Biology subjects

Rivera, A.

Publications and source records attributed to Rivera, A..

30 records · Page 2Linked to original sources

bioRxiv2023

Interferon epsilon restricts Zika virus infection in the female reproductive tract

Interferon {varepsilon} (IFN{varepsilon}) is a unique type I IFN that has been implicated in host defense against sexually transmitted infections (STIs). Zika virus (ZIKV), an emerging pathogen, can infect the female reproductive tract (FRT) and cause devastating diseases, particularly in pregnant women. How IFN{varepsilon} contributes to protection against ZIKV infection in vivo is unknown. Here, we show that IFN{varepsilon} plays a critical role in host protection against vaginal ZIKV infection in mice. We found that IFN{varepsilon} was expressed not only by epithelial cells in the FRT, but also by certain immune and other cells at baseline or after exposure to viruses or specific TLR agonists. IFN{varepsilon}-deficient mice exhibited abnormalities in the epithelial border and underlying tissue in the cervicovaginal tract, and these defects were associated with increased susceptibility to vaginal, but not subcutaneous ZIKV infection. IFN{varepsilon}-deficiency resulted in an increase in magnitude, duration, and depth of ZIKV infection in the FRT. Critically, intravaginal administration of recombinant IFN{varepsilon} protected Ifn{varepsilon}-/- mice and highly susceptible Ifnar1-/-mice against vaginal ZIKV infection, indicating that IFN{varepsilon} was sufficient to provide protection even in the absence of signals from other type I IFNs and in an IFNAR1-independent manner. Our findings reveal a potentially critical role for IFN{varepsilon} in mediating protection against transmission of ZIKV in the context of sexual contact. SignificanceInterferon {varepsilon} (IFN{varepsilon}), a unique Type I IFN that is highly expressed in the epithelium of the female reproductive tract (FRT), is thought to protect the host against sexually transmitted infections (STIs) but the mechanism of action is not defined. Zika virus (ZIKV), a causative agent for preterm birth and other severe diseases in pregnant women, can be spread through vaginal transmission. Here, we show that mice lacking the Ifn{varepsilon} gene have abnormal epithelial development and tissue architecture in the cervicovaginal tract. The role of IFN{varepsilon} in protecting host against ZIKV is FRT-specific and is independent of IFNAR1 signaling. Our findings suggest potential preventive strategies based on harnessing mucosal immunity against STIs.

immunology↗

bioRxiv2022

Development of a heat-killed fbp1 mutant strain as a therapeutic agent to treat invasive Cryptococcus infection

In previous studies we determined that the F-box protein Fbp1, a subunit of the SCF(Fbp1) E3 ligase in Cryptococcus neoformans, is essential for fungal pathogenesis. Heat-killed fbp1{Delta} cells (HK-fbp1) can confer vaccine-induced immunity against lethal challenge with clinically important invasive fungal pathogens, e.g., C. neoformans, C. gattii, and Aspergillus fumigatus. In this study, we found that either CD4+ T cells or CD8+ T cells are sufficient to confer protection against lethal challenge of C. neoformans in HK-fbp1 induced-immunity. Given the potent effect of HK-fbp1 as a preventative vaccine, we further tested the potential efficacy of administering HK-fbp1 cells as a therapeutic agent for treating animals after infection. Remarkably, administration of HK-fbp1 provided robust host protection against pre-existing C. neoformans infection. The mice infected with wild type H99 cells and then treated with HK-fbp1 showed significant reduction of fungal CFU in the infected lung, and no dissemination of fungal cells to the brain and spleen. we find that early treatment is critical for the effective use of HK-fbp1 as a therapeutic agent. Immune analysis revealed that early treatment with HK-fbp1 cells elicited Th1 biased protective immune responses that help block fungal dissemination and promote better host protection. Our data thus suggest that HK-fbp1 is both an effective prophylactic vaccine candidate against C. neoformans infection in both immunocompetent and immunocompromised populations, as well as a potential novel therapeutic strategy to treat early stage cryptococcosis. ImportanceInvasive fungal infections, e.g., cryptococcosis, are often life threatening and difficult to treat with very limited therapeutic options. There is no vaccine available in clinical use to prevent or treat fungal infections. Our previous studies demonstrated that heat-killed fbp1{Delta} cells (HK-fbp1) in Cryptococcus neoformans can be harnessed to confer protection against a challenge by the virulent parental strain, even in immunocompromised animals, such as the ones lacking CD4+ T cells. In this study, we further determined that T cells are required for vaccine-induced protection against homologous challenge and that either CD4+ or CD8+ cells are sufficient. This finding is particularly important for the potential utility of this vaccine candidate in the context of HIV/AIDS-induced immune deficiency, the main risk factor for cryptococcosis in humans. Furthermore, in addition to the utility of HK-fbp1 as a prophylactic vaccine, we found that HK-fbp1 administration can inhibit disease dissemination when animals are treated at an early-stage during Cryptococcus infection. Our findings could significantly expand the utility of HK-fbp1 not only as prophylactic vaccine but also as a novel therapy against cryptococcosis. Conceptually, therapeutic administration of HK-fbp1 could have an advantage over small molecule antifungal drugs in that it is expected to have minimal side effects and lower cost. In all, our studies showed that HK-fbp1 strain can be used both preventively and therapeutically to elicit robust host protection against cryptococcosis.

