Swiss Webster Mice Research Articles

Analysis of the antigenic and immunogenic properties of the native rabies virus glycoprotein purified by Lens culinaris lectin affinity chromatography

Rabies virus glycoprotein (RABV-G) is responsible for the recognition of specific cell surface receptors and induces the production of neutralizing antibodies (VNA). Since RABV-G is a glycoprotein, this work aimed to evaluate Lens culinaris (LCA) chromatography as a simple and effective purification method. The purity and identification of the protein obtained were analyzed by SDS-PAGE, ELISA and lectin-binding assay. The antigenic properties of the purified RABV-G were evaluated by direct ELISA using human serum samples from individuals who had received rabies pre-exposurevaccination. For the immunogenicity study, Swiss Webster mice were immunized with purified RABV-G and the specific antibodies were measured by direct ELISA and RFFIT. As results, it was observed that the purified protein reveled a molecular mass of 55 KDa and the presence of carbohydrate; additionally, it was recognized by anti-rabies virus glycoprotein monoclonal antibody. Purified RABV-G induced high VNA titers (>50.0 IU/ml) in vivo, as detected by RFFIT, as well as RABV-G specific IgG1 (0.8 mean OD±SD) and IgG2a (0.3 mean OD±SD) antibodies, with a predominance of IgG1 (p< 0.001). In addition, it was observed that RABV-G was efficient in selectively detecting anti- RABV-G IgG in the sera of vaccinated individuals compared to the negative control. Therefore, LCA chromatography was efficient in preserving the native properties of RABV-G that are essential in inducing an adequate humoral immune response. In addition, the purified RABV-G presented analytical potential as an ELISA reagent.

Captopril inhibits the overproduction of proopiomelanocortin and adrenocorticotropic hormone in the pituitary gland of male diabetic mice in close relationship with an increase in glucocorticoid receptor expression.

Prior investigation shows that diabetic patients present hypothalamus-pituitary-adrenal (HPA) axis hyperactivity related to impaired negative feedback. This study investigates the effect of Captopril on the overproduction of adrenocorticotropic hormone (ACTH) and its precursor proopiomelanocortin (POMC) in the pituitary gland of male diabetic mice. Diabetes was induced by intravenous injection of alloxan into fasted Swiss-webster mice, and the animals were treated with Captopril for 14 consecutive days, starting 7 days post-diabetes induction. Plasma corticosterone levels were evaluated by ELISA, while pituitary gland expressions of angiotensin-II type 1 receptor (AT1), angiotensin-II type 2 receptor (AT2), ACTH, Bax, Bcl-2, KI-67, POMC, and glucocorticoid receptor (GR) were evaluated using immunohistochemistry or western blot. Diabetic mice showed pituitary gland overexpression of AT1, without altering AT2 levels, which were sensitive to Captopril treatment. Furthermore, diabetic mice presented hypercortisolism, along with an increase in the number of corticotroph cells, POMC and ACTH expression, and number of proliferative cells, and a decrease of GR expression in the pituitary gland. In addition, treatment with Captopril reduced systemic corticosterone levels, corticotroph and proliferative cell numbers, and Bcl-2, POMC, and ACTH expression in the pituitary gland of diabetic mice, besides increasing the expression of Bax and GR. In conclusion, these findings show that Captopril is a promising therapy for treating complications associated with HPA axis hyperactivity in diabetic patients, in a mechanism probably related to the downregulation of POMC production in the pituitary gland and subsequent reduction of systemic corticosterone levels.

Effects of Nesting Material and Housing Parameters on Feed Wastage Behavior in Female Swiss Webster Mice.

