Biology subjects

Cruz, E.

Publications and source records attributed to Cruz, E..

11 recordsLinked to original sources

bioRxiv2025

SLC11A2 affects nutritional immunity in the gastrointestinal epithelium

There is a constant tug-of-war for transition metals at the pathogen-host interface. A goal of the vertebrate host is to modulate the availability of metals to pathogens, in a process known as nutritional immunity, but pathogens have evolved numerous countermeasures to regulate intracellular trace metal levels. The bioavailability of trace metals therefore shapes the outcome of disease. In the human body, epithelial cells lining the intestine are a major site of metal absorption. Intestinal epithelial cells (IECs) are also a target for invading enteric pathogens but the contribution of epithelium-intrinsic factors towards nutritional immunity has been understudied. Using Salmonella enterica serovar Typhimurium (STm) harboring metal-responsive fluorescent reporters in a bovine ligated intestinal loop infection model, we mapped the spatiotemporal nature of metal competition during enteric salmonellosis. We show that STm experiences a temporal, cell-specific restriction of iron, manganese, and zinc in the intestinal mucosa during the early stages of infection. We have further studied the contribution of the broad specificity metal cation transporter, SLC11A2, in IECs to nutritional immunity against STm. Knockout of SLC11A2 in IECs leads to enhanced replication of STm, indicating a protective role for this transporter. Using fluorescence-based biosensors and bacterial gene deletion mutants, we pinpoint manganese and iron restriction as the mechanism by which SLC11A2 limits bacterial proliferation. We conclude that SLC11A2-mediated sequestration of metals is an intrinsic defense mechanism of the intestinal epithelium against enteric bacteria. Significance statementThere is limited source of trace metals in the gut that invading pathogens and the infected host must compete for. Using Salmonella enterica as a model enteric pathogen, along with fluorescent reporters that respond to metal ion availability, we traced the sites of metal ion limitation in the intestinal mucosa to intestinal epithelial cells (IECs) and phagocytes in the underlying lamina propria. We further show that SLC11A2 (NRAMP2), which is the sole SLC11 family member expressed in IECs and localizes to the apical membrane and endosomal network, limits the intracellular proliferation of Salmonella enterica by withholding iron and manganese. Therefore SLC11A2-mediated nutritional immunity is an IEC-intrinsic defense mechanism that protects against microbial pathogens.

microbiology↗

bioRxiv2025

Medial preoptic area FoxO1 controls metabolic adaptation in a sexually dimorphic manner

The medial preoptic area (MPOA) of the hypothalamus is essential for metabolic adaptation to environmental challenges, though the molecular mechanisms underlying this process remain poorly understood. Here, we investigate the role of Forkhead transcription factor O1 (FoxO1), a key mediator of stress adaptation, in MPOA-dependent metabolic responses to temperature and nutritional changes. Our findings reveal sex-specific responses to both nutritional and temperature challenges. In female mice, but not males, a high-fat diet (HFD) challenge decreased FoxO1 expression in the MPOA. Specific deletion of FoxO1 in MPOA neurons (FoxO1-KOMPOA) had no effect on body weight under normal chow-fed conditions but protected females from HFD-induced obesity (DIO). These protected females exhibited increased lean mass, decreased fat mass, enhanced thermogenesis, increased energy expenditure, and reduced food intake under HFD conditions. They also showed enhanced cold-induced heat production at 6{degrees}C, though this effect vanished at thermoneutrality (30{degrees}C). The protection against DIO was abolished by ovariectomy (OVX) and was not restored by 17{beta}-estradiol supplementation, suggesting an estrogen-independent mechanism. Conversely, constitutive activation of FoxO1 in MPOA neurons (FoxO1-CAMPOA) increased DIO susceptibility in both sexes. Together, these findings demonstrate that FoxO1MPOA plays a crucial role in coordinating metabolic adaptation to nutritional and temperature challenges specifically in female mice.

physiology↗

bioRxiv2024

Pathogenic diversification of the gut commensal Providencia alcalifaciens via acquisition of a second type III secretion system

