Intranasal coadministration of the Cry1Ac protoxin with amoebal lysates increases protection against Naegleria fowleri meningoencephalitis

Cry1Ac protoxin has potent mucosal and systemic adjuvant effects on antibody responses to proteins or polysaccharides. In this work, we examined whether Cry1Ac increased protective immunity against fatal Naegleria fowleri infection in mice, which resembles human primary amoebic meningoencephalitis. Higher immunoglobulin G (IgG) than IgA anti-N. fowleri responses were elicited in the serum and tracheopulmonary fluids of mice immunized by the intranasal or intraperitoneal route with N. fowleri lysates either alone or with Cry1Ac or cholera toxin. Superior protection against a lethal challenge with 5 x 10(4) live N. fowleri trophozoites was achieved for immunization by the intranasal route. Intranasal immunization of N. fowleri lysates coadministered with Cry1Ac increased survival to 100%; interestingly, immunization with Cry1Ac alone conferred similar protection to that achieved with amoebal lysates alone (60%). When mice intranasally immunized with Cry1Ac plus lysates were challenged with amoebae, both IgG and IgA mucosal responses were rapidly increased, but only the increased IgG response persisted until day 60 in surviving mice. The brief rise in the level of specific mucosal IgA does not exclude the role that this isotype may play in the early defense against this parasite, since higher IgA responses were detected in nasal fluids of mice intranasally immunized with lysates plus either Cry1Ac or cholera toxin, which, indeed, were the treatments that provided the major protection levels. In contrast, serum antibody responses do not seem to be related to the protection level achieved. Both acquired and innate immune systems seem to play a role in host defense against N. fowleri infection, but further studies are required to elucidate the mechanisms involved in protective effects conferred by Cry1Ac, which may be a valuable tool to improve mucosal vaccines.

Regionalization of pIgR expression in the mucosa of mouse small intestine

Few reports exist on the differences in cell populations or immunological functions between the proximal and distal segments of the small intestine (SI). In the current contribution we analyzed the expression of the polymeric immunoglobulin receptor (pIgR) and alpha chains as well as the density of IgA-producing cells from the proximal and distal intestinal segments from Balb/c mice. Furthermore, by using real-time RT-PCR we quantified the expression of cytokines (TNF-alpha, IFN-gamma, IL-4 and TGF-beta), Toll-like receptor-4 (TLR-4), and the glucocorticoid receptor (GR) involved in pIgR expression in intestinal epithelial cells (IEC). In this study, for the first time it has been demonstrated that the expression of the pIgR as well as alpha chain was greater in the proximal than the distal segment of the small intestine of normal mice. Moreover, we found striking differences in the expression of cytokines at the different intestinal compartments. Whereas the expression of TNF-alpha, IFN-gamma and TGF-beta was higher in lamina propria lymphocytes (LPL) of the distal than proximal segment, it was higher in IEC of the proximal than distal segment. In contrast, the expression of the gene for IL-4 was higher in the LPL of the proximal segment and the IEC of the distal segment. Although the overall expression of TNF-alpha, IL-4, IFN-gamma and TGF-beta was higher in the whole mucosa of the distal than proximal segment, we propose that cytokines produced by epithelial cells (TNF-alpha, IFN-gamma and TGF-beta) autocrinally up-regulate the expression of mRNA for the pIgR. Finally the expression of the GR was higher in the proximal segment, while the expression of the gene for TLR-4 was significantly higher in the IEC of the distal than proximal segment. The higher expression of pIgR found in the proximal segment is probably related to the effect on epithelial cells of the higher production of TNF-alpha, IFN-gamma and TGF-beta, as well as the higher expression of the glucocorticoid receptors. The increased expression of pIgR in the proximal segment appears primarily responsible for the increased secretory IgA levels in the small intestine of mice. These results confirm and extend previous findings supporting the compartmentalization of the intestinal immune system.

Effects of boron-containing compounds on immune responses: review and patenting trends

INTRODUCTION

Boron-containing compounds induce effects on immune responses. Such effects are interesting to the biomedical field for the development of therapeutic tools to modulate the immune system.

