Laboratory of Molecular Immunology

Frederick, MD, United States

Laboratory of Molecular Immunology

Frederick, MD, United States
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Asensi G.F.,Federal University of Rio de Janeiro | de Sales N.F.F.,Federal University of Rio de Janeiro | Dutra F.F.,Federal University of Rio de Janeiro | Feijo D.F.,Federal University of Rio de Janeiro | And 9 more authors.
Microbial Cell Factories | Year: 2013

Background: Staphylococcus aureus is unrestrictedly found in humans and in animal species that maintain thermal homeostasis. Inadequate cleaning of processing equipment or inappropriate handling can contaminate processed food and cause severe food poisoning. Staphylococcal enterotoxin B (SEB), a potent superantigenic exotoxin, is produced by 50% of clinical isolates of S. aureus and is associated with massive food poisoning and with the induction of toxic shock syndrome.Results: A gene sequence encoding a recombinant SEB (rSEB), devoid of superantigenic activity, was successfully cloned and expressed in a cytoplasmic or a secreted form in the food-grade lactic acid bacterium Lactococcus lactis. The recombinant protein detected in the cytoplasm or in the culture medium exhibited the expected molecular mass and was recognized by a SEB-polyclonal antibody. Oral immunization with the recombinant L. lactis strains induced a protective immune response in a murine model of S. aureus infection. Immunized mice survived intraperitoneal challenge with an S. aureus SEB-producer strain. Counts of S. aureus in the spleen of rSEB-immunized mice were significantly reduced. The rSEB-immunized mice showed significant titers of anti-SEB IgA and IgG in stools and serum, respectively. Both recombinant L. lactis strains were able to elicit cellular or systemic immune responses in mice, with no significant difference if rSEB was produced in its cytoplasmic or secreted form. However, recombinant L. lactis expressing the cytoplasmic rSEB increased the survival rate of the challenged mice by 43%.Conclusions: These findings show the vaccine efficacy of L. lactis carrying an attenuated SEB, in a murine model, following lethal S. aureus challenge. © 2013 Asensi et al.; licensee BioMed Central Ltd.

Lim J.K.,Laboratory of Molecular Immunology | McDermott D.H.,Laboratory of Molecular Immunology | Lisco A.,U.S. National Institutes of Health | Foster G.A.,Red Cross | And 4 more authors.
Journal of Infectious Diseases | Year: 2010

Background. West Nile virus (WNV) is a neurotropic flavivirus transmitted to humans by mosquito vectors. Homozygosity for CCR5Δ32, a complete loss-of-function mutation in CC chemokine receptor 5 (CCR5), has been previously associated with severe symptomatic WNV infection in patients who present with clinical disease; however, whether it acts at the level of initial infection or in promoting clinical progression is unknown. Methods. Here, we address this gap in knowledge by comparing CCR5Δ32 distribution among US blood donors identified through a comprehensive blood supply screening program (34,766,863 donations from 2003 through 2008) as either WNV true positive (634 WNV-positive cases) or false positive (422 WNV-negative control participants). All subjects self-reported symptoms occurring during the 2 weeks following blood donation using a standardized questionnaire. Results. No difference was observed in CCR5Δ32 homozygous frequency between the WNV-positive cases and WNV-negative control participants. However, CCR5Δ32 homozygosity was associated in cases but not controls with clinical symptoms consistent with WNV infection (P = .002). Conclusions. CCR5 deficiency is not a risk factor for WNV infection per se, but it is a risk factor for both early and late clinical manifestations after infection. Thus, CCR5 may function normally to limit disease due to WNV infection in humans. © 2010 by the Infectious Diseases Society of America. All rights reserved.

