Bidirectional crosstalk between the peripheral nervous system and lymphoid tissues/organs

Investigating the effect of neuro-immune communication on immune responses in health and disease: Exploring immunological disorders

Recent recognition of the intricate nervous-immune system interplay has prompted research into the specific cellular components involved in these interactions. Emerging evidence suggests that immune and neural cells collaborate within distinct units and act in concert to regulate tissue function and provide protection. These specialized neuro-immune cell units have been identified in diverse body tissues, ranging from lymphoid organs to the bone marrow and mucosal barriers. Their significance has become increasingly apparent as they are recognized as pivotal regulators influencing a broad spectrum of physiological and pathological processes. This recognition extends to critical roles in hematopoiesis, organ function, inflammatory responses, and intricate tissue repair processes. This review explores the bidirectional communication between the nervous and immune systems. The focus is on understanding the profound impact of this communication on immune cells within key anatomical sites, such as the bone marrow, gastrointestinal tract, and lymphoid organs. By examining these interactions, this review aims to shed light on how this intricate network operates under normal and pathological conditions, offering insights into the mechanisms underlying health and disease.

Peripheral CD4+ T cells mediate the destructive effects of maternal separation on prefrontal myelination and cognitive functions

Maternal separation (MS), a chronic stress event in early life, impairs myelination in the prefrontal cortex (PFC) and leads to PFC cognitive disorders. It remains largely unclear how such deficits are mediated. Here, we show that peripheral CD4+ T cells play an essential role in mediating the destructive effects of MS on medial prefrontal cortical (mPFC) myelination and cognitive functions in mice. Offspring mice with MS experience (MS mice) exhibited an increase in CD4+ T cells and xanthine levels in peripheral blood and a severe deficit in mPFC-dependent cognitive functions such as working memory, social interaction, and anxiety/depression emotion regulation, along with a decrease in oligodendrocyte precursor cells (OPCs) and oligodendrocytes (OLs) in the mPFC. These phenotypes were rescued upon treatment with the antibody neutralizing peripheral CD4+ T cells. Rag1-/- immunodeficient mice receiving transplantation of CD4+ T cells isolated from the peripheral blood of MS mice showed similar phenotypes as observed in MS mice. Immunofluorescence staining revealed a rich expression of adenosine receptor A1 (A1) in OPCs in the mPFC, and the A1-expressing OPCs decreased in the Rag1-/- mice receiving CD4+ T cell transplantation. The present study demonstrates a causal link between peripheral CD4+ T cells and MS-induced prefrontal cortical hypomyelination and cognitive dysfunction, and such a link is probably mediated via xanthine-adenosine receptor A1 signaling in OPCs.

Unraveling the peripheral nervous System's role in tumor: A Double-edged Sword

The peripheral nervous system (PNS) includes all nerves outside the brain and spinal cord, comprising various cells like neurons and glial cells, such as schwann and satellite cells. The PNS is increasingly recognized for its bidirectional interactions with tumors, exhibiting both pro- and anti-tumor effects. Our review delves into the complex mechanisms underlying these interactions, highlighting recent findings that challenge the conventional understanding of PNS's role in tumorigenesis. We emphasize the contradictory results in the literature and propose novel perspectives on how these discrepancies can be resolved. By focusing on the PNS's influence on tumor initiation, progression, and microenvironment remodeling, we provide a comprehensive analysis that goes beyond the structural description of the PNS. Our review suggests that a deeper comprehension of the PNS-tumor crosstalk is pivotal for developing targeted anticancer strategies. We conclude by emphasizing the need for future research to unravel the intricate dynamics of the PNS in cancer, which may lead to innovative diagnostic tools and therapeutic approaches.

The impact of COVID-19 on accelerating of immunosenescence and brain aging

The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2, has profoundly impacted global health, affecting not only the immediate morbidity and mortality rates but also long-term health outcomes across various populations. Although the acute effects of COVID-19 on the respiratory system have initially been the primary focus, it is increasingly evident that the virus can have significant impacts on multiple physiological systems, including the nervous and immune systems. The pandemic has highlighted the complex interplay between viral infection, immune aging, and brain health, that can potentially accelerate neuroimmune aging and contribute to the persistence of long COVID conditions. By inducing chronic inflammation, immunosenescence, and neuroinflammation, COVID-19 may exacerbate the processes of neuroimmune aging, leading to increased risks of cognitive decline, neurodegenerative diseases, and impaired immune function. Key factors include chronic immune dysregulation, oxidative stress, neuroinflammation, and the disruption of cellular processes. These overlapping mechanisms between aging and COVID-19 illustrate how the virus can induce and accelerate aging-related processes, leading to an increased risk of neurodegenerative diseases and other age-related conditions. This mini-review examines key features and possible mechanisms of COVID-19-induced neuroimmune aging that may contribute to the persistence and severity of long COVID. Understanding these interactions is crucial for developing effective interventions. Anti-inflammatory therapies, neuroprotective agents, immunomodulatory treatments, and lifestyle interventions all hold potential for mitigating the long-term effects of the virus. By addressing these challenges, we can improve health outcomes and quality of life for millions affected by the pandemic.

