Thymic atrophy induced by Plasmodium berghei ANKA and Plasmodium yoelii 17XL infection.

The thymus is the anatomical site where T cells undergo a complex process of differentiation, proliferation, selection, and elimination of autorreactive cells which involves molecular signals in different intrathymic environment. However, the immunological functions of the thymus can be compromised upon exposure to different infections, affecting thymocyte populations. In this work, we investigated the impact of malaria parasites on the thymus by using C57BL/6 mice infected with Plasmodium berghei ANKA and Plasmodium yoelii 17XL; these lethal infection models represent the most severe complications, cerebral malaria, and anemia respectively. Data showed a reduction in the thymic weight and cellularity involving different T cell maturation stages, mainly CD4-CD8- and CD4+CD8+ thymocytes, as well as an increased presence of apoptotic cells, leading to significant thymic cortex reduction. Thymus atrophy showed no association with elevated serum cytokines levels, although increased glucocorticoid levels did. The severity of thymic damage in both models reached the same extend although it occurs at different stages of infection, showing that thymic atrophy does not depend on parasitemia level but on the specific host-parasite interaction.

Development of Anxiolytic and Depression-like Behavior in Mice Infected with Mycobacterium lepraemurium.

Murine leprosy is a systemic infectious disease of mice caused by Mycobacterium lepraemurium (MLM) in which the central nervous system (CNS) is not infected; nevertheless, diseased animals show measurable cognitive alterations. For this reason, in this study, we explored the neurobehavioral changes in mice chronically infected with MLM. BALB/c mice were infected with MLM, and 120 days later, the alterations in mice were evaluated based on immunologic, histologic, endocrine, neurochemical, and behavioral traits. We found increases in the levels of IL-4 and IL-10 associated with high bacillary loads. We also found increase in the serum levels of corticosterone, epinephrine, and norepinephrine in the adrenal gland, suggesting neuroendocrine deregulation. Mice exhibited depression-like behavior in the tail suspension and forced swimming tests and anxiolytic behavior in the open field and elevated plus maze tests. The neurobehavioral alterations of mice were correlated with the histologic damage in the prefrontal cortex, ventral hippocampus, and amygdala, as well as with a blood-brain barrier disruption in the hippocampus. These results reveal an interrelated response of the neuroimmune--endocrinological axis in unresolved chronic infections that result in neurocognitive deterioration.

Monocyte Locomotion Inhibitory Factor confers neuroprotection and prevents the development of murine cerebral malaria.

Cerebral malaria (CM) is a neurological complication derived from the Plasmodium falciparum infection in humans. The mechanisms involved in the disease progression are still not fully understood, but both the sequestration of infected red blood cells (iRBC) and leukocytes and an exacerbated host inflammatory immune response are significant factors. In this study, we investigated the effect of Monocyte Locomotion Inhibitory Factor (MLIF), an anti-inflammatory peptide, in a well-characterized murine model of CM. Our data showed that the administration of MLIF increased the survival and avoided the neurological signs of CM in Plasmodium berghei ANKA (PbA) infected C57BL/6 mice. MLIF administration down-regulated systemic inflammatory mediators such as IFN-γ, TNF-α, IL-6, CXCL2, and CCL2, as well as the in situ expression of TNF-α in the brain. In the same way, MLIF reduced the expression of CD31, CD36, CD54, and CD106 in the cerebral endothelium of infected animals and prevented the sequestration of iRBC and leucocytes in the brain microvasculature. Furthermore, MLIF inhibited the activation of astrocytes and microglia and preserved the integrity of the blood-brain barrier (BBB). In conclusion, our results demonstrated that the administration of MLIF increased survival and conferred neuroprotection by decreasing neuroinflammation in murine CM.

Trimethylamine N-oxide levels are associated with NASH in obese subjects with type 2 diabetes.