Providencia alcalifaciens is a Gram-negative bacterium found in a wide variety of water and land environments and organisms. It has been isolated as part of the gut microbiome of animals and insects, as well as from stool samples of patients with diarrhea. Specific P. alcalifaciens strains encode gene homologs of virulence factors found in other pathogenic members of the same Enterobacterales order, such as Salmonella enterica serovar Typhimurium and Shigella flexneri. Whether these genes are also pathogenic determinants in P. alcalifaciens is not known. Here we have used P. alcalifaciens 205/92, a clinical isolate, with in vitro and in vivo infection models to investigate P. alcalifaciens-host interactions at the cellular level. Our particular focus was the role of two type III secretion systems (T3SS) belonging to the Inv-Mxi/Spa family. T3SS1b is widespread in Providencia spp. and encoded on the chromosome. T3SS1a is encoded on a large plasmid that is present in a subset of P. alcalifaciens strains, which are primarily isolates from diarrheal patients. Using a combination of electron and fluorescence microscopy and gentamicin protection assays we show that P. alcalifaciens 205/92 is internalized into eukaryotic cells, rapidly lyses its internalization vacuole and proliferates in the cytosol. This triggers caspase-4 dependent inflammasome responses in gut epithelial cells. The requirement for the T3SS1a in entry, vacuole lysis and cytosolic proliferation is host-cell type specific, playing a more prominent role in human intestinal epithelial cells as compared to macrophages. In a bovine ligated intestinal loop model, P. alcalifaciens colonizes the intestinal mucosa, inducing mild epithelial damage with negligible fluid accumulation. No overt role for T3SS1a or T3SS1b was seen in the calf infection model. However, T3SS1b was required for the rapid killing of Drosophila melanogaster. We propose that the acquisition of two T3SS by horizontal gene transfer has allowed P. alcalifaciens to diversify its host range, from a highly virulent pathogen of insects to an opportunistic gastrointestinal pathogen of animals.

microbiology↗

bioRxiv2024

Proteostasis as a fundamental principle of Tau immunotherapy

The microtubule-associated protein Tau is a driver of neuronal dysfunction in Alzheimers disease and numerous other tauopathies. In this process, Tau initially undergoes subtle changes to its abundance, subcellular localisation and a vast array of post-translational modifications including phosphorylation, that progressively result in the proteins aggregation and dysregulation of multiple Tau-dependent cellular processes. Given the various loss- and gain-of-functions of Tau in disease and the brain-wide changes in the proteome that characterise tauopathies, we asked whether targeting Tau would restore the alterations in proteostasis observed in disease. To this end, we generated a novel pan-Tau antibody, RNJ1, that preferentially binds human Tau and neutralises proteopathic seeding activity in multiple cell lines and benchmarked it against a clinically tested pan-Tau antibody, HJ8.5 (murine version of tilavonemab). We next evaluated both antibodies, alone and in combination, in the K3 mouse model of tauopathy, showing reduced Tau pathology and improvements in neuronal function following 14 weekly treatments, without obtaining synergistic effects for the combination treatment. To gain insight into molecular mechanisms contributing to improvements in neuronal function, we employed quantitative proteomics and phosphoproteomics to first establish alterations in K3 mice relative to WT controls at the proteome level. This revealed 342 proteins with differential abundance in K3 mice, which are predominantly involved in metabolic and microtubule-associated processes, strengthening previously reported findings of defects in several functional domains in multiple tauopathy models. We next asked whether antibody-mediated Tau target engagement indirectly affects levels of deregulated proteins in the K3 model. Importantly, both immunotherapies, in particular RNJ1, induced abundance shifts in this protein subset towards a restoration to wild-type levels (proteostasis). A total of 257 of 342 ([~]75.1%) proteins altered in K3 were closer in abundance to WT levels after RNJ1 treatment. The same analysis indicated a similar response in K3 mice treated with HJ8.5, with approximately 72.5% of these altered proteins also showing changes in the same direction as wild-type. Furthermore, analysis of the phosphoproteome showed an even stronger restoration effect with RNJ1, with [~]82.1% of altered phosphopeptides in K3 showing a shift to WT levels, and 75.4% with HJ8.5. Gene set over-representation analysis (ORA) further confirmed that proteins undergoing restoration are involved in biological pathways affected in K3 mice. Together, our study suggests that a Tau immunotherapy-induced restoration of proteostasis links target engagement and treatment efficacy.

