Category: Animals

Mouse Adapted SARS-CoV-2 Model Induces “Long-COVID” Neuropathology in BALB/c Mice

Abstract:

The novel coronavirus SARS-CoV-2 has caused significant global morbidity and mortality and continues to burden patients with persisting neurological dysfunction. COVID-19 survivors develop debilitating symptoms to include neuro-psychological dysfunction, termed “Long COVID”, which can cause significant reduction of quality of life. Despite vigorous model development, the possible cause of these symptoms and the underlying pathophysiology of this devastating disease remains elusive.

Mouse adapted (MA10) SARS-CoV-2 is a novel mouse-based model of COVID-19 which simulates the clinical symptoms of respiratory distress associated with SARS-CoV-2 infection in mice. In this study, we evaluated the long-term effects of MA10 infection on brain pathology and neuroinflammation. 10-week and 1-year old female BALB/cAnNHsd mice were infected intranasally with 10 4 plaque-forming units (PFU) and 10 3 PFU of SARS-CoV-2 MA10, respectively, and the brain was examined 60 days post-infection (dpi).

Immunohistochemical analysis showed a decrease in the neuronal nuclear protein NeuN and an increase in Iba-1 positive amoeboid microglia in the hippocampus after MA10 infection, indicating long-term neurological changes in a brain area which is critical for long-term memory consolidation and processing. Importantly, these changes were seen in 40-50% of infected mice, which correlates to prevalence of LC seen clinically.

Our data shows for the first time that MA10 infection induces neuropathological outcomes several weeks after infection at similar rates of observed clinical prevalence of “Long COVID”. These observations strengthen the MA10 model as a viable model for study of the long-term effects of SARS-CoV-2 in humans. Establishing the viability of this model is a key step towards the rapid development of novel therapeutic strategies to ameliorate neuroinflammation and restore brain function in those suffering from the persistent cognitive dysfunction of “Long-COVID”.

Source: Gressett TE, Leist SR, Ismael S, Talkington G, Dinnon KH, Baric RS, Bix G. Mouse Adapted SARS-CoV-2 Model Induces “Long-COVID” Neuropathology in BALB/c Mice. bioRxiv [Preprint]. 2023 Mar 20:2023.03.18.533204. doi: 10.1101/2023.03.18.533204. PMID: 36993423; PMCID: PMC10055301. https://www.biorxiv.org/content/10.1101/2023.03.18.533204v1.full (Full text)

SARS-CoV-2 infection induces DNA damage, through CHK1 degradation and impaired 53BP1 recruitment, and cellular senescence

Abstract:

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the RNA virus responsible for the coronavirus disease 2019 (COVID-19) pandemic. Although SARS-CoV-2 was reported to alter several cellular pathways, its impact on DNA integrity and the mechanisms involved remain unknown. Here we show that SARS-CoV-2 causes DNA damage and elicits an altered DNA damage response.

Mechanistically, SARS-CoV-2 proteins ORF6 and NSP13 cause degradation of the DNA damage response kinase CHK1 through proteasome and autophagy, respectively. CHK1 loss leads to deoxynucleoside triphosphate (dNTP) shortage, causing impaired S-phase progression, DNA damage, pro-inflammatory pathways activation and cellular senescence. Supplementation of deoxynucleosides reduces that. Furthermore, SARS-CoV-2 N-protein impairs 53BP1 focal recruitment by interfering with damage-induced long non-coding RNAs, thus reducing DNA repair.

Key observations are recapitulated in SARS-CoV-2-infected mice and patients with COVID-19. We propose that SARS-CoV-2, by boosting ribonucleoside triphosphate levels to promote its replication at the expense of dNTPs and by hijacking damage-induced long non-coding RNAs’ biology, threatens genome integrity and causes altered DNA damage response activation, induction of inflammation and cellular senescence.

