Detection of an ABCA1 variant associated with type 2 diabetes mellitus susceptibility for biochemistry and genetic laboratory courses.

We selected diabetes mellitus for this laboratory exercise to provide students with an explicit model for scientific research concerning the association between the R230C polymorphism and susceptibility to type 2 diabetes mellitus, which is highly prevalent in the Mexican population. We used a collaborative project-based learning to engage students to direct their own learning process. Students worked in small groups with the same learning goal to research, organize data, and present seminars to experimentally genotype the C230 variant and correctly interpret their results. At the conclusion of this laboratory exercise, the students were able to demonstrate a clear understanding of the relevant biological molecular principles to genotype the C230 variant, showed technical competency to carry out the experimental protocols with proficiency, and interpret their results using statistical analyses. The students discussed their understanding of the genetic technologies and the broader social and ethical implications of the research. A randomly selected team was trained to work as a "sentinel" to monitor their classmates and ensure the proper application of techniques. Moreover, the evaluation of this exercise is shared between the students and the instructors; the students evaluate their own work and the performance of their classmates. At the end of the course, the students complete a questionnaire to anonymously provide feedback and information regarding their perception of the learning outcomes. Overall, the student feedback was positive, indicating that the exercise was useful and that it would help to prepare the students for professional practice.

Nitric oxide is involved in the upregulation of IFN-γ and IL-10 mRNA expression by CD8⁺ T cells during the blood stages of P. chabaudi AS infection in CBA/Ca mice.

Nitric oxide (NO) is involved in the clearance of several types of bacteria, viruses and parasites. Although the roles of NO and CD8⁺ T cells in the immune response to malaria have been extensively studied, their actual contributions during the blood stages of malaria infection remain unclear.In this work, we corroborate that serum NO levels are not associated with the in vivo elimination of the blood stages of Plasmodium chabaudi AS. In addition, we show that CD8⁺ T cells exhibit increased apoptosis and up regulate the expression of TNF-α mRNA on day 4 post-infection and IFN-γ and IL-10 mRNA on day 11 post-infection. Interestingly, only the levels of IFN-γ and IL-10 expression are affected when iNOS is inhibited with aminoguanidine (AG), suggesting that NO could be involved in the activation of CD8⁺ T cells during the blood stages of plasmodium infection.

Immunomodulatory role of chloroquine and pyrimethamine in Plasmodium yoelii 17XL infected mice.

Chloroquine (CLQ) and Pyrimethamine (PYR) are used for the treatment of malaria and some autoimmune diseases; although their mechanism of action is only partially understood, their therapeutic effectiveness in the second case has been attributed to their ability to increase apoptosis of T lymphocytes. In view of the potential for immunomodulation during malaria chemotherapy, we investigated the effects of CLQ and PYR treatment on lymphocyte apoptosis and cytokine expression during infection with blood-stage Plasmodium. This work shows that infection of BALB/c mice with Plasmodium yoelii 17XL (Py17XL) reduced apoptosis in spleen cells but when infected mice were treated with CLQ, apoptosis of B and T lymphocytes increased significantly via a Fas-mRNA expression independent mechanism associated with downregulation of Bcl-2 expression, whereas treatment with PYR increased apoptosis to a lesser extent and only in B lymphocytes. CLQ treatment of Py17XL infected mice upregulated tumour necrosis factor-alpha mRNA expression, while PYR treatment increased interferon-gamma mRNA expression. In infected mice, treatment with CLQ downregulated expression of the anti-inflammatory cytokines, interleukin-10 and transforming growth factor-beta (TGF-beta), while PYR treatment upregulated TGF-beta. Thus, in addition to their anti-malarial effects, both drugs modulate the immune response in malaria by increasing apoptosis and modulating the mRNA expression of cytokines involved in parasite elimination and regulation of inflammatory responses.

Gene expression in human macrophages infected with dengue virus serotype-2.

