Granuloma encapsulation is a key factor for containing tuberculosis infection in minipigs

Altres ajuts: MISA/FIS/PI080785Altres ajuts: I+D+I/FIS/CM06/00123A transthoracic infection involving a low dose of Mycobacterium tuberculosis has been used to establish a new model of infection in minipigs. The 20-week monitoring period showed a marked Th1 response and poor humoral response for the whole infection. A detailed histopathological analysis was performed after slicing the formalin-fixed whole lungs of each animal. All lesions were recorded and classified according to their microscopic aspect, their relationship with the intralobular connective network and their degree of maturity in order to obtain a dissemination ratio (DR) between recent and old lesions. CFU counts and evolution of the DR with time showed that the proposed model correlated with a contained infection, decreasing from week 9 onwards. These findings suggest that the infection induces an initial Th1 response, which is followed by local fibrosis and encapsulation of the granulomas, thereby decreasing the onset of new lesions. Two therapeutic strategies were applied in order to understand how they could influence the model. Thus, chemotherapy with isoniazid alone helped to decrease the total number of lesions, despite the increase in DR after week 9, with similar kinetics to those of the control group, whereas addition of a therapeutic M. tuberculosis fragment-based vaccine after chemotherapy increased the Th1 and humoral responses, as well as the number of lesions, but decreased the DR. By providing a local pulmonary structure similar to that in humans, the mini-pig model highlights new aspects that could be key to a better understanding tuberculosis infection control in humans

Oral administration of heat-killed mycobacterium manresensis delays progression toward active tuberculosis in C3HeB/FeJ mice

Altres ajuts: MS 13/00174Low-dose tolerance using heat-killed mycobacteria has been tested as a means of stopping progression toward active tuberculosis (TB) lesions in a human-like murine model using C3HeB/FeJ mice. In the present study, we studied the effect of different treatment schedules with heat-killed non-tuberculous-mycobacteria (NTM) species when given orally, based on the hypothesis of generating oral tolerance. This study included M. manresensis, a new species belonging to the fortuitum group, present in drinking water. Oral treatment with M. manresensis for 2 weeks was able to induce a PPD-specific Tregs population, which has been related to a decrease in the neutrophilic infiltration found in TB lesions. Further mechanistic analysis using PPD-stimulated splenocytes links this 2-week treatment with heat-killed M. manresensis to IL-10 production and memory PPD-specific Tregs, and also to a weak PPD-specific global immune response stimulation, increasing IL-6, TNF, and IFN-γ production. In lungs, this treatment decreased the bacillary load, granulomatous infiltration and pro-inflammatory cytokines (TNF, IFN-γ, IL-6, and IL-17). Oral administration of M. manresensis during standard treatment for TB also significantly reduced the relapse of active TB after ending the treatment. Overall the data suggest that the use of heat-killed M. manresensis could be a new and promising tool for avoiding active TB induction and as adjunctive to TB treatment. This supports the usefulness of generating a new kind of protection based on a complex balanced immune response focused on both destroying the bacilli and including control of an excessive inflammatory response

Granuloma encapsulation is a key factor for containing tuberculosis infection in minipigs

A transthoracic infection involving a low dose of Mycobacterium tuberculosis has been used to establish a new model of infection in minipigs. The 20-week monitoring period showed a marked Th1 response and poor humoral response for the whole infection. A detailed histopathological analysis was performed after slicing the formalin-fixed whole lungs of each animal. All lesions were recorded and classified according to their microscopic aspect, their relationship with the intralobular connective network and their degree of maturity in order to obtain a dissemination ratio (DR) between recent and old lesions. CFU counts and evolution of the DR with time showed that the proposed model correlated with a contained infection, decreasing from week 9 onwards. These findings suggest that the infection induces an initial Th1 response, which is followed by local fibrosis and encapsulation of the granulomas, thereby decreasing the onset of new lesions. Two therapeutic strategies were applied in order to understand how they could influence the model. Thus, chemotherapy with isoniazid alone helped to decrease the total number of lesions, despite the increase in DR after week 9, with similar kinetics to those of the control group, whereas addition of a therapeutic M. tuberculosis fragment-based vaccine after chemotherapy increased the Th1 and humoral responses, as well as the number of lesions, but decreased the DR. By providing a local pulmonary structure similar to that in humans, the mini-pig model highlights new aspects that could be key to a better understanding tuberculosis infection control in humans

