The DARC Side of Inflamm-Aging: Duffy Antigen Receptor for Chemokines (DARC/ACKR1) as a Potential Biomarker of Aging, Immunosenescence, and Breast Oncogenesis among High-Risk Subpopulations

Novel neutrophil biology insights underlying atypical chemokine receptor-1/Duffy antigen receptor of chemokines-associated neutropenia

PURPOSE OF REVIEW

Atypical chemokine receptor-1 (ACKR1)/Duffy antigen receptor of chemokines (DARC)-associated neutropenia (ADAN; OMIM 611862), previously named benign ethnic neutropenia, and present in two-thirds of individuals identifying as Black in the USA, is associated with mild to moderate decreases in peripheral neutrophil counts that nevertheless do not lead to increased infections. Consequently, recent initiatives have sought to establish normal neutrophil count reference ranges for ADAN, considering it a normal variant rather than a clinical disorder requiring medical intervention.

RECENT FINDINGS

A limited number of studies elucidating the mechanism of neutropenia in ADAN has suggested that neutrophils may redistribute from peripheral blood to the tissues including the spleen: this might explain why ADAN is not associated with increased risks of infection since the total number of neutrophils in the body remains normal. In this review, we critically examine the research underlying the molecular basis of ADAN.

SUMMARY

Insights into the biology of neutrophils and their trafficking may inform the clinical interpretation of neutropenia in ADAN. The bulk of research suggests that ADAN does not lead to a diminished host defense as do other forms of neutropenia. However, ADAN may lead to increased proinflammatory signaling, with possible implications for senescence of the immune system and predisposition to autoimmunity and cancer.

CXCL8 and its cognate receptors CXCR1/CXCR2 in primary myelofibrosis

BCR::ABL1 negative myeloproliferative neoplasms (MPN) form a distinct group of hematologic malignancies characterized by sustained proliferation of cells from multiple myeloid lineages. With a median survival of 16-35 months in patients with high-risk disease, primary myelofibrosis (PMF) is considered the most aggressive entity amongst all BCR::ABL1 MPN. Additionally, for a significant subset of patients, MPN evolve into secondary acute myeloid leukemia (AML), which has an even poorer prognosis compared to de novo AML. As the exact mechanisms of disease development and progression remain to be elucidated, current therapeutic approaches fail to prevent disease progression or transformation into secondary AML. As each MPN entity is characterized by sustained activation of various immune cells and raised cytokine concentrations within bone marrow (BM) and peripheral blood (PB), MPN may be considered to be typical inflammation-related malignancies. However, the exact role and consequences of increased cytokine concentrations within BM and PB plasma has still not been completely established. Up-regulated cytokines can stimulate cellular proliferation, or contribute to the development of an inflammation-related BM niche resulting in genotoxicity and thereby supporting mutagenesis. The neutrophil chemoattractant CXCL8 is of specific interest as its concentration is increased within PB and BM plasma of patients with PMF. Increased concentration of CXCL8 negatively correlates with overall survival. Furthermore, blockage of the CXCR1/2 axis appears to be able to reduce BM fibrosis and megakaryocyte dysmorphia in murine models. In this review, we summarize available evidence on the role of the CXCL8-CXCR1/2 axis within the pathogenesis of PMF, and discuss potential therapeutic modalities targeting either CXCL8 or its cognate receptors CXCR1/2.

High expression of ACKR1 predicts a good prognosis and suppresses sarcoma cell progression via regulating the tumor immune microenvironment

Sarcoma is a malignant tumor originating from mesenchymal tissue with a poor prognosis. Atypical chemokine receptor 1 (ACKR1) is found closely related to cancer progression. However, the effects of ACKR1 in soft tissue sarcoma have not been well investigated. Therefore, our present study is devoted to analyze the functions of ACKR1 in sarcoma progression and its potential mechanism. We detected the expression of ACKR1 in the Cancer Genome Atlas (TCGA)-pan-cancer database, TCGA-Sarcoma from TCGA databases, and GSE21122 from Gene Expression Omnibus (GEO) database. The relationships between ACKR1 expression, clinicopathological data, and survival status were evaluated in the TCGA-Sarcoma database. Moreover, overexpression negative control (OE-NC) and overexpression ACKR1 (OE-ACKR1) were used to further verify the effects of ACKR1 overexpression in the progression of sarcoma cells by using Reverse Transcription-Quantitative Polymerase Chain Reaction (RT-qPCR), cell counting kit-8 (CCK-8), 5-Ethyny-2'-Deoxyuridine (EdU), wound healing, transwell assay, and flow cytometry assays. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA) analyses were carried out to explore the potential enriched biological process of ACKR1 expression in sarcoma. Furthermore, tumor-immune system interactions databases (TISIDB) were applied to further confirm the relations between ACKR1 and tumor immune microenvironment in sarcoma. Our study found that ACKR1 is downregulated in multiple cancers (including sarcoma), and low expression of ACKR1 is related to poor survival status in sarcoma. The biological experiments found that promoting expression of ACKR1 can suppress sarcoma cell proliferation, migration, invasion, promote cell apoptosis, and arrest cell cycle. The GO-KEGG, GSEA, and TISIDB analysis showed that ACKR1 is related to the tumor immune microenvironment. In conclusion, low expression of ACKR1 presented as an independent prognostic biomarker in sarcoma. Overexpression of ACKR1 can significantly suppress cell progression ability in sarcoma by regulating the immune microenvironment.

