Generalized Resistance Resources in the Salutogenic Model of Health

This chapter presents and discusses theoretical considerations and empirical findings regarding the concepts generalized resistance resources (GRRs) and generalized resistance deficits (GRDs). Recent research findings are presented, showing how these resources or deficits impact sense of coherence (SOC). Suggestions for future research directions (e.g., individuals’ differential susceptibility to environmental effects and eudaimonia/hedonia perspectives) and interventional implications are presented.

The associations of active and passive social media use with well-being: A critical scoping review

A recurring claim in the literature is that active social media use (ASMU) leads to increases in well-being, whereas passive social media use (PSMU) leads to decreases in well-being. The aim of this review was to investigate the validity of this claim by comparing the operationalizations and results of studies into the association of ASMU and PSMU with well-being (e.g. happiness) and ill-being (e.g. depressive symptoms). We found 40 survey-based studies, which utilized a hodgepodge of 36 operationalizations of ASMU and PSMU and which yielded 172 associations of ASMU and/or PSMU with well-/ill-being. Most studies did not support the hypothesized associations of ASMU and PSMU with well-/ill-being. Time spent on ASMU and PSMU may be too coarse to lead to meaningful associations with well-/ill-being. Therefore, future studies should take characteristics of the content of social media (e.g. the valence), its senders (e.g. pre-existing mood), and receivers (e.g. differential susceptibility) into account.

Mapping of novel loci involved in lung and colon tumor susceptibility by the use of genetically selected mouse strains

Two non-inbred mouse lines, phenotypically selected for maximal (AIRmin) and minimal (AIRmax) acute inflammatory response, show differential susceptibility/resistance to the development of several chemically-induced tumor types. An intercross pedigree of these mice was generated and treated with the chemical carcinogen dimethylhydrazine, which induces lung and intestinal tumors. Genome wide high-density genotyping with the Restriction Site-Associated DNA genotyping (2B-RAD) technique was used to map genetic loci modulating individual genetic susceptibility to both lung and intestinal cancer. Our results evidence new common quantitative trait loci (QTL) for those phenotypes and provide an improved understanding of the relationship between genomic variation and individual genetic predisposition to tumorigenesis in different organs.

Cannabinoids in Breast Cancer: Differential Susceptibility According to Subtype

Although cannabinoids have been used for centuries for diverse pathological conditions, recently, their clinical interest and application have emerged due to their diverse pharmacological properties. Indeed, it is well established that cannabinoids exert important actions on multiple sclerosis, epilepsy and pain relief. Regarding cancer, cannabinoids were first introduced to manage chemotherapy-related side effects, though several studies demonstrated that they could modulate the proliferation and death of different cancer cells, as well as angiogenesis, making them attractive agents for cancer treatment. In relation to breast cancer, it has been suggested that estrogen receptor-negative (ER−) cells are more sensitive to cannabinoids than estrogen receptor-positive (ER+) cells. In fact, most of the studies regarding their effects on breast tumors have been conducted on triple-negative breast cancer (TNBC). Nonetheless, the number of studies on human epidermal growth factor receptor 2-positive (HER2+) and ER+ breast tumors has been rising in recent years. However, besides the optimistic results obtained thus far, there is still a long way to go to fully understand the role of these molecules. This review intends to help clarify the clinical potential of cannabinoids for each breast cancer subtype.