Infection by any of the four serotypes of dengue viruses (DEN-1, -2, -3 and -4) may result in either a relatively benign fever, called dengue fever (DF), a fatal disease, such as dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS). Several lines of evidence suggest that soluble immune response mediators may be involved in the severity of dengue infections. For instance, elevated seric levels of IL-8 are a common feature in DHF patients. Because other chemokines, cytokines, adhesion molecules, chemokine and cytokine receptors, as well as cytokine-related molecules may also be involved in dengue virus pathogenesis, we aimed at analysing the gene expression of such molecules in the course of an in vitro DEN-2 infection of human peripheral blood monocyte-derived macrophages, a cell type regarded as a primary target for DEN. Nylon membrane gene arrays containing 375 different human cytokine-related genes were used as a first step to search for differentially expressed genes upon infection. Transcripts for IL-8, IL-1beta, osteopontin, GRO-alpha, -beta and -gamma, I-309, and some other molecules showed to be upregulated upon infection, whereas others such as MIC-1, CD27L and CD30L, were downregulated. Four genes were selected for reverse transcriptase-polymerase chain reaction based gene-expression analysis as a way to partially confirm microarray results. This approach pointed out 25 macrophage-expressed cytokine-related genes that could be relevant in DEN-2 pathogenesis.

Early treatment during a primary malaria infection modifies the development of cross immunity.

We have used a murine model to study the kinetics of cross-protection when a primary infection is halted at different times. We analysed how parasitaemia is modified during a second infection with the homologous parasite, a heterologous parasite, or a mixture of the two. In addition, possible mechanisms involved in cross-protection were analysed. Results show that treatment with pyrimethamine on day 5 during a primary infection with P. chabaudi AS (non-lethal), prevents the generation of cross-protection to a new challenge with lethal P. yoelii 17XL. In contrast, when treatment is on day 7, mice survive a P. yoelii infection. Differences between both groups suggest that in order for 'preimmune' mice to survive a lethal challenge, a predominantly TH2-type response is required, with a higher mRNA expression level of IL-4 and IL-10, and a lower mRNA expression of IFN-gamma. This work shows that an early treatment of a malaria infection produced by a non-lethal parasite drives the immune response towards a loss of cross-protection to further infections, in particular with more virulent parasites. This finding should be taken into account for the development of effective malaria vaccines.

Multiple Mycobacterium microti derived lipids stimulate iNOS gene expression in the J774 murine macrophage cell line.

The inducible nitrogen oxygen synthase (iNOS) and nitric oxide (NO) system acting in concert with superoxide radicals is recognized as a powerful macrophage microbicidal mechanism. However, experimentation with iNOS knockout mice has rendered contradictory results on the protective role of iNOS/NO in the course of mycobacterial infections. On the other hand, NO also plays an immunoregulatory role. Knowing the nature of the mycobacterial constituents that induce iNOS gene expression would help to better understand the host-parasite relationship. Lipoarabinomannan (LAM) and a 19 KDa lipoprotein are the two known mycobacterial constituents that have shown to induce iNOS. By screening a set of methanol extracted lipids from Mycobacterium microti, here we provide evidence that multiple mycobacterial molecules of lipidic nature both of intermediate and of high polarity, with free amino groups or carbohydrates but no phosphate groups as part of their structure are capable of inducing iNOS gene expression in J774 cells, thus implying a complex relationship between mycobacteria and their host immune system in regard to iNOS gene expression.

Anti-Thy-1 treated and irradiated spleen cells from (BALB/c x C57Bl/6) F1 mice infected with Plasmodium chabaudi chabaudi can transfer protection into irradiated hosts.

The transfer of spleen cells from (BALB/c x C57Bl/6) F1 mice recovered from a Plasmodium chabaudi chabaudi AS infection into irradiated syngeneic recipients conferred protection. Neither elimination of Thy-1+ cells nor in vitro irradiation of immune cells before transfer affected protection while both anti-Thy-1 treatment and irradiation abolished the appearance of anti-P. c. chabaudi antibodies in the recipients. Superinfection of immune spleen cell donors did not improve their capability to transfer protection which was also unaffected by anti-Thy-1 treatment. The serum of mice after one infection was only marginally protective when transferred into irradiated recipients and a second infection improved the protective activity of serum which was not further improved by six infections. The co-transfer of immune serum and immune cells did not result in any synergistic effect. On the other hand, when P. c. chabaudi AS (BALB/c x C57Bl/6) F1 infected mice were challenged with a high dose of Plasmodium yoelii 17XL at crisis, the mice were unable to control the heterologous parasite. When mice were challenged with P. yoelii 17XL several weeks after infection with P. c. chabaudi AS, a good degree of cross-protection was observed.