Feed wastage in laboratory mice, also known as chewing or grinding behavior, is problematic for program management and animal welfare. The destruction of pelleted feed without consumption produces a powder accumulation on the cage floor called orts. Ort accumulation disrupts the cage microenvironment and can clog Lixits resulting in flooding. Moreover, added labor adds cost, and cage disruption increases animal stress. Published studies examining the behavior and ways to mitigate it have had inconsistent results, and the cause or causes have not yet been fully identified. The purpose of this study was to identify methods to reduce the development of chewing behavior in laboratory mice. Female Swiss Webster (Tac:SW) mice (n = 144) were randomly assigned to one of 8 groups (12 cages per group) with 2 housing densities (single and pair) and 4 nesting material paradigms. Mice were housed on clean bedding for 8 wk and then soiled bedding for the next 8 wk. Chewing behavior was evaluated by feed weight, cage weight, and feed scores. The addition of a Diamond Twist significantly increased ort production, while nest transfer decreased it but not significantly. Pair housing increased overall orts but not when adjusted for animal number. These results identified potential contributing factors to chewing behavior. However, further research is needed to elucidate the exact causes and solutions.

The Injected Plasma of Myasthenia Gravis Patient with A Low T-reg Level Caused Clinical Myasthenic Syndromes in Swiss-Webster Mice

BACKGROUND: Myasthenia gravis (MG) is a rare autoimmune disease affecting neuromuscular junction involvement. The finding that T-reg level in MG patients was lower than that in normal persons leads to the idea that the primary pathology of the disease is T-reg dependent. The T-reg level of MG patients seems to be decreasing compared to that of normal persons. The study was conducted to observe the contribution of T-reg level in plasma injected into Swiss-Webster mice to develop clinically and pathologically myasthenic syndromes.METHODS: Swiss-Webster mice were grouped into three groups: the groups received plasma with normal, low, and high T-reg levels, respectively. The T-reg levels of the mice were measured with flow cytometry analysis and a human regulatory T-cell cocktail for T-cell surface cell marker. The motor function, interleukin (IL)-2, interferon (IFN)-γ, and thymus weight of mice were measured after the injection. Histopathological examination was performed to analyze mice’s muscles and thymus.RESULTS: The result identified that the motor function (2-week treatment group: p=0.021 and 3-week treatment group: p=0.032) and muscle width (p=0.014, p=0.032 and p≤0.001) were significantly lower in the low T-reg level plasma group compared to control and high T-reg level plasma groups. The thymus showed an increase in weight without an increase in the cortex-medulla ratio of the thymus, indicating hyperplasia. Both IL-2 and IFN-γ levels were lower in the low and high T-reg level groups compared with the control group, indicating the autoimmune process.CONCLUSION: Low T-reg level was associated with lower motor function, muscle width, increased thymus weight, as well as lower IL-2 and IFN-γ levels. T-reg level contributed to clinical myasthenic syndromes but not pathological findings. This research method is expected to be a basis for the development of animal models with Swiss-Webster mice.KEYWORDS: animal model, Myasthenia gravis, Swiss-Webster mice

Effect of Ajwa Date Fruit (Phoenix dactylifera) Methanol Extract on Blood Glucose Levels in Mice with Diabetes Mellitus

Highlights: The widespread incidence of DM leads to costly treatments and often results in undesirable side effects. Flavonoids in ajwa date fruit are believed to lower blood glucose levels through several mechanisms. Methanol extract of ajwa date fruit can effectively lower blood glucose levels in diabetic mice at specific optimal doses. Abstract Introduction: High diabetes mellitus (DM) cases result in costly medical expenses. Ajwa date fruit contains triterpenoids, carbohydrates, and flavonoids believed to lower blood glucose, which requires research validation using methanol extract on streptozotocin (STZ)-induced mice. This study aimed to determine the effect of methanol extract of ajwa dates with several dose levels, namely 3 g/WB, 5 g/WB, and 7 g/WB, given orally to mice induced by STZ. Methods: This study utilized a randomized pre- and post-test control group design to assess ajwa date fruit methanol extract effects on blood glucose in Swiss-Webster mice (Mus musculus). The mice were divided into four groups: Group K (6 mice without date extract intervention), P1 (6 mice with 3 g/WB/day oral dose date extract intervention), P2 (7 mice with 5 g/WB/day oral dose date extract intervention), and P3 (7 mice with 7 g/WB/day oral dose date extract intervention) and were induced with 100 mg/WB streptozotocin. Administered daily for three weeks, ajwa dates fruit extract showed varying impacts. Weekly blood glucose measurements and analysis of variance (ANOVA) in the International Business Machines Corporation (IBM) Statistical Package for the Social Sciences (SPSS) version 27.0 disclosed significant group differences. Results: In the third week, blood glucose measurements revealed significant differences (p = 0.017), with an optimal reduction in P3 (7 mice with 7 g/WB/day oral dose date extract intervention). Conclusion: In the third week, ajwa dates fruit extract, at an optimal 7 g/WB dose, effectively reduced blood glucose levels via flavonoid hypoglycemic mechanisms.