microbiology↗

bioRxiv2022

The ATLAS™ screening assay reveals distinct CD4+ and CD8+ SARS-CoV-2 antigen response profiles which have implications to Omicron cellular immunity

The emergence of SARS-CoV-2 variants are a persistent threat to the efficacy of currently developed prophylactic vaccines and therapeutic antibodies. These variants accumulate mutations in the spike protein which encodes the epitopes necessary for neutralizing antibody binding. Moreover, emerging evidence suggest that robust antibody responses are insufficient to prevent severe disease and long-lasting viral immunity requires T cells. Thus, understanding how the T cell antigen landscape evolves in the context of these emerging variants remains crucial. T cells responses are durable and recognize a wider breadth of epitopes reducing the possibility of immune escape through mutation. Here, we deploy the ATLAS assay which identifies CD4+ and CD8+ T cell antigens by utilizing the endogenous HLA class-I and class-II peptide processing pathways. Profiling of T cells from exposed and unexposed donors revealed rich and complex patterns which highlighted the breadth of antigenic potential encoded in SARS-CoV-2. ATLAS revealed several common or frequent antigenic regions as well as an abundance of responses in the unexposed cohort potentially the result of pre-exposure to related coronaviruses. ORF10 was a common CD4+ response in the unexposed cohort while spike was identified as a common and frequent target in both cohorts. Moreover, the spike response profiles allowed us to accurately predict the impact of Omicron spike mutations. This analysis could thus be applied to study the impact of future emerging VOCs.

immunology↗

bioRxiv2021

The In Vivo Source of Type I and Type III IFNs is Pathogen Dependent

Type I (-, {beta}) and type III (-{lambda}) interferons (IFNs) are produced in response to virus infection and upregulate a largely overlapping set of IFN stimulated genes which mediate the protective effects of these antiviral cytokines. In vitro studies have demonstrated the redundancy of these two cytokine families which activate the same transcription factor, IFN stimulated gene factor 3 (ISGF3), via distinct ligands and receptors. However, in vivo, these IFN types do have distinct functions based on receptor distribution, but also ligand availability. Using a newly generated IFN-{lambda} reporter mouse strain we have observed that both type I and type III IFNs are produced in response to respiratory tract infection by Newcastle disease virus (NDV) and influenza A virus (IAV). In the case of NDV these IFNs are synthesized by different cell types. Type I IFNs are produced primarily by alveolar macrophages, type III IFNs are made only by epithelial cells, and production of either is dependent on MAVS. While epithelial cells of the respiratory tract represent the primary target of IAV infection, we found that they did not significantly contribute to IFN-{lambda} production, and IFN-{lambda} protein levels were largely unaffected in the absence of MAVS. Instead we found that pDCs, a cell type known for robust IFN- production via TLR/MyD88 signaling, were the major producers of IFN-{lambda} during IAV infection, with pDC depletion during influenza infection resulting in significantly reduced levels of both IFN- and IFN-{lambda}. In addition, we were able to demonstrate that pDCs rely on type I IFN for optimal IFN-{lambda} production. These studies therefore demonstrate that the in vivo producers of Type III IFNs in response to respiratory virus infection are pathogen dependent, a finding which may explain the varying levels of cytokine production induced by different viral pathogens.

immunology↗

bioRxiv2020

Monocyte-derived alveolar macrophages mediate resistance to migrating helminths through depletion of arginine availability