The evolved divergence of γ-secretase-susceptibility of homologous proteins Ngfrb and Nradd in zebrafish

Objective NGFR/p75NTR and NRADD/NRH proteins are closely related structurally and are encoded by genes that arose from a duplication event early in vertebrate evolution. The transmembrane domain (TMD) of NGFR is cleaved by γ-secretase but there is conflicting data around the susceptibility to γ-secretase cleavage of NRADD proteins. If NGFR and NRADD show differential susceptibility to γ-secretase, then they can be used to dissect the structural constraints determining substrate susceptibility. We sought to test this differential susceptibility. Results We developed labelled, lumenally-truncated forms of zebrafish Ngfrb and Nradd and a chimeric protein in which the TMD of Nradd was replaced with the TMD of Ngfrb. We expressed these in zebrafish embryos to test their susceptibility to γ-secretase cleavage by monitoring their stability using western immunoblotting. Inhibition of γ-secretase activity using DAPT increased the stability of only the Ngfrb construct. Our results support that only NGFR is cleaved by γ-secretase. Either NGFR evolved γ-secretase-susceptibility since its creation by gene duplication, or NRADD evolved to be refractory to γ-secretase. Protein structure outside of the TMD of NGFR is likely required for susceptibility to γ-secretase.

Regional gray matter oligodendrocyte- and myelin-related measures are associated with differential susceptibility to stress-induced behavior in rats and humans

Individual reactions to traumatic stress vary dramatically, yet the biological basis of this variation remains poorly understood. Recent studies demonstrate the surprising plasticity of oligodendrocytes and myelin with stress and experience, providing a potential mechanism by which trauma induces aberrant structural and functional changes in the adult brain. In this study, we utilized a translational approach to test the hypothesis that gray matter oligodendrocytes contribute to traumatic-stress-induced behavioral variation in both rats and humans. We exposed adult, male rats to a single, severe stressor and used a multimodal approach to characterize avoidance, startle, and fear-learning behavior, as well as oligodendrocyte and myelin basic protein (MBP) content in multiple brain areas. We found that oligodendrocyte cell density and MBP were correlated with behavioral outcomes in a region-specific manner. Specifically, stress-induced avoidance positively correlated with hippocampal dentate gyrus oligodendrocytes and MBP. Viral overexpression of the oligodendrogenic factor Olig1 in the dentate gyrus was sufficient to induce an anxiety-like behavioral phenotype. In contrast, contextual fear learning positively correlated with MBP in the amygdala and spatial-processing regions of the hippocampus. In a group of trauma-exposed US veterans, T1-/T2-weighted magnetic resonance imaging estimates of hippocampal and amygdala myelin associated with symptom profiles in a region-specific manner that mirrored the findings in rats. These results demonstrate a species-independent relationship between region-specific, gray matter oligodendrocytes and differential behavioral phenotypes following traumatic stress exposure. This study suggests a novel mechanism for brain plasticity that underlies individual variance in sensitivity to traumatic stress.

OTC intron 4 variations mediate pathogenic splicing patterns caused by the c.386G>A mutation in humans and spfash mice, and govern susceptibility to RNA-based therapies

Background Aberrant splicing is a common outcome in the presence of exonic or intronic variants that might hamper the intricate network of interactions defining an exon in a specific gene context. Therefore, the evaluation of the functional, and potentially pathological, role of nucleotide changes remains one of the major challenges in the modern genomic era. This aspect has also to be taken into account during the pre-clinical evaluation of innovative therapeutic approaches in animal models of human diseases. This is of particular relevance when developing therapeutics acting on splicing, an intriguing and expanding research area for several disorders. Here, we addressed species-specific splicing mechanisms triggered by the OTC c.386G>A mutation, relatively frequent in humans, leading to Ornithine TransCarbamylase Deficiency (OTCD) in patients and spfash mice, and its differential susceptibility to RNA therapeutics based on engineered U1snRNA. Methods Creation and co-expression of engineered U1snRNAs with human and mouse minigenes, either wild-type or harbouring different nucleotide changes, in human (HepG2) and mouse (Hepa1-6) hepatoma cells followed by analysis of splicing pattern. RNA pulldown studies to evaluate binding of specific splicing factors. Results Comparative nucleotide analysis suggested a role for the intronic +10-11 nucleotides, and pull-down assays showed that they confer preferential binding to the TIA1 splicing factor in the mouse context, where TIA1 overexpression further increases correct splicing. Consistently, the splicing profile of the human minigene with mouse +10-11 nucleotides overlapped that of mouse minigene, and restored responsiveness to TIA1 overexpression and to compensatory U1snRNA. Swapping the human +10-11 nucleotides into the mouse context had opposite effects. Moreover, the interplay between the authentic and the adjacent cryptic 5′ss in the human OTC dictates pathogenic mechanisms of several OTCD-causing 5′ss mutations, and only the c.386+5G>A change, abrogating the cryptic 5′ss, was rescuable by engineered U1snRNA. Conclusions Subtle intronic variations explain species-specific OTC splicing patterns driven by the c.386G>A mutation, and the responsiveness to engineered U1snRNAs, which suggests careful elucidation of molecular mechanisms before proposing translation of tailored therapeutics from animal models to humans.