AIMS: Trimethylamine N-oxide (TMAO), choline and betaine serum levels have been associated with metabolic diseases including type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD). These associations could be mediated by insulin resistance. However, the relationships among these metabolites, insulin resistance and NAFLD have not been thoroughly investigated. Moreover, it has recently been suggested that TMAO could play a role in NAFLD by altering bile acid metabolism. We examined the association between circulating TMAO, choline and betaine levels and NAFLD in obese subjects. METHODS: Serum TMAO, choline, betaine and bile acid levels were measured in 357 Mexican obese patients with different grades of NAFLD as determined by liver histology. Associations of NAFLD with TMAO, choline and betaine levels were tested. Moreover, association of TMAO levels with non-alcoholic steatohepatitis (NASH) was tested separately in patients with and without T2D. RESULTS: TMAO and choline levels were significantly associated with NAFLD histologic features and NASH risk. While increased serum TMAO levels were significantly associated with NASH in patients with T2D, in non-T2D subjects this association lost significance after adjusting for sex, BMI and HOMA2-IR. Moreover, circulating secondary bile acids were associated both with increased TMAO levels and NASH. CONCLUSIONS: In obese patients, circulating TMAO levels were associated with NASH mainly in the presence of T2D. Functional studies are required to evaluate the role of insulin resistance and T2D in this association, both highly prevalent in NASH patients.

Circulation of M. tuberculosis Beijing genotype in Latin America and the Caribbean.

Lineage 2 (East Asian), which includes the Beijing genotype, is one of the most prevalent lineages of Mycobacterium tuberculosis (Mtb) throughout the world. The Beijing family is associated to hypervirulence and drug-resistant tuberculosis. The study of this genotype's circulation in Latin America is crucial for achieving total control of TB, the goal established by the World Health Organization, for the American sub-continent, before 2035. In this sense, the present work presents an overview of the status of the Beijing genotype for this region, with a bibliographical review, and data analysis of MIRU-VNTRs for available Beijing isolates. Certain countries present a prevalent trend of <5%, suggesting low transmissibility for the region, with the exception of Cuba (17.2%), Perú (16%) and Colombia (5%). Minimum Spanning Tree analysis, obtained from MIRU-VNTR data, shows distribution of specific clonal complex strains in each country. From this data, in most countries, we found that molecular epidemiology has not been a tool used for the control of TB, suggesting that the Beijing genotype may be underestimated in Latin America. It is recommended that countries with the highest incidence of the Beijing genotype use effective control strategies and increased care, as a requirement for public health systems.

Tuberculosis and cigarette smoke exposure: An update of in vitro and in vivo studies.

Tuberculosis (TB) has been declared the first cause of death by an infectious agent. Annually, 10.4 million people suffer active TB. Most infected individuals live in low-income countries, where social and economic conditions enhance the dissemination and progression of the disease. These countries have a high percentage of smokers. Thousands of studies have linked cigarette smoke (CS) with increased risk of many diseases, such as cancer and lung diseases. Numerous in vitro studies have been conducted to evaluate the general and specific toxic effects of CS in lung immune function. Smoke exposure increases the risk of TB development three-fold. However, until now, only few animal studies have been performed to analyze the association between smoke and TB. In the present work, we review in vitro and in vivo studies whose aim was to analyze the molecular basis of TB susceptibility caused by exposure to CS.

CCR9 Is a Key Regulator of Early Phases of Allergic Airway Inflammation.

Airway inflammation is the most common hallmark of allergic asthma. Chemokine receptors involved in leukocyte recruitment are closely related to the pathology in asthma. CCR9 has been described as a homeostatic and inflammatory chemokine receptor, but its role and that of its ligand CCL25 during lung inflammation remain unknown. To investigate the role of CCR9 as a modulator of airway inflammation, we established an OVA-induced allergic inflammation model in CCR9-deficient mice. Here, we report the expression of CCR9 and CCL25 as early as 6 hours post-OVA challenge in eosinophils and T-lymphocytes. Moreover, in challenged CCR9-deficient mice, cell recruitment was impaired at peribronchial and perivenular levels. OVA-administration in CCR9-deficient mice leads to a less inflammatory cell recruitment, which modifies the expression of IL-10, CCL11, and CCL25 at 24 hours after OVA challenge. In contrast, the secretion of IL-4 and IL-5 was not affected in CCR9-deficient mice compared to WT mice. These results demonstrate for the first time that CCR9 and CCL25 expressions are induced in the early stages of airway inflammation and they have an important role modulating eosinophils and lymphocytes recruitment at the first stages of inflammatory process, suggesting that they might be a potential target to regulate inflammation in asthma.

Helicobacter pylori vacA and cagA genotype diversity and interferon gamma expression in patients with chronic gastritis and patients with gastric cancer.

