Senolytic CAR T cells reverse aging-associated defects in intestinal regeneration and fitness.

Intestinal stem cells (ISCs) drive the rapid regeneration of the gut epithelium to maintain organismal homeostasis. Aging, however, significantly reduces intestinal regenerative capacity. While cellular senescence is a key feature of the aging process, little is known about the in vivo effects of senescent cells on intestinal fitness. Here, we identify the accumulation of senescent cells in the aging gut and, by harnessing senolytic CAR T cells to eliminate them, we uncover their detrimental impact on epithelial integrity and overall intestinal homeostasis in natural aging, injury and colitis. Ablation of intestinal senescent cells with senolytic CAR T cells in vivo or in vitro is sufficient to promote the regenerative potential of aged ISCs. This intervention improves epithelial integrity and mucosal immune function. Overall, these results highlight the ability of senolytic CAR T cells to rejuvenate the intestinal niche and demonstrate the potential of targeted cell therapies to promote tissue regeneration in aging organisms.

Sensitive, non-immunogenic in vivo imaging of cancer metastases and immunotherapy response.

Non-invasive imaging of tumors expressing reporter transgenes is a popular preclinical method for studying tumor development and response to therapy in vivo due to its ability to distinguish signal from tumors over background noise. However, the utilized transgenes, such as firefly luciferase, are immunogenic and, therefore, impact results when expressed in immune-competent hosts. This represents an important limitation, given that cancer immunology and immunotherapy are currently among the most impactful areas of research and therapeutic development. Here we present a non-immunogenic preclinical tumor imaging approach. Based on the expression of murine sodium iodide symporter (mNIS), it facilitates sensitive, non-invasive detection of syngeneic tumor cells in immune-competent tumor models without additional immunogenicity arising from exogenous transgenic protein or selection marker expression. NIS-expressing tumor cells internalize the gamma-emitting [99mTc]pertechnetate ion and so can be detected by SPECT (single photon emission computed tomography). Using a mouse model of pancreatic ductal adenocarcinoma hepatic metastases in immune-competent C57BL/6 mice, we demonstrate that the technique enables the detection of very early metastatic lesions and longitudinal assessment of immunotherapy responses using precise and quantifiable whole-body SPECT/CT imaging.

Ketogenic diet promotes tumor ferroptosis but induces relative corticosterone deficiency that accelerates cachexia.

The dependency of cancer cells on glucose can be targeted with high-fat low-carbohydrate ketogenic diet (KD). However, hepatic ketogenesis is suppressed in IL-6 producing cancers, which prevents the utilization of this nutrient source as energy for the organism. In two IL-6 associated murine models of cancer cachexia we describe delayed tumor growth but accelerated onset of cancer cachexia and shortened survival when mice are fed KD. Mechanistically, we find this uncoupling is a consequence of the biochemical interaction of two simultaneously occurring NADPH-dependent pathways. Within the tumor, increased production of lipid peroxidation products (LPPs) and, consequently, saturation of the glutathione (GSH) system leads to ferroptotic death of cancer cells. Systemically, redox imbalance and NADPH depletion impairs the biosynthesis of corticosterone, the main regulator of metabolic stress, in the adrenal glands. Administration of dexamethasone, a potent glucocorticoid, improves food intake, normalizes glucose homeostasis and utilization of nutritional substrates, delays onset of cancer cachexia and extends survival of tumor-bearing mice fed KD, while preserving reduced tumor growth. Our study highlights that the outcome of systemic interventions cannot necessarily be extrapolated from the effect on the tumor alone, but that they have to be investigated for anti-cancer and host effects. These findings may be relevant to clinical research efforts that investigate nutritional interventions such as KD in patients with cancer.

Ketogenic diet promotes tumor ferroptosis but induces relative corticosterone deficiency that accelerates cachexia.

Glucose dependency of cancer cells can be targeted with a high-fat, low-carbohydrate ketogenic diet (KD). However, in IL-6-producing cancers, suppression of the hepatic ketogenic potential hinders the utilization of KD as energy for the organism. In IL-6-associated murine models of cancer cachexia, we describe delayed tumor growth but accelerated cachexia onset and shortened survival in mice fed KD. Mechanistically, this uncoupling is a consequence of the biochemical interaction of two NADPH-dependent pathways. Within the tumor, increased lipid peroxidation and, consequently, saturation of the glutathione (GSH) system lead to the ferroptotic death of cancer cells. Systemically, redox imbalance and NADPH depletion impair corticosterone biosynthesis. Administration of dexamethasone, a potent glucocorticoid, increases food intake, normalizes glucose levels and utilization of nutritional substrates, delays cachexia onset, and extends the survival of tumor-bearing mice fed KD while preserving reduced tumor growth. Our study emphasizes the need to investigate the effects of systemic interventions on both the tumor and the host to accurately assess therapeutic potential. These findings may be relevant to clinical research efforts that investigate nutritional interventions such as KD in patients with cancer.

Neurotensin neurons in the extended amygdala control dietary choice and energy homeostasis.

Obesity is a global pandemic that is causally linked to many life-threatening diseases. Apart from some rare genetic conditions, the biological drivers of overeating and reduced activity are unclear. Here, we show that neurotensin-expressing neurons in the mouse interstitial nucleus of the posterior limb of the anterior commissure (IPAC), a nucleus of the central extended amygdala, encode dietary preference for unhealthy energy-dense foods. Optogenetic activation of IPACNts neurons promotes obesogenic behaviors, such as hedonic eating, and modulates food preference. Conversely, acute inhibition of IPACNts neurons reduces feeding and decreases hedonic eating. Chronic inactivation of IPACNts neurons recapitulates these effects, reduces preference for sweet, non-caloric tastants and, furthermore, enhances locomotion and energy expenditure; as a result, mice display long-term weight loss and improved metabolic health and are protected from obesity. Thus, the activity of a single neuronal population bidirectionally regulates energy homeostasis. Our findings could lead to new therapeutic strategies to prevent and treat obesity.