL) increased both [Ca2+]i and whole-cell currents, which were suppressed by either the TRPV1-blocker AMG 9810 or the TRPM8-blocker AMTB (both 20 µM). The N-terminal peptide C5L2p (20-50 ng/mL) blocked rises in [Ca2+]i induced by C5a. Moreover, the MR-induced rise in Ca2+-influx was suppressed by AMG 9810 and AMTB, as well as 0.05 ng/mL C5a. In conclusion, crosstalk between C5a and MR controls human conjunctival cell function through modulating interactions between TRPV1 and TRPM8 channel activity.
Insights
The complement factor C5a and Mucor racemosus (MR) impact eye immune cells by altering calcium signaling via TRPV1 and TRPM8 channels. This study reveals crosstalk between C5a and MR in regulating human conjunctival epithelial cell function.
Area of Science:
- Immunology
- Cell Biology
- Ophthalmology
Background:
- The conjunctiva possesses immune functions to defend the eye against pathogens like fungi.
- The complement factor C5a is crucial for initiating immune responses.
- Transient receptor potential channels (TRPV1 and TRPM8) are implicated in immune reactions and inflammation.
Purpose of the Study:
- To investigate if C5a and Mucor racemosus (MR) modulate calcium signaling in human conjunctival epithelial cells (HCjECs) by altering TRP channel activity.
- To examine the crosstalk between C5a and MR in regulating calcium.
Main Methods:
- Intracellular calcium concentration ([Ca2+]i) was measured using fluorescence calcium imaging.
- Whole-cell currents were recorded via the planar-patch-clamp technique.
- Purified Mucor racemosus (MR) extract was utilized.
Main Results:
- C5a application increased [Ca2+]i and whole-cell currents, which were inhibited by TRPV1 and TRPM8 blockers.
- The C5a-related peptide C5L2p inhibited C5a-induced [Ca2+]i increases.
- MR-induced calcium influx was reduced by TRPV1/TRPM8 blockers and low-dose C5a.
Conclusions:
- C5a and MR interact to regulate human conjunctival cell function.
- This regulation occurs through modulation of TRPV1 and TRPM8 channel activity.
- Crosstalk between C5a and MR influences immune responses in the conjunctiva.