Resident memory T cells are a cellular reservoir for HIV in the cervical mucosa

HIV viral reservoirs are established very early during infection. Resident memory T cells (TRM) are present in tissues such as the lower female genital tract, but the contribution of this subset of cells to the pathogenesis and persistence of HIV remains unclear. Here, we show that cervical CD4+TRM display a unique repertoire of clusters of differentiation, with enrichment of several molecules associated with HIV infection susceptibility, longevity and self-renewing capacities. These protein profiles are enriched in a fraction of CD4+TRM expressing CD32. Cervical explant models show that CD4+TRM preferentially support HIV infection and harbor more viral DNA and protein than non-TRM. Importantly, cervical tissue from ART-suppressed HIV+ women contain high levels of viral DNA and RNA, being the TRM fraction the principal contributor. These results recognize the lower female genital tract as an HIV sanctuary and identify CD4+TRM as primary targets of HIV infection and viral persistence. Thus, strategies towards an HIV cure will need to consider TRM phenotypes, which are widely distributed in tissues.We would like to thank all the patients who participated in the study and their providers. We thank José L. Poza, Mª Elena Suárez, Mª Assumpció Pérez-Benavente and Cristina Carrato for referral of patients and sample collection, Irian Lorencés and Laia Pérez-Roca from the Tumor Bank of the IGTP-HUGTiP for sample management, Alba Ruiz and Ruth Peña for generating the viral stock R5-Bal and Gerard Requena from the Flow Cytometry Facility at the IGTP for excellent technical assistance, as well as Isabel Crespo from the Flow Cytometry Platform at the IDIBAPS for her excellent technical assistance on Amnis technology. This work was primarily supported by grants from the Spanish “Ministerio de Economía y Competitividad, Instituto de Salud Carlos III” (ISCIII, PI14/01235 and PI17/01470) and a fellowship award from the Dexeus foundation for women’s health research to M.G., grants R21AI118411 and SAF2015-67334-R (from the Spanish Secretariat of Science and Innovation and FEDER funds) to M.J.B and grants from the ISCIII (PI14/01058 and PI17/00164) to J.G.P. M.G., M.J.B., and. J.G.P. are supported by the Spanish AIDS network Red Temática Cooperativa de Investigación en SIDA (RD16/0025/0007) M.G. is currently supported by the “Pla estratègic de recerca i innovació en salut” (PERIS, SLT002/16/00353), from the Catalan government, while the Miguel Servet program from the ISCIII supports M.J.B. (CP17/00179) and J.G.P. (CP15/00014)

Resident memory T cells are a cellular reservoir for HIV in the cervical mucosa

HIV viral reservoirs are established very early during infection. Resident memory T cells (T) are present in tissues such as the lower female genital tract, but the contribution of this subset of cells to the pathogenesis and persistence of HIV remains unclear. Here, we show that cervical CD4T display a unique repertoire of clusters of differentiation, with enrichment of several molecules associated with HIV infection susceptibility, longevity and self-renewing capacities. These protein profiles are enriched in a fraction of CD4T expressing CD32. Cervical explant models show that CD4T preferentially support HIV infection and harbor more viral DNA and protein than non-T. Importantly, cervical tissue from ART-suppressed HIV women contain high levels of viral DNA and RNA, being the T fraction the principal contributor. These results recognize the lower female genital tract as an HIV sanctuary and identify CD4T as primary targets of HIV infection and viral persistence. Thus, strategies towards an HIV cure will need to consider T phenotypes, which are widely distributed in tissues

Dissemination of Mycobacterium tuberculosis is associated to a SIGLEC1 null variant that limits antigen exchange via trafficking extracellular vesicles

The identification of individuals with null alleles enables studying how the loss of gene function affects infection. We previously described a non-functional variant in SIGLEC1, which encodes the myeloid-cell receptor Siglec-1/CD169 implicated in HIV-1 cell-to-cell transmission. Here we report a significant association between the SIGLEC1 null variant and extrapulmonary dissemination of Mycobacterium tuberculosis (Mtb) in two clinical cohorts comprising 6,256 individuals. Local spread of bacteria within the lung is apparent in Mtb-infected Siglec-1 knockout mice which, despite having similar bacterial load, developed more extensive lesions compared to wild type mice. We find that Siglec-1 is necessary to induce antigen presentation through extracellular vesicle uptake. We postulate that lack of Siglec-1 delays the onset of protective immunity against Mtb by limiting antigen exchange via extracellular vesicles, allowing for an early local spread of mycobacteria that increases the risk for extrapulmonary dissemination