Macrophages are known to mediate anti-helminth responses, but it remains uncertain which subsets are involved or how macrophages actually kill helminths. Here we show rapid monocyte recruitment to the lung after infection with the nematode parasite, Nippostrongylus brasiliensis. In this inflamed tissue microenvironment these monocytes differentiate into an alveolar-like macrophage (AM) phenotype, expressing both Siglec-F and CD11c, surround invading parasitic larvae and preferentially kill parasites in vitro. Monocyte-derived AMs (Mo-AMs) express type 2-associated markers and show distinct remodeling of the chromatin landscape relative to tissue-derived AMs. In particular, they express high amounts of Arg1 (arginase-1), which we demonstrate mediates helminth killing through L-arginine depletion. These studies indicate that recruited monocytes are selectively programmed in the pulmonary environment to express AM markers and an anti-helminth phenotype.

immunology↗

bioRxiv2020

Synaptic silencing affects the density and complexity of oligodendrocyte precursor cells in the adult mouse hippocampus

Oligodendrocyte progenitor cells (OPCs) are responsible for generating oligodendrocytes, the myelinating cells of the CNS. Life-long myelination is promoted by neuronal activity and is essential for neural network plasticity and learning. OPCs are known to contact synapses and it is proposed that neuronal synaptic activity in turn regulates OPC proliferation and differentiation. To examine this in the adult, we performed unilateral injection of the synaptic blocker botulinum neurotoxin A (BoNT/A) into the hippocampus of adult mice. We confirm BoNT/A cleaves SNAP-25 in the CA1 are of the hippocampus, which has been proven to block neurotransmission. Notably, synaptic silencing by BoNT/A significantly decreased OPC density and caused their shrinkage, as determined by immunolabelling for the OPC marker NG2. Inhibition of synaptic activity resulted in an overall decrease in the number of OPC processes, as well as a decrease in their lengths and branching frequency. These data indicate that synaptic activity is important for maintaining adult OPC numbers and cellular integrity, which is relevant to pathological scenarios characterized by decreased synaptic activity.

neuroscience↗

bioRxiv2020

Drug connectivity mapping and functional analysis reveals therapeutic small molecules that differentially modulate myelination

Oligodendrocytes are the myelin forming cells of the central nervous system (CNS) and are generated from oligodendrocyte progenitor cells (OPCs). Disruption or loss of oligodendrocytes and myelin has devastating effects on CNS function and integrity, which occurs in diverse neurological disorders, including Multiple Sclerosis (MS), Alzheimers disease (AD) and neuropsychiatric disorders. Hence, there is a need to develop new therapies that promote oligodendrocyte regeneration and myelin repair. A promising approach is drug repurposing, but most agents have potentially contrasting biological actions depending on the cellular context and their dose-dependent effects on intracellular regulatory pathways. Here, we have used a combined drug connectivity systems biology and neurobiological approach to identify compounds that exert positive and negative effects on oligodendroglia, depending on concentration. Notably, LY294002, a potent inhibitor of PI3K/Akt signalling, was the most highly ranked small molecule for both pro- and anti-oligodendroglial effects. We validated these in silico findings in multiple in vivo and ex vivo neurobiological models and demonstrate that low and high doses of LY294002 have a profoundly bipartite effect on the generation of OPCs and their differentiation into myelinating oligodendrocytes. Finally, we employed transcriptional profiling and signalling pathway activity assays to determine cell-specific mechanisms of action of LY294002 on oligodendrocytes and resolve optimal in vivo conditions required to promote myelin repair. These results demonstrate the power of multifactorial neurobiological and in silico strategies in determining the therapeutic potential of small molecules in neurodegenerative disorders. One-sentence summaryDrug discovery and CNS myelination

systems biology↗

bioRxiv2020

MDA5 is an essential vita-PAMP sensor necessary for host resistance against Aspergillus fumigatus