AREAS COVERED

The scope of BCC use to modify immune responses is expanding, mainly with regard to inflammatory diseases. The information was organized to demonstrate the breadth of reported effects. BCCs act as modulators of innate and adaptive immunity, with the former including regulation of cluster differentiation and cytokine production. In addition, BCCs exert effects on inflammation induced by infectious and noninfectious agents, and there are also reports regarding their effects on mechanisms involving hypersensitivity and transplants. Finally, the authors discuss the beneficial effects of BCCs on pathologies involving various targets and mechanisms.

EXPERT OPINION

Some BCCs are currently used as drugs in humans. The mechanisms by which these BCCs modulate immune responses, as well as the required structure-activity relationship for each observed mechanism of action, should be clarified. The former will allow for the development of improved immunomodulatory drugs with extensive applications in medicine. Patenting trends involve claims concerning the synthesis and actions of identified molecules with a defined profile regarding cytokines, cell differentiation, proliferation, and antibody production.

Infections of Diabetic Foot Ulcers With Methicillin-Resistant Staphylococcus aureus

Infected diabetic foot is the most common reason for hospitalization and complications in patients with type 2 diabetes mellitus (DM2). Methicillin-resistant Staphylococcus aureus (MRSA) is frequently isolated from such lesions, and its presence is growing, seriously deteriorating the infected patient’s quality of life. The aim of this study was to assess the prevalence of MRSA as well as other microbiota in 100 patients diagnosed with (DM2) and with infected foot ulcers at the Hospital General de Mexico. The main results obtained show a prevalence of Staphylococcus aureus (42%), followed by Escherichia coli (36%) and, in lower percentages, other bacteria. MRSA was predominant (34%), and we conclude that the use of cefoxitin instead of oxacillin as the first-choice antibiotic has an advantage because it is a better inducer of methicillin-resistance expression.

Changes in protein and gene expression of angiotensin II receptors (AT1 and AT2) in aorta of diabetic and hypertensive rats

Diabetes and hypertension have been associated with cardiovascular diseases and stroke. Some reports have related the coexistence of hypertension and diabetes with increase in the risk of developing vascular complications. Recently some studies have shown results suggesting that in the early stages of diabetes and hypertension exist a reduced functional response to vasopressor agents like angiotensin II (Ang II), which plays an important role in blood pressure regulation mechanism through the activation of its AT1 and AT2 receptors. For that reason, the aim of this work was to study the gene and protein expression of AT1 and AT2 receptors in aorta of diabetic SHR and WKY rats. Diabetes was induced by the administration of streptozotocin (60 mg/kg i.p.). After 4 weeks of the onset of diabetes, the protein expression was obtained by western blot and the mRNA expression by RT-PCR. Our results showed that the hypertensive rats have a higher mRNA and protein expression of AT1 receptors than normotensive rats while the AT2 expression remained unchanged. On the other hand, the combination of diabetes and hypertension increased the mRNA and protein expression of AT1 and AT2 receptors significantly. In conclusion, our results suggest that diabetes with hypertension modifies the mRNA and protein expression of AT1 and AT2 receptors. However, the overexpression of AT2 could be associated with the reduction in the response to Ang II in the early stage of diabetes.

Different antiamebic antibody isotype patterns in the large and small intestine after local and systemic immunization of mice with glutaraldehyde fixed Entamoeba histolytica trophozoites

We have determined the major immunoglobulin isotypes (IgG, IgA, IgM) of antiamebic antibodies induced in the serum and in the large and small intestine after local (oral and rectal) or systemic (intraperitoneal and intramuscular) immunization of mice with glutaraldehyde-fixed Entamoeba histolytica trophozoites (GFT). IgA predominated in the small intestine after immunization through all routes, whereas in the large intestine similar antibody levels of the major isotypes were induced by rectal, intraperitoneal and intramuscular immunization. The intramuscular route elicited intestinal responses lower than those induced by the rectal and intraperitoneal routes, but higher than the slight IgA antibody increase observed after oral immunization. The differences in antiamebic antibody response patterns at the large and small intestine suggest that there are different mucosal effector compartments. They also indicate that isotype analysis of mucosal antibodies from the sites where an infectious agent resides is needed to evaluate whether a vaccine candidate induces responses of higher protective value in the appropriate site, and that the study of antibody responses must not be limited to sampling the serum or mucosal sites distant to the relevant one.