BACKGROUND: Helicobacter pylori (H. pylori) is the main risk factor for the development of chronic gastritis, gastric ulcer, and gastric cancer. In H. pylori-infected individuals, the clinical result is dependent on various factors, among which are bacterial components, the immune response, and environmental influence. AIMS: To compare IFN-γ expression with the H. pylori vacA and cagA genotypes in patients with chronic gastritis and patients with gastric cancer. METHODS: Ninety-five patients diagnosed with chronic gastritis and 20 with gastric cancer were included in the study. Three gastric biopsies were taken; one was used for the molecular detection and genotyping of H. pylori; another was fixed in absolute alcohol and histologic sections were made for determining IFN-γ expression through immunohistochemistry. RESULTS: No differences were found in the cells that expressed IFN-γ between the patients with chronic gastritis (median percentage of positive cells: 82.6% in patients without H. pylori and 82% in infected persons) and those with gastric cancer (70.5% in H. pylori-negative patients and 78.5% in infected persons). IFN-γ expression was 69% in chronic gastritis patients infected with H. pylori vacAs2m2/cagA⁻ it was 86.5% in patients infected with H. pylori vacAs1m2/cagA⁻, 86.5% in vacAs1m1/cagA⁻, and 82% in vacAs1m1/cagA⁺. Similar data were found in the patients with gastric cancer. CONCLUSIONS: IFN-γ expression varied depending on the H. pylori vacA and cagA genotype, but not in accordance with the presence of chronic gastritis or gastric cancer.

A novel antigen-carrier system: the Mycobacterium tuberculosis Acr protein carried by raw starch microparticles.

Microparticles have been used as promising carriers for in vivo vaccine delivery. However, the processes for immobilizing peptides or proteins on microparticles usually require the use of undesirable compounds and complex protocols. In this work, we propose a new immobilization and delivery system with raw starch microparticles and a starch binding domain (SBD) tag fusion protein. The heat shock protein alpha crystallin from Mycobacterium tuberculosis was used as model. The immunogenicity of the system was investigated in BALB/c mice inoculated with purified Acr-SBDtag protein (pAcr-SBDtag) and starch immobilized Acr-SBDtag protein (µAcr-SBDtag) by oral and intranasal routes. We demonstrated mucosal immunization with the µAcr-SBDtag protein induced systemic antibodies that were predominantly immunoglobulin G2a (IgG2a). An analysis of the cytokines from spleen cells and lung homogenates revealed that loaded microparticles induced the secretion of interferon-γ (INF-γ), suggesting an adjuvant effect from the immobilization. The immune responses induced by immobilized protein were primarily affected by the route of administration. These results demonstrate that the system exhibits the necessary characteristics to improve antigen release and presentation to antigen presenting cells (APCs) in the mucosae. Because no extra adjuvants were used, we posit that the system may be suitable for delivery and presentation to the field of subunit vaccine development.

Sulforaphane reduces the alterations induced by quinolinic acid: modulation of glutathione levels.

Glutamate-induced excitotoxicity involves a state of acute oxidative stress, which is a crucial event during neuronal degeneration and is part of the physiopathology of neurodegenerative diseases. In this work, we evaluated the ability of sulforaphane (SULF), a natural dietary isothiocyanate, to induce the activation of transcription factor Nrf2 (a master regulator of redox state in the cell) in a model of striatal degeneration in rats infused with quinolinic acid (QUIN). Male Wistar rats received SULF (5mg/kg, i.p.) 24h and 5min before the intrastriatal infusion of QUIN. SULF increased the reduced glutathione (GSH) levels 4h after QUIN infusion, which was associated with its ability to increase the activity of glutathione reductase (GR), an antioxidant enzyme capable to regenerate GSH levels at 24h. Moreover, SULF treatment increased glutathione peroxidase (GPx) activity, while no changes were observed in γ-glutamyl cysteine ligase (GCL) activity. SULF treatment also prevented QUIN-induced oxidative stress (measured by oxidized proteins levels), the histological damage and the circling behavior. These results suggest that the protective effect of SULF could be related to its ability to preserve GSH levels and increase GPx and GR activities.

Low-dose amphotericin B and murine dialyzable spleen extracts protect against systemic candida infection in mice.