neuroscience↗

bioRxiv2024

Sensitivity of dairy calf Salmonella enterica serotype Cerro isolates to infection-relevant stressors

Salmonella enterica serotype Cerro (S. Cerro) is an emerging Salmonella serotype isolated from cattle, but the association of S. Cerro with disease is not well understood. While comparative genomic analyses of bovine S. Cerro isolates have indicated mutations in elements associated with virulence, the correlation of S. Cerro fecal shedding with clinical disease in cattle varies between epidemiologic studies. The primary objective of this study was to characterize the infection-relevant phenotypes of S. Cerro fecal isolates obtained from neonatal calves born on a dairy farm in Wisconsin, USA. The S. Cerro isolates varied in biofilm production and sensitivity to the bile salt deoxycholate. All S. Cerro isolates were sensitive to sodium hypochlorite, hydrogen peroxide, and acidic shock. However, S. Cerro isolates were resistant to nitric oxide stress. Two S. Cerro isolates were unable to compete with S. Typhimurium during infection of calf ligated intestinal loops, indicating decreased fitness in vivo. Together, our data suggest that S. Cerro is sensitive to some innate antimicrobial defenses present in the gut, many of which are also used to control Salmonella in the environment. The observed phenotypic variation in S. Cerro isolates from a single farm suggest phenotypic plasticity that could impact infectious potential, transmission, and persistence on a farm. ImportanceSalmonella enterica is a zoonotic pathogen that threatens both human and animal health. Salmonella enterica serotype Cerro is being isolated from cattle at increasing frequency over the past two decades, however its association with clinical disease is unclear. The goal of this study was to characterize infection-relevant phenotypes of S. Cerro isolates obtained from dairy calves from a single farm. Our work shows that there can be variation among temporally-related S. Cerro isolates and that these isolates are sensitive to killing by toxic compounds of the innate immune system and those used for environmental control of Salmonella. This work contributes to our understanding of the pathogenic potential of the emerging pathogen S. Cerro.

microbiology↗

bioRxiv2023

nanoCLAMP potently neutralizes SARS-CoV-2 and protects K18-hACE2 mice from infection

Intranasal treatments, combined with vaccination, has the potential to slow mutational evolution of virusues by reducing transmission and replication. Here we illustrate the development of a SARS-CoV-2 receptor binding domain (RBD) nanoCLAMP and demonstrate its potential as an intranasally administered therapeutic. A multi-epitope nanoCLAMP was made by fusing a pM affinity single-domain nanoCLAMP (P2710) to alternate epitope binding nanoCLAMP, P2609. The resulting multimerised nanoCLAMP P2712 had sub-pM affinity for the Wuhan and South African (B.1.351) RBD (KD < 1 pM), and decreasing affinity for the Delta (B.1.617.2) and Omicron (B.1.1.529) variants (86 pM and 19.7 nM, respectively). P2712 potently inhibited ACE2:RBD interaction, suggesting its utility as a therapeutic. With an IC50 = 0.4 {+/-} 0.1 nM obtained from neutralization experiments using pseudoviral particles as well as patient cultured SARS-CoV-2 samples, nanoCLAMP P2712 protected K18-hACE2 mice from SARS-CoV-2 infection, reduced viral loads in the lungs and brains, and reduced associated upregulation of inflammatory cytokines and chemokines. Together, our findings warrant further investigation into the development of nanoCLAMPs as effective intranasally delivered COVID19 therapeutics.