Striatal compartmentalization and clustering of different subtypes of astrocytes is altered in the zQ175 Huntington′s disease mouse model

Huntington′s disease (HD) is a devastating neurodegenerative disease that primarily affects the striatum, a brain region that controls movement and some forms of cognition. Dysfunction and loss of medium spiny neurons of the striatum is accompanied by astrogliosis (increased astrocyte density and pathology). For decades, astrocytes were considered a homogeneous cell type, but recent transcriptomic analyses revealed astrocytes are a heterogeneous population classified into multiple subtypes depending on the expression of different gene markers. Here, we studied whether three different striatal astrocyte subtypes expressing glutamine synthetase (GS), glial fibrillary acidic protein (GFAP), or S100 calcium-binding protein B (S100B) are differentially altered in HD. We conducted a comparative immunofluorescence analysis in the striatum of WT and the heterozygous zQ175 HD mouse model and found that the expression and abundance of GFAP+ and S100B+ astrocytes increased in zQ175 mice, while GS+ astrocytes showed no alteration. We then explored whether there was a differential spatial distribution of any of these subtypes within the striatum. We developed a systematic brain compartmentalization approach and found that while GS+ and S100B+ astrocytes were more homogeneously distributed throughout the striatum in zQ175 mice, GFAP+ astrocytes preferentially accumulated in the dorsomedial and dorsolateral striatum, which are regions associated with goal-directed and habitual behaviors. Additionally, GFAP+ astrocytes in zQ175 mice showed increased clustering, a parameter that indicates increased proximity and that is associated with localized inflammation and/or neurodegeneration. Our data suggest a differential susceptibility in both increased density and striatal compartmentalization of different subtypes of astrocytes in zQ175. These results highlight new potential implications for our understanding of astrocyte pathology in HD.

A brief video-coaching intervention buffers young children's vulnerability to the impact of caregivers’ depressive symptoms: Examination of differential susceptibility

Informed by the National Institute of Mental Health's Research Domain Criteria (RDoC) and developmental psychopathology frameworks, the current study used cortisol area under the curve with respect to ground (AUCg) as an index of differential sensitivity to context, which was expected to predispose young children with elevated vulnerability to adverse caregiving experiences and adaptive sensitivity to intervention effects. Particularly, the study aimed to determine whether improving caregivers’ responsive parenting through the Filming Interactions to Nurture Development (FIND) intervention would buffer children's biologically embedded vulnerability to caregivers’ depressive symptoms. Data were derived from a randomized controlled trial using pretest–posttest design with low-income families of children aged 4 to 36 months (N = 91). Young children's differential sensitivity was measured using cortisol AUCg during a structured stress paradigm. As hypothesized, children whose cortisol AUCg indicated greater sensitivity to social context exhibited more internalizing and externalizing behaviors in relation to caregivers’ elevated depressive symptoms. Critically, the intervention program was effective in attenuating psychopathology symptoms among the more biologically sensitive children. As proven by rigorous statistical tests, the findings of this study partially supported the differential susceptibility hypotheses, indicating both greater vulnerability to adverse conditions and responsiveness to intervention among children with high levels of cortisol AUCg.