Teneurin C-terminal associated peptide (TCAP)-1 attenuates the development and expression of naloxone-precipitated morphine withdrawal in male Swiss Webster mice.

Corticotropin-releasing factor (CRF), the apical stress-inducing hormone, exacerbates stress and addictive behaviors. TCAP-1 is a peptide that directly inhibits both CRF-mediated stress and addiction-related behaviors; however, the direct action of TCAP-1 on morphine withdrawal-associated behaviors has not previously been examined. To determine whether TCAP-1 administration attenuates behavioral and physiological consequences of morphine withdrawal in mice. Mice were administered via subcutaneous route TCAP-1 either before or after initial morphine exposure, after which jumping behavior was quantified to assess the effects of TCAP-1 on naloxone-precipitated morphine withdrawal. As a comparison, mice were treated with nonpeptide CRF1 receptor antagonist CP-154,526. In one experiment, plasma corticosterone (CORT) was also measured as a physiological stress indicator. Pretreatment with TCAP-1 (10-250 nmol/kg) before morphine treatment significantly inhibited the development of naloxone-precipitated withdrawal. TCAP-1 (250-500 nmol/kg) treatment administered after morphine treatment attenuated the behavioral expression of naloxone-precipitated withdrawal. TCAP-1 (250 nmol/kg) treatment during morphine treatment was more effective than the optimal dosing of CP-154,526 (20mg/kg) at suppressing the behavioral expression of naloxone-precipitated withdrawal, despite similar reduction of withdrawal-induced plasma CORT level increases. These findings establish TCAP-1 as a potential therapeutic candidate for the prevention and treatment of morphine withdrawal.

Tropospheric ozone effect on olfactory perception and olfactory bulb dopaminergic interneuron excitability

Ozone (O3) forms in the Earth’s atmosphere, both naturally and by reactions of man-made air pollutants. Deleterious effects of O3 have been found in the respiratory system. Here, we examine whether O3 alters olfactory behavior and cellular properties in the olfactory system. For this purpose, mice were exposed to O3 at a concentration found in highly polluted city air [0.8 ppm], and the behavior elicited by social and non-social odors in habituation/dishabituation tests was assessed. In addition, the electrical responses of dopaminergic olfactory bulb (OB) neurons were also evaluated. O3 differentially compromises olfactory perception to odors: it reduces responses to social and non-social odors in Swiss Webster mice, while this effect was observed in C57BL/6 J mice only for some non-social odors. Additionally, O3 reduced the rate of spontaneous spike firing in periglomerular dopaminergic cells (PG-DA) of the OB. Because this effect could reflect changes in excitability and/or synaptic inputs, the ability of O3 to alter PG-DA spontaneous activity was also tested together with cell membrane resistance, membrane potential, rheobase and chronaxie. Taken together, our data suggest the ability of O3 to affect olfactory perception.

