Biology subjects

Bustamante, P.

Publications and source records attributed to Bustamante, P..

4 recordsLinked to original sources

bioRxiv2024

Persistence phenotype of adherent-invasive Escherichia coli in response to ciprofloxacin, revealing high-persistence strains

Persister cells correspond to a bacteria subpopulation able to survive antibiotic treatments and are thought to contribute to chronicity and symptom relapse of chronic diseases. Crohns disease (CD) is a multifactorial chronic inflammatory condition of the gastrointestinal tract, and adherent-invasive Escherichia coli (AIEC) has emerged as a key contributor to its pathogenesis. AIEC can survive, replicate, and produce persister cells within macrophages; however, out of the LF82 reference strain, a lack of knowledge of the persistence phenotype and its variability among AIEC strains is lacking. Here, two AIEC reference strains were analyzed after ciprofloxacin challenge, a fluoroquinolone antibiotic common in CD treatments. Four clinical isolates with an AIEC phenotype and five different E. coli pathotypes were also analyzed. We investigated the roles of the resident antibiotic resistance plasmid and the stress response protein HtrA, along with macrophage-induced persister formation. We observed a broad variability of persister cell formation capability among AIEC strains. Remarkably, the reference NRG857c strain showed a threatening high-persistence phenotype, with persistence levels higher than LF82 (65-fold) and some AIEC clinical isolates. The resident antibiotic resistance plasmid and the stress protein HtrA were dispensable for the NRG857c persistence phenotype. Among E. coli pathotypes, only EPEC showed persistence levels comparable to NRG857c, while other pathotypes resembled the lower persistence levels of LF82. Macrophage internalization did not increase NRG857c persister fraction, opposite to the LF82 behavior. Overall, our findings show that variable persistence phenotypes are found among AIEC. Opposite to LF82, NRG857c is a high-persistence strain, and this characteristic is shared with one AIEC clinical isolated and the EPEC reference strain. Undoubtedly, bacterial persistence should be considered in CD antibiotic treatments, especially with the feasible presence of AIEC high-persistence strains. Author SummaryAdherent-invasive Escherichia coli (AIEC) are common bacteria found in Crohns disease patients and recognized to survive within macrophages. The reference strain LF82 is known to form persistent cells, an enigmatic subpopulation of cells able to survive antibiotic treatments and thought to contribute to chronicity and symptoms relapses of chronic diseases. However, out of LF82, there is a lack of knowledge on AIEC persister cell formation, as well as the genetic factors contributing to this phenotype. In this study, it was observed a that the persistence phenotype was variable among both AIEC strains and E. coli pathotypes. Unlike LF82, the reference strain NRG857c displayed inherently high-persistence levels, regardless of whether it carries its native antibiotic resistance plasmid or the htrA and hipA genes. Notably, stress conditions within macrophages did not trigger increased persister cell formation in NRG857c. This study highlights the importance to decipher the role of AIEC persisters in ongoing Crohns disease, symptom relapses, and responses to antibiotic treatment, especially given the potential existence of high-persistence AIEC strains.

microbiology↗

bioRxiv2023

Identification and distribution of novel candidate T6SS effectors encoded in Salmonella Pathogenicity Island 6

The type VI secretion system (T6SS) is a contact-dependent contractile multiprotein apparatus widely distributed in Gram-negative bacteria. These systems can deliver different effector proteins into target bacterial and/or eukaryotic cells, contributing to the environmental fitness and virulence of many bacterial pathogens. Salmonella harbors five different T6SSs encoded in different genomic islands. The T6SS encoded in Salmonella Pathogenicity Island 6 (SPI-6) contributes to Salmonella competition with the host microbiota and its interaction with infected host cells. Despite its relevance, information regarding the total number of effector proteins encoded within SPI-6 and its distribution among different Salmonella enterica serotypes is limited. In this work, we performed bioinformatic and comparative genomics analyses of the SPI-6 T6SS gene cluster to expand our knowledge regarding the T6SS effector repertoire and the global distribution of these effectors in Salmonella. The analysis of a curated dataset of 60 Salmonella enterica genomes from the Secret6 database revealed the presence of 23 novel putative T6SS effector/immunity protein (E/I) modules. These effectors were concentrated in the variable regions 1 to 3 (VR1-3) of the SPI-6 T6SS gene cluster. VR1-2 were enriched in candidate effectors with predicted peptidoglycan hydrolase activity, while VR3 was enriched in candidate effectors of the Rhs family with C-terminal extensions with predicted DNase, RNase, deaminase, or ADP-ribosyltransferase activity. A global analysis of known and candidate effector proteins in Salmonella enterica genomes from the NCBI database revealed that T6SS effector proteins are differentially distributed among Salmonella serotypes. While some effectors are present in over 200 serotypes, others are found in less than a dozen. A hierarchical clustering analysis identified Salmonella serotypes with distinct profiles of T6SS effectors and candidate effectors, highlighting the diversity of T6SS effector repertoires in Salmonella enterica. The existence of different repertoires of effector proteins suggests that different effector protein combinations may have a differential impact on the environmental fitness and pathogenic potential of these strains.

microbiology↗

bioRxiv2021

Nelfinavir induces cytotoxicity towards high-grade serous ovarian cancer cells regardless of platinum sensitivity, involving induction of the unfolded protein response, modulation of protein synthesis, DNA damage, lysosomal impairment, and potentiation of toxicity caused by proteasome inhibition

High-grade serous ovarian cancer (HGSOC) is a significant cause of mortality among women worldwide. Traditional treatment consists of platinum-based therapy; however, rapid development of platinum resistance contributes to lower life expectancy, warranting newer therapies to supplement the current platinum-based protocol. Repurposing market-available drugs as cancer therapeutics is a cost- and time-effective way to avail new therapies to drug-resistant patients. The anti-HIV agent nelfinavir (NFV) has shown promising toxicity against various cancers; however, its role against HGSOC is unknown. Here, we studied the effect of NFV against HGSOC cells obtained from patients along disease progression and carrying different sensitivities to platinum. NFV triggered, independently of platinum sensitivity, a dose-dependent reduction of HGSOC cell number and viability, and a parallel increase in hypo-diploid DNA content. Moreover, a dose-dependent reduction of clonogenic survival of cells escaping the acute toxicity was indicative of long-term residual damage. In addition, dose- and time-dependent phosphorylation of H2AX indicated NFV-mediated DNA damage, which was associated with decreased survival and proliferation signals driven by the AKT and ERK pathways. NFV also mediated a dose-dependent increase in endoplasmic reticulum stress-related molecules associated with long-term inhibition of protein synthesis and concurrent cell death; such events were accompanied by a proapoptotic environment, signaled by increased phospho- eIF2, ATF4, and CHOP, increased Bax/Bcl-2 ratio, and cleaved executer caspase-7. Finally, we show that NFV potentiates the short-term cell cycle arrest and long-term toxicity caused by the proteasome inhibitor bortezomib. Overall, our in vitro study demonstrates that NFV can therapeutically target HGSOC cells of differential platinum sensitivities via several mechanisms, suggesting its prospective repurposing benefit considering its good safety profile.

cancer biology↗

bioRxiv2018

Sexual segregation in a highly pagophilic and sexually dimorphic marine predator

AO_SCPLOWBSTRACTC_SCPLOWSexual segregation is common in many species and has been attributed to intra-specific competition, sex-specific differences in foraging efficiency or in activity budgets and habitat choice. However, very few studies have simultaneously quantified sex-specific foraging strategies, at sea distribution, habitat use, and trophic ecology. Moreover, these studies come from low latitude areas reflecting a lack of evidence for polar species. We investigated sexual segregation in snow petrels Pagodroma nivea and combined movement, foraging trip efficiency, stable isotope and oceanographic data to test whether sexual segregation results from sex-specific habitat use. Breeding birds foraging in the Dumont dUrville sea, Antarctica, were tracked during incubation. Some similarities between males and females foraging characteristics did not support the sexual segregation hypothesis. Indeed, space-use sharing and utilization distribution, {delta}13C values and foraging trip performances (trip duration, length, speed and directions, mass gain, proportion mass gain) were similar between males and females.. However, there was support for sexual segregation in foraging characteristics linked to foraging habitats. Females foraged less than males in areas with higher sea ice concentration (SIC >70%) and had lower {delta}15N values in plasma, blood cells and feathers. Foraging efficiency (proportionate daily mass gain while foraging), was greater for females than for males, and was greater for larger females with deeper bills. Females were more efficient than males during short (<2 days) foraging trips, and for females, but not for males, mass gain, proportion mass gain and body condition at return from a foraging trip were positively correlated to SIC of the foraging areas. Together, these results suggest an absence of sexual segregation at large spatial scales in snow petrels during incubation, but strongly support habitat segregation between high (>70%) more profitable SIC (males) and low SIC areas (females), probably driven by intraspecific competition. Therefore, male and female snow petrels segregate at small spatial scales mainly determined by habitat (SIC) characteristics.

ecology↗