Source: Gioia U, Tavella S, Martínez-Orellana P, Cicio G, Colliva A, Ceccon M, Cabrini M, Henriques AC, Fumagalli V, Paldino A, Presot E, Rajasekharan S, Iacomino N, Pisati F, Matti V, Sepe S, Conte MI, Barozzi S, Lavagnino Z, Carletti T, Volpe MC, Cavalcante P, Iannacone M, Rampazzo C, Bussani R, Tripodo C, Zacchigna S, Marcello A, d’Adda di Fagagna F. SARS-CoV-2 infection induces DNA damage, through CHK1 degradation and impaired 53BP1 recruitment, and cellular senescence. Nat Cell Biol. 2023 Mar 9. doi: 10.1038/s41556-023-01096-x. Epub ahead of print. PMID: 36894671. https://www.nature.com/articles/s41556-023-01096-x (Full text)

Panax ginseng improves physical recovery and energy utilization on chronic fatigue in rats through the PI3K/AKT/mTOR signalling pathway

Abstract:

Context: Panax ginseng C. A. Meyer (Araliaceae) is a tonic herb used in ancient Asia.

Objective: This study investigated the antifatigue effect of P. ginseng on chronic fatigue rats.

Materials and methods: Sprague-Dawley rats were divided into control, model and EEP (ethanol extraction of P. ginseng roots) (50, 100 and 200 mg/kg) groups (n = 8). The rats were subcutaneously handled with loaded swimming once daily for 26 days, except for the control group. The animals were intragastrically treated with EEP from the 15th day. On day 30, serum, liver and muscles were collected, and the PI3K/Akt/mTOR signalling pathway was evaluated.

Results: The swimming times to exhaust of the rats with EEP were significantly longer than that without it. EEP spared the amount of muscle glycogen, hepatic glycogen and blood sugar under the chronic state. In addition, EEP significantly (p < 0.05) decreased serum triglycerides (1.24 ± 0.17, 1.29 ± 0.04 and 1.20 ± 0.21 vs. 1.58 ± 0.13 mmol/L) and total cholesterol (1.64 ± 0.36, 1.70 ± 0.15 and 1.41 ± 0.19 vs. 2.22 ± 0.19 mmol/L) compared to the model group. Regarding the regulation of energy, EEP had a positive impact on promoting ATPase activities and relative protein expression of the PI3K/Akt/mTOR pathway.

Conclusions: Our results suggested that EEP effectively relieved chronic fatigue, providing evidence that P. ginseng could be a potential dietary supplement to accelerate recovery from fatigue.

Source: Zhang G, Lu B, Wang E, Wang W, Li Z, Jiao L, Li H, Wu W. Panax ginseng improves physical recovery and energy utilization on chronic fatigue in rats through the PI3K/AKT/mTOR signalling pathway. Pharm Biol. 2023 Dec;61(1):316-323. doi: 10.1080/13880209.2023.2169719. PMID: 36695132; PMCID: PMC9879180. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9879180/ (Full text)

Effect of herbal cake-separated moxibustion on behavioral stress reactions and blood lactic acid level and muscular AMPK/PGC-1α signaling in rats with chronic fatigue syndrome

Abstract:

in English, Chinese

Objective: To observe the effect of herbal cake-separated moxibustion (HCSM) on serum lactic acid (BLA) level and AMPK/PGC-1α signaling pathway in the quadriceps femoris in chronic fatigue syndrome (CFS) rats, so as to explore its mechanisms underlying improvement of CFS.

Methods: According to the random number table, 50 SD rats were divided into blank control, model, HCSM, sham HCSM and medication (herbal medicine gavage) groups, with 10 rats in each group. The CFS model was established by using chronic restraint and exhaustive swimming, alternately, once daily for 21 days. The herbal cake was made of Xiaoyao Powder (Mental Ease Powder, composed of [Danggui (Radix Angelicae Sinensis), Baishao (Radix Paeoniae Alba), Chaihu (Radix Bupleuri), Fuling (Poria), Baizhu (Rhizoma Atractylodis, Macrocephalae), etc.]. The HCSM was applied to “Shenque” (CV8), “Guanyuan “(CV4), bilateral “Zusanli” (ST36) and “Qimen” (LR14), 5 moxa-cones for each acupoint, once daily for 10 days. For sham HCSM, the excipient was instead of herbal cake, and the same 5 moxa-cones was given as the HCSM group. Rats of the medication group received gavage of Xiaoyao Powder suspension (60 mg·kg-1), once daily for 10 days. The open field test and tail suspension test were conducted for determining the animals’ locomotor activity. The blood sample was taken from the abdominal aorta under anesthesia for assaying the levels of serum BLA, chemokine ligand CXCL9 and β-endorphin (EP) by ELISA. Bilateral quadriceps femoris were sampled for observing histopathological changes after staining with conventional H.E. technique, and for detecting the expression levels of phosphorylated AMP-activated protein kinase (p-AMPK) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) by using immunohistochemistry.