Effect of aging on the human myometrium at single-cell resolution

Age-associated myometrial dysfunction can prompt complications during pregnancy and labor, which is one of the factors contributing to the 7.8-fold increase in maternal mortality in women over 40. Using single-cell/single-nucleus RNA sequencing and spatial transcriptomics, we have constructed a cellular atlas of the aging myometrium from 186,120 cells across twenty perimenopausal and postmenopausal women. We identify 23 myometrial cell subpopulations, including contractile and venous capillary cells as well as immune-modulated fibroblasts. Myometrial aging leads to fewer contractile capillary cells, a reduced level of ion channel expression in smooth muscle cells, and impaired gene expression in endothelial, smooth muscle, fibroblast, perivascular, and immune cells. We observe altered myometrial cell-to-cell communication as an aging hallmark, which associated with the loss of 25 signaling pathways, including those related to angiogenesis, tissue repair, contractility, immunity, and nervous system regulation. These insights may contribute to a better understanding of the complications faced by older individuals during pregnancy and labor.

Neighborhood Disadvantage, African Genetic Ancestry, Cancer Subtype, and Mortality Among Breast Cancer Survivors

Importance

Racial disparities in breast cancer (BC) survival arise from multilevel causes, which may exert influence at different stages of BC progression. Clarifying the importance of genetic and social factors could help prioritize interventions.

Objective

To jointly examine associations between African genetic ancestry, social environment, and mortality from any cause and BC in Black BC survivors.

Design, Setting, and Participants

This population-based cohort study enrolled self-identified Black women aged 20 to 75 years with histologically confirmed BC from June 2005 to May 2019 and followed them up until death or censoring in September 2021. Participants lived in 10 New Jersey counties. Data were analyzed between December 2022 and April 2023.

Exposures

A neighborhood socioeconomic status (nSES) index composed of census tract measures (education, income, wealth, employment status, and occupation) was linked to residential addresses at diagnosis. Percentage African ancestry was estimated using the ADMIXTURE program.

Main Outcomes and Measures

Sequentially adjusted (age adjusted: age and interview year; fully adjusted: age adjusted with individual SES, lifestyle factors, and comorbidities) logistic regression models were fit to estimate associations with tumor subtypes (estrogen receptor-negative [ER-] vs estrogen receptor-positive [ER+]; triple-negative breast cancer [TNBC] vs luminal A), and Cox models were fit for associations with all-cause mortality (ACM) and breast cancer-specific mortality (BCSM). Models for BCSM were fit using Fine-Gray competing risks models, and robust standard errors were used to account for census tract-level clustering.

Results

Among 1575 participants, median (IQR) African ancestry was 85% (76%-90%), and median (IQR) age was 55 (46-63) years. A 10-percentage point increase in African ancestry was associated with higher odds of ER- vs ER+ (adjusted odds ratio [aOR], 1.08; 95% CI, 0.98-1.18) and TNBC vs luminal (aOR, 1.15; 95% CI, 1.02-1.31) tumors, but not with ACM or BCSM. A 1-IQR increase in nSES was associated with lower ACM (adjusted hazard ratio [aHR], 0.76; 95% CI, 0.63-0.93), and the HR for BCSM was less than 1 but not statistically significant (aHR, 0.81; 95% CI, 0.62-1.04) in age-adjusted models, but associations attenuated following further adjustment for potential mediators (individual SES, lifestyles, comorbidities).

Conclusions and Relevance

In this cohort study of Black female BC survivors, higher African ancestry was associated with aggressive tumor subtypes. Compared with genetic ancestry, mediating pathways related to social environments may be more important for survival in these patients.