Inflammation, microbiome and colorectal cancer disparity in African-Americans: Are there bugs in the genetics?

Population-enriched innate immune variants may identify candidate gene targets at the intersection of cancer and cardio-metabolic disease

Both cancer and cardio-metabolic disease disparities exist among specific populations in the US. For example, African Americans experience the highest rates of breast and prostate cancer mortality and the highest incidence of obesity. Native and Hispanic Americans experience the highest rates of liver cancer mortality. At the same time, Pacific Islanders have the highest death rate attributed to type 2 diabetes (T2D), and Asian Americans experience the highest incidence of non-alcoholic fatty liver disease (NAFLD) and cancers induced by infectious agents. Notably, the pathologic progression of both cancer and cardio-metabolic diseases involves innate immunity and mechanisms of inflammation. Innate immunity in individuals is established through genetic inheritance and external stimuli to respond to environmental threats and stresses such as pathogen exposure. Further, individual genomes contain characteristic genetic markers associated with one or more geographic ancestries (ethnic groups), including protective innate immune genetic programming optimized for survival in their corresponding ancestral environment(s). This perspective explores evidence related to our working hypothesis that genetic variations in innate immune genes, particularly those that are commonly found but unevenly distributed between populations, are associated with disparities between populations in both cancer and cardio-metabolic diseases. Identifying conventional and unconventional innate immune genes that fit this profile may provide critical insights into the underlying mechanisms that connect these two families of complex diseases and offer novel targets for precision-based treatment of cancer and/or cardio-metabolic disease.

Structural enrichment attenuates colitis-associated colon cancer

Colorectal cancer (CRC) is a major public health concern and disproportionately impacts racial/ethnic minority populations in the US. Animal models are helpful in examining human health disparities because many stress-induced human health conditions can be recapitulated using mouse models. Azoxymethane (AOM)/ dextran sodium sulfate (DSS) treatment can be used to model colitis-associated cancers. While colitis-associated cancers account for only 2% of colon cancers, the AOM/DSS model is useful for examining links between inflammation, immunity, and colon cancer. Mice were housed in enriched and impoverished environments for 1-month prior to behavioral testing. Following behavioral testing the mice were subjected to the AOM/DSS model. While our analysis revealed no significant behavioral variances between the impoverished and enriched housing conditions, we found significant effects in tumorigenesis. Enriched mice had fewer tumors and smaller tumor volumes compared to impoverished mice. African Americans are at higher risk for early onset colorectal cancers in part due to social economic status. Furthermore, housing conditions and environment may reflect social economic status. Research aimed at understanding links between social economic status and colorectal cancer progression is important for eliminating disparities in health outcomes.

sPDGFRβ and neuroinflammation are associated with AD biomarkers and differ by race: The ASCEND Study

INTRODUCTION

There remains an urgent need to identify preclinical pathophysiological mechanisms of Alzheimer's disease (AD) development in high-risk, racially diverse populations. We explored the relationship between cerebrospinal fluid (CSF) markers of vascular injury and neuroinflammation with AD biomarkers in middle-aged Black/African American (B/AA) and non-Hispanic White (NHW) participants.

METHODS

Adults (45-65 years) with a parental history of AD were enrolled (n = 82). CSF and blood biomarkers were collected at baseline and year 2.

RESULTS

CSF total tau (t-tau), phosphorylated tau (p-tau), and amyloid beta (Aβ)40 were elevated at year 2 compared to baseline. CSF soluble platelet-derived growth factor receptor β (sPDGFRβ) levels, a marker of pericyte injury, correlated positively with t-tau, p-tau, Aβ40 markers of vascular injury, and cytokines at baseline and year 2. CSF sPDGFRβ and tau were significantly lower in B/AA than NHW.

DISCUSSION

Vascular dysfunction and neuroinflammation may precede cognitive decline and disease pathology in the very early preclinical stages of AD, and there are race-related differences in these relationships.

HIGHLIGHTS

Cerebrospinal fluid (CSF) Alzheimer's disease (AD) biomarkers changed over 2 years in high-risk middle-aged adults. Markers of vascular dysfunction were associated with the CSF biomarkers amyloid beta and tau. AD biomarkers were lower in Black compared to non-Hispanic White individuals. Markers of vascular dysfunction were lower among Black individuals.

Investigation of trends in gut microbiome associated with colorectal cancer using machine learning

Background

The rapid growth of publications on the gut microbiome and colorectal cancer (CRC) makes it feasible for text mining and bibliometric analysis.

Methods

Publications were retrieved from the Web of Science. Bioinformatics analysis was performed, and a machine learning-based Latent Dirichlet Allocation (LDA) model was used to identify the subfield research topics.

Results

A total of 5,696 publications related to the gut microbiome and CRC were retrieved from the Web of Science Core Collection from 2000 to 2022. China and the USA were the most productive countries. The top 25 references, institutions, and authors with the strongest citation bursts were identified. Abstracts from all 5,696 publications were extracted for a text mining analysis that identified the top 50 topics in this field with increasing interest. The colitis animal model, expression of cytokines, microbiome sequencing and 16s, microbiome composition and dysbiosis, and cell growth inhibition were increasingly noticed during the last two years. The 50 most intensively investigated topics were identified and further categorized into four clusters, including "microbiome sequencing and tumor," "microbiome compositions, interactions, and treatment," "microbiome molecular features and mechanisms," and "microbiome and metabolism."

Conclusion

This bibliometric analysis explores the historical research tendencies in the gut microbiome and CRC and identifies specific topics of increasing interest. The developmental trajectory, along with the noticeable research topics characterized by this analysis, will contribute to the future direction of research in CRC and its clinical translation.