The common human-biting tick, Ixodes pacificus , is the primary vector of the Lyme disease spirochete, Borrelia burgdorferi sensu stricto (ss) in western North America and has been found to harbor other closely-related spirochetes in the Borrelia burgdorferi sensu lato (sl) complex. Between 2008–2015, 11,066 adult and 3,815 nymphal I . pacificus and five adult and 144 nymphal Ixodes spinpalpis , a commonly collected wildlife tick, were collected from 42 California counties. Borrelia burgdorferi sl was detected in 1.2% and 3.8% I . pacificus adults and nymphs, respectively. Results from this study indicate genetic diversity and geographic structure of B . burgdorferi sl in California I . pacificus ticks, by sequence comparison of the16S rRNA gene, with B . burgdorferi ss, the agent of Lyme disease, found only in I . pacificus collected from the north and central coastal and Sierra Nevada foothill regions; B . burgdorferi ss was not detected in ticks tested from southern California. In contrast, Borrelia bissettiae , a member of the B . burgdorferi sl complex, was detected in both I . pacificus and I . spinipalpis , in the coastal region of both northern and southern California, but was absent from ticks in the Sierra Nevada foothills. In a similar pattern to B . bissettiae , Borrelia americana (a member of the B . burgdorferi sl complex) was detected in a single adult I . pacificus from the north coast and two I . spinipalpis nymphs from south-coastal California. This study highlights that the geographic area of Lyme disease acarological risk in California is the north-central and Sierra Nevada foothill regions of the state with little to no risk in the southern regions of the state.

Areas of a junction between two types of epithelia are known to be cancer-prone in many organ systems. However, mechanisms for preferential malignant transformation at the junction areas remain insufficiently elucidated. Here we report that inactivation of tumor suppressor genes Trp53 and Rb1 in the gastric squamous-columnar junction (SCJ) epithelium results in preferential formation of metastatic poorly differentiated neoplasms, which are similar to human gastroesophageal carcinoma. Unlike transformation-resistant antral cells, SCJ cells contain a highly proliferative pool of immature Lgr5−CD44+ cells, which are prone to transformation in organoid assays, comprise early dysplastic lesions, and constitute up to 30% of all neoplastic cells. CD44 ligand osteopontin (OPN) is preferentially expressed in and promotes organoid formation ability and transformation of the SCJ glandular epithelium. OPN and CD44 overexpression correlate with the worst prognosis of human gastroesophageal carcinoma. Thus, detection and selective targeting of the active OPN-CD44 pathway may have direct clinical relevance.

A substantial fraction of ovarian/extra-uterine high-grade serous carcinomas (HGSCs) likely originate in the distal region of the Fallopian tube's epithelium (TE) before implanting/metastasizing to the ovary. Unfortunately, molecular and cellular mechanisms rendering preferential cancer susceptibility of the human distal TE remain insufficiently elucidated, largely due to limited primary human TE gene expression data. Here we report an in depth bioinformatic characterization of 34 primary TE cell mRNA-seq samples.These samples were prepared from the proximal and distal TE regions of 12 normal Fallopian tubes. TE cells were segregated based on their aldehyde dehydrogenase (ALDH) activity. As compared to the proximal TE, cells from the distal region form organoids with higher frequency and larger size during serial organoid formation assays. Consistent with enrichment for organoid-forming stem/progenitor cells, ALDH+ cells have greater WNT signaling activity. Comparative evaluation of proximal and distal TE cell population's shows heightened inflammatory signaling in distal differentiated (ALDH-) TE.Furthermore, comparisons of proximal and distal TE cell populations finds that the distal TE express gene sets characteristic of four HGSC molecular sub-types, and that distal ALDH+ cell populations exhibit greater enrichment than their ALDH-counterparts. Taken together, our study shows that increased organoid forming capacity, WNT and inflammatory signaling, and HGSC signatures underlie the differences between distal and proximal regions of the human TE. These findings provide the basis for further mechanistic studies of distal TE susceptibility to the malignant transformation.

Many high-grade serous carcinomas (HGSCs) likely originate in the distal region of the Fallopian tube’s epithelium (TE) before metastasizing to the ovary. Unfortunately, molecular mechanisms promoting malignancy in the distal TE are obfuscated, largely due to limited primary human TE gene expression data. Here we report an in depth bioinformatic characterization of 34 primary TE mRNA-seq samples. These samples were prepared from proximal and distal TE regions of 12 normal Fallopian tubes. Samples were segregated based on their aldehyde dehydrogenase (ALDH) activity. Distal cells form organoids with higher frequency and larger size during serial organoid formation assays when compared to proximal cells. Consistent with enrichment for stem/progenitor cells, ALDH+ cells have greater WNT signaling. Comparative evaluation of proximal and distal TE cell population’s shows heightened inflammatory signaling in distal differentiated (ALDH−) TE. Furthermore, comparisons of proximal and distal TE cell populations finds that the distal ALDH+ TE cells exhibit pronounced expression of gene sets characteristic of HGSC sub-types. Overall, our study indicates increased organoid forming capacity, WNT/inflammatory signaling, and HGSC signatures underlie differences between distal and proximal regions of the human TE. These findings provide the basis for further mechanistic studies of distal TE susceptibility to the malignant transformation.

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