The Effect of Carica pubescens Seeds Ethanol Extract on Lymphocyte Count and Paw Edema in Male White Swiss Webster Mice

Inflammation is a natural tissue response to infection in the body. The potential anti-inflammatory effect of secondary metabolites in carica seeds has been overlooked. This study aimed to investigate and develop the anti-inflammatory activity of the ethanolic extract of carica seeds (Carica pubescens) against foot edema and lymphocyte count in male white mice. Bioactive carica seeds were extracted using the maceration method with 70 % ethanol solvent. The identification of secondary metabolites was conducted using the thin-layer chromatography method. Treatments were administered to six groups: the negative control group (sick), solvent control, positive control with Diclofenac Sodium, and three doses of the ethanol extract of carica seeds (cS) at 100, 200, and 400 mg/kg body weight (BW). Edema was induced using intraplantar 1 % carrageenan on the soles of mice, and lymphocyte count was determined by blood sampling from the lateral tail vein using a hematology analyzer. Carica seeds doses of 200 mg/kg BW and 400 mg/kg BW demonstrated anti-inflammatory activity comparable to the positive control Diclofenac Sodium (p 0.05). Variations in CS doses influenced the lymphocyte count at the 3rd and 6th hours. In conclusion, the ethanolic extract of carica seeds exhibits anti-inflammatory effects in male white mice induced by 1 % carrageenan, reducing edema thickness and affecting leukocyte count.

VP1 is the primary determinant of neuropathogenesis in a mouse model of enterovirus D68 acute flaccid myelitis.

Emerging viruses allow us to investigate mutations leading to increased disease severity. Enterovirus D68 (EV-D68), once the cause of rare cases of respiratory illness, recently acquired the ability to cause severe respiratory and neurologic disease. Chimeric viruses were used to demonstrate that viral structural protein VP1 determines growth in the spinal cord, motor neuron loss, and paralysis following intramuscular (IM) injection of neonatal Swiss Webster (SW) mice with EV-D68. These results have relevance for predicting the clinical outcome of future EV-D68 epidemics as well as targeting retrograde transport as a potential strategy for treating virus-induced neurologic disease.

Novel extended-release transdermal formulations of the psychedelic N,N-dimethyltryptamine (DMT)

There is considerable evidence from the literature that psychedelics, such as N,N-dimethyltryptamine (DMT), are safe and effective treatments for depression. However, clinical administration to induce psychedelic effects and expensive psychotherapy-assisted treatments likely limit accessibility to the average patient. There is emerging evidence that DMT promotes positive behavioral changes in vivo at sub-hallucinogenic dosages, and depending on the target indication, subjecting patients to high, bolus dosages may not be necessary. Due to rapid metabolic degradation, achieving target levels of DMT in subjects is difficult, requiring IV administration, which poses risks to patients during the intense hallucinogenic and subjective drug effects. The chemical and physical properties of DMT make it an excellent candidate for non-invasive, transdermal delivery platforms. This paper outlines the formulation development, in vitro, and in vivo testing of transdermal drug-in-adhesive DMT patches using various adhesives and permeation enhancers. In vivo behavioral and pharmacokinetic studies were performed with lead patch formulation (F5) in male and female Swiss Webster mice, and resulting DMT levels in plasma and brain samples were quantified using LC/MS/MS. Notable differences were seen in female versus male mice during IV administration; however, transdermal administration provided consistent, extended drug release at a non-hallucinogenic dose. The IV half-life of DMT was extended by 20-fold with administration of the transdermal delivery system at sub-hallucinogenic plasma concentrations not exceeding 60 ng/mL. Results of a translational head twitch assay (a surrogate for hallucinogenic effects in non-human organisms) were consistent with absence of hallucinations at low plasma levels achieved with our TDDS. Despite the reported low bioavailability of DMT, the non-invasive transdermal DMT patch F5 afforded an impressive 77 % bioavailability compared to IV at two dosages. This unique transdermal delivery option has the potential to provide an out-patient treatment option for ailments not requiring higher, bolus doses and is especially intriguing for therapeutic indications requiring non-hallucinogenic alternatives.

Humane Endpoints in Swiss Webster Mice Infected with Toxoplasma gondii RH Strain.

