Equine Enteric Glial Culture and Application to the Study of a Neural Inflammatory Mechanism in Equine Colic

Summary

Enteric glia are becoming increasingly recognized for their roles in intestinal homeostasis and disease processes, including postoperative complications. Equine patients recovering from emergency exploratory laparotomy suffer from a high risk of inflammatory postoperative conditions, highlighting the importance of establishing repeatable equine enteric glial primary cell culture for study.

Abstract

Inflammatory postoperative conditions of equine colic (acute abdomen) contribute not only to increased client cost, patient discomfort, and hospitalization time, but in many cases, prove to be life-threatening. A unique population of intestinal cells, enteric glia, are increasingly acknowledged for their roles in sensing the gastrointestinal environment and communicating with surrounding cell types. Interactions between enteric glia and intestinal epithelia may prove critical in establishing how equine enteric glia can alter the mucosal barrier to modulate inflammation in health and colic.

To study this interaction, we present a method of establishing primary equine enteric glial cultures from equine jejunum and exposing the cultures to inflammatory conditions known to be present in colic. Primary enteric glial cultures were obtained from adult horses euthanized for reasons unrelated to colic. Intestinal villi and lamina propria were micro-dissected to expose the submucosa. The isolated submucosa underwent enzymatic digestion with collagenase, protease, and bovine serum albumin for 2-3 h. Next, mechanical digestion involving centrifugation, pipetting, and cell strainers (40-100 µm), yielded a pellet used for plating on 0.05 mg/mL poly-L-lysine-coated wells at a concentration of ~400,000 cells/300 µL of media.

Following confluence and first passage, the enteric glial cells were then exposed to equine recombinant IL-1β (0, 10, 25 ng) for 24 h. To model epithelial-glial interactions at the time of colic, medium conditioned by either control or treated enteric glia was added directly to confluent equine jejunal monolayers while measuring transepithelial electrical resistance (TEER) using a dual-electrode EndOhm chamber. These data demonstrate just one of many potential impactful applications of equine enteric glial culture.

Introduction

Equine colic is the most prevalent medical presenting complaint for emergency consultation¹. With up to 17% of those horses requiring surgical correction, efforts to increase postoperative outcomes should be at the forefront of equine medical research². Currently, postoperative colic patients experience a high risk of several life-threatening disorders including sepsis/endotoxemic shock (12.3% of patients) and postoperative ileus (13.7% of patients)³. Despite progress in treatment for postoperative complications, there continues to be a need for advanced treatments for preventing or treating these....

Protocol

Equine enteric glial primary cultures were obtained from three horses humanely euthanized with an overdose of a barbiturate for reasons unrelated to this study. The horses selected for the culture studies were adult horses with no current history of gastrointestinal disease.

1. Submucosal equine enteric glial primary culture

1. Grow equine epithelial monolayers from jejunal crypts obtained from three separate adult equine horses.
   1. Coat 24-well plates with c.......

Discussion

The aim of this study was to develop a repeatable method of primary culture of equine submucosal enteric glia and demonstrate its application to model epithelial-glial interactions at the time of colic. Enteric glia isolation and culture, which is novel in the horse, has proven beneficial in understanding intestinal disease pathways in pig and rodent models and in humans^6,7,13,14. Studying this.......

Materials

Name	Company	Catalog Number	Comments
1 M HEPES buffer	Gibco	15630-080
10 mM HEPES	Life Technologies	15630-106
2 mM GlutaMAX	Life Technologies	25050-061
4’6-Diaminidino-2-Phenylindol	Invitrogen	D3571
Advanced DMEM/F12	Life Technologies	12634-010
Alpha smooth muscle actin antibody	Abcam	7817
Amphotericin B	Sigma	AA9529	4.4 g/mL stock aliquots, final concentration 1.1 µg/mL
Anti-Antimicotic 1x	Gibco	15240-096
B27	Gibco	12587010
Bovine Serum Albumin	Sigma	AA3311
BSA 50 mg/mL stock solution	Sigma	A3311
CaCL2	ACROS Organiics	206791000	Component of Equine Ringer ‘s Stock 1: combine with other ingredients, then add 100 mL of this stock to a graduated cylinder and dilute to 1L with deionized water. Adjust pH to 7.4 with 5% CO2. Combine with Equine Ringer’s Stock 2 to make complete “Ringer’s Solution”.
Collagenase	Sigma	9891
DMEM-F12 media	Thermo Fisher	11320033
Donkey anti-rabbit IgG Alexa Fluor 594	Invitrogen	21207
EVOM EndOhm dual electrode TEER-measuring chamber	World Precision Instruments	EVM-EL-03-01
EVOM Manual for TEER Measurement	World Precision Instruments	EVM-MT-03-01
G5	Gibco	17503012
Gentamicin solution	Sigma	G1272	Final concentration 20 µg/mL
GFAP antibody	Abcam	4674
Goat anti-mouse IgG Alexa Fluor 488	Invitrogen	28175
IL-1β ELISA	Thermo Fisher	ESIL1B
KCl	Thermo Fisher	P330-500	Component of Equine Ringer’s Stock 1: combine with other ingredients, then add 100 mL of this stock to a graduated cylinder and dilute to 1L with deionized water. Adjust pH to 7.4 with 5% CO2. Combine with Equine Ringer’s Stock 2 to make complete “Ringer’s Solution”.
L-glutamine solution	Corning	25-00-Cl
Matrigel	BD Bioscience	354277
MgCl2	Thermo Fisher	M33-500	Component of Equine Ringer’s Stock 1: combine with other ingredients, then add 100 mL of this stock to a graduated cylinder and dilute to 1L with deionized water. Adjust pH to 7.4 with 5% CO2. Combine with Equine Ringer’s Stock 2 to make complete “Ringer’s Solution”.
N2	Gibco	17502048
Na2HPO4	Thermo Fisher	BP332-1	Component of Equine Ringer’s Stock 2: combine with other ingredients, then add 100 mL of this stock to a graduated cylinder and dilute to 1L with deionized water. Adjust pH to 7.4 with 5% CO2. Combine with Equine Ringer’s Stock 1 to make complete “Ringer’s Solution”.
NaCl	Thermo Fisher	S271-10	Component of Equine Ringer’s Stock 1: combine with other ingredients, then add 100 mL of this stock to a graduated cylinder and dilute to 1L with deionized water. Adjust pH to 7.4 with 5% CO2. Combine with Equine Ringer’s Stock 2 to make complete “Ringer’s Solution”.
NaH2PO4	Thermo Fisher	BP329-500	Component of Equine Ringer’s Stock 2: combine with other ingredients, then add 100 mL of this stock to a graduated cylinder and dilute to 1L with deionized water. Adjust pH to 7.4 with 5% CO2. Combine with Equine Ringer’s Stock 1 to make complete “Ringer’s Solution”.
NaHCO3	Thermo Fisher	S637-212	Component of Equine Ringer’s Stock 2: combine with other ingredients, then add 100 mL of this stock to a graduated cylinder and dilute to 1L with deionized water. Adjust pH to 7.4 with 5% CO2. Combine with Equine Ringer’s Stock 1 to make complete “Ringer’s Solution”.
Pen/Strep solution	Gemini	400-109
Poly-L-lysine	Sigma	P2636	0.5 mg/mL in 1x borate buffer
Prism software	GraphPad
Protease	Sigma	P4630
Sodium bicarbonate solution	Sigma	S8761	7.5% stock solution