A comprehensive guide for the care and use of laboratory animals

Our body has a remarkable ability to remember its past encounters with allergens, pathogens, wounds and irritants, and to react more quickly to the next experience. This accentuated sensitivity also helps us to cope with new threats. Despite maintaining a state of readiness and broadened resistance to subsequent pathogens, memories can also be maladaptive, leading to chronic inflammatory disorders and cancers. With the ever-increasing emergence of new pathogens, allergens and pollutants in our world, the urgency to unravel the molecular underpinnings of these phenomena has risen to new heights. Here we reflect on how the field of inflammatory memory has evolved, since 2007, when researchers realized that non-specific memory is contained in the nucleus and propagated at the epigenetic level. We review the flurry of recent discoveries revealing that memory is not just a privilege of the immune system but also extends to epithelia of the skin, lung, intestine and pancreas, and to neurons. Although still unfolding, epigenetic memories of inflammation have now been linked to possible brain disorders such as Alzheimer disease, and to an elevated risk of cancer. In this Review, we consider the consequences—good and bad—of these epigenetic memories and their implications for human health and disease. A Review on inflammatory memory in non-immune cells of different epithelia and neurons, and the potential mechanisms controlling these epigenetic memories and their implications in human health and disease. 

Inflammatory memory and tissue adaptation in sickness and in health

http://www.cell.com/article/S107476132200139X/pdf

Nonresolving inflammation redux

Objectives To assess the diagnosis of somatic symptom disorder (SSD) in patients with unexplained neurological symptoms occurring after SARS-CoV-2 infection, also referred to as long COVID. Design Single-centre observational study. Participants Adult patients experiencing unexplained long-lasting neurological symptoms after mild COVID. Of the 58 consecutive patients referred in our centre, 50 were included. Intervention Patients were contacted for a standardised psychometric evaluation by phone, followed by a self-survey. Main outcome Positive diagnosis of SSD according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5). Results Although the patients did not meet the DSM-5 criteria for a functional neurological symptom disorder specifically, SSD diagnosis based on DSM-5 criteria was positive in 32 (64%) patients. In the remaining 18 patients, SSD was considered possible given the high score on diagnostic scales. Physical examination were normal for all. Brain MRI showed unspecific minor white matter hyperintensities in 8/46 patients. Neuropsychological assessment showed exclusively mild impairment of attention in 14 out of 15 tested patients, in discrepancy with their major subjective complaint. Forty-five (90%) patients met criteria for Chronic Fatigue Syndrome. Seventeen (32%) patients were screened positive for mood-anxiety disorders, 19 (38%) had a history of prior SSD and 27 (54%) reported past trauma. Additional self-survey highlighted post-traumatic stress disorder in 12/43 (28%), high levels of alexithymia traits and perfectionism. Long-lasting symptoms had a major impact with a high rate of insomnia (29/43, 67%), psychiatric follow-up (28/50, 56%) and work or pay loss (25/50, 50%). Conclusion A majority of patients with unexplained long-lasting neurological symptoms after mild COVID met diagnostic criteria for SSD and may require specific management. Trial registration number NCT04889313.

https://jnnp.bmj.com/content/jnnp/93/11/1174.full.pdf

Somatic symptom disorder in patients with post-COVID-19 neurological symptoms: a preliminary report from the somatic study (Somatic Symptom Disorder Triggered by COVID-19)

Brain borders at the central stage of neuroimmunology.

Insular cortex neurons encode and retrieve specific immune responses

Increasing evidence indicates that the brain regulates peripheral immunity. Yet, it remains unclear whether and how the brain represents the state of the immune system. Here, we show that immune-related information is stored in the brain9s insular cortex (InsCtx). Using activity-dependent cell labeling in mice (FosTRAP), we captured neuronal ensembles in the InsCtx that were active under two different inflammatory conditions (DSS-induced colitis and Zymosan-induced peritonitis). Chemogenetic reactivation of these neuronal ensembles was sufficient to broadly retrieve the inflammatory state under which these neurons were captured. Thus, we show that the brain can encode and initiate specific immune responses, extending the classical concept of immunological memory to neuronal representations of immunity.

https://biorxiv.org/content/10.1101/2020.12.03.409813v1.full.pdf

Mariam Amer

Papers

Insular cortex neurons encode and retrieve specific immune responses

Remembering immunity: Neuronal ensembles in the insular cortex encode and retrieve specific immune responses