RIG-I like receptors (RLR) are cytosolic RNA sensors that signal through the MAVS adaptor to activate interferon responses against viruses. Whether the RLR family has broader effects on host immunity against other pathogen families remains to be fully explored. Herein we demonstrate that MDA5/MAVS signaling was essential for host resistance against pulmonary Aspergillus fumigatus challenge through the regulation of antifungal leukocyte responses in mice. Activation of MDA5/MAVS signaling was driven by dsRNA from live A. fumigatus serving as a key vitality-sensing pattern-recognition receptor. Interestingly, induction of type I interferons after A. fumigatus challenge was only partially dependent on MDA5/MAVS signaling, whereas type III interferon expression was entirely dependent on MDA5/MAVS signaling. Ultimately, type I and III interferon signaling drove the expression of CXCL10. Furthermore, the MDA5/MAVS-dependent interferon response was critical for the induction of optimal antifungal neutrophil killing of A. fumigatus spores. In conclusion, our data broaden the role of the RLR family to include a role in regulating antifungal immunity against A. fumigatus. KEY POINTSO_LIMDA5 is essential for maintaining host resistance against Aspergillus fumigatus C_LIO_LIMDA5 serves as a critical vitality sensor after fungal challenge C_LIO_LIMDA5 is essential for IFN{lambda} expression and anti-fungal neutrophil killing C_LI

immunology↗

bioRxiv2020

During Aspergillus infection, neutrophil, monocyte-derived DC, and plasmacytoid DC enhance innate immune defense through CXCR3-dependent crosstalk

Aspergillus fumigatus, a ubiquitous mold, is a common cause of invasive aspergillosis (IA) in immunocompromised patients. Host defense against IA relies on lung-infiltrating neutrophils and monocyte-derived dendritic cells (Mo-DCs). Here, we demonstrate that plasmacytoid dendritic cells (pDCs), which are prototypically anti-viral cells, participate in innate immune crosstalk underlying mucosal antifungal immunity. Aspergillus-infected murine Mo-DCs and neutrophils recruited pDCs to the lung by releasing the CXCR3 ligands, CXCL9 and CXCL10, in a Dectin-1/Card9- and type I and III interferon-signaling dependent manner, respectively. During aspergillosis, circulating pDCs entered the lung in response to CXCR3-dependent signals. Via targeted pDC ablation, we found that pDCs were essential for host defense in the presence of normal neutrophil and Mo-DC numbers. Although interactions between pDC and fungal cells were not detected, pDCs regulated neutrophil NADPH oxidase activity and conidial killing. Thus, pDCs act as positive feedback amplifiers of neutrophil effector activity against inhaled mold conidia.

immunology↗

bioRxiv2019

Transects, quadrats, or points? What is the best combination to get a precise estimation of a coral community?

The characteristics of coral reef sampling and monitoring are highly variable, with numbers of units and sampling effort varying from one study to another. Numerous works have been carried out to determine an appropriate effect size through statistical power, however, always from a univariate perspective. In this work, we used the pseudo multivariate dissimilarity-based standard error (MultSE) approach to assess the precision of sampling scleractinian coral assemblages in reefs of Venezuela between 2017 and 2018 when using different combinations of number of transects, quadrats and points. For this, the MultSE of 36 sites previously sampled was estimated, using four 30m-transects with 15 photo-quadrats each and 25 random points per quadrat. We obtained that the MultSE was highly variable between sites and is not correlated with the univariate standard error nor with the richness of species. Then, a subset of sites was re-annotated using 100 uniformly distributed points, which allowed the simulation of different numbers of transects per site, quadrats per transect and points per quadrat using resampling techniques. The magnitude of the MultSE stabilized by adding more transects, however, adding more quadrats or points does not improve the estimate. For this case study, the error was reduced by half when using 10 transects, 10 quadrats per transect and 25 points per quadrat. We recommend the use of MultSE in reef monitoring programs, in particular when conducting pilot surveys to optimize the estimation of the community structure.

ecology↗

bioRxiv2019

Characterization of C. difficile strains isolated from companion animals and the associated changes in the host fecal microbiota

