Abstract
​
For 80 years there has been a link between autism and immune activation.

Studies point to dysfunction in immune responses in peripheral blood, gut mucosa, and brain.

Human postmortem brain studies in autism show increased differential expression of inflammatory immune genes, increased pro-inflammatory cytokine levels, and glial activation.

Immune cells in the brain are comprised of both tissue-resident cells and those recruited from the blood.

This includes regulatory T cells (Tregs) that foster immune tolerance and tissue repair.

Tregs reduce microglial reactivity, assist in regenerative and reparative processes, and promote differentiation of myelin-producing oligodendrocytes in the brain, thus modulating white matter development.

Neuroinflammation may be a universal autism phenotype independent of the underlying etiology that can be controlled by Tregs promoting homeostasis, microglia and oligodendrocyte function, and white matter development.

​Background:  Post-traumatic stress disorder (PTSD) is a debilitating psychological disorder that also presents with neuroimmune irregularities.

Patients display elevated sympathetic tone and are at an increased risk of developing secondary autoimmune diseases.

​Conclusions: Our data depict a novel role for β1/2 adrenergic and cAMP signaling in the balance of TH17/Treg lymphocytes.

​These findings provide a new target for pharmacological therapy in both psychiatric and autoimmune diseases associated with IL-17A-related pathology.

Abstract

Recent research has shed light on the intricate relationship between mood disorders, such as major depressive disorder (MDD) and bipolar disorder (BD), and inflammation.

This chapter explores the complex interplay involving immune and metabolic dysfunction in the pathophysiology of these disorders, emphasizing their association with:
* autoimmunity/inflammatory conditions,
* chronic low-grade systemic inflammation,
*T cell overactivation, and
*immunosenescence [the Aging  of the Immune System]

This perspective underscores the notion that MDD [Major Depressive Disorder]and BD [Bipolar Disorder] are not solely brain disorders, highlighting their nature as multi-system conditions.

​Immune abnormalities including an insufficiency of regulatory T cells (Treg) and increased blood-based inflammatory markers have been observed in bipolar disorders (BD), particularly during depression.

​As Tregs are pivotal to control inflammation, Treg stimulation by low-dose IL-2 (IL-2LD) could have a therapeutic impact on bipolar depression.

​Conclusions: These hypothesis-generating findings highlight T cell dysfunction in AGA+ positive SRD  [Schizophrenia Related Disorders], suggesting Tregs protecting against negative symptom severity but also an unidentified other T cell population to possibly be driving negative symptom severity.

​Strong causal relationships existed between immune cells, circulating inflammatory factors, and NDDs. Inflammatory factors mediated the pathways between immune cells and NDDs [Neurodevelopmental Disorders].

​A case study of a 9-year-old girl diagnosed with seronegative autoimmune encephalitis, who displayed severe obsessive-compulsive disorder (OCD) and aggressive behavior, exemplifies the complexities involved in treatment.

Promising interventions, including CAR-T-cell therapy and nanomedicine, are under development for various autoimmune diseases, such as vitiligo and refractory autoimmune rheumatic diseases (ARDs).

​Furthermore, emerging therapies, including CAR-T-cell therapy, mRNA-based strategies, and microbiome modulation, are being explored alongside advancements in personalized medicine and early diagnostic techniques to improve patient outcomes for individuals affected by autoimmune diseases.

​Since most brain diseases are either incurable or irreversible, they place a considerable burden on both society and the economy, highlighting the essential role of primary prevention in preserving brain health (Lazar et al., 2021).

​Modifiable lifestyle factors—behaviors that can be changed without professional intervention, such as smoking, alcohol consumption, and physical activity—are important targets for these prevention efforts.

​Our results demonstrate that changes in repetitive-like and social behaviors that are induced by MIA [Maternal Immune Activation] in male mice are not exacerbated by subsequent inflammatory challenge and highlights the importance of considering the timing of stressors in the appearance of developmental pathology.

Highlights

• 
  Maternal immune activation (MIA) may act as a disease primer for neurodevelopmental pathology.
• 
  Here we investigated if MIA synergized with postnatal inflammation to exacerbate pathology.
• 
  MIA decreases sociability and increases repetitive-like behaviors in males.
• 
  CD8 + T cells are impacted by MIA in a sex-dependent manner.
• 
  Postnatal immune inflammation did not exacerbate ASD-like pathology in either sex.

​Given the contribution of neuroimmune mechanisms to pain chronicity and mood disorders, we further conducted an in-depth investigation into the role of neuroimmune factors, including resident immune cells, infiltrating immune cells, and the release of inflammatory mediators.

This review further discusses current therapeutic strategies, encompassing pharmacological interventions, neuromodulation, and integrative approaches, and emphasizes the necessity of targeted treatments that address both pain and emotional components.

​Finally, it identifies gaps in the current understanding and outlines future research directions aimed at elucidating the complex interplay between chronic pain and emotional disorders, thereby laying the foundation for more effective and holistic treatment paradigms.

​Highlights

• Provided evidence for the causal association between mitochondrial function and psychiatric disorders.​


• Performed analyses utilizing multiple large-scale genome-wide association study databases.


• Offered novel insights into the pathogenesis and therapeutic strategies for psychiatric disorders.


• Emphasized the potential of genomics research.