Results: Compared with the blank control group, the number of rearing and horizontal grid-crossing times, struggling times of tail suspension test were significantly decreased (P<0.05), and the immobility time was obviously prolonged (P<0.05) in the model group. Compared with the model group, both HCSM and medication groups had a significant increase of rearing, horizontal grid-crossing times and struggling times (P<0.05), and the immobility time had a significant decrease (P<0.05). But there were no significant differences in the total movement distance among the 5 groups (P>0.05), and in the 5 indexes of behavioral measurements between the HCSM and medication groups (P>0.05). The sham HCSM could also evidently increase the struggling times and reduce the immobility time (P<0.05). The contents of serum BLA, CXCL9 and β-EP were obviously higher in the model group than in the blank control group (P<0.05), as well as remarkably lower in the HCSM and medication groups than in the model group (P<0.05). Whereas the expression levels of muscular p-AMPK and PGC-1α were considerably lower in the model group than in the blank control group (P<0.05), and significantly increased in both HCSM and medication groups relevant to the model group (P<0.05). Compared with the sham HCSM group, the contents of BLA, CXCL9 and β-EP in serum of the HCSM group and contents of CXCL9, β-EP in medication group were significantly decreased (P<0.05), and the protein expressions of p-AMPK and PGC-1α in quadriceps femoris in both HCSM and medication groups were significantly increased (P<0.05). H.E. staining showed smaller intercellular space, uneven cytoplasmic staining in some muscle fibers, nucleus pyknosis and condensation, and inflammatory cell infiltration in the model group, which was milder in both HCSM and medication groups.

Conclusion: HCSM can mitigate the stress behavioral state in CFS rats, which may be related with its functions in lowering the levels of serum BLA, CXCL9 and β-EP, and activating AMPK/PGC-1α signaling pathway (balancing energy metabolism) in the quadriceps femoris.

Source: Xu XS, Ma W, Xiong LJ, Zhai CT, Li W, Tian YF. [Effect of herbal cake-separated moxibustion on behavioral stress reactions and blood lactic acid level and muscular AMPK/PGC-1α signaling in rats with chronic fatigue syndrome]. Zhen Ci Yan Jiu. 2022 Oct 25;47(10):878-84. Chinese. doi: 10.13702/j.1000-0607.20220017. PMID: 36301164. https://pubmed.ncbi.nlm.nih.gov/36301164/

After the virus has cleared-Can preclinical models be employed for Long COVID research?

Abstract:

Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) can cause the life-threatening acute respiratory disease called COVID-19 (Coronavirus Disease 2019) as well as debilitating multiorgan dysfunction that persists after the initial viral phase has resolved. Long COVID or Post-Acute Sequelae of COVID-19 (PASC) is manifested by a variety of symptoms, including fatigue, dyspnea, arthralgia, myalgia, heart palpitations, and memory issues sometimes affecting between 30% and 75% of recovering COVID-19 patients. However, little is known about the mechanisms causing Long COVID and there are no widely accepted treatments or therapeutics.

After introducing the clinical aspects of acute COVID-19 and Long COVID in humans, we summarize the work in animals (mice, Syrian hamsters, ferrets, and nonhuman primates (NHPs)) to model human COVID-19. The virology, pathology, immune responses, and multiorgan involvement are explored. Additionally, any studies investigating time points longer than 14 days post infection (pi) are highlighted for insight into possible long-term disease characteristics.