The highly virulent Toxoplasma gondii RH strain is maintained through successive passages in mice, but there is still a lack of studies that refine these procedures from a 3Rs perspective, where humanitarian ideals aim to minimize the stress, pain, or suffering of the animals used in the research without the loss of results. The aim of this study was to establish humane endpoints in Swiss Webster mice inoculated with the T. gondii RH strain. A total of 52 mice were infected with 5 × 106 tachyzoites/mL and monitored for periods of up to 5 days. The parameters body weight; hair condition; higher than normal body temperature; hypothermia; respiratory function; pain; soft stools or diarrhea; bloody diarrhea; tense, nervous, or in distress during handling; and ascites were recorded daily in score tables. The results showed that prominent piloerection, respiratory function, pain parameters, and ascites are important clinical signs to be used as a cut-off point for implementing euthanasia. The application of this refinement method helped to avoid animal suffering and pain without compromising the number of parasites recovered. We therefore suggest adopting these parameters in research protocols that require the maintenance of the T. gondii RH strain in murine models to avoid and reduce animal suffering.

Unveiling Lovastatin's Anti-Inflammatory Potential in Mouse's Brain during Acute Trypanosoma cruzi Infection.

Neurological commitment is a neglected manifestation of Chagas disease (CD). Meningoencephalitis mainly affects children and immunosuppressed patients, while stroke can occur with or without cardiac compromise. One of the possible causes of stroke development is microvascular commitment. Our group previously described that experimental Trypanossoma cruzi acute infection leads to cerebral microvasculopathy. This condition is characterized by decreased capillary density, increased leukocyte rolling and adhesion, and endothelial dysfunction. CD was discovered 114 years ago, and until today, only two drugs have been available for clinical treatment: benznidazole and nifurtimox. Both present a high cure rate for the acute phase (80%) and small cure rate for the chronic phase (20%). In addition, the high occurrence of side-effects, without proper medical follow-up, can result in treatment abandonment. Therefore, the search for new therapeutic schemes is necessary. Statins are drugs already used in the clinic that have several pleiotropic effects including endothelial function improvement, anti-inflammatory action, as well as trypanocidal effects, making them a potential alternative treatment for brain microvasculopathy in CD. Here, we investigate the effect of lovastatin (LOV) on brain microvasculopathy and inflammatory parameters. Swiss Webster mice were intraperitoneally inoculated with the Y strain of T. cruzi. Treatment with lovastatin (20 mg/kg/day) was initiated 24 h after the infection and continued for 14 consecutive days. We observed that LOV treatment did not affect parasitemia, brain microcirculation alterations, or the reduction in cerebral blood flow caused by T. cruzi infection. Also, LOV did not prevent the increased number of CD3+ cells and eNOS levels in the T. cruzi-infected brain. No alterations were observed on VCAM-1 and MCP-1 expressions, neither caused by infection nor LOV treatment. However, LOV prevented the increase in F4/80+ cells and ICAM-1 levels in the brain caused by acute infection with T. cruzi. These results suggest an anti-inflammatory activity of LOV, but more studies are needed to elucidate the role of LOV in CD acute infection.

Dim light at night shifts microglia to a pro-inflammatory state after cerebral ischemia, altering stroke outcome in mice

Circadian rhythms are endogenous biological cycles that regulate physiology and behavior and are set to precisely 24-h by light exposure. Light at night (LAN) dysregulates physiology and function including immune response; a critical component that contributes to stroke pathophysiological progression of neuronal injury and may impair recovery from injury. The goal of this study is to explore the effects of dim LAN (dLAN) in a murine model of ischemic stroke to assess how nighttime lighting from hospital settings can affect stroke outcome. Further, this study sought to identify mechanisms underlying pathophysiological changes to immune response after circadian disruption. Male and female adult Swiss Webster (CFW) mice were subjected to transient or permanent focal cerebral ischemia, then were subsequently placed into either dark night conditions (LD) or one night of dLAN (5 lx). 24 h post-stroke, sensorimotor impairments and infarct sizes were quantified. A single night of dLAN following MCAO increased infarct size and sensorimotor deficits across both sexes and reduced survival in males after 24 h. Flow cytometry was performed to assess microglial phenotypes after MCAO, and revealed that dLAN altered the percentage of microglia that express pro-inflammatory markers (MHC II+ and IL-6) and microglia that express CD206 and IL-10 that likely contributed to poor ischemic outcomes. Following these results, microglia were reduced in the brain using Plexxikon 5622 (PLX 5622) a CSFR1 inhibitor, then the mice received an MCAO and were exposed to LD or dLAN conditions for 24 h. Microglial depletion by PLX5622 resulted in infarct sizes that were comparable between lighting conditions. This study provides supporting evidence that environmental lighting exacerbates ischemic injury and post-stroke mortality by a biological mechanism that exposure to dLAN causes a fundamental shift of activated microglial phenotypes from beneficial to detrimental at an early time point after stroke, resulting in irreversible neuronal death.