Mabuchi T.,Medical College of Wisconsin | Singh T.P.,Laboratory of Molecular Immunology | Takekoshi T.,Medical College of Wisconsin | Jia G.-F.,Medical College of Wisconsin | And 5 more authors.
Journal of Investigative Dermatology | Year: 2013

A subset of CC chemokine receptor-6 + (CCR6 +), γδ-low (GDL) T cells that express Th17 cytokines in mouse skin participates in IL-23-induced psoriasiform dermatitis. We use CCR6-deficient (knockout, KO) and wild-type (WT) mice to analyze skin trafficking patterns of GDL T cells and function-blocking mAbs to determine the role of CCR6 in IL-23-mediated dermatitis. Herein, CCL20 was highly upregulated in IL-23-injected WT mouse ear skin as early as 24 hours after initial treatment, and large numbers of CCR6 + cells were observed in the epidermis of IL-23-injected WT mice. Anti-CCL20 mAbs reduced psoriasiform dermatitis and blocked recruitment of GDL T cells to the epidermis. In CCR6 KO mice, GDL T cells failed to accumulate in the epidermis after IL-23 treatment, but the total numbers of GDL T cells in the dermis of WT and CCR6 KO mice were equivalent. There was an ∼70% reduction in the proportion of IL-22 + GDL T cells in the dermis of CCR6 KO mice (vs WT mice), suggesting that effector function and epidermal recruitment of GDL T cells are impaired in CCR6-deficient mice. Thus, these data show that CCR6 regulates epidermal trafficking of γδ-T-cell subsets in the skin and suggest the potential of CCR6 as a therapeutic target for psoriasis. © 2013 The Society for Investigative Dermatology.

PubMed | Laboratory of Molecular Immunology, Fred Hutchinson Cancer Research Center, Beth Israel Deaconess Medical Center and Scripps Research Institute
Type: | Journal: Nature communications | Year: 2016

VRC01-class broadly neutralizing HIV-1 antibodies protect animals from experimental infection and could contribute to an effective vaccine response. Their predicted germline forms (gl) bind Env inefficiently, which may explain why they are not elicited by HIV-1 Env-immunization. Here we show that an optimized Env immunogen can engage multiple glVRC01-class antibodies. Furthermore, this immunogen activates naive B cells expressing the human germline heavy chain of 3BNC60, paired with endogenous mouse light chains in vivo. To address whether it activates B cells expressing the fully humanized gl3BNC60 B-cell receptor (BCR), we immunized mice carrying both the heavy and light chains of gl3BNC60. B cells expressing this BCR display an autoreactive phenotype and fail to respond efficiently to soluble forms of the optimized immunogen, unless it is highly multimerized. Thus, specifically designed Env immunogens can activate naive B cells expressing human BCRs corresponding to precursors of broadly neutralizing HIV-1 antibodies even when the B cells display an autoreactive phenotype.