Finally, we discuss how the models can be leveraged for treatment evaluation, including pharmacological agents that are currently in human clinical trials for treating Long COVID. The establishment of a recognized Long COVID preclinical model representing the human condition would allow the identification of mechanisms causing disease as well as serve as a vehicle for evaluating potential therapeutics.

Source: Jansen EB, Orvold SN, Swan CL, Yourkowski A, Thivierge BM, Francis ME, Ge A, Rioux M, Darbellay J, Howland JG, Kelvin AA. After the virus has cleared-Can preclinical models be employed for Long COVID research? PLoS Pathog. 2022 Sep 7;18(9):e1010741. doi: 10.1371/journal.ppat.1010741. PMID: 36070309; PMCID: PMC9451097. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9451097/ (Full text)

COVID-19 induces CNS cytokine expression and loss of hippocampal neurogenesis

Abstract:

Infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with acute and postacute cognitive and neuropsychiatric symptoms including impaired memory, concentration, attention, sleep and affect. Mechanisms underlying these brain symptoms remain understudied.

Here we report that SARS-CoV-2-infected hamsters exhibit a lack of viral neuroinvasion despite aberrant blood-brain barrier permeability. Hamsters and patients deceased from coronavirus disease 2019 (COVID-19) also exhibit microglial activation and expression of interleukin (IL)-1β and IL-6, especially within the hippocampus and the medulla oblongata, when compared with non-COVID control hamsters and humans who died from other infections, cardiovascular disease, uraemia or trauma. In the hippocampal dentate gyrus of both COVID-19 hamsters and humans, we observed fewer neuroblasts and immature neurons.

Protracted inflammation, blood-brain barrier disruption and microglia activation may result in altered neurotransmission, neurogenesis and neuronal damage, explaining neuropsychiatric presentations of COVID-19. The involvement of the hippocampus may explain learning, memory and executive dysfunctions in COVID-19 patients.

Source: Soung AL, Vanderheiden A, Nordvig AS, Sissoko CA, Canoll P, Mariani MB, Jiang X, Bricker T, Rosoklija GB, Arango V, Underwood M, Mann JJ, Dwork AJ, Goldman JE, Boon ACM, Boldrini M, Klein RS. COVID-19 induces CNS cytokine expression and loss of hippocampal neurogenesis. Brain. 2022 Aug 25:awac270. doi: 10.1093/brain/awac270. Epub ahead of print. PMID: 36004663. https://academic.oup.com/brain/advance-article/doi/10.1093/brain/awac270/6672950?login=false  (Full text)

Histamine production by the gut microbiota induces visceral hyperalgesia through histamine 4 receptor signaling in mice

Abstract:

The gut microbiota has been implicated in chronic pain disorders, including irritable bowel syndrome (IBS), yet specific pathophysiological mechanisms remain unclear. We showed that decreasing intake of fermentable carbohydrates improved abdominal pain in patients with IBS, and this was accompanied by changes in the gut microbiota and decreased urinary histamine concentrations.

Here, we used germ-free mice colonized with fecal microbiota from patients with IBS to investigate the role of gut bacteria and the neuroactive mediator histamine in visceral hypersensitivity. Germ-free mice colonized with the fecal microbiota of patients with IBS who had high but not low urinary histamine developed visceral hyperalgesia and mast cell activation. When these mice were fed a diet with reduced fermentable carbohydrates, the animals showed a decrease in visceral hypersensitivity and mast cell accumulation in the colon. We observed that the fecal microbiota from patients with IBS with high but not low urinary histamine produced large amounts of histamine in vitro.

We identified Klebsiella aerogenes, carrying a histidine decarboxylase gene variant, as a major producer of this histamine. This bacterial strain was highly abundant in the fecal microbiota of three independent cohorts of patients with IBS compared with healthy individuals. Pharmacological blockade of the histamine 4 receptor in vivo inhibited visceral hypersensitivity and decreased mast cell accumulation in the colon of germ-free mice colonized with the high histamine-producing IBS fecal microbiota. These results suggest that therapeutic strategies directed against bacterial histamine could help treat visceral hyperalgesia in a subset of patients with IBS with chronic abdominal pain.