Naegleria fowleri immunization modifies lymphocytes and APC of nasal mucosa

We investigated whether intranasal immunization with amoebic lysates plus cholera toxin modified the populations of T and B lymphocytes, macrophages and dendritic cells by flow cytometry from nose-associated lymphoid tissue (NALT), cervical lymph nodes (CN), nasal passages (NP) and spleen (SP). In all immunized groups, the percentage of CD4 was higher than CD8 cells. CD45 was increased in B cells from mice immunized. We observed IgA antibody-forming cell (IgA-AFC) response, mainly in NALT and NP. Macrophages from NP and CN expressed the highest levels of CD80 and CD86 in N. fowleri lysates with either CT or CT alone immunized mice, whereas dendritic cells expressed high levels of CD80 and CD86 in all compartment from immunized mice. These were lower than those expressed by macrophages. Only in SP from CT-immunized mice, these costimulatory molecules were increased. These results suggest that N. fowleri and CT antigens are taking by APCs, and therefore, protective immunity depends on interactions between APCs and T cells from NP and CN. Consequently, CD4 cells stimulate the differentiation from B lymphocytes to AFC IgA-positive; antibody that we previously found interacting with trophozoites in the nasal lumen avoiding the N. fowleri attachment to nasal epithelium.

Diversity of effects induced by boron-containing compounds on immune response cells and on antibodies in basal state

BACKGROUND

It has been reported that boron induces changes in the immune response, including in inflammatory processes. Recently, the effect of boric acid has been documented on the differentiation of lymphocyte clusters in mice and rats. However, the differences among boron-containing compounds (BCC) have been poorly explored.

METHODS

In this study, we analyzed the effects after oral administration of boric acid (BOR), methylboronic (MET), 3-thyenylboronic (3TB), 4-hydroxymethyl-phenylboronic (4MP) and 4-methanesulfonyl-phenylboronic (4SP) acids on the populations of lymphocytes from spleen and Peyer's patch (PP) as well as on antibodies. Groups of six male BALB/c were orally treated with 4.6 mg/kg of body weight with BOR, MET, 3TB, 4MP, and 4SP/daily for 10 days or vehicle (VEH) as a control group. After euthanasia, the spleen and small intestine were dissected. We conducted flow cytometry assays to assess B, CD3+ T, CD4+ T, and CD8+ T cells. Levels of IgG and IgM in serum, and IgA in intestinal fluid samples were analyzed by enzyme immunoassay.

RESULTS

In particular, we observed the effects of the administration of boronic acids on the number of lymphocytes; these changes were more notable in spleen than in PP. We found different profiles for each boron-containing compound, that is BOR induced an increase in the percentage of CD8+ T and CD19+/IgA+ cells in spleen, but a decrease in CD8+ T and B220+/CD19+ cells in PP. Meanwhile MET induced a decrease of CD4+ T in spleen, but induced an increase of CD4+ T cells and a decrease in the number of CD8+ T cells in PP. Boronic acids with an aromatic ring moiety induced changes in serum immunoglobulins levels, while 3TB acid induced a notable increase in S-IgA.

CONCLUSIONS

Effects in lymphocyte populations and antibodies are different for each tested compound. These results highlight the establishment of the necessary structure-activity relationship for BCC as immunomodulatory drugs. This is relevant in the biomedical field due to their attractiveness for selecting compounds to develop therapeutic tools.

Effect on Adipose Tissue of Diabetic Mice Supplemented with n-3 Fatty Acids Extracted from Microalgae

BACKGROUND

Type 2 Diabetes Mellitus (T2DM) is considered a chronic noncommunicable disease in which oxidative stress is expected as a result of hyperglycaemia. One of the most recent approaches is the study of microalgae fatty acids and their possible antioxidant effect.

OBJECTIVE

This study aimed to analyse the effect of supplementation with n-3 fatty acids extracted from microalgae on the total antioxidant capacity (TAC) and lipid peroxidation of adipose tissue and plasma from diabetic (db/db) and healthy (CD1) mice.

METHODS

Mice were supplemented with lyophilized n-3 fatty acids extracted from microalgae or added to the diet, from week 8 to 16. TAC assay and Thiobarbituric Acid Reactive Substances assay (TBARS) were performed on adipose tissue and plasma samples.