News Article | January 28, 2017

HIV patients can cheer up, as an effective suppression of the HIV virus from a combination of three antibodies in the treatment is in sight. This was according to a new study by researchers at the Rockefeller University, revealing that the virus eventually runs out of options and dies if the method of three antibodies is tried. The HIV virus has a notorious ability to mutate and is hard to eliminate. Once the virus enters a body, it will remain infected forever and block immune therapies trying to neutralize it. Antiretroviral drug treatment has been an indispensable part for HIV-infected people in saving them from full-blown AIDS. Without it, the body will lose the power to control the virus. Failure rate in some HIV treatments including ART is also high because the virus mutates and escapes the immune system. However, the new treatment method promises to trap the virus and end its cat-and-mouse game. In the experiments, a combination of three antibodies was administered to HIV-infected mice, and it gave results of complete suppression of the virus. Failure of the immune system follows HIV infection. However, some infected patients, known as elite controllers, have the capacity to defeat the virus by neutralizing antibodies. The research was conducted at the laboratory of Michel C. Nussenzweig, who is Zanvil A. Cohn and Ralph M. Steinman professor at The Rockefeller University and head of the Laboratory of Molecular Immunology. Three antibodies — BG18, NC37, and BG1 — were administered to HIV-infected mice. The antibodies get attached to an epitope, which is a part of the virus, and supports each other in shutting down HIV. "Some people with HIV produce these antibodies, but most of the time the virus eventually escapes them through mutations in the antibody's corresponding epitope," said Natalia Freund first author of the study. Freund compared the relationship between the antibodies and the virus to an arms race. Mutation helps some of the virus escape the antibodies and evolve. The plank of the research was in showing that an elite controller's immune system can defeat the HIV virus by using neutralizing antibodies that produce immune cells — cytotoxic T cells — in destroying infected cells and immobilize the virus. "What we've shown in this study is that after several rounds of escape from these particular antibodies, the virus seems to run out of options," she added. The patient whose blood serum was used by researchers to create the antibodies contracted HIV infection 30 years ago. Meanwhile, another viable method to block type 1 interferon using antiretroviral therapy to boost immune function has been proven successful. This enhances viral suppression against HIV, according to a study published in the Journal of Clinical Investigation. The study demonstrated the role of type 1 interferon in destroying the body's immunity during HIV infection. "This findings is completely counterintuitive, because many believe that the more interferon at work, the better," said investigator Scott Kitchen. He said the type of interferon produced during chronic HIV infection is harmful to the body's ability to fight off HIV and other infections and accelerate the HIV disease. By blocking type 1 interferon, reduced chronic activation of the immune cells was possible and let the weakened CD8 T cells restore the fighting abilities and strength. The HIV-infected mice were treated with antibodies that blocked type 1 interferons to restore immune power. It revived the immune system and activated sufficient CD8 T cells to attack HIV-infected cells. Combining it with ART showed the treatment accelerated the impact of ART in suppressing HIV. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.

Lu Z.,U.S. National Institutes of Health | Bourdi M.,Laboratory of Molecular Immunology | Li J.H.,U.S. National Institutes of Health | Aponte A.M.,Proteomic Core Facility | And 5 more authors.
EMBO Reports | Year: 2011

Acetaminophen/paracetamol-induced liver failure-which is induced by the binding of reactive metabolites to mitochondrial proteins and their disruption-is exacerbated by fasting. As fasting promotes SIRT3-mediated mitochondrial-protein deacetylation and acetaminophen metabolites bind to lysine residues, we investigated whether deacetylation predisposes mice to toxic metabolite-mediated disruption of mitochondrial proteins. We show that mitochondrial deacetylase SIRT3 -/- mice are protected from acetaminophen hepatotoxicity, that mitochondrial aldehyde dehydrogenase 2 is a direct SIRT3 substrate, and that its deacetylation increases acetaminophen toxic-metabolite binding and enzyme inactivation. Thus, protein deacetylation enhances xenobiotic liver injury by modulating the binding of a toxic metabolite to mitochondrial proteins. © 2011 European Molecular Biology Organization.

Stumpfe D.,Chemical Biology and Medicinal Chemistry | Bill A.,C o Kekule Institute of Organic Chemistry and Biochemistry | Novak N.,Laboratory of Molecular Immunology | Loch G.,University of Bonn | And 8 more authors.
ACS Chemical Biology | Year: 2010

Virtual screening (VS) of chemical libraries formatted in silico provides an alternative to experimental high-throughput screening (HTS) for the identification of small molecule modulators of protein function. We have tailored a VS approach combining fingerprint similarity searching and support vector machine modeling toward the identification of small molecular probes for the study of cytohesins, a family of cytoplasmic regulator proteins with multiple cellular functions. A total of 40 new structurally diverse inhibitors were identified, and 26 of these compounds were more active than the primary VS template, a single known inhibitory chemotype, in at least one of three different assays (guanine nucleotide exchange, Drosophila insulin signaling, and human leukocyte cell adhesion). Moreover, these inhibitors displayed differential inhibitory profiles. Our findings demonstrate that, at least for the cytohesins, computational extrapolation from known active compounds was capable of identifying small molecular probes with highly diversified functional profiles. © 2010 American Chemical Society.