Cardioprotective and Hepatoprotective Potential of Silymarin in Paracetamol-Induced Oxidative Stress.

Silymarin, derived from Silybum marianum, has been used in traditional medicine for various ailments. In this study, the cardioprotective and hepatoprotective effects of silymarin against paracetamol-induced oxidative stress were examined in 28 male Swiss Webster mice, divided into four groups and treated for 7 days (via the oral route) with (a) saline 1 mL/kg (control group), (b) saline 1 mL/kg + single dose of paracetamol 110 mg/kg on the 7th day; (c) silymarin 50 mg/kg; and (d) silymarin 50 mg/kg + single dose of paracetamol 110 mg/kg on the 7th day. In vitro and in vivo antioxidant activity together with liver enzyme activity were evaluated. Histopathological and immunohistochemical assessment was performed. Silymarin mitigated paracetamol-induced liver injury by reducing oxidative stress markers such as lipid peroxidation and restoring antioxidant enzyme activity. Silymarin treatment resulted in a significant decrease in liver enzyme levels. Reduced necrosis and inflammatory infiltrate in liver tissues of silymarin-treated groups were detected as well. Immunohistochemical analysis demonstrated reduced expression of inflammatory markers (COX2, iNOS) and oxidative stress marker (SOD2) in the liver tissues of the silymarin-treated groups. Similar trends were observed in cardiac tissue. These results suggest that silymarin exerts potent hepatoprotective and cardioprotective effects against paracetamol-induced oxidative stress, making it a promising therapeutic agent for liver and heart diseases associated with oxidative damage.

Phytochemistry and Antidiabetic Activity from the Leaf Midrib of &lt;i&gt;Nypa fruticans&lt;/i&gt; Wurm.

This study aims to determine the antidiabetic activity of n-hexane and ethanol extracts of Nypa fruticans leaf sheaths. The ethanol extract, with the most active antidiabetic properties from the n-hexane extract, was characterized using GC-MS. The total phenol, total flavonoid, and antioxidant properties were determined, and then the ethanol extract was fractionated. An antidiabetic activity test was carried out using the glucose tolerance method in male Swiss Webster mice. The results showed that subfraction A (the effect of fractionation of ethanol extract) was the most capable of reducing blood sugar levels, namely 247.67 mg/dL in 30 min (the activity is 98.67% compared to glibenclamide). The ethanol extract can reduce blood glucose levels by 203.34 mg/dL at 30 min (81.01% compared to glibenclamide). The results of total phenolic and total flavonoid content tests for the ethanol extract were obtained at 18.0349 mg gallic acid equivalents/g and 2.8309 mg quercetin equivalents/g, respectively. On the other hand, the IC50 antioxidant activity of the extract is 417.4399 ppm. Characterization using GC-MS on the extract showed that the dominant phytoconstituent in the extract is 4-methoxy-6-(2-propenyl)-1,3-benzodioxole, with a composition of 63.45%.

A nanochitosan-D-galactose formulation increases the accumulation of primaquine in the liver.

