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Caroline Johnson, PhD

Assistant Professor of Epidemiology (Environmental Health Sciences)

Extensive Research Description

Microbial metabolites and colon cancer

Colon cancers that present on the right versus the left side of the colon have significantly worse prognosis for the patient. A recent discovery revealed that right-sided colon cancers (RCCs) harbor mucosal bacterial biofilms, whereas left-sided colon cancers (LCC) are predominantly devoid of biofilms. These biofilms are associated with increased cellular proliferation and inflammation even in normal colon tissues. Using mass spectrometry-based metabolomics, we investigated the metabolism of colon cancers with and without biofilms, and observed a correlation between increased diacetylspermine production and biofilm presence on RCCs. Using antibiotic treatment, IHC, and stable isotope-assisted metabolomics we showed that diacetylspermine is an end product of polyamine metabolism produced by bacterial biofilms. We thus hypothesized that microbiota use host-derived polyamines to form biofilms. It is still not known why biofilms only form only on RCC, but it could be due to other factors such as diet and genetic predisposition.

Therefore, we aim are to examine the influence of these factors in LCC and RCC pathogenicity by investigating the roles of dietary metabolites, microbial communities and genetic predisposition.

Assessment of chemical exposures and adverse pregnancy outcomes

Preterm birth can cause serious life-long health problems for the child, importantly it is the greatest contributor to neonatal mortality. One of the major causes for preterm birth is preterm premature rupture of the membranes (PPROM). The mechanism for PPROM is unknown but hypothesized to be caused by placental inflammation which induces early labor. One potential mediator of placental inflammation is exposure to environmental toxins.

In the Johnson Lab we will be developing methods for measuring exposures during pregnancy and identify novel mechanisms for PPROM. We will be using samples collected locally from the Yale Pregnancy and prediction Outcome Study (YPOPS)


Research Interests

Environmental Exposure; Mass Spectrometry; Metabolomics; Biostatistics

Public Health Interests

Biomarkers; Cancer; Environmental Health; Genetics, Genomics, Epigenetics; Maternal & Child Health; Women's Health; Microbiome; Metabolomics; Perinatal/Prenatal Health

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Selected Publications