RESULTS

The supplementation of lyophilized n-3 fatty acids from microalgae increased the total antioxidant capacity in adipose tissue of diabetic mice (615.67μM Trolox equivalents vs 405.02μM Trolox equivalents from control mice, p<0.01) and in the plasma of healthy mice (1132.97±85.75μM Trolox equivalents vs 930.64±32μM Trolox equivalents from modified diet mice, p<0.01). There was no significant effect on lipid peroxidation on both strains.

CONCLUSION

The use of n-3 fatty acids extracted from microalgae could be a useful strategy to improve total antioxidant capacity in T2DM.

Protective Effect of Moderate Exercise for BALB/c Mice with Salmonella Typhimurium Infection

Moderate exercise enhances resistance to pathogen-associated infections. However, its influence on intestinal IgA levels and resistance to Salmonella typhimurium in mice has not been reported. The aim of this study was to assess the impact of moderate exercise on bacterial resistance and the intestinal-IgA response in a murine typhoid model. Sedentary and exercised (under a protocol of moderate swimming) BALB/c mice were orally infected with Salmonella typhimurium and sacrificed on days 7 or 14 post-infection (n=5 per group). Compared with infected sedentary mice, infected exercised animals had i) lower intestinal and systemic bacterial loads; ii) higher total and specific intestinal-IgA levels, iii) a higher percentage of IgA plasma cells in lamina propria; iv) a higher level on day 7 and lower level on day 14 of intestinal α- and J-chain mRNA and plasma corticosterone, v) unchanged mRNA expression of intestinal pIgR, and vi) a higher mRNA expression of liver pIgR, α-chain and J-chain on day 7. Hence, it is likely that an increase in corticosterone levels (stress response) induced by moderate exercise increased intestinal IgA levels by enabling greater liver expression of pIgR mRNA, leading to a rise in IgA transcytosis from the liver to intestine. The overall effect of these changes is an enhanced resistance to infection.

Differences between the large and small intestine in the immunodominant amoebic proteins recognized by IgG and IgA antibodies in BALB/c mice

We have previously reported that there are differences in the number of predominant amoebic antigens recognized by serum and small intestinal antibodies induced after local and systemic immunization with glutarldehyde-fixed Entamoeba histolytica trophozoites (GFT) in BALB/c mice, by an immunoblot analysis. Moreover, by enzyme-linked immunosorbent assay (ELISA) analysis, we found differences in the antiamoebic antibody isotype patterns elicited at the large and small intestines. To further characterize the antiamoebic immune response induced in BALB/c mice, after local (oral and rectal) and systemic (intraperitoneal and intramuscular) immunization with GFT, we performed an immunoblot analysis of the amoebic proteins predominantly recognized by immunoglobulins (Ig)G, IgA and IgM in the serum and in the small and large intestines. The present work shows differences between the large and small intestine in the IgG- and IgA-antibody recognition pattern of amoebic proteins, thus confirming and extending our previous findings supporting the compartmentalization of the intestinal immune response. Furthermore, our reported observation that there are differences in the amoebic proteins predominantly recognized by antibodies of different isotypes was extended to the intestines, as some proteins with relative molecular weights of 24-25, 66, 140 kDa are strongly recognized by IgG but not by other antibody isotypes.

Moderate Aerobic Exercise Induces Homeostatic IgA Generation in Senile Mice

A T-cell-independent (TI) pathway activated by microbiota results in the generation of low-affinity homeostatic IgA with a critical role in intestinal homeostasis. Moderate aerobic exercise (MAE) provides a beneficial impact on intestinal immunity, but the action of MAE on TI-IgA generation under senescence conditions is unknown. This study aimed to determine the effects of long-term MAE on TI-IgA production in young (3 month old) BALB/c mice exercised until adulthood (6 months) or aging (24 months). Lamina propria (LP) from the small intestine was obtained to determine B cell and plasma cell sub-populations by flow cytometry and molecular factors related to class switch recombination [Thymic Stromal Lymphopoietin (TSLP), A Proliferation-Inducing Ligand (APRIL), B Cell Activating Factor (BAFF), inducible nitric oxide synthase (iNOS), and retinal dehydrogenase (RDH)] and the synthesis of IgA [α-chain, interleukin (IL)-6, IL-21, and Growth Factor-β (TGF-β)]; and epithelial cells evaluated IgA transitosis [polymeric immunoglobulin receptor (pIgR), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-4] by the RT-qPCR technique. The results were compared with data obtained from sedentary age-matched mice. Statistical analysis was computed with ANOVA, and p < 0.05 was considered to be a statistically significant difference. Under senescence conditions, MAE promoted the B cell and IgA+ B cells and APRIL, which may improve the intestinal response and ameliorate the inflammatory environment associated presumably with the downmodulation of pro-inflammatory mediators involved in the upmodulation of pIgR expression. Data suggested that MAE improved IgA and downmodulate the cytokine pro-inflammatory expression favoring homeostatic conditions in aging.