bioengineering↗

bioRxiv2022

Non-redundant dimethyl sulfoxide reductases influence Salmonella enterica serotype Typhimurium anaerobic growth and virulence

Facultative anaerobic enteric pathogens can utilize a diverse array of alternate electron acceptors to support anaerobic metabolism and thrive in the hypoxic conditions within the mammalian gut. Dimethyl sulfoxide (DMSO) is produced by methionine catabolism and can act as an alternate electron acceptor to support anaerobic respiration. The DMSO reductase complex consists of three subunits, DmsA, DmsB, and DmsC, and allows bacteria to grow anaerobically with DMSO as an electron acceptor. The genomes of non-typhoidal S. enterica encode three putative dmsABC operons, but the impact of the apparent genetic redundancy in DMSO reduction on fitness of non-typhoidal S. enterica during infection remains unknown. We hypothesized that DMSO reduction would be needed for S. enterica serotype Typhimurium (S. Typhimurium) to colonize the mammalian gut. We demonstrate a S. Typhimurium mutant with loss of function in all three putative DMSO reductases ({Delta}dmsA3) poorly colonizes the mammalian intestine when the microbiota are intact and when inflammation is absent. DMSO reduction enhances anaerobic growth through non-redundant contributions of two of the DMSO reductases. Furthermore, DMSO reduction influences the expression of the type-3 secretion systems needed for virulence. Collectively, our data demonstrate that the DMSO reductases of S. Typhimurium are functionally non-redundant and suggest DMSO is a physiologically relevant electron acceptor that supports S. enterica fitness in the gut.

microbiology↗

bioRxiv2022

Proteome capacity constraints favor respiratory ATP generation

Cells face competing metabolic demands. These include efficient use of both limited substrates and limited proteome capacity, as well as flexibility to deal with different environments. Flexibility requires spare enzyme capacity, which is proteome inefficient. ATP generation can occur via fermentation or respiration. Fermentation is much less substrate-efficient, but often assumed to be more proteome efficient 1-3, thereby favoring fast-growing cells engaging in aerobic glycolysis 4-8. Here, however, we show that mitochondrial respiration is actually more proteome-efficient than aerobic glycolysis. Instead, aerobic glycolysis arises from cells maintaining the flexibility to grow also anaerobically. These conclusions emerged from an unbiased assessment of metabolic regulatory mechanisms, integrating quantitative metabolomics, proteomics, and fluxomics, of two budding yeasts, Saccharomyces cerevisiae and Issatchenkia orientalis, the former more fermentative and the latter respiratory. Their energy pathway usage is largely explained by differences in proteome allocation. Each organisms proteome allocation is remarkably stable across environmental conditions, with metabolic fluxes predominantly regulated at the level of metabolite concentrations. This leaves extensive spare biosynthetic capacity during slow growth and spare capacity of their preferred bioenergetic machinery when it is not essential. The greater proteome-efficiency of respiration is also observed in mammals, with aerobic glycolysis occurring in yeast or mammalian cells that maintain a fermentation-capable proteome conducive to both aerobic and anaerobic growth.

systems biology↗

bioRxiv2022

Global Protein-Turnover Quantification in Escherichia coli Reveals Cytoplasmic Recycling under Nitrogen-Limitation

Protein turnover is critical for proteostasis, but turnover quantification is challenging, and even in well-studied E. coli, proteome-wide measurements remain scarce. Here, we quantify the degradation rates of [~]3.2k E. coli proteins under 12 conditions by combining heavy isotope labeling with complement reporter ion quantification and find that cytoplasmic proteins are recycled when nitrogen is limited. We use knockout experiments to assign substrates to the known cytoplasmic ATP-dependent proteases. Surprisingly, none of these proteases are responsible for the observed cytoplasmic protein degradation in nitrogen limitation, suggesting that a major proteolysis pathway in E. coli remains to be discovered. Lastly, we show that protein degradation rates are generally independent of cell division rates. Thus, we introduce broadly applicable technology for protein turnover measurements and provide a rich resource for protein half-lives and protease substrates in E. coli, complementary to genomics data, that will allow researchers to decipher the control of proteostasis.

