139 episodes

Audio versions of bioRxiv paper abstracts

PaperPlayer biorxiv immunolog‪y‬ Multimodal LLC

    • Life Sciences

Audio versions of bioRxiv paper abstracts

    DPP9 directly sequesters the NLRP1 C-terminus to repress inflammasome activation

    DPP9 directly sequesters the NLRP1 C-terminus to repress inflammasome activation

    Link to bioRxiv paper:
    http://biorxiv.org/cgi/content/short/2020.08.14.246132v1?rss=1

    Authors: Hollingsworth, L. R., Sharif, H., Griswold, A. R., Fontana, P., Mintseris, J., Dagbay, K. B., Paulo, J. A., Gygi, S. P., Bachovchin, D. A., Wu, H.

    Abstract:
    NLRP1 is a cytosolic inflammasome sensor that mediates activation of caspase-1, which in turn induces cytokine maturation and pyroptotic cell death. Gain-of-function NLPR1 mutations cause skin inflammatory diseases including carcinoma, keratosis, and papillomatosis. NLRP1 contains a unique function-to-find domain (FIIND) that autoproteolyzes into noncovalently associated subdomains. Proteasomal degradation of the autoinhibitory N-terminal fragment (NT) activates NLRP1 by releasing the inflammatory C-terminal fragment (CT). Cytosolic dipeptidyl peptidases 8 and 9 (DPP8/9) interact with NLRP1, and small-molecule DPP8/9 inhibitors activate NLRP1 by poorly characterized mechanisms. Here, we report cryo-EM structures of the human NLRP1-DPP9 complex, alone and in complex with the DPP8/9 inhibitor Val-boroPro (VbP). Surprisingly, the NLRP1-DPP9 complex is a ternary complex comprised of DPP9, one intact FIIND of a non-degraded full-length NLRP1 (NLRP1-FL) and one NLRP1-CT freed by NT degradation. The N-terminus of the NLRP1-CT unfolds and inserts into the DPP9 active site but is not cleaved by DPP9, and this binding is disrupted by VbP. Structure-based mutagenesis reveals that the binding of NLRP1-CT to DPP9 requires NLRP1-FL and vice versa, and inflammasome activation by ectopic NLRP1-CT expression is rescued by co-expressing autoproteolysis-deficient NLRP1-FL. Collectively, these data indicate that DPP9 functions as a "bomb-diffuser" to prevent NLRP1-CTs from inducing inflammation during homeostatic protein turnover.

    Copy rights belong to original authors. Visit the link for more info

    New models to study plasma cells in mouse based on the restriction of IgJ expression to antibody secreting cells.

    New models to study plasma cells in mouse based on the restriction of IgJ expression to antibody secreting cells.

    Link to bioRxiv paper:
    http://biorxiv.org/cgi/content/short/2020.08.13.249441v1?rss=1

    Authors: Ayala, M. V., Bonaud, A., Bender, S., Lambert, J.-M., Lechouane, F., Carrion, C., Cogne, M., Pascal, V., Sirac, C.

    Abstract:
    Plasma cells (PC) represent the last stage of B cell development and are mainly characterized by their capacity of secreting large quantities of antibodies. They can be implicated in a broad-spectrum of neoplastic disorders, including Multiple Myeloma, Waldenstrom macroglobulinemia or Monoclonal Gammopathy of Clinical Significance, all characterized by the abnormal proliferation of a PC clone. Up to date, there are only few reporter models to specifically follow PC development, migration and homing in mouse and none allowing the genetic manipulation of these cells. We created a transgenic mouse model in which a green fluorescent protein gene was placed under the control of the well-characterized regulatory elements of the murine immunoglobulin J (IgJ) chain locus. Thanks to this model, we demostrated that IgJ is an early and specific marker of antibody secreting cells (ASCs) and appears before the expression of CD138, making it a good candidate to targeted genetic modifications of plasma cells. Therefore, a conditional deletion model using a Tamoxifen-dependent Cre recombinase inserted into the IgJ locus was characterized. Using a reporter model, we showed that, in contrast with existing models of B cell lineage genetic modification, the activity of the CRE recombinase only affects ASCs after tamoxifen treatment. Additionally, we used this model in a functional in vitro assay, to show that Ig modifications directly affect plasma cell survival. These two new mouse models, IgJGFP and IgJCreERT2 represent exquisite tools to study PCs. In pathology, the IgJCreERT2model opens new frontiers for in vivo genetic modifications of PCs to better reflect the pathophysiology of PC-related diseases.