Primaquine is the mainstream antimalarial drug to prevent Plasmodium vivax relapses. However, this drug can induce hemolysis in patients with glucose-6-phosphate dehydrogenase deficiency. Nanostructure formulations of primaquine loaded with D-galactose were used as a strategy to target the drug to the liver and decrease the hemolytic risks. Nanoemulsion (NE-Pq) and nanochitosan (NQ-Pq) formulations of primaquine diphosphate containing D-galactose were prepared and characterized by their physicochemistry properties. Pharmacokinetic and biodistribution studies were conducted using Swiss Webster mice. A single dose of 10 mg/kg of each nanoformulation or free primaquine solution was administered by gavage to the animals, which were killed at 0.5, 1, 2, 4, 8, and 24 hours. Blood samples and tissues were collected, processed, and analyzed by high-performance liquid chromatography. The nanoformulation showed sizes around 200 nm (NE-Pq) and 400 nm (NQ-Pq) and physicochemical stability for over 30 days. Free primaquine solution achieved higher primaquine Cmax in the liver than NE-Pq or NQ-Pq at 0.5 hours. However, the half-life and mean residence time (MRT) of primaquine in the liver were three times higher with the NQ-Pq formulation than with free primaquine, and the volume distribution was four times higher. Conversely, primaquine's half-life, MRT, and volume distribution in the plasma were lower for NQ-Pq than for free primaquine. NE-Pq, on the other hand, accumulated more in the lungs but not in the liver. Galactose-coated primaquine nanochitosan formulation showed increased drug targeting to the liver compared to free primaquine and may represent a promising strategy for a more efficient and safer radical cure for vivax malaria.

Monitoring Staphylococcus aureus nasal colonization murine model using a bioluminescent methicillin-resistant S. aureus (MRSA).

Staphylococcus aureus nasal carriage is considered a risk factor for infections, and the development of nasal decolonization strategies is highly relevant. Despite they are not naturally colonized by Staphylococcus, mice are a good model for S. aureus nasal colonization. Murine models are easy to manipulate, and inter-laboratory reproducibility makes them suitable for nasal colonization studies. Strategies using bioluminescent bacteria allow for the monitoring of infection over time without the need to sacrifice animals for bacterial quantification. In this study, we evaluated S. aureus nasal colonization in three mouse strains (BALB/c, C57BL/6, and Swiss Webster) using a bioluminescent strain (SAP231). In vitro, a visible Bioluminescent Signal Emission (BLSE) was observed until 106 bacteria and detected by IVIS® imaging system up to 104 cells. Animals were inoculated with one or two doses of approximately 109 colony-forming units (CFU) of SAP231. Swiss Webster mice showed the longest colonization time, with some animals presenting BLSE for up to 140 h. In addition, BLSE was higher in this strain. BALB/c and C57BL/6 strains showed consistent BLSE results for 48 h. BLSE intensity was higher in Swiss Webster inoculated with both doses. Three different positions for image capture were evaluated, with better results for the lateral and ventrodorsal positions. After the loss of BLSE, bacterial quantification was performed, and Swiss Webster mice presented more bacteria in the nasal cavity (approximately 105 CFU) than the other strains. Our results demonstrate that bioluminescent S. aureus allow monitoring of nasal colonization and estimation of the bacterial burden present in live animals until 48 h.

A6 LYSOPHOSPHATIDYLCHOLINE (LPC) AND LYSOPHOSPHATIDIC ACID (LPA) INDUCE VISCERAL HYPERSENSITIVITY IN IRRITABLE BOWEL SYNDROME (IBS)