systems biology↗

bioRxiv2021

Ultrasound-mediated delivery of novel tau-specific monoclonal antibody enhances brain uptake but not therapeutic efficacy

Tau-specific immunotherapy is an attractive therapeutic strategy for the treatment of Alzheimers disease and other tauopathies. However, targeting tau effectively remains a considerable challenge due to the restrictive nature of the blood-brain barrier (BBB), which excludes 99.9% of peripherally administered antibodies. We have previously shown that the delivery of tau-specific monoclonal antibody (mAb) with low-intensity scanning ultrasound in combination with intravenously injected microbubbles (SUS+MB) increases the passage of IgG antibodies into the brain. SUS+MB transiently opens tight junctions to allow paracellular transport, but also facilitates transcellular transport, particularly for larger cargoes. However, therapeutic efficacy after enhanced brain delivery has not been explored. To assess whether ultrasound-mediated delivery of tau-specific mAbs leads to an enhanced therapeutic response, K369I tau transgenic K3 mice were passively immunised once weekly for 12 weeks with a novel mAb, RNF5, in combination with SUS+MB. While none of the treatment arms improved behaviour or motor functions in these mice, we found that both RNF5 and SUS+MB treatments on their own reduced tau pathology, but, surprisingly, the combination of both (RNF5+SUS+MB) did not achieve an additive reduction in tau pathology. This was despite observing increased antibody penetration in the brain. Interestingly, a significant fraction of the antibody in the combination treatment was visualized in brain endothelial cells, suggesting that paracellular transport may not be the preferred uptake mechanism for RNF5. Taken altogether, more research is warranted to develop SUS+MB as a delivery modality for anti-tau antibodies.

neuroscience↗

bioRxiv2021

Claudin-5 binder enhances focused ultrasound-mediated opening in an in vitro blood-brain barrier model

RationaleThe blood-brain barrier (BBB) while functioning as a gatekeeper of the brain, impedes cerebral drug delivery. An emerging technology to overcome this limitation is focused ultrasound (FUS). When FUS interacts with intravenously injected microbubbles (FUS+MB), the BBB opens, transiently allowing the access of therapeutic agents into the brain. However, the ultrasound parameters need to be tightly tuned: when the acoustic pressure is too low there is no opening, and when it is too high, bleeds can occur. We therefore asked whether BBB permeability can be increased by combining FUS+MB with a second modality such that in a clinical setting lower acoustic pressures could be potentially used. MethodsGiven that FUS achieves BBB opening by the disruption of tight junction (TJ) proteins such as claudin-5 of brain endothelial cells, we generated a stable MDCK II cell line (eGFP-hCldn5-MDCK II) that expresses fluorescently tagged human claudin-5. Two claudin-5 binders, mC5C2 (a peptide) and cCPEm (a truncated form of an enterotoxin), that have been reported previously to weaken the barrier, were synthesized and assessed for their abilities to enhance the permeability of cellular monolayers. We then performed a comparative analysis of single and combination treatments. ResultsWe successfully generated a novel cell line that formed functional monolayers as validated by an increased transendothelial electrical resistance (TEER) reading and a low (< 0.2%) permeability to sodium fluorescein (376 Da). We found that the binders exerted a time- and concentration-dependent effect on BBB opening when incubated over an extended period, whereas FUS+MB caused a rapid barrier opening followed by recovery after 12 hours within the tested pressure range. Importantly, preincubation with cCPEm prior to FUS+MB treatment resulted in greater barrier opening compared to either FUS+MB or cCPEm alone as measured by reduced TEER values and an increased permeability to fluorescently labelled 40 kDa dextran (FD40). ConclusionThe data suggest that pre-incubation with clinically suitable binders to TJ proteins may be a general strategy to facilitate safer and more effective ultrasound-mediated BBB opening in cellular and animal systems and potentially also for the treatment of human diseases of the brain.

neuroscience↗