Mercedes Gonzalez-Juarrero

Bio: Mercedes Gonzalez-Juarrero is an academic researcher from Colorado State University. The author has contributed to research in topics: Tuberculosis & Mycobacterium tuberculosis. The author has an hindex of 33, co-authored 69 publications receiving 3434 citations.

In Vivo IL-10 Production Reactivates Chronic Pulmonary Tuberculosis in C57BL/6 Mice

Abstract: The production of immunosuppressive cytokines, such as IL-10 and TGF-beta, has been documented in individuals diagnosed with active tuberculosis. In addition, IL-10 production is increased within the lungs of mice that have chronic mycobacterial infection. Therefore, we hypothesized that the down-regulatory properties of IL-10 might contribute to the reactivation of chronic Mycobacterium tuberculosis infection in mice. To determine the influence of IL-10 on the course of infection, transgenic mice producing increased amounts of IL-10 under the control of the IL-2 promotor were infected with M. tuberculosis via the respiratory route. Mice that overexpressed IL-10 showed no increase in susceptibility during the early stages of infection, but during the chronic phase of the infection showed evidence of reactivation tuberculosis with a highly significant increase in bacterial numbers within the lungs. Reactivation was associated with the formation of macrophage-dominated lesions, decreased mRNA production for TNF and IL-12p40, and a decrease in Ag-specific IFN-gamma secretion. These data support the hypothesis that IL-10 plays a pivotal role during the chronic/latent stage of pulmonary tuberculosis, with increased production playing a potentially central role in promoting reactivation tuberculosis.

Temporal and spatial arrangement of lymphocytes within lung granulomas induced by aerosol infection with Mycobacterium tuberculosis.

Abstract: The progression of the immune response in the lungs after aerosol infection with Mycobacterium tuberculosis is a complex cellular event dominated by macrophages and lymphocytes. Although the phenotype of lymphocytes participating in this response is becoming increasingly well characterized, the dynamic influx of these cells during the infection and their spatial arrangements within the lung tissue are still poorly understood. This study shows that in the first month after aerosol infection with M. tuberculosis there was a steady increase in the percentages of total CD3+, CD3+ CD4+ and CD3+ CD8+ cells, with consistently larger numbers of CD3+ CD4+ cells than of CD3+ CD8+ cells. As granuloma formation continued, the granuloma was found to consist of macrophages, CD4, and CD8 T cells, as well as a smaller number of B cells. Whereas CD4 T cells formed organized aggregates, CD8 T cells were fewer and more scattered and tended to be more prominent toward the periphery of the granulomas. The possible ramifications of the juxtapositions of these two major T-cell subsets are discussed.

Interleukin-10 promotes Mycobacterium tuberculosis disease progression in CBA/J mice.

Abstract: IL-10 is a potent immunomodulatory cytokine that affects innate and acquired immune responses The immunological consequences of IL-10 production during pulmonary tuberculosis (TB) are currently unknown, although IL-10 has been implicated in reactivation TB in humans and with TB disease in mice Using Mycobacterium tuberculosis-susceptible CBA/J mice, we show that blocking the action of IL-10 in vivo during chronic infection stabilized the pulmonary bacterial load and improved survival Furthermore, this beneficial outcome was highly associated with the recruitment of T cells to the lungs and enhanced T cell IFN-γ production Our results indicate that IL-10 promotes TB disease progression These findings have important diagnostic and/or therapeutic implications for the prevention of reactivation TB in humans

Dynamics of macrophage cell populations during murine pulmonary tuberculosis.

Abstract: The influx of macrophages into the lungs is the major component of the granulomatous response to infection with Mycobacterium tuberculosis . In this investigation we used flow cytometric analysis to define macrophage populations entering the airways and lung tissues of infected mice. We demonstrate that by the judicious use of cell surface markers, especially CD11b and CD11c, several cell populations can be distinguished, allowing cell sorting and morphological definition. Primary populations of CD11b − /CD11c +/high were defined as alveolar macrophages, CD11b high /CD11c +/high as dendritic cells, and CD11b +/mid /CD11c +/mid as small macrophages or monocytes, and changes in the activation phenotype of these populations were followed over the early course of the infection. In further studies, these cell populations were compared with cells harvested during the chronic stage of the disease. During the chronic stage of infection, Ag-presenting class II molecules and activation markers were poorly expressed on dendritic, small macrophage, and monocyte cell populations, which may have important implications for the breakdown of the lesions during reactivation disease. This analytical approach may facilitate the further characterization of macrophage populations entering into the lung tissues and their relative contributions to host resistance to tuberculosis infection.

Characterization of murine lung dendritic cells infected with Mycobacterium tuberculosis.

Abstract: Lung dendritic cells were identified by immunohistochemistry in lung tissue sections from C57BL/6 mice. Following isolation from the lungs using CD11c magnetic beads, the flow cytometric analysis of I-Ab+ and CD11c+ cells indicated a mixed population of dendritic cells at different stages of maturation, with most expressing an immature phenotype. When cultured for 7 days with recombinant murine granulocyte-macrophage colony-stimulating factor, 99% of cells were CD11c+ and had a morphology typical of immature dendritic cells. These cells were negative for CD34, CD14, and CD8α antigens but expressed low levels of the myeloid marker F4/80 and moderate levels of MAC3. All expressed high levels of CD11a (LFA-1), CD11b (Mac1), and CD54 antigens, with low levels of class II major histocompatibility complex. Most cells expressed CD80 but only a small percentage of cells were positive for CD40 and CD86. Both overnight and 7-day cultures of lung dendritic cells were able to phagocytose Mycobacterium tuberculosis, and this was associated with the production of interleukin-12 and stimulation of both naive and immune T cells to produce gamma interferon.