Candida albicans causes opportunistic systemic infections with high mortality (30%-50%). Despite significant nephrotoxicity, amphotericin (AmB) is still used for the treatment of this serious fungal infection. Therefore, alternative treatments are urgently needed. Dialyzable leukocyte extracts have been used successfully to treat patients with mucocutaneous candidiasis, but their effectiveness in systemic candidiasis has not been evaluated. In this study, low-dose AmB (0.1 mg/kg) plus 10 pg of murine dialyzable spleen extracts (mDSE) were tested in a systemic candidiasis mouse model. Survival, tissue fungal burden, kidney damage, kidney cytokines, and serum levels of IL-6 and hepcidin were evaluated. Our results showed that the combined treatment of low-dose AmB plus mDSE improved survival and reduced kidney fungal burden and histopathology; these effects correlated with increased kidney concentration of IFN- γ and TGF- ß 1, decreased levels of TNF- α , IL-6, and IL-10, as well as high levels of systemic IL-6 and hepcidin. Low-dose AmB and mDSE synergized to clear the infectious agent and reduced tissue damage, confirming the efficacy of a low dose of AmB, which might decrease the risk of drug toxicity. Further studies are necessary to explore these findings and its implications in future therapeutic approaches.

Immunotherapeutic effects of recombinant adenovirus encoding granulocyte-macrophage colony-stimulating factor in experimental pulmonary tuberculosis.

BALB/c mice with pulmonary tuberculosis (TB) develop a T helper cell type 1 that temporarily controls bacterial growth. Bacterial proliferation increases, accompanied by decreasing expression of interferon (IFN)-γ, tumour necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS). Activation of dendritic cells (DCs) is delayed. Intratracheal administration of only one dose of recombinant adenoviruses encoding granulocyte-macrophage colony-stimulating factor (AdGM-CSF) 1 day before Mycobacterium tuberculosis (Mtb) infection produced a significant decrease of pulmonary bacterial loads, higher activated DCs and increased expression of TNF-α, IFN-γ and iNOS. When AdGM-CSF was given in female mice B6D2F1 (C57BL/6J X DBA/2J) infected with a low Mtb dose to induce chronic infection similar to latent infection and corticosterone was used to induce reactivation, a very low bacilli burden in lungs was detected, and the same effect was observed in healthy mice co-housed with mice infected with mild and highly virulent bacteria in a model of transmissibility. Thus, GM-CSF is a significant cytokine in the immune protection against Mtb and gene therapy with AdGM-CSF increased protective immunity when administered in a single dose 1 day before Mtb infection in a model of progressive disease, and when used to prevent reactivation of latent infection or transmission.

Effect of glycolysis inhibition on mitochondrial function in rat brain.

Inhibition of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase enhances the neural vulnerability to excitotoxicity both in vivo and in vitro through an unknown mechanism possibly related to mitochondrial failure. However, as the effect of glycolysis inhibition on mitochondrial function in brain has not been studied, the aim of the present work was to evaluate the effect of glycolysis inhibition induced by iodoacetate on mitochondrial function and oxidative stress in brain. Mitochondria were isolated from brain cortex, striatum and cerebellum of rats treated systemically with iodoacetate (25 mg/kg/day for 3 days). Oxygen consumption, ATP synthesis, transmembrane potential, reactive oxygen species production, lipoperoxidation, glutathione levels, and aconitase activity were assessed. Oxygen consumption and aconitase activity decreased in the brain cortex and striatum, showing that glycolysis inhibition did not trigger severe mitochondrial impairment, but a slight mitochondrial malfunction and oxidative stress were present.

Use of mouse models to study the variability in virulence associated with specific genotypic lineages of Mycobacterium tuberculosis.

The host response against Mycobacterium tuberculosis show a wide spectrum of clinical manifestations in those patients who fail to control the infection. The course of the infection and its epidemiological consequences depend upon a complex interplay of host, environmental and bacterial factors. Experimental animal models have helped to define the influence of bacterial genetic diversity on virulence and on the immune response that is induced. For this purpose, experimental animals such as mice, guinea pigs and rabbits have been infected with selected clinical isolates obtained from outbreaks or from clinical epidemiology settings. Here we review the contribution of mouse models to defining the variability in virulence and immune response in relation to mycobacterial genetic diversity. Low dose aerosol infection in C57Bl mice or high dose intratracheal infection in BALB/c mice have demonstrated wide variability in virulence and immune responses induced by different bacterial genotypes, and each genotype has different phenotypes, with high and low virulence variants. In general, these studies have shown that high prevalent strains from big clusters are more virulent than low prevalent sporadic clinical isolates, and highly virulent strains induce non-protective immune responses with some correlation with clinical-epidemiological data. In the future selected strains from these types of studies should be analyzed with molecular technologies. These kinds of study will contribute to the identification of mycobacterial genes associated with virulence and immunogenicity.

