Effects of interleukin-2 on the expression of corticotropin-releasing hormone in nerves and lymphoid cells in secondary lymphoid organs from the Fischer 344 rat

Right Cervical Vagotomy Aggravates Viral Myocarditis in Mice Via the Cholinergic Anti-inflammatory Pathway

The autonomic nervous system dysfunction with increased sympathetic activity and withdrawal of vagal activity may play an important role in the pathogenesis of viral myocarditis. The vagus nerve can modulate the immune response and control inflammation through a ‘cholinergic anti-inflammatory pathway’ dependent on the α7-nicotinic acetylcholine receptor (α7nAChR). Although the role of β-adrenergic stimulation on viral myocarditis has been investigated in our pervious studies, the direct effect of vagal tone in this setting has not been yet studied. Therefore, in the present study, we investigated the effects of cervical vagotomy in a murine model of viral myocarditis. In a coxsackievirus B3 murine myocarditis model (Balb/c), effects of right cervical vagotomy and nAChR agonist nicotine on echocardiography, myocardial histopathology, viral RNA, and proinflammatory cytokine levels were studied. We found that right cervical vagotomy inhibited the cholinergic anti-inflammatory pathway, aggravated myocardial lesions, up-regulated the expression of TNF-α, IL-1β, and IL-6, and worsened the impaired left ventricular function in murine viral myocarditis, and these changes were reversed by co-treatment with nicotine by activating the cholinergic anti-inflammatory pathway. These results indicate that vagal nerve plays an important role in mediating the anti-inflammatory effect in viral myocarditis, and that cholinergic stimulation with nicotine also plays its peripheral anti-inflammatory role relying on α7nAChR, without requirement for the integrity of vagal nerve in the model. The findings suggest that vagus nerve stimulation mediated inhibition of the inflammatory processes likely provide important benefits in myocarditis treatment.

Stress induced neuroendocrine-immune plasticity: A role for the spleen in peripheral inflammatory disease and inflammaging?

Research over the past decade has revealed close interaction between the nervous and immune systems in regulation of peripheral inflammation linking psychosocial stress with chronic somatic disease and aging. Moreover emerging data suggests that chronic inflammations lead to a pro-inflammatory status underlying premature aging called inflammaging. In this context, the spleen can be seen as a switch board monitoring peripherally derived neuroendocrine-immune mediators in the blood and keeping up a close communication with the central stress response via its mainly sympathetic innervation. The effect aims at balanced and well-timed stress axis activation and immune adaptation in acute peripheral inflammatory events. Constant adjustment to the needs generated by environmental and endogenous challenges is provided by neuroendocrine-immune plasticity. However, maladaptive plasticity induced e.g., by chronic stress-axis activation and excessive non-neuronal derived neuroendocrine mediators may be at the heart of the observed stress sensitivity promote inflammaging under chronic inflammatory conditions. We here review the role of neurotransmitters, neuropeptides and neurotrophins as stress mediators modulating the immune response in the spleen and their potential role in inflammaging.

Stress-related modulation of inflammation in experimental models of bowel disease and post-infectious irritable bowel syndrome: role of corticotropin-releasing factor receptors

The interaction between gut inflammatory processes and stress is gaining increasing recognition. Corticotropin-releasing factor (CRF)-receptor activation in the brain is well established as a key signaling pathway initiating the various components of the stress response including in the viscera. In addition, a local CRF signaling system has been recently established in the gut. This review summarize the present knowledge on mechanisms through which both brain and gut CRF receptors modulate intestinal inflammatory processes and its relevance towards increased inflammatory bowel disease (IBD) activity and post-infectious irritable bowel syndrome (IBS) susceptibility induced by stress.

Neuropeptides as signal molecules in common with leukocytes and the hypothalamic-pituitary-adrenal axis

There exists a bidirectional regulatory circuit between the nervous and immune systems. This regulation has been shown to be mediated in part through neuroendocrine hormones and cytokines. Both systems have receptors for both types of signal molecules. The nervous system has receptors for cytokines and it also synthesizes cytokines. The immune system synthesizes and responds to cytokines. So, it is not too far-fetched to believe that neuroendocrine peptide hormones could bind to leukocytes and modulate immune functions. However, it is not widely known that the immune system also synthesizes functional, neuropeptide hormones. This will be discussed in this paper citing a plethora of evidence. The aim of this paper is to summarize this evidence by using three neuropeptides that are synthesized by leukocytes and modulate immune functions as examples; corticotropin (ACTH), endorphin (END), and corticotropin releasing factor (CRF). The production and action of these three neuropeptides in the immune system will be explained. Finally, the potential physiological role of leukocyte-derived ACTH, END, and CRF in inflammation as a localized hypothalamic-pituitary-like axis is discussed.

Corticotropin Releasing Factor (CRF) activation of NF-kappaB-directed transcription in leukocytes

1. The aim of this study was to test whether CRF enhanced nuclear factor kappa B (NF-kappaB)-directed gene transcription in leukocytes and the receptor specificity of the effect. Initially, we examined the ability of CRF to modulate an antigen-specific, in vitro antibody response. Since that could be mediated by NF-kappaB transcription factor activity, we tested CRF in a NF-kappaB driven luciferase gene expression reporter assay. 2. CRF enhanced the antigen-specific antibody production in a dose- and time-dependent manner. RAW 264.7 macrophage cells and splenocytes stained by immunohistochemistry were positive for CRF receptors and CRF. Expression of both was up-regulated by mitogen treatment of the splenocytes. CRF also enhanced the NF-kappaB-regulated reporter assay and this could be blocked by a CRF-R1 receptor antagonist. 3. In light of these findings, it seems likely that CRF enhanced the antigen-specific antibody response through the CRF-R1 receptor by elevation of NF-kappaB activity. This study provides further support for the concept that CRF can act as an immunomodulator mediating neuro-immune interactions.

Neuropeptide neurotensin stimulates intestinal wound healing following chronic intestinal inflammation

Because neurotensin (NT) and its high-affinity receptor (NTR1) modulate immune responses, chloride secretion, and epithelial cell proliferation, we sought to investigate their role in the repair process that follows the development of mucosal injuries during a persistent inflammation. Colonic NT and NTR1, mRNA, and protein significantly increased only after dextran sodium sulfate (DSS)-induced inflammatory damage developed. Colitis-induced body weight loss, colonic myeloperoxidase activity, and histological damage were significantly enhanced by SR-48642 administration, a nonpeptide NTR1 antagonist, whereas continuous NT infusion ameliorated colitis outcome. To evaluate the NT and