Hypobaric hypoxia drives selection of altitude-associated adaptative alleles in the Himalayan population

High-altitude hypoxia exacerbates chemotherapy-induced myelosuppression by lowering serum G-CSF/GM-CSF and regulating apoptosis and proliferation

The unique hypoxic environment in high-altitude regions is increasingly drawing attention for its impact on the health of residents, particularly in patients post-chemotherapy. This study aimed to investigate the effects and potential mechanisms of high-altitude hypoxia on myelosuppression following chemotherapy, with the goal of providing a theoretical basis for clinical treatment. A retrospective clinical study of 80 patients with breast cancer revealed that patients in the plateau exhibited a significantly higher incidence of grade 3 or higher neutropenia and any level of neutropenia post-chemotherapy than those in the plain, with propensity score matching (PSM) confirming these associations. Animal experiments revealed that high-altitude hypoxia reduced the white blood cell (WBC) count, granulocyte count, lymphocyte count, and number of bone marrow nucleated cells (BMNCs) in cyclophosphamide (CTX)-treated mice. Additionally, high-altitude hypoxia induced a significant reduction in the proliferation index and an elevation in apoptosis rates in BMNCs. High-altitude hypoxia also significantly reduced serum levels of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Transcriptomic analysis of BMNCs demonstrated that high-altitude hypoxia might modulate the hematopoietic function in CTX-induced myelosuppression mice through pathways related to hematopoiesis, such as porphyrin metabolism, hematopoietic cell lineage, ECM-receptor interaction, and PI3K-Akt signaling pathway. Our results suggest that high-altitude hypoxia exacerbates chemotherapy-induced myelosuppression, possibly through reducing the serum level of G-CSF/GM-CSF and regulating apoptosis and proliferation by PI3K-Akt signaling pathway, highlighting that cancer patients undergoing chemotherapy in hypoxic environments may require enhanced supportive care to mitigate these adverse effects.

Whole Genome Analysis Reveals Evolutionary History and Introgression Events in Bale Monkeys

Background/Objective: The Bale monkey (Chlorocebus djamdjamensis) is a threatened primate species endemic to Ethiopia and, in contrast to other members of the genus Chlorocebus, lives at high altitudes and feeds mainly on bamboo. Two populations of the species are present, one in continuous bamboo forest (CF) in the eastern part of the species' range, and the other in fragmented forest (FF) in the western part. Based on mitochondrial DNA and phenotypic characteristics, previous studies have suggested introgression by parapatric congeners into the FF population but not into the CF population. The objective of this study was to gain insights into the evolutionary history of Bale monkeys and their potential genetic adaptations to high altitudes and for bamboo consumption. Methods: We sequenced the whole genomes of individuals from both populations and compared their genomes with those of the other five Chlorocebus species. We applied phylogenetic methods and conducted population demographic simulations to elucidate their evolutionary history. A genome-wide analysis was conducted to assess gene flow and identify mutations potentially associated with adaptations to high altitudes and for bamboo metabolism. Results: Our analyses revealed Bale monkeys as the sister clade to Chlorocebus aethiops and showed that gene flow occurred between C. aethiops and FF but not between C. aethiops and CF. In addition, we detected non-synonymous mutations in genes potentially associated with the adaptation to high altitudes (EPAS1) in both populations and with the adaptation for bamboo metabolism (TAS2R16, MPST, and TST) mainly in the CF population. Conclusions: Our study provides insights into the evolutionary history of a threatened primate species and reveals the genetic basis for its adaptions to unique environments and for diet specialization.

Evaluation of circulating plasma proteins in prostate cancer using mendelian randomization

BACKGROUND

The proteome is an important resource for exploring potential diagnostic and therapeutic targets for cancer. This study aimed to investigate the causal associations between plasma proteins and prostate cancer (PCa), and to explore the downstream phenotypes that plasma proteins may influence and potential upstream intervening factors.

METHODS

Proteome-wide Mendelian randomization was used to investigate the causal effects of plasma proteins on PCa. Colocalization analysis examined the common causal variants between plasma proteins and PCa. Summary-statistics-based Mendelian Randomization (SMR) analyses identified associations between the expression of protein-coding genes and PCa. Phenome-wide association study was performed to explore the effect of target proteins on downstream phenotypes. Finally, a systematic Mendelian randomization analysis between lifestyle factors and plasma proteins was performed to assess upstream intervening factors for plasma proteins.

RESULTS

The findings revealed a positive genetic association between the predicted plasma levels of nine proteins and an elevated risk of PCa, while four proteins exhibited an inverse association with PCa risk. SMR analyses revealed ZG16B, PEX14 in blood and ZG16B, NAPG in prostate tissue were potential drug targets for PCa. The genetic association of PEX14 with PCa was further supported by colocalization analysis. Further Phenome-wide association study showed possible side effects of ZG16B, PEX14 and NAPG as drug targets. 10 plasma proteins (RBP7, TPST1, NFASC, LAYN, HDGF, SERPIMA5, DLL4, EFNA3, LIMA1, and CCL27) could be modulated by lifestyle-related factors.

CONCLUSION

This study explores the genetic associations between plasma proteins and PCa, provides evidence that plasma proteins serve as potential drug targets and enhances the understanding of the molecular etiology, prevention and treatment of PCa.

High altitude polycythemia and its maladaptive mechanisms: an updated review

High altitude polycythemia is a maladaptation of highlanders exposed to hypoxic environment, leading to high blood viscosity and severe cardiorespiratory dysfunction. Prolonged hypoxia causes respiratory depression and severe hypoxemia, and further mediates changes in genetic and molecular mechanisms that regulate erythropoiesis and apoptosis, ultimately resulting in excessive erythrocytosis (EE). This updated review investigated the maladaptive mechanisms of EE, including respiratory chemoreceptor passivation, sleep-related breathing disorders, sex hormones, iron metabolism, and hypoxia-related factors and pathways.

Moderate altitude as a risk factor for isolated congenital malformations. Results from a case-control multicenter-multiregional study

BACKGROUND

Living in high-altitude regions has been associated with a higher prevalence of some birth defects. Moderate altitudes (1500-2500 m) have been associated with some congenital heart diseases and low birth weight. However, no studies have been conducted for other isolated congenital malformations.

OBJECTIVES

To estimate the prevalence at birth of isolated congenital malformations in low and moderate altitudes and to determine if moderate altitudes are a risk factor, such as high altitudes, for isolated congenital malformations adjusted for other factors.

METHODS

The study consisted of a case-control multicenter-multiregional study of 13 isolated congenital malformations. Cases included live births with isolated congenital malformations and controls at low (10-1433 m) and moderate altitudes (1511-2426 m) from a Mexican registry from January 1978 to December 2019. Prevalence per 10,000 (95% CI) per altitude group was estimated. We performed unadjusted and adjusted logistic regression models (adjusted for maternal age, parity, malformed relatives, socioeconomic level, and maternal diabetes) for each isolated congenital malformation.

RESULTS

Hydrocephaly and microtia had a higher at-birth prevalence, and spina bifida, preauricular tag, and gastroschisis showed a lower at-birth prevalence in moderate altitudes. Moderate altitudes were a risk factor for hydrocephaly (aOR 1.39), microtia (aOR 1.60), cleft-lip-palate (aOR 1.27), and polydactyly (aOR 1.32) and a protective effect for spina bifida (aOR 0.87) compared with low altitudes.

CONCLUSIONS

Our findings provide evidence that moderate altitudes as higher altitudes are an associated risk or protective factor to some isolated congenital malformations, suggesting a possible gradient effect.