Source: De Palma G, Shimbori C, Reed DE, Yu Y, Rabbia V, Lu J, Jimenez-Vargas N, Sessenwein J, Lopez-Lopez C, Pigrau M, Jaramillo-Polanco J, Zhang Y, Baerg L, Manzar A, Pujo J, Bai X, Pinto-Sanchez MI, Caminero A, Madsen K, Surette MG, Beyak M, Lomax AE, Verdu EF, Collins SM, Vanner SJ, Bercik P. Histamine production by the gut microbiota induces visceral hyperalgesia through histamine 4 receptor signaling in mice. Sci Transl Med. 2022 Jul 27;14(655):eabj1895. doi: 10.1126/scitranslmed.abj1895. Epub 2022 Jul 27. PMID: 35895832. https://pubmed.ncbi.nlm.nih.gov/35895832/

Olmesartan alleviates symptoms of chronic fatigue syndrome in mice

Abstract:

Chronic fatigue syndrome (CFS) or myalgic encephalomyelitis (ME) is a lifestyle-related ailment that affects physical and mental abilities.

The etiology is largely unidentified but there are certain multifactorial mechanisms responsible such as mitochondrial aerobic pathways aberrations, hypothalamic-pituitary-adrenal (HPA) axis deregulation, immune hyperactivation, free radicals, pathogen infections, and central neurohumoral alterations.

Olmesartan is an antihypertensive drug that acts on the angiotensin 1 (AT1 ) receptor. The present research evaluated the efficiency of Olmesartanagainst CFS.

CFS was induced by lipopolysaccharide (LPS, 1mg/kg, i.p.) once on day 1 trailed by a forced swim (10 minutes) continued for 21 consecutive times once each day. Olmesartan (1and 3mg/kg, p.o.) and dexamethasone (standard drug, 0.5mg/kg, i.p.) were given from the 1 st to 21 st day.

Immobility time was noted in the forced swim test (FST). Elevated plus maze, raised zero maze, and open field tests were employed to assess animal behavior. Plasma glucose and cortisol, lipid peroxidation, and GSH levels were determined in the whole brain. LPS and repeated forced swim sessions instigated symptoms of CFS such as memory deficit and depression and anxiety-like symptoms.

Findings suggested that Olmesartan shortened the immobility period of mice against CFS in FST. Olmesartan reduced memory deficits, increased ambulation, and exerted an anxiolytic effect. Olmesartan treatment reduced blood cortisol levels, brain TBARS, and enhanced brain GSHin the CFS mouse model.

Hence, Olmesartan may prove to be an effective treatment for CFS and related behavioral discrepancies.

Source:

Animal Models for Neuroinflammation and Potential Treatment Methods

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic disease of unknown etiology and without effective treatment options. The onset of ME/CFS is often associated with neuroinflammation following bacterial or viral infection.

A positron emission tomography imaging study revealed that the degree of neuroinflammation was correlated with the severity of several symptoms in patients with ME/CFS. In animal studies, lipopolysaccharide- and polyinosinic-polycytidylic acid-induced models are thought to mimic the pathological features of ME/CFS and provoke neuroinflammation, characterized by increased levels of proinflammatory cytokines and activation of microglia.

In this review, we described the anti-inflammatory effects of three compounds on neuroinflammatory responses utilizing animal models. The findings of the included studies suggest that anti-inflammatory substances may be used as effective therapies to ameliorate disease symptoms in patients with ME/CFS.

Source: Tamura Y, Yamato M, Kataoka Y. Animal Models for Neuroinflammation and Potential Treatment Methods. Front Neurol. 2022 Jun 27;13:890217. doi: 10.3389/fneur.2022.890217. PMID: 35832182; PMCID: PMC9271866. https://pubmed.ncbi.nlm.nih.gov/35832182/  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9271866/ (Full study)