    Copy rights belong to original authors. Visit the link for more info

    An easy and reliable whole blood freezing method for flow cytometry immuno- phenotyping and functional analyses

    An easy and reliable whole blood freezing method for flow cytometry immuno- phenotyping and functional analyses

    Link to bioRxiv paper:
    http://biorxiv.org/cgi/content/short/2020.08.12.248450v1?rss=1

    Authors: Braudeau, C., Salabert-Le Guen, N., Chevreuil, J., Rimbert, M., Martin, J. C., Josien, R.

    Abstract:
    Background: Immune profiling by flow cytometry is not always possible on fresh blood samples due to time and/or transport constraints. Besides, the cryopreservation of peripheral blood mononuclear cells (PBMC) requires on-site specialized lab facilities, thus severely restricting the extent by which blood immune monitoring can be applied to multicenter clinical studies. These major limitations can be addressed through the development of simplified whole blood freezing methods. Methods: In this report, we describe an optimized easy protocol for rapid whole blood freezing with the CryoStor CS10 solution. Using flow cytometry, we compared cellular viability and composition on cryopreserved whole blood samples to matched fresh blood, as well as fresh and frozen PBMC. Results: Though partial loss of neutrophils was observed, leucocyte viability was routinely >75% and we verified the preservation of viable T cells, NK cells, monocytes, dendritic cells and eosinophils in frequencies similar to those observed in fresh samples. A moderate decrease in B cell frequencies was observed. Importantly, we validated the possibility to analyze major intracellular markers, such as FOXP3 and Helios in regulatory T cells. Finally, we demonstrated good functional preservation of CS10-cryopreserved cells through the analysis of intracellular cytokine production in ex vivo stimulated T cells (IFNg, IL-4, IL-17A,) and monocytes (IL-1b, IL-6, TNFa). Conclusions: In conclusion, our protocol provides a robust method to apply reliable immune monitoring studies to cryopreserved whole blood samples, hence offering new important opportunities for the design of future multicenter clinical trials.

    Copy rights belong to original authors. Visit the link for more info

    Structural and biochemical mechanisms of NLRP1 inhibition by DPP9

    Structural and biochemical mechanisms of NLRP1 inhibition by DPP9

    Link to bioRxiv paper:
    http://biorxiv.org/cgi/content/short/2020.08.13.250241v1?rss=1

    Authors: Chai, J., Zhong, F. L., Huang, M., zhang, X., Wang, J., Wu, B., Han, Z., Ann, T. G., Gong, Q.

    Abstract:
    The nucleotide-binding domain (NBD) and leucine-rich repeat (LRR)-containing receptors (NLRs) mediate innate immunity by forming inflammasomes. Activation of the NLR protein NLRP1 requires auto-cleavage within its FIIND domain1-7. In resting cells, the dipeptidyl peptidase DPP9 interacts with NLRP1-FIIND and together with a related enzyme DPP8, suppresses spontaneous NLRP1 activation8,9. The mechanisms of DPP8/9-mediated NLRP1 inhibition, however, remain elusive. Here we provide structural and biochemical evidence demonstrating that rat NLRP1 (rNLRP1) interacts with rDPP9 in a stepwise manner to form a 2:1 complex. An auto-inhibited rNLRP1 molecule first interacts with rDPP9 via its ZU5 domain. This 1:1 rNLRP1-rDPP9 complex then captures the UPA domain of a second rNLRP1 molecule via a UPA-interacting site on DPP9 and dimeric UPA-UPA interactions with the first rNLRP1. The 2:1 rNLRP1-rDPP9 complex prevents NLRP1 UPA-mediated higher order oligomerization and maintains NLRP1 in the auto-inhibited state. Structure-guided biochemical and functional assays show that both NLRP1-binding and its enzymatic activity are required for DPP9 to suppress NLRP1, supporting guard-type activation of the NLR. Together, our data reveal the mechanism of DPP9-mediated inhibition of NLRP1 and shed light on activation of the NLRP1 inflammasome.

    Copy rights belong to original authors. Visit the link for more info

    Sero-Prevalence and Associated Risk Factors of Bovine Brucellosis in Sendafa, Oromia Special Zone Surrounding Addis Ababa, Ethiopia

    Sero-Prevalence and Associated Risk Factors of Bovine Brucellosis in Sendafa, Oromia Special Zone Surrounding Addis Ababa, Ethiopia

    Link to bioRxiv paper:
    http://biorxiv.org/cgi/content/short/2020.08.13.249243v1?rss=1

    Authors: Gugsa, G., Bifo, H., Kifleyohannes, T., Abebe, E., Ahmed, M.

    Abstract:
    Bovine brucellosis is an infectious bacterial disease caused by members of genus Brucella, affecting both animals and humans, and resulting in a serious economic loss in animal production sector and deterioration of public health. This cross-sectional study was conducted from November 2014 to April 2015 to determine the sero-prevalence and associated risk factors of bovine brucellosis in Sendafa, Oromia special Zone, Ethiopia. A total of 503 blood samples were collected using simple random sampling technique from dairy cattle of above 6 months of age with no history of previous vaccination against brucellosis. All sera samples were demonstrated using both Rose Bengal Plate Test for screening and Compliment Fixation Test for confirmation. Accordingly, the overall sero-prevalence of bovine brucellosis in this area was 0.40%. The result showed that the sero-prevalence of bovine brucellosis in the study area was not statistically significant with all proposed risk factors. Thus, the study revealed the absence of significant statistical variation in the sero-prevalence of bovine brucellosis in different age, sex groups, breeding method and history of previous abortions (P>0.05). No reactors were observed in male animals. Sero-prevalence of 0.40% was observed in animals without previous history of abortion. Moreover, information was gathered on individual animal and farm-level risk factors and other farm characteristics using a questionnaire. The awareness among the society was poor, so the positive animals can be a potential hazard to animals and humans in the study area. Therefore, public education should be done in order to improve the awareness of people on bovine brucellosis and its public health impact with due consideration on the safely consumption of food of animal origin.

    Copy rights belong to original authors. Visit the link for more info

    IL-27 enhances the lymphocyte mediated innate resistance to primary hookworm infection in the lungs

    IL-27 enhances the lymphocyte mediated innate resistance to primary hookworm infection in the lungs

    Link to bioRxiv paper:
    http://biorxiv.org/cgi/content/short/2020.08.12.248021v1?rss=1

    Authors: Noon, J. B., Sharma, A., Platten, J., Quinton, L. J., Reinhardt, C., Bosmann, M.

    Abstract:
    Interleukin-27 (IL-27) is a heterodimeric cytokine of the IL-12 family, formed by non-covalent association of the promiscuous EBI3 subunit and selective p28 subunit. IL-27 is produced by mononuclear phagocytes and unfolds pleiotropic immune-modulatory functions through high affinity ligation to IL-27 receptor alpha (IL-27RA). While IL-27 is known to contribute to immunity and to end inflammation following numerous types of infections, its relevance for host defense against multicellular parasites is still poorly defined. Here, we investigated the role of IL-27 during infection with the soil-transmitted hookworm, Nippostrongylus brasiliensis, in its early intrapulmonary life cycle. IL-27(p28) was detectable in broncho-alveolar lavage fluids of C57BL/6J wild type mice on day 1 after subcutaneous N. brasiliensis inoculation. The expression of IL-27RA was most abundant on lung invading {gamma}{delta} T cells followed by CD8+ T cells, CD4+ T cells and NK cells. IL-27RA was weakly present on CD19+ B cells and absent on neutrophils, alveolar macrophages and eosinophils. Il27ra-/- mice showed increased parasite burden together with aggravated pulmonary hemorrhage and higher alveolar albumin leakage as a surrogate for disruption of the epithelial/vascular barrier. Conversely, recombinant mouse IL-27 injections of wild type mice reduced parasite burdens and lung injury. In multiplex screens, we identified higher airway accumulations of IL-6, TNF and MCP-3 (CCL7) in Il27ra-/- mice, while rmIL-27 treatment showed a reciprocal effect. Finally, {gamma}{delta} T cell infiltration of the airways required endogenous IL-27 expression. In summary, this report demonstrates protective functions of IL-27 to control the early larval stage of hookworm infection in the lungs.

    Copy rights belong to original authors. Visit the link for more info

Top Podcasts In Life Sciences