Abstract Background Chronic abdominal pain is the key symptom in IBS. Gut microbiota produces a large variety of molecules that can regulate pain perception, including bioactive lipids. LPC and LPA are phospholipids, known to generate and maintain neurogenic pain in mammals, by directly activating multiple channels and G-protein coupled receptors on sensory neurons. LPC and LPA result from the conversion of phosphatidylcholine (PC), a major membrane-forming phospholipid in eucaryotes, as byproducts of inflammation. PC is also present in high concentration in eggs, meat and soybeans. It is unknown whether these two phospholipids play any role in chronic abdominal pain and whether they can be produced by the gut microbiota. Aims To investigate whether 1) LPC and LPA are increased in stool of IBS patients, and 2) whether microbiota from IBS patients can produce LPC and LPA and lead to visceral hypersensitivity. Methods Stool samples from 27 patients with IBS, collected both during periods of severe and minimal/no pain, were assessed for LPC and LPA levels by ELISA. Germ-free (GF) NIH Swiss and Swiss Webster mice (n=101) both sexes were colonized with fecal microbiota from IBS patients with either high or low fecal LPC and LPA levels, or microbiota from healthy controls. Mice were fed with control diet or diet enriched with PC diet (2g/kg of diet) for 5 weeks. Their visceral sensitivity was then assessed by measuring visceromotor responses to colorectal distension. The fecal samples were collected to measure the production of LPC and LPA Results The fecal concentrations of LPC and LPA were higher in IBS patients when experiencing severe abdominal pain, compared to periods of minimal or no pain. Mice colonized with fecal microbiota from IBS patients with high fecal LPC and/or LPA displayed visceral hypersensitivity compared to mice colonized with microbiota from healthy controls, or microbiota from patients with low fecal LPC and/or LPA levels. However, this increase in visceral sensitivity was only found in mice fed with diet enriched with PC. Furthermore, the increased pain responses to colorectal distension correlated with higher concentrations of fecal LPC and LPA. Conclusions Our data suggest that bacterial LPC and LPA is responsible for chronic abdominal pain in a subset of patients with IBS. Further studies are needed to identify the specific bacterial strains that produce these nociceptive phospholipids and precise mechanisms by which LPC and LPA induce visceral hypersensitivity. Funding Agencies CIHRThe W.Garfield Weston Foundation

A comparison of Bartonella henselae infection in immunocompetent and immunocompromised mice.

Bartonellosis refers to disease caused by the Bartonella genus of bacteria. The breadth of disease manifestations associated with Bartonella is currently expanding and includes regional lymphadenopathy, rheumatic, ocular, and neurological disorders. The dearth of knowledge regarding diagnosis, treatment and pathogenesis of this disease can be partially attributed to the lack of a reliable small animal model for the disease. For this study, Bartonella henselae, the most common species associated with human disease, was injected into Swiss Webster (SW) mice. When the outcome indicated that productive infection did not occur, SCID/Beige (immune compromised) mice were inoculated. While SW mice may potentially harbor an acute infection, less than 10 days in length, the SCID/Beige model provided a sustained infection lasting up to 30-days. These data indicate that SCID/Beige mice can provide a model to study Bartonella infection, therapeutics, and vector dynamics in the future.

FABP4 and Metabolite Profile in Lipopolysaccharide-Induced Mice Model Treated with Moringa oleifera Ethanol Leaf Extract

Sepsis, a life-threatening organ dysfunction resulting from a dysregulated host response to infection, induces changes in blood cells and metabolic alterations. Fatty acid binding protein 4 (FABP4), a lipid chaperone predominantly expressed in adipose tissue, is modulated in sepsis and may contribute to metabolic and immunologic changes. Moringa oleifera (M. oleifera) leaf extract (MOLE) is known to modulate immune system activity, but its potential for treating acute inflammatory conditions like sepsis remains unclear. This study investigates the ability of MOLE to modulate metabolite and hematological profiles in lipopolysaccharide (LPS)-induced sepsis in mice. Thirty-five male Swiss Webster mice (Mus musculus) were divided into five groups, including healthy control pre-treated with 0.5% carboxymethyl cellulose (CMC), an LPS-induced negative control, an LPS-induced positive control treated with dexamethasone (DMX) 7mg/KgBW/day and two MOLE treatment groups with doses of 5.6 and 11.2 mg/20 gBW. Mice received MOLE pre-treatment for three days before LPS induction. Three hours post-LPS injection, the LPS-induced group exhibited leukopenia (1.4 [0.9-2.5] x109 cells/L) and a 68.3% increase in triglyceride levels. However, the MOLE-treated group showed improved erythrocyte levels compared to the positive control group; [(9.9(9.3-10.0) x1012 cell/L) vs (7.7(7.0-9.0) x1012 cells/L), p&lt;0.05]. The study suggests that MOLE administration may positively impact sepsis conditions, particularly by enhancing RBC levels. Further research with an extended observation period is recommended to address limitations in metabolite level assessment.