Climate shock: Moving to colder climates and immigrant mortality

Exploring the paradoxical nature of cold temperature mortality in Europe

While low winter temperatures are associated with increased mortality, this phenomenon has been suggested to be most severe in regions with seemingly mild winters. The study aimed to establish a temperature-based formula that could elucidate the previously ambiguous regional differences in vulnerability to low temperature. European weekly mortality data (2000-2019) were matched with meteorological data to determine for each region vulnerability to temperature decrease and the optimal temperature with lowest mortality. Regression models were developed to generalize and explain these findings considering regional temperature characteristics. Optimal temperature could be predicted based on local average summer temperature (R2 = 85.6%). Regional vulnerability to temperature decrease could be explained by combination of winter and summer temperatures (R2 = 86.1%). Regions with warm winters and cold summers showed the highest vulnerability to decrease of temperature during winter. Contrary to theories about economic disparities Eastern Europe exhibited resistance comparable to Scandinavia. The southern edges of Europe demonstrated serious low temperature vulnerability to decreased temperatures, even if temperature was relatively high around 20 °C. This suggests that the observed connection primarily reflects the modulation of the length of respiratory virus infection seasons by climate conditions, counterbalanced by varying levels of acquired immunity and the presence of heatwaves eliminating the most frail individuals. Thus, relatively low vulnerability and a flat mortality cycle in countries with harsh climates paradoxically imply the presence of threats throughout the whole year.

A systematic review of the effects of cold exposure on pathological cardiac remodeling in mice

Exposure to cold promotes cardiac remodeling, characterized by deleterious effects on structure and function, contributing to increased mortality from cardiovascular diseases. The mechanisms associated with these changes are poorly understood. This review gathers the literature data on the main alterations and mechanisms associated with the adverse cardiac structural and functional remodeling induced by cold exposure in mice. Original studies were identified by searching PubMed, Scopus, and Embase databases from January 1990 to June 2022. This systematic review was conducted in accordance with the criteria established by PRISMA and registered in PROSPERO (CRD42022350637). The risk of bias was evaluated by the SYRCLE. Eligible studies included original papers published in English that evaluated cardiac outcomes in mice submitted to short- or long-time cold exposure and had a control group at room temperature. Seventeen original articles were included in this review. Cold exposure induces pathological cardiac remodeling, characterized by detrimental structural and functional parameters, changes in metabolism and autophagy process, and increases in oxidative stress, inflammation, and apoptosis. In addition, Nppa, AT1_A, Fbp3, BECN, ETA, and MT, appear to play fundamental roles in regulating cardiac remodeling. We suggest that strategies that seek to minimize the CVD risk and adverse effects of cold exposure should target these agents.

The Intersection of Immigrant and Environmental Health: A Scoping Review of Observational Population Exposure and Epidemiologic Studies

BACKGROUND

Transnational immigration has increased since the 1950s. In countries such as the United States, immigrants now account for > 15 % of the population. Although differences in health between immigrants and nonimmigrants are well documented, it is unclear how environmental exposures contribute to these disparities.

OBJECTIVES

We summarized current knowledge comparing immigrants' and nonimmigrants' exposure to and health effects of environmental exposures.

METHODS

We conducted a title and abstract review on articles identified through PubMed and selected those that assessed environmental exposures or health effects separately for immigrants and nonimmigrants. After a full text review, we extracted the main findings from eligible studies and categorized each article as exposure-focused, health-focused, or both. We also noted each study's exposure of interest, study location, exposure and statistical methods, immigrant and comparison groups, and the intersecting socioeconomic characteristics controlled for.

RESULTS

We conducted a title and abstract review on 3,705 articles, a full text review on 84, and extracted findings from 50 studies. There were 43 studies that investigated exposure (e.g., metals, organic compounds, fine particulate matter, hazardous air pollutants) disparities, but only 12 studies that assessed health disparities (e.g., mortality, select morbidities). Multiple studies reported higher exposures in immigrants compared with nonimmigrants. Among immigrants, studies sometimes observed exposure disparities by country of origin and time since immigration. Of the 50 studies, 43 were conducted in North America.

DISCUSSION

The environmental health of immigrants remains an understudied area, especially outside of North America. Although most identified studies explored potential exposure disparities, few investigated subsequent differences in health effects. Future research should investigate environmental health disparities of immigrants, especially outside North America. Additional research gaps include the role of immigrants' country of origin and time since immigration, as well as the combined effects of immigrant status with intersecting socioeconomic characteristics, such as race/ethnicity, income, and education attainment. https://doi.org/10.1289/EHP9855.

A Global Meta-analysis of the Immigrant Mortality Advantage

A large body of research on the “Healthy Immigrant Effect” (or “Paradox”) has reported an immigrant mortality advantage. However, other studies do not find such significant effects, and some even present contradictory evidence. This article is the first systematic meta-analysis that investigates the immigration-mortality relationship from a global perspective, examining 1,933 all-cause and cardiovascular mortality risk estimates from 103 publications. Our comprehensive analysis allows us to assess interactions between origin and destination regions and to reexamine, on a global scale, some of the most notable explanations for the immigrant mortality advantage, including suggestions that this paradox may be primarily the result of selection effects. We find evidence for the existence of a mild immigrant mortality advantage for working-age individuals. However, the relationship holds only for immigrants who moved between certain world regions, particularly those who immigrated from Northern Africa, Asia, and Southern Europe to richer countries. The results highlight the need in the broader migration literature for an increased focus on selection effects and on outcomes for people who chose not to migrate or who were denied entry into their planned destination country.

Beclin1 haploinsufficiency rescues low ambient temperature-induced cardiac remodeling and contractile dysfunction through inhibition of ferroptosis and mitochondrial injury

OBJECTIVE

Cold exposure provokes cardiac remodeling and cardiac dysfunction. Autophagy participates in cold stress-induced cardiovascular dysfunction. This study was designed to examine the impact of Beclin1 haploinsufficiency (BECN^+/-) in cold stress-induced cardiac geometric and contractile responses.

METHODS AND MATERIALS

Wild-type (WT) and BECN^+/- mice were assigned to normal or cold exposure (4 °C) environment for 4 weeks prior to evaluation of cardiac geometry, contractile and mitochondrial properties. Autophagy, apoptosis and ferroptosis were evaluated.

RESULTS

Our data revealed that cold stress triggered cardiac remodeling, compromised myocardial contractile capacity including ejection fraction, fractional shortening, peak shortening and maximal velocity of shortening/relengthening, duration of shortening and relengthening, intracellular Ca²⁺ release, intracellular Ca²⁺ decay, mitochondrial ultrastructural disarray, superoxide production, unchecked autophagy, apoptosis and ferroptosis, the effects of which were negated by Beclin1 haploinsufficiency. Circulating levels of corticosterone were elevated in both WT and BECN^+/- mice. Treatment of corticosterone synthesis inhibitor metyrapone or ferroptosis inhibitor liproxstatins-1 rescued cold stress-induced cardiac dysfunction and mitochondrial injury. In vitro study noted that corticosterone challenge compromised cardiomyocyte function, provoked lipid peroxidation and mitochondrial injury, the effects of which were nullified by Beclin1 haploinsufficiency, inhibitors of lipoxygenase, ferroptosis and autophagy. In addition, ferroptosis inducer erastin abrogated Beclin1 deficiency-offered cardioprotection.

CONCLUSION

These data suggest that Beclin1 haploinsufficiency protects against cold exposure-induced cardiac dysfunction possibly through corticosterone- and ferroptosis-mediated mechanisms.