Detection of Mycobacterium avium subsp. paratuberculosis by a Direct In Situ PCR Method.

In situ detection of Mycobacterium avium subsp. paratuberculosis is useful for diagnosis and research of paratuberculosis. The aim of this paper was to detect this agent in formalin-fixed, paraffin-embedded tissue samples by a direct in situ PCR. The technique was performed on ileum or ileocaecal lymph node samples from 8 naturally infected cattle and 1 healthy calf, by using p89 and p92 primers for amplification of IS900 sequence. Moderate positive signal was detected in all positive samples and not in negative control, but tissues resulted were affected in many cases due to the enzymatic treatment and the high temperature exposition. Although the technique was useful for Map detection, the signal was lower than immunohistochemistry probably because of the fixation process. In one case, signal was higher, which might be due to the detection of spheroplasts. Thus, the described method should be recommended when others resulted negative or for spheroplasts detection.

Hypoxia inducible factor promotes murine allergic airway inflammation and is increased in asthma and rhinitis.

BACKGROUND: New therapies are necessary to address inadequate asthma control in many patients. This study sets out to investigate whether hypoxia-inducible factor (HIF) is essential for development of allergic airway inflammation (AAI) and therefore a potential novel target for asthma treatment. METHODS: Mice conditionally knocked out for HIF-1ß were examined for their ability to mount an allergic inflammatory response in the lung after intratracheal exposure to ovalbumin. The effects of treating wild-type mice with either ethyl-3,4-dihydroxybenzoate (EDHB) or 2-methoxyestradiol (2ME), which upregulate and downregulate HIF, respectively, were determined. HIF-1α levels were also measured in endobronchial biopsies and bronchial fluid of patients with asthma and nasal fluid of patients with rhinitis after challenge. RESULTS: Deletion of HIF-1ß resulted in diminished AAI and diminished production of ovalbumin-specific IgE and IgG(1) . EDHB enhanced the inflammatory response, which was muted upon simultaneous inhibition of vascular endothelial growth factor (VEGF). EDHB and 2ME antagonized each other with regard to their effects on airway inflammation and mucus production. The levels of HIF-1α and VEGF increased in lung tissue and bronchial fluid of patients with asthma and in the nasal fluid of patients with rhinitis after challenge. CONCLUSIONS: Our results support the notion that HIF is directly involved in the development of AAI. Most importantly, we demonstrate for the first time that HIF-1α is increased after challenge in patients with asthma and rhinitis. Therefore, we propose that HIF may be a potential therapeutic target for asthma and possibly for other inflammatory diseases.

Induction of ß-defensins by l-isoleucine as novel immunotherapy in experimental murine tuberculosis.

Tuberculosis is a worldwide health problem, and multidrug-resistant (MDR) and extensively multidrug-resistant (XMDR) strains are rapidly emerging and threatening the control of this disease. These problems motivate the search for new treatment strategies. One potential strategy is immunotherapy using cationic anti-microbial peptides. The capacity of l-isoleucine to induce beta-defensin expression and its potential therapeutic efficiency were studied in a mouse model of progressive pulmonary tuberculosis. BALB/c mice were infected with Mycobacterium tuberculosis strain H37Rv or with a MDR clinical isolate by the intratracheal route. After 60 days of infection, when disease was in its progressive phase, mice were treated with 250 µg of intratracheal l-isoleucine every 48 h. Bacillary loads were determined by colony-forming units, protein and cytokine gene expression were determined by immunohistochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR), respectively, and tissue damage was quantified by automated morphometry. Administration of l-isoleucine induced a significant increase of beta-defensins 3 and 4 which was associated with decreased bacillary loads and tissue damage. This was seen in animals infected with the antibiotic-sensitive strain H37Rv and with the MDR clinical isolate. Thus, induction of beta-defensins might be a potential therapy that can aid in the control of this significant infectious disease.

Mycobacterium tuberculosis strains with the Beijing genotype demonstrate variability in virulence associated with transmission.