Gazumyan A.,Laboratory of Molecular Immunology | Gazumyan A.,Howard Hughes Medical Institute | Bothmer A.,Laboratory of Molecular Immunology | Klein I.A.,Laboratory of Molecular Immunology | And 3 more authors.
Advances in Cancer Research | Year: 2012

DNA damage, rearrangement, and mutation of the human genome are the basis of carcinogenesis and thought to be avoided at all costs. An exception is the adaptive immune system where lymphocytes utilize programmed DNA damage to effect antigen receptor diversification. Both B and T lymphocytes diversify their antigen receptors through RAG1/2 mediated recombination, but B cells undergo two additional processes-somatic hypermutation (SHM) and class-switch recombination (CSR), both initiated by activation-induced cytidine deaminase (AID). AID deaminates cytidines in DNA resulting in U:G mismatches that are processed into point mutations in SHM or double-strand breaks in CSR. Although AID activity is focused at Immunoglobulin (Ig) gene loci, it also targets a wide array of non- Ig genes including oncogenes associated with lymphomas. Here, we review the molecular basis of AID regulation, targeting, and initiation of CSR and SHM, as well as AID's role in generating chromosome translocations that contribute to lymphomagenesis. © 2012 Elsevier Inc.

Filardy A.A.,Laboratory of Molecular Immunology | He J.,Laboratory of Molecular Immunology | Bennink J.,Laboratory of Viral Diseases | Yewdell J.,Laboratory of Viral Diseases | Kelsall B.L.,Laboratory of Molecular Immunology
Mucosal Immunology | Year: 2016

Colonic macrophages (cMPs) are important for intestinal homeostasis as they kill microbes and yet produce regulatory cytokines. Activity of the NLRP3 (nucleotide-binding leucine-rich repeat-containing pyrin receptor 3) inflammasome, a major sensor of stress and microorganisms that results in pro-inflammatory cytokine production and cell death, must be tightly controlled in the intestine. We demonstrate that resident cMPs are hyporesponsive to NLRP3 inflammasome activation owing to a remarkable level of posttranscriptional control of NLRP3 and pro-interleukin-1β (proIL-1β) protein expression, which was also seen for tumor necrosis factor- and IL-6, but lost during experimental colitis. Resident cMPs rapidly degraded NLRP3 and proIL-1β proteins by the ubiquitin/proteasome system. Finally, blocking IL-10R-signaling in vivo enhanced NLRP3 and proIL-1β protein but not mRNA levels in resident cMPs, implicating a role for IL-10 in environmental conditioning of cMPs. These data are the first to show dramatic posttranscriptional control of inflammatory cytokine production by a relevant tissue-derived macrophage population and proteasomal degradation of proIL-1β and NLRP3 as a mechanism to control inflammasome activation, findings which have broad implications for our understanding of intestinal and systemic inflammatory diseases.

PubMed | Howard Hughes Medical Institute, Laboratory of Molecular Immunology and National Institute of Arthritis and Musculoskeletal and Skin Diseases
Type: Journal Article | Journal: Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Activation-induced cytidine deaminase (AID) initiates class switch recombination (CSR) and somatic hypermutation (SHM) by deaminating cytosine residues in immunoglobulin genes (Igh, Ig, and Ig). At a lower frequency, AID also causes collateral DNA damage at non-Ig loci, including genes that are rearranged or mutated in B-cell lymphoma. Precisely how AID is recruited to these off-target sites is not entirely understood. To gain further insight into how AID selects its targets, we compared AID-mediated translocations in two different cell types, B cells and mouse embryonic fibroblasts (MEFs). AID targets a distinct set of hotspots in the two cell types. In both cases, hotspots are concentrated in highly transcribed but stalled genes. However, transcription alone is insufficient to recruit AID activity. Comparison of genes similarly transcribed in B cells and MEFs but targeted in only one of the two cell types reveals a common set of epigenetic features associated with AID recruitment in both cells. AID target genes are enriched in chromatin modifications associated with active enhancers (such as H3K27Ac) and marks of active transcription (such as H3K36me3) in both fibroblasts and B cells, indicating that these features are universal mediators of AID recruitment.

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