ALI	Air-Liquid Interface
BHI	brain heart infusion
BSA	bovine serum albumin
CRP	C-reactive protein
DAMGO	[D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin acetate salt
DAPI	4ʹ,6-Diamidino-2-Phenylindole, Dihydrochloride
DPDPE	[D-Pen 2,5] Enkephalin
EV	extracellular vesicles
GC-MS	gas chromatography-mass spectrometry
GI	gastrointestinal
HBV	Hepatitis B Virus
HCV	Hepatitis C Virus
HIV	Human immunodeficiency virus
IBD	Inflammatory Bowel Disease
IL-1β	Interleukin-1β
IL-6	Interleukin-6
IL-8	Interleukin-8
IFABP	Intestinal-type fatty acid-binding protein
LCN2	Lipocalin-2
LBP	Lipopolysaccharide binding protein
MIP1α	macrophage inflammatory protein 1 α
MMT	methadone maintenance treatment
MRPS	microfluidic resistive pulse sensing
ns	not significant
OIBD	opioid-induced bowel dysfunction
OR	opioid receptors
OD	optical density
OMV	outer membrane vesicles
PCA	Principal component analysis
SCFAs	short chain fatty acids
TFF	tangential flow filtration
TJ	tight junctions
TEER	transepithelial electrical resistance
TNFα	tumor necrosis factor α.