Aging and CNS Myeloid Cell Depletion Attenuate Breast Cancer Brain Metastasis

PURPOSE

Breast cancer diagnosed in young patients is often aggressive. Because primary breast tumors from young and older patients have similar mutational patterns, we hypothesized that the young host microenvironment promotes more aggressive metastatic disease.

EXPERIMENTAL DESIGN

Triple-negative or luminal B breast cancer cell lines were injected into young and older mice side-by-side to quantify lung, liver, and brain metastases. Young and older mouse brains, metastatic and naïve, were analyzed by flow cytometry. Immune populations were depleted using antibodies or a colony-stimulating factor-1 receptor (CSF-1R) inhibitor, and brain metastasis assays were conducted. Effects on myeloid populations, astrogliosis, and the neuroinflammatory response were determined.

RESULTS

Brain metastases were 2- to 4-fold higher in young as compared with older mouse hosts in four models of triple-negative or luminal B breast cancer; no age effect was observed on liver or lung metastases. Aged brains, naïve or metastatic, contained fewer resident CNS myeloid cells. Use of a CSF-1R inhibitor to deplete myeloid cells, including both microglia and infiltrating macrophages, preferentially reduced brain metastasis burden in young mice. Downstream effects of CSF-1R inhibition in young mice resembled that of an aged brain in terms of myeloid numbers, induction of astrogliosis, and Semaphorin 3A secretion within the neuroinflammatory response.

CONCLUSIONS

Host microenvironmental factors contribute to the aggressiveness of triple-negative and luminal B breast cancer brain metastasis. CSF-1R inhibitors may hold promise for young brain metastasis patients.

Trauma and Adult Attention Deficit Hyperactivity Disorder

This study investigated the relationship between adult attention deficit hyperactivity disorder (ADHD) and trauma. Fifty-eight adults admitted to hospital with musculoskeletal trauma were evaluated using scales that determine the presence of ADHD in childhood and adulthood. Each patient was also interviewed by an adult psychiatrist and a child and adolescent psychiatrist. The control group consisted of 30 adult patients with complaints other than trauma who did not have a history of repetitive traumas. There were 36 (62.2%) cases of ADHD in the patient group compared with four (13.3%) in the control group; this difference was statistically significant. When the level of trauma was evaluated, ADHD was identified in 23 of the 26 (88.5%) patients with high energy traumas compared with 14 of the 32 (43.8%) patients with low energy traumas; this difference was also statistically significant. This study shows that patients with adult ADHD are more prone to injuries, particularly high energy traumas such as motor vehicle accidents. Patients who have repeated high energy traumas should be evaluated by a psychiatrist for ADHD.

Clozapine-induced myoclonic seizures and valproic acid

Within a 3-year period, in 220 patients receiving clozapine, we observed myoclonic seizures in two who had no previous epileptic history. Seizures appeared at the titration phase at relatively low doses, and resolved with the addition of valproic acid, allowing further increases of the clozapine dose to therapeutic levels.