Region-specific involvement of interneuron subpopulations in trauma-related pathology and resilience.

Only a minority of trauma-exposed individuals develops Posttraumatic stress disorder (PTSD) and active processes may support trauma resilience. Individual behavioral profiling allows investigating neurobiological alterations related to resilience or pathology in animal models of PTSD and is utilized here to examine the activation of different interneuron subpopulations of the dentate gyrus-amygdala system associated with trauma resilience or pathology. To model PTSD, rats were exposed to juvenile stress combined with underwater trauma (UWT) in adulthood. Four weeks later, individual anxiety levels were assessed in the elevated plus maze test for classifying rats as highly anxious 'affected' vs. 'non-affected', i.e. behaving as control animals. Analyzing the activation of specific interneuron subpopulations in the dorsal and ventral dentate gyrus (DG), the basolateral (BLA) and central amygdala by immunohistochemical double-labeling for cFos and different interneuron markers, revealed an increased activation of cholecystokinin (CCK)-positive interneurons in the ventral DG, together with increased activation of parvalbumin- and CCK-positive interneurons in the BLA of affected trauma-exposed rats. By contrast, increased activation of neuropeptide Y (NPY)-positive interneurons was observed in the dorsal DG of trauma-exposed, but non-affected rats. To test for a direct contribution of NPY in the dorsal DG to trauma resilience, a local shRNA-mediated knock down was performed after UWT. Such a treatment significantly reduced the prevalence of resilient animals. Our results suggest that distinct interneuron populations are associated with resilience or pathology in PTSD with high regional specificity. NPY within the dorsal DG was found to significantly contribute to trauma resilience.

Too Much of a Good Thing: The Association of Elevated Vitamin B12 Levels and Outcomes in Patients With Cancer Treated With Immunotherapy.

Metabolic pathways may regulate responses to cancer immunotherapy (IO). Due to its immunomodulatory properties, we sought to examine the association between serum vitamin B12 (VitB12) and survival in individuals with cancer treated with immune checkpoint inhibitors, compared with biological and chemotherapy. We collected data on patients with advanced cancer initiating intravenous antineoplastic treatment and a concomitant VitB12 measurement (elevated: >820 ng/L), between January 2010 and January 2022. Patients on IO and other regimens (control) were compared using the Mann-Whitney test for continuous variables, χ 2 test or Fisher test for categorical variables, and multivariate Cox regression models assessed the effect of VitB12 on overall survival and progression-free survival, adjusting for confounders. Patient groups (control: n = 408; IO: n = 93) were balanced for the treatment line and VitB12 (elevated 29.9% vs 23.7%; mean 762.4 vs 687.6 ng/L). In multivariate analysis, overall survival in all patients was negatively associated with VitB12 [control: hazard ratio (HR): 1.4, 95% CI: 1.01-1.96, P = 0.04, false discovery rate (FDR): 0.069; IO: HR: 2.74 as sum of linear baseline and interaction effects, log scale], age (HR: 1.03, 95% CI: 1.02-1.04, P < 0.01), male sex (HR: 0.66, 95% CI: 0.50-0.88, P < 0.01), and neutrophil-to-lymphocyte ratio (HR: 1.05, 95% CI: 0.48-0.99, P = 0.01). However, VitB12 was significantly negatively associated with progression-free survival only in the IO group ( P < 0.001, FDR < 0.001, calculated HR: 8.34; biological treatment P = 0.08; FDR: 0.111; neutrophil-to-lymphocyte ratio, P = 0.07; FDR: 0.09). Taken together, elevated VitB12 was a negative predictor for outcomes on IO, independently of other known prognostic factors. Further research is needed to elucidate the immune-metabolic interplay and its interaction with the gut microbiome, as well as interventional strategies to enhance IO responses.

Hippocampal GABAergic interneurons and their co-localized neuropeptides in stress vulnerability and resilience.

Studies in humans and rodents suggest a critical role for the hippocampal formation in cognition and emotion, but also in the adaptation to stressful events. Successful stress adaptation promotes resilience, while its failure may lead to stress-induced psychopathologies such as depression and anxiety disorders. Hippocampal architecture and physiology is shaped by its strong control of activity via diverse classes of inhibitory interneurons that express typical calcium binding proteins and neuropeptides. Celltype-specific opto- and chemogenetic intervention strategies that take advantage of these biochemical markers have bolstered our understanding of the distinct role of different interneurons in anxiety, fear and stress adaptation. Moreover, some of the signature proteins of GABAergic interneurons have a potent impact on emotion and cognition on their own, making them attractive targets for interventions. In particular, neuropeptide Y is a promising endogenous agent for mediating resilience against severe stress. In this review, we evaluate the role of the major types of interneurons across hippocampal subregions in the adaptation to chronic and acute stress and to emotional memory formation.