BackgroundClostridioides difficile is an enteric pathogen historically known to cause hospital associated (HA)-infections in humans. A major risk factor for CDI in humans is antibiotic usage as it alters the gut microbiota and there is a loss of colonization resistance against C. difficile. In recent years there has been an increase in community associated (CA)-C. difficile infection that does not have the same risk factors as HA-CDI. Potential sources of CA-CDI have been proposed and include animals, food, water, and the environment, however these sources remain poorly investigated. Here, we define the prevalence of C. difficile strains found in different companion animals (canines, felines, and equines) to investigate a potential zoonotic link. C. difficile strains were identified by toxin gene profiling, fluorescent PCR ribotyping, and antimicrobial susceptibility testing. 16s rRNA gene sequencing was done on animal feces to investigate the relationship between the presence of C. difficile and the gut microbiota in different hosts.\n\nResultsHere, we show that C. difficile was recovered from 20.9% of samples (42/201), which included 33 canines, 2 felines, and 7 equines. Over 69% (29/42) of the isolates were toxigenic and belonged to 14 different ribotypes, with overlap between HA- and CA-CDI cases in humans. The presence of C. difficile results in a shift in the fecal microbial community structure in both canines and equines. Commensal Clostridia C. hiranonis was negatively associated with C. difficile in canines. Further experimentation showed a clear antagonistic relationship between the two strains in vitro, suggesting that commensal Clostridia might play a role in colonization resistance against C. difficile in different hosts.\n\nConclusionsIn this study we investigated a potentially important source of C. difficile transmission: the companion animal population. C. difficile carriage was common in dogs, cats, and horses. C. difficile isolates from companion animals included many of the same ribotypes known to cause HA- and CA-CDI in humans, and had similar antimicrobial resistance profiles as those isolated from human populations. These data contribute to our understanding of non-hospital exposure to C. difficile in the human population and suggest new avenues for reducing C. difficile prevalence in companion animals and, perhaps, thereby reducing CA-CDI in humans.

microbiology↗

bioRxiv2019

Secondary bile acid ursodeoxycholic acid (UDCA) alters weight, the gut microbiota, and the bile acid pool in conventional mice

Ursodeoxycholic acid (commercially available as Ursodiol) is a naturally occurring bile acid that is used to treat a variety of hepatic and gastrointestinal diseases. Ursodiol can modulate bile acid pools, which have the potential to alter the gut microbiota community structure. In turn, the gut microbial community can modulate bile acid pools, thus highlighting the interconnectedness of the gut microbiota-bile acid-host axis. Despite these interactions, it remains unclear if and how exogenously administered ursodiol shapes the gut microbial community structure and bile acid pool. This study aims to characterize how ursodiol alters the gastrointestinal ecosystem in conventional mice. C57BL/6J wildtype mice were given one of three doses of ursodiol (50, 150, or 450 mg/kg/day) by oral gavage for 21 days. Alterations in the gut microbiota and bile acids were examined including stool, ileal, and cecal content. Bile acids were also measured in serum. Significant weight loss was seen in mice treated with the low and high dose of ursodiol. Alterations in the microbial community structure and bile acid pool were seen in ileal and cecal content compared to pretreatment, and longitudinally in feces following the 21-day ursodiol treatment. In both ileal and cecal content, members of the Lachnospiraceae family significantly contributed to the changes observed. This study is the first to provide a comprehensive view of how exogenously administered ursodiol shapes the gastrointestinal ecosystem. Further studies to investigate how these changes in turn modify the host physiologic response are important.\n\nImportanceUrsodeoxycholic acid (commercially available as ursodiol) is used to treat a variety of hepatic and gastrointestinal diseases. Despite its widespread use, how ursodiol impacts the gut microbial community structure and bile acid pool remains unknown. This study is the first to provide a comprehensive view of how exogenously administered ursodiol shapes the gastrointestinal ecosystem. Ursodiol administration in conventional mice resulted in significant alterations in the gut microbial community structure and bile acid pool, indicating that ursodiol has direct impacts on the gut microbiota-bile acid-host axis which should be considered when this medication is administered.\n\nBile Acid AbbreviationsMCA - -Muricholic acid; {beta}MCA -{beta}-Muricholic acid; {omega}MCA -{omega}-Muricholic acid; CA - Cholic acid; CDCA - Chenodeoxycholic acid; DCA - Deoxycholic acid; GCDCA - Glycochenodeoxycholic acid; GDCA - Glycodeoxycholic acid; GLCA - Glycolithocholic acid; GUDCA - Glycoursodeoxycholic acid; HCA - Hyodeoxycholic acid; iDCA - Isodeoxycholic acid; iLCA - Isolithocholic acid; LCA - Lithocholic acid; TCA - Taurocholic acid; TCDCA - Taurochenodeoxycholic acid; TDCA - Taurodeoxycholic acid; THCA - Taurohyodeoxycholic acid; TUDCA - Tauroursodeoxycholic acid; T{beta}MCA - Tauro-{beta}-muricholic acid; T{omega}MCA -Tauro {omega}-muricholic acid; UDCA - Ursodeoxycholic acid.

microbiology↗