Pharmacological induction of diabetes mellitus in pregnant female mice: a comparison of two doses and routes of administration

OBJECTIVE: This study aimed to compare two routes of administration and different dosages of streptozotocin (STZ) for the pharmacological induction of gestational diabetes mellitus (GDM) in pregnant CD1 females. MATERIALS AND METHODS: 35 female CD1 mice were divided into 5 groups (n = 7). Diabetes mellitus (DM) was induced with STZ by two routes and two doses: 1) Control Group without administration of STZ (CL), 2) Intraperitoneal Group with 200 mg of STZ/Kg of weight (IP200), 3) Intraperitoneal Group with 230 mg of STZ/Kg of weight (IP230), 4) Subcutaneous Group with 200 mg of STZ/Kg of weight (SC200) and 5) Subcutaneous Group with 230 mg of STZ/Kg of weight (SC230). Body weight, food and water intake, glycemia, Homeostatic Model Assessment of Insulin Resistance Index (HOMA-IR), survival, and birth rate were identified. RESULTS: The SC230 group turned out to be the most effective dose and route for the induction of GDM in pregnant females. This scheme managed to reproduce sustained hyperglycemia with high HOMA-IR, the presence of polyphagia, polydipsia, and weight loss. In addition, the birth rate and survival were high compared to the other doses and routes of administration. CONCLUSIONS: The administration of a single dose of 230 mg/kg of weight by subcutaneous route supposes advantages compared to previously used models since it decreases the physiological stress due to manipulation and the costs since it does not require repeated doses or adjuvants such as high lipid diets to potentiate the diabetogenic effect of STZ.

Graphical Abstract

https://www.europeanreview.org/wp/wp-content/uploads/Graphical-abstract-12.jpg.

Diversity of effects induced by boron-containing compounds on immune response cells and on antibodies in basal state

BACKGROUND

It has been reported that boron induces changes in the immune response, including in inflammatory processes. Recently, the effect of boric acid has been documented on the differentiation of lymphocyte clusters in mice and rats. However, the differences among boron-containing compounds (BCC) have been poorly explored.

METHODS

In this study, we analyzed the effects after oral administration of boric acid (BOR), methylboronic (MET), 3-thyenylboronic (3TB), 4-hydroxymethyl-phenylboronic (4MP) and 4-methanesulfonyl-phenylboronic (4SP) acids on the populations of lymphocytes from spleen and Peyer's patch (PP) as well as on antibodies. Groups of six male BALB/c were orally treated with 4.6 mg/kg of body weight with BOR, MET, 3TB, 4MP, and 4SP/daily for 10 days or vehicle (VEH) as a control group. After euthanasia, the spleen and small intestine were dissected. We conducted flow cytometry assays to assess B, CD3⁺ T, CD4⁺ T, and CD8⁺ T cells. Levels of IgG and IgM in serum, and IgA in intestinal fluid samples were analyzed by enzyme immunoassay.

RESULTS

In particular, we observed the effects of the administration of boronic acids on the number of lymphocytes; these changes were more notable in spleen than in PP. We found different profiles for each boron-containing compound, that is BOR induced an increase in the percentage of CD8⁺ T and CD19⁺/IgA⁺ cells in spleen, but a decrease in CD8⁺ T and B220⁺/CD19⁺ cells in PP. Meanwhile MET induced a decrease of CD4⁺ T in spleen, but induced an increase of CD4⁺ T cells and a decrease in the number of CD8⁺ T cells in PP. Boronic acids with an aromatic ring moiety induced changes in serum immunoglobulins levels, while 3TB acid induced a notable increase in S-IgA.

CONCLUSIONS

Effects in lymphocyte populations and antibodies are different for each tested compound. These results highlight the establishment of the necessary structure-activity relationship for BCC as immunomodulatory drugs. This is relevant in the biomedical field due to their attractiveness for selecting compounds to develop therapeutic tools.