Phylogenetic analysis has shown that Beijing genotype strains can be grouped into at least 7 different sublineages. We aimed to test the hypothesis that the virulence of Beijing genotype strains differed among members of the different sublineages and that the level of virulence correlated with their ability to spread and cause disease. BALB/c mice were infected with Beijing strains representative of the different lineages and of different epidemiological characteristics (transmitted vs. non-transmitted). Survival times, lung pathology, bacterial load and immunology kinetics were evaluated at defined intervals post-infection. Transmissibility was determined by co-housing infected and uninfected mice in close contact for 1-2 months. The results show that mice infected with the highly transmitted Beijing strains began showing mortality 3 weeks post-infection and all had died by 5 weeks, suggesting high virulence phenotypes. In contrast, >80% of mice infected with the non-transmitted strains survived 4 months post-infection, suggesting low virulence phenotypes. Our co-housing transmission model confirmed these virulence phenotypes. Extensive tissue damage and the induction of lower levels of IFNγ and iNOS expression, as well as high but ephemeral TNFα expression were associated with the high virulence phenotype. In contrast, minimal tissue damage and progressive expression of IFNγ and TNFα were associated with the low virulence phenotype. Both virulence phenotypes induced similar levels of IL-4 expression during the early stages of infection after which the high virulence strain induced significantly higher levels of IL-4 expression. In conclusion, this study demonstrates that Beijing genotype strains display a spectrum of virulence phenotypes in mice which mimic their epidemiological characteristics. Both transmissible and non-transmissible strains may exist in the same sublineage.

Kinetics and cellular sources of cathelicidin during the course of experimental latent tuberculous infection and progressive pulmonary tuberculosis.

In spite of advances in immunology on mycobacterial infection, there are few studies on the role of anti-microbial peptides in tuberculosis. The cathelin-related anti-microbial peptide (CRAMP) is the only cathelicidin isolated from mice. In this work we investigated the cellular sources and the production kinetics of this molecule during experimental tuberculosis, using two well-characterized models of latent or chronic infection and progressive disease. The lung of non-infected control mice expressed CRAMP at very low levels. In both models of experimental tuberculosis the main cells immunolabelled for CRAMP were bronchial epithelial cells, macrophages and pneumocytes types II and I. After intratracheal infection with a high bacilli dose (H37Rv strain) in Balb/c mice to produce progressive disease, a high CRAMP gene expression was induced showing three peaks: very early after 1 day of infection, at day 21 when the peak of protective immunity in this model is raised, and at day 28 when the progressive phase starts and the immunoelectronmicroscopy study showed intense immunolabelling in the cell wall and cytoplasm of intracellular bacilli, as well as in cytoplasmic vacuoles. Interestingly, at day 60 post-infection, when advanced progressive disease is well established, characterized by high bacillary loads and extensive tissue damage, CRAMP gene expression decreased but strong CRAMP immunostaining was detected in vacuolated macrophages filled with bacilli. Thus, cathelicidin is highly produced during experimental pulmonary tuberculosis from diverse cellular sources and could have significant participation in its pathogenesis.

T-cell responses and in vivo cytotoxicity in the target organ and the regional lymphoid tissue during airborne infection with the virulent Mycobacterium tuberculosis MT103 and its lipid mutant fadD26.

To ascertain the in vivo role of mycobacterial lipids phthiocerol dimycocerosates (PDIM) in experimental murine tuberculosis (Tb), airways infection was used to compare the parental virulent clinical isolate MT103 with its mutant fadD26, lacking PDIM. Lungs were assessed as the Tb-target organ and mediastinal lymph nodes as the corresponding lymphoid tissue, in order to quantify: the major T-cell subsets (CD4+/CD8+/gammadelta+) and their activation kinetics, bacillary burden, and in vivo cytotoxicity against inoculated target cells loaded with mycobacterial Ags. After 4 weeks, infection augmented total and activated CD4+ and CD8+ T cells in lungs and nodes mainly with MT103, while gammadelta+ T cells increased earlier in nodes. MT103 bacillary burden was bigger and appeared earlier than the mutant fadD26, especially in the lung than in mediastinal nodes. At day 14 of MT103 infection, there was no cytotoxicity in lungs and nodes; while with fadD26 there was some in the nodes. At day 21 of MT103 infection, important cytotoxicity was detected only in lungs; while with fadD26 both tissues showed important activity. Interestingly, unlike the infection with fadD26, cytotoxicity under MT103 fell considerably in the target organ (lung) from days 21 to 60, the advanced phase. Although upon airways infection both mycobacteria behaved similarly regarding T cell (CD4/CD8/gammadelta) stimulation kinetics; they differed in the magnitude of these responses, in the bacterial load within tissues, and to trigger in vivo cytotoxicity in lungs and regional lymph nodes. This highlights the relevance of certain mycobacterial lipids to modify crucial effector branches of immunity.