Inflammatory monocytes recruited after skeletal muscle injury switch into antiinflammatory macrophages to support myogenesis

Abstract: Macrophages (MPs) are important for skeletal muscle regeneration in vivo and may exert beneficial effects on myogenic cell growth through mitogenic and antiapoptotic activities in vitro. However, MPs are highly versatile and may exert various, and even opposite, functions depending on their activation state. We studied monocyte (MO)/MP phenotypes and functions during skeletal muscle repair. Selective labeling of circulating MOs by latex beads in CX3CR1GFP/+ mice showed that injured muscle recruited only CX3CR1lo/Ly-6C+ MOs from blood that exhibited a nondividing, F4/80lo, proinflammatory profile. Then, within muscle, these cells switched their phenotype to become proliferating antiinflammatory CX3CR1hi/Ly-6C− cells that further differentiated into F4/80hi MPs. In vitro, phagocytosis of muscle cell debris induced a switch of proinflammatory MPs toward an antiinflammatory phenotype releasing transforming growth factor β1. In co-cultures, inflammatory MPs stimulated myogenic cell proliferation, whereas antiinflammatory MPs exhibited differentiating activity, assessed by both myogenin expression and fusion into myotubes. Finally, depletion of circulating MOs in CD11b–diphtheria toxin receptor mice at the time of injury totally prevented muscle regeneration, whereas depletion of intramuscular F4/80hi MPs at later stages reduced the diameter of regenerating fibers. In conclusion, injured skeletal muscle recruits MOs exhibiting inflammatory profiles that operate phagocytosis and rapidly convert to antiinflammatory MPs that stimulate myogenesis and fiber growth.

Mycobacterium tuberculosis Pathogenesis and Molecular Determinants of Virulence

Abstract: Tuberculosis (TB), one of the oldest known human diseases. is still is one of the major causes of mortality, since two million people die each year from this malady. TB has many manifestations, affecting bone, the central nervous system, and many other organ systems, but it is primarily a pulmonary disease that is initiated by the deposition of Mycobacterium tuberculosis, contained in aerosol droplets, onto lung alveolar surfaces. From this point, the progression of the disease can have several outcomes, determined largely by the response of the host immune system. The efficacy of this response is affected by intrinsic factors such as the genetics of the immune system as well as extrinsic factors, e.g., insults to the immune system and the nutritional and physiological state of the host. In addition, the pathogen may play a role in disease progression since some M. tuberculosis strains are reportedly more virulent than others, as defined by increased transmissibility as well as being associated with higher morbidity and mortality in infected individuals. Despite the widespread use of an attenuated live vaccine and several antibiotics, there is more TB than ever before, requiring new vaccines and drugs and more specific and rapid diagnostics. Researchers are utilizing information obtained from the complete sequence of the M. tuberculosis genome and from new genetic and physiological methods to identify targets in M. tuberculosis that will aid in the development of these sorely needed antitubercular agents.

Monocyte-Mediated Defense Against Microbial Pathogens

Abstract: Circulating blood monocytes supply peripheral tissues with macrophage and dendritic cell (DC) precursors and, in the setting of infection, also contribute directly to immune defense against microbial pathogens. In humans and mice, monocytes are divided into two major subsets that either specifically traffic into inflamed tissues or, in the absence of overt inflammation, constitutively maintain tissue macrophage/DC populations. Inflammatory monocytes respond rapidly to microbial stimuli by secreting cytokines and antimicrobial factors, express the CCR2 chemokine receptor, and traffic to sites of microbial infection in response to monocyte chemoattractant protein (MCP)-1 (CCL2) secretion. In murine models, CCR2-mediated monocyte recruitment is essential for defense against Listeria monocytogenes, Mycobacterium tuberculosis, Toxoplasma gondii, and Cryptococcus neoformans infection, implicating inflammatory monocytes in defense against bacterial, protozoal, and fungal pathogens. Recent studies indicate that inflammatory monocyte recruitment to sites of infection is complex, involving CCR2-mediated emigration of monocytes from the bone marrow into the bloodstream, followed by trafficking into infected tissues. The in vivo mechanisms that promote chemokine secretion, monocyte differentiation and trafficking, and finally monocyte-mediated microbial killing remain active and important areas of investigation.

The Immune Response in Tuberculosis

Abstract: There are 9 million cases of active tuberculosis reported annually; however, an estimated one-third of the world's population is infected with Mycobacterium tuberculosis and remains asymptomatic. Of these latent individuals, only 5–10% will develop active tuberculosis disease in their lifetime. CD4+ T cells, as well as the cytokines IL-12, IFN-γ, and TNF, are critical in the control of Mycobacterium tuberculosis infection, but the host factors that determine why some individuals are protected from infection while others go on to develop disease are unclear. Genetic factors of the host and of the pathogen itself may be associated with an increased risk of patients developing active tuberculosis. This review aims to summarize what we know about the immune response in tuberculosis, in human disease, and in a range of experimental models, all of which are essential to advancing our mechanistic knowledge base of the host-pathogen interactions that influence disease outcome.