Papers by Jenny Hernandez
PLoS ONE, 2011
The severity of urinary tract infection (UTI) reflects the quality and magnitude of the host resp... more The severity of urinary tract infection (UTI) reflects the quality and magnitude of the host response. While strong local and systemic innate immune activation occurs in patients with acute pyelonephritis, the response to asymptomatic bacteriuria (ABU) is low. The immune response repertoire in ABU has not been characterized, due to the inherent problem to distinguish bacterial differences from host-determined variation. In this study, we investigated the host response to ABU and genetic variants affecting innate immune signaling and UTI susceptibility. Patients were subjected to therapeutic urinary tract inoculation with E. coli 83972 to ensure that they were exposed to the same E. coli strain. The innate immune response repertoire was characterized in urine samples, collected from each patient before and after inoculation with bacteria or PBS, if during the placebo arm of the study. Long-term E. coli 83972 ABU was established in 23 participants, who were followed for up to twelve months and the innate immune response was quantified in 233 urine samples. Neutrophil numbers increased in all but two patients and in an extended urine cytokine/chemokine analysis (31 proteins), the chemoattractants IL-8 and GRO-a, RANTES, Eotaxin-1 and MCP-1, the T cell chemoattractant and antibacterial peptide IP-10, inflammatory regulators IL-1-a and sIL-1RA and the T lymphocyte/dendritic cell product sIL-2Ra were detected and variably increased, compared to sterile samples. IL-6, which is associated with symptomatic UTI, remained low and numerous specific immune mediators were not detected. The patients were also genotyped for UTI-associated IRF3 and TLR4 promoter polymorphisms. Patients with ABU associated TLR4 polymorphisms had low neutrophil numbers, IL-6, IP-10, MCP-1 and sIL-2Ra concentrations. Patients with the ABU-associated IRF3 genotype had lower neutrophils, IL-6 and MCP-1 responses than the remaining group. The results suggest that the host-specific, low immune response to ABU mainly includes innate immune mediators and that host genetics directly influence the magnitude of this response.
Journal of Clinical Investigation, 2013
The normal flora furnishes the host with ecological barriers that prevent pathogen attack while m... more The normal flora furnishes the host with ecological barriers that prevent pathogen attack while maintaining tissue homeostasis. Urinary tract infections (UTIs) constitute a highly relevant model of microbial adaptation in which some patients infected with Escherichia coli develop acute pyelonephritis, while other patients with bacteriuria exhibit an asymptomatic carrier state similar to bacterial commensalism. It remains unclear if the lack of destructive inflammation merely reflects low virulence or if carrier strains actively inhibit disease-associated responses in the host. Here, we identify a new mechanism of bacterial adaptation through broad suppression of RNA polymerase II-dependent (Pol II-dependent) host gene expression. Over 60% of all genes were suppressed 24 hours after human inoculation with the prototype asymptomatic bacteriuria (ABU) strain E. coli 83972, and inhibition was verified by infection of human cells. Specific repressors and activators of Pol II-dependent transcription were modified, Pol II phosphorylation was inhibited, and pathogen-specific signaling was suppressed in cell lines and inoculated patients. An increased frequency of strains inhibiting Pol II was epidemiologically verified in ABU and fecal strains compared with acute pyelonephritis, and a Pol II antagonist suppressed the disease-associated host response. These results suggest that by manipulating host gene expression, ABU strains promote tissue integrity while inhibiting pathology. Such bacterial modulation of host gene expression may be essential to sustain asymptomatic bacterial carriage by ensuring that potentially destructive immune activation will not occur. Suppression of Pol II phosphorylation by E. coli 83972. (A) Active Ser2 phosphorylated Pol II was stained using monoclonal primary human phospho CTD Ser2 antibodies and peroxidase-labeled secondary antibodies (brown). E. coli 83972 markedly suppressed Pol II phosphorylation compared with uninfected or CFT073-infected human kidney cells (A498). E. coli CFT073 had a nonsuppressive effect. (B) Inhibition by E. coli 83972 of Pol II phosphorylation in primary human kidney cells (HRTEC) compared with uninfected or CFT073-infected cells. (C) The specific Pol II inhibitor DRB (60 μM) abrogated Pol II phosphorylation in response to E. coli CFT073 compared with A498 cells without an inhibitor. For dose-dependent inhibition of Pol II phosphorylation in uninfected A498 cells, see Supplemental Figure 7A. (D) Competition between E. coli CFT073 and 83972 in A498 cells. E. coli 83972 inhibited Pol II phosphorylation in the presence of E. coli CFT073. (A and C) Scale bars: 50 μm and 10 μm (insets). # P = compared with medium control; ## P = compared with CFT073-infected cells; χ 2 test for independence.
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Papers by Jenny Hernandez