Aging brain: exploring the interplay between bone marrow aging, immunosenescence, and neuroinflammation

Aging is a complex process characterized by a myriad of physiological changes, including alterations in the immune system termed immunosenescence. It exerts profound effects on both the bone marrow and the central nervous system, with significant implications for immunosenescence in neurological contexts. Our mini-review explores the complex relationship between bone marrow aging and its impact on immunosenescence, specifically within the context of neurological diseases. The bone marrow serves as a crucial hub for hematopoiesis and immune cell production, yet with age, it undergoes significant alterations, including alterations in hematopoietic stem cell function, niche composition, and inflammatory signaling. These age-related shifts in the bone marrow microenvironment contribute to dysregulation of immune cell homeostasis and function, impacting neuroinflammatory processes and neuronal health. In our review, we aim to explore the complex cellular and molecular mechanisms that link bone marrow aging to immunosenescence, inflammaging, and neuroinflammation, with a specific focus on their relevance to the pathophysiology of age-related neurological disorders. By exploring this interplay, we strive to provide a comprehensive understanding of how bone marrow aging impacts immune function and contributes to the progression of neurological diseases in aging individuals. Ultimately, this knowledge can hold substantial promise for the development of innovative therapeutic interventions aimed at preserving immune function and mitigating the progression of neurological disorders in the elderly population.

Innate and adaptive immune system consequences of post-traumatic stress disorder

In the field of psychiatry, biological markers are rarely, if ever, used in the diagnosis of mental health disorders. Clinicians rely primarily on patient histories and behavioral symptoms to identify specific psychopathologies, which makes diagnosis highly subjective. Moreover, therapies for mental health disorders are aimed specifically at attenuating behavioral manifestations, which overlooks the pathophysiological indices of the disease. This is highly evident in posttraumatic stress disorder (PTSD) where inflammation and immune system perturbations are becoming increasingly described. Further, patients with PTSD possess significantly elevated risks of developing comorbid inflammatory diseases such as autoimmune and cardiovascular diseases, which are likely linked (though not fully proven) to the apparent dysregulation of the immune system after psychological trauma. To date, there is little to no evidence that demonstrates current PTSD therapies are able to reverse the increased risk for psychological trauma-induced inflammatory diseases, which suggests the behavioral and somatic consequences of PTSD may not be tightly coupled. This observation provides an opportunity to explore unique mechanisms outside of the brain that contribute to the long-term pathology of PTSD. Herein, we provide an overview of neuroimmune mechanisms, describe what is known regarding innate and adaptive immunity in PTSD, and suggest new directions that are needed to advance the understanding, diagnosis, and treatment of PTSD moving forward.

Cutaneous-immuno-neuro-endocrine (CINE) system: A complex enterprise transforming skin into a super organ

Skin is now emerging as a complex realm of three chief systems viz. immune system, nervous system, and endocrine system. The cells involved in their intricate crosstalk, namely native skin cells, intra-cutaneous immune cells and cutaneous sensory neurons have diverse origin and distinct functions. However, recent studies have explored their role beyond their pre-defined functional boundaries, such that the cells shun their traditional functions and adopt unconventional roles. For example, the native skin cells, apart from providing for basic structural framework of skin, also perform special immune functions and participate in extensive neuro-endocrine circuitry, which were traditionally designated as functions of cutaneous resident immune cells and sensory neurons respectively. At the cellular level, this unique collaboration is brought out by special molecules called neuromediators including neurotransmitters, neuropeptides, neurotrophins, neurohormones and cytokines/chemokines. While this intricate crosstalk is essential for maintaining cutaneous homeostasis, its disruption is seen in various cutaneous diseases. Recent study models have led to a paradigm shift in our understanding of pathophysiology of many such disorders. In this review, we have described in detail the interaction of immune cells with neurons and native skin cells, role of neuromediators, the endocrine aspect in skin and current understanding of cutaneous neuro-immuno-endocrine loop in one of the commonest skin diseases, psoriasis. An accurate knowledge of this unique crosstalk can prove crucial in understanding the pathophysiology of different skin diseases and allow for generation of targeted therapeutic modalities.

Transcriptomic Profiling of Influenza A Virus-Infected Mouse Lung at Recovery Stage Using RNA Sequencing

Influenza A virus (IAV) is known to cause mild to severe respiratory illness. Under some conditions, the infection can lead to pneumonia (viral or bacterial), acute respiratory distress syndrome, and other complications that can be fatal, especially in vulnerable populations such as the elderly, young children, and individuals with underlying health conditions. Despite previous studies, little is known about the host immune response and neuroimmune interactions in IAV infection. Using RNA sequencing, we performed transcriptomic analysis of murine lung tissue 21 days post infection (dpi) with IAV (H1N1) in order to find the differentially expression genes (DEGs) related to the host immune response and neuroimmune interactions inside the lung during recovery. Among 792 DEGs, 434 genes were up-regulated, whereas 358 genes were down-regulated. The most prominent molecular functions of the up-regulated genes were related to the immune response and tissue repair, whereas a large proportion of the down-regulated genes were associated with neural functions. Although further molecular/functional studies need to be performed for these DEGs, our results facilitate the understanding of the host response (from innate immunity to adaptive immunity) and neuroimmune interactions in infected lungs at the recovery stage of IAV infection. These genes might have potential uses as mechanistic/diagnostic biomarkers and represent possible targets for anti-IAV therapies.