Metabolic profiling of listeria rhombencephalitis in small ruminants by ¹H high‐resolution magic angle spinning NMR spectroscopy

Abstract

Listeria rhombencephalitis is caused by infection with Listeria monocytogenes and is associated with a high mortality rate in humans and ruminants. Little is known about the metabolic changes associated with neurolisteriosis in particular and infectious central nervous system (CNS) diseases in general. The purpose of our study was to investigate the metabolic changes associated with listeria rhombencephalitis in small ruminants (goats and sheep) as a model for inflammatory CNS disease by 1H high‐resolution magic angle spinning nuclear magnetic resonance (1H HR‐MAS NMR) spectroscopy of brain biopsies obtained from the brainstem and thalamus. Statistical analysis revealed distinct differences in the metabolic profile of brainstem biopsies, the primary location of listeria rhombencephalitis with moderate or severe inflammatory changes. N‐Acetylaspartate (NAA), N‐acetylaspartylglutamate, choline, myo‐inositol and scyllo‐inositol were decreased, and glycine, phosphocholine, taurine and lactate were increased, in the diseased group (n = 13) in comparison with the control group (n = 12). In the thalamus, which showed no or only mild inflammatory changes in the majority of animals, no statistically significant metabolic changes were observed. However, trends for metabolic alterations were partly the same as those found in the brainstem, including NAA, choline and lactate. This may be an indicator of metabolic changes occurring in the early stages of the disease. Therefore, further research with a larger number of animals is needed to evaluate the presence of subtle metabolic changes associated with mild inflammatory changes in the thalamus. In conclusion, 1H HR‐MAS NMR investigation of listeria rhombencephalitis identified brain metabolite changes, offering new insights into the disease pathophysiology.

Sampling Method Affects HR-MAS NMR Spectra of Healthy Caprine Brain Biopsies

“…In accordance with previous studies [7,13], we observed relatively increased concentrations of NAAG and mIns in the brainstem compared to the thalamus, and NAA and PC in the thalamus compared to the brainstem in both in vivo-and postmortemharvested samples, underlining the importance of the differences in the metabolic profiles of brain regions.…”

“…Within 3 min after the insertion of the biopsy needle the biopsy was snap frozen in liquid nitrogen and stored at −80 • C. Up to 4 biopsies were taken at each target by turning the needle clockwise and obtaining a biopsy at positions 0 • , 90 • , 180 • and 240 • . As the goats served as the control group in another study [13], only one of the biopsies was used for this study. The goats were euthanized immediately after in vivo biopsy using pentobarbitalum (Euthasol ® , Virbac AG, Switzerland, dosage: 400 mg/kg intravenously).…”

“…In addition, care was taken to ensure that the time between taking the sample out of the freezer and the start of the first scan at a stable temperature of 278 K remained as identical as possible for all samples (in vivo samples: 36 +/− 8 min; postmortem samples: 45 +/− 11 min). All experiments were performed in a 500.13 MHz Bruker Avance II spectrometer (Bruker Biospin AG, Fällanden, Switzerland) equipped with a 4 mm HR-MAS dual inverse ( 1 H, 13 C) probe. Spectra were acquired in a randomized order using a 1D 1 H sequence with water presaturation and with a T2-filter eliminating J-modulation ("PROJECT" Periodic Refocusing of J Evolution by Coherence Transfer [26]) at a 3 kHz MAS rate and nominal 278 K. Each 1D 1 H NMR spectrum was acquired by applying 512 transients, a spectral width of 6010 Hz, a data size of 32 K points, an acquisition time of 2.73 s, a relaxation delay of 4 s, an echo time (TE) of 400 ms, and a rotor-synchronized interpulse delay of 1.33 ms [27].…”

Neurotropic Lineage III Strains of Listeria monocytogenes Disseminate to the Brain without Reaching High Titer in the Blood

“…In an early study, L. monocytogenes strain 511 was injected into the lips of goats, and this resulted in circling and other neurological signs; however, the infection was lethal for most of the animals ( 50 ). More recently, the Oevermann group has done elegant studies of rhombencephalitis in sheep and cows ( 20 , 51 – 53 ), but work with large animals is expensive, and these model systems lack the extensive mutant and transgenic tools available for the study of host responses to infection in mice. Another group inoculated low doses of strain EGD into the middle ear of gerbils, causing a persistent otitis media that eventually led to brain infection ( 54 ).…”

Evaluation of MMP-9 and iNOS expressions in sheep with encephalitic listeriosis

“…This infection can lead to different clinical symptoms such as gastroenteritis with high fever, mastitis, encephalitis, septicemia and abortion (3,20). Encephalitic listeriosis caused by only species-L. monocytogenes is more common especially in small ruminants and has high mortality rates (1,37). Sheep are more sensitive to listeriosis than cattle (9).…”