On Demand

Developing a collaborative network to study TB and HIV biomarkers

Dr. Andrade lab is dedicated to identifying reliable host biomarkers that can predict susceptibility to infection and disease severity in tuberculosis (TB) and HIV. By establishing a strong network of collaborators from different TB endemic countries, such as India, China, South Africa and Brazil, his group has designed cohort studies in which synchronization of clinical and immunologic data collection results in validation of biomarker findings across countries. In addition, the Andrade Lab performs integrative analyses merging epidemiologic, socioeconomic, clinical, immunologic, microbiologic and geographic data to more robustly describe the TB determinants and help to delineate more reliable decision-making strategies.

In silico B-cell epitope prediction: developing differential diagnosis for haemorraghic diseases caused by orthohantaviruses
Orthohantaviruses are the etiological agents of serious rodent-borne neglected human diseases named as hemorrhagic fever with renal syndrome (HFRS) and orthohantavirus cardiopulmonary syndrome (HCPS). These distinct clinical manifestations of disease are related to specific orthohantavirus species and it is believed that HFRS-associated orthohantavirus mainly circulate into Old World (Asia and Europe) whereas HCPS-associated orthohantaviruses are predominant into New World countries (Americas). However, since Seoul orthohantavirus, associated with HFRS, was isolated in America and its natural host (Rattus norvegicus) are widely distributed around the world, it raised the question if the viral underreporting is associated to lower medical awareness of the symptoms or if it is associated to misdiagnosis with other tropical hemorrhagic diseases (leptospirosis, yellow fever). In this context, considering that the HFRS are clinically indistinguishable from order hemorrhagic diseases, and that serological tests are predominantly based on serology tests against nucleoprotein, a highly conserved protein among different orthohantavirus, we hypothesize that current available tests do not detect all HFRS-associated orthohantavirus. In this sense; we aimed to identify B-cell linear epitopes exclusively conserved on HFRS-associated orthohantavirus nucleoprotein, using a combination of in silico and experimental approaches, to identify targets that could be applied in the development of novel immunodiagnostic tools able to identify different HFRS orthohantavirus species.

Intestinal vitamin D receptor determines cell fate via apoptosis and autophagy

Rong Lu, Yongguo Zhang, Yinglin Xia, Jun Sun*

Medicine, University of Illinois at Chicago, IL 60612, USA

*Corresponding Author

    Vitamin D receptor (VDR) deficiency leads to abnormal Paneth cells and impaired autophagy function. We have demonstrated that human vdr gene is a key host factor to shape gut microbiome (Wang, et al., Nature Genetics 2016). Further, we have shown that intestinal epithelial VDR conditional knockout (VDRΔIEC) leads to dysbiosis (imbalanced microbiome) through suppressing ATG16L1 (Wu, et al., Gut 2015). Apoptosis and autophagy are dynamic processes that determine the fate of cells in intestine. Here, we will elucidate the mechanisms of the intestinal epithelial VDR regulation of autophagy and apoptosis. We used in vivo VDRlox and VDR∆IEC mice and ex vivo organoids generated from small intestine and colon tissues. We found that the pro-apoptotic protein Bax was enhanced, whereas ATG16L1 and Beclin-1 were decreased in the intestines of VDRΔIEC mice. Apoptosis induced by Bax reduced autophagy by enhancing the caspase-mediated cleavage of Beclin-1. VDR deficiency induced more apoptotic cells and significantly increased cell death in VDR∆IEC. Bacterial endotoxin levels were high in the serum from VDR∆IEC mice. In the VDR+/+ organoids, vitamin D treatment increased VDR and ATG16L1 protein expression levels, which activated autophagic responses. However, VDR∆IEC organoids did not respond to vitamin D treatment. The growth of VDR∆IEC organoids was significantly slower than that of VDR+/+ organoids. The expression levels of Beclin-1 and lysozyme were decreased in VDR∆IEC organoids. Intestinal epithelial VDR regulates autophagy/apoptosis through ATG16L1 and Beclin-1. Our studies provide fundamental insights into the tissue-specific function of VDR in modulating cell fate. As such, intestinal VDR may represent a useful therapeutic target in a diverse range of human diseases (e.g. chronic inflammation and infection).


References:
1.    Dapeng Jin, et al. Lack of Vitamin D Receptor Causes Dysbiosis and Changes the Functions of the Murine Intestinal Microbiome. Clinical Therapeutics. 2015, 37(5): 996-1009
2.    Shaoping Wu, et al. Intestinal vitamin D receptor deletion leads to defective autophagy. Gut, 2015 Jul;64(7):1082-94.
3.    Jun Wang, et al. Genome wide association analysis identifies variation in vitamin D receptor and other host factors influencing the gut microbiota. Nature Genetics. 48,1396–1406(2016).

Funding: NIH/NIDDKR01 DK105118 and DOD CDMRP BC160450P1

Cancer is a major cause of mortality worldwide, killing about 9 million people each year. Ovarian cancer is one of the ten most common cancers in women, considered the most fatal among gynecological tumors; and prostate cancer one of the most frequent and fatal in men. The detection of these tumor types currently has important limitations, hindering the efficiency of treatment and consequently patient’s survival. Specific molecules produced by tumors could be used as biomarkers and are considered good targets for diagnosis. Thus, the use of aptamers represents an important tool that could be applied to improve specificity in tumor diagnosis and personalized therapy. Aptamers are small, single-stranded synthetic oligonucleotides, capable of binding with high specificity to a molecular target, and are promising due to their unique pharmacokinetic properties: they are not immunogenic and are susceptible to chemical modifications and bioconjugations to nanoparticles, imaging agents and therapeutic drugs. In this way, the application of this technology could generate diagnoses for rapid and preventive detection that improve the life expectancy of patients with ovarian and prostate tumors. The main goal of this project is the creation of a tumor-specific diagnostic method, which differentiates benign, metastatic, and non-metastatic tumors, for application in liquid biopsies and magnetic resonance for ovarian and prostate cancer. In this purpose, the Cell-Selex method was applied for the selection of specific aptamers for each tumor type considering its condition as: benign, metastatic, and non-metastatic. Although the use of this methodology is being explored in several diseases, its application in ovarian and prostate tumors has an innovative character and will contribute to the technological development of public health in Brazil.

Alejandro Rodriguez Gama1, Tejbir Kandola1, Shriram Venkatesan1, Jianzheng Wu1,2, Minling Hu1, and Randal Halfmann1,2
1Stowers Institute for Medical Research, Kansas City, MO, USA,
2Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
    
Multiple signaling proteins of the innate immune system exert their cellular activities by assembling into large macromolecular complexes known as signalosomes. We previously discovered that two such proteins – the pyroptosome scaffold ASC, and the antiviral signaling protein MAVS – each assemble through self-templating polymerization that is reminiscent of infectious protein particles known as prions 1. More recently we revealed that prion-like activity broadly arises from structurally encoded kinetic barriers to nucleation – the probabilistic formation of a self-templating multimer de novo 2. For proteins like MAVS and ASC, the nucleation barrier is so high that their soluble inactive states persist despite physiological concentrations that are highly supersaturated with respect to the assembled active state. To identify other innate immune signaling proteins that may function in this manner, we used DAmFRET, a flow cytometric cell-based assay of nucleation barriers 2, to screen 138 candidate prion-like modules from 129 human proteins that function in programmed cell death and innate immune signaling. We discovered 36 of these proteins that are inherently capable of supersaturation and switch-like self-templating activation in living cells. We have further discovered a network of nucleating interactions between them, wherein polymerization of one protein nucleates the polymerization of specific additional proteins. This widespread kinetic control over cell fate indicates that cells are literally waiting to die -- pyroptosis, necroptosis, and alternative cell fates downstream of these proteins are thermodynamically favored, and therefore inevitable with time. I will discuss our investigations into the implications of this phenomenon for aging-associated inflammation and innate immune memory in human monocytes.
1.    Cai, X. et al. Prion-like polymerization underlies signal transduction in antiviral immune defense and inflammasome activation. Cell 156, 1207–1222 (2014).
2.    Khan, T. et al. Quantifying Nucleation In Vivo Reveals the Physical Basis of Prion-like Phase Behavior. Mol. Cell 71, 155-168.e7 (2018).

SCARF1 in the Pathogenesis of Systemic Lupus Erythematosus
April Jorge1, Taotao Lao1, Terry K. Means1,2, Zaida G. Ramirez-Ortiz1,3
1 Massachusetts General Hospital. Department of Rheumatology, Allergy and Immunology. Charlestown, MA 02129
2 Sanofi Immunology and Inflammation Research Therapeutic Area. Cambridge, MA 02139
3 University of Massachusetts Medical School. Department of Medicine. Worcester MA 01605


Defects at the cellular level in the detection and clearance of apoptotic cells (ACs) contribute to the pathogenesis of Systemic Lupus Erythematosus (SLE). We previously identified Scavenger Receptor Class F 1 (SCARF1) expressed on dendritic cells (DCs) where it functions as a receptor for C1q and mediates capture and engulfment of apoptotic cells. Deficiency in SCARF1 results in impaired removal of ACs (Figure 1) SCARF1 deficient mice develop a lupus-like autoimmune disease with symptoms similar to human SLE, such as production of anti-nuclear and anti-chromatin antibodies, nephritis and dermatitis. However, the role of human SCARF1 in the removal of ACs is unknown. We hypothesize a dysregulation of SCARF1 in SLE patients results in the accumulation of ACs and contributes to SLE disease activity. In order to identify which cells express SCARF1, we used flow cytometry from healthy donors PBMCs. We found that SCARF1 was highly expressed on DCs and monocytes. Treatment with ACs results in a significant decrease in the cell surface expression of SCARF1. Furthermore, using Nanostring and qPCR, we observed an upregulation in autophagy, TLR, and anti-inflammatory genes in cells expressing high levels of SCARF1. Next, we tested whether soluble SCARF1 (sSCARF1) can interact with ACs. Opsonizing ACs for 30 min with recombinant SCARF1 results in an upregulation of SCARF1 expression measured by flow cytometry and qPCR. Lastly, we obtained serum and PBMCs from SLE patient samples. First, we measured the expression of SCARF1 by flow cytometry in the PMBCs. Unexpectedly, there was no significant difference in SCARF1 expression in the SLE patients compared to healthy donors. Next, we measured the concentration of sSCARF1 in the serum by ELISA. We observed a significant increase in sSCARF1 in the SLE patients compared to control patients. We also detected anti-SCARF1 autoantibodies in 26% of SLE patients, which was associated with dsDNA antibody positivity and higher SLE disease activity. Our data demonstrates that human SCARF1 is an ACs receptor in DCs, playing a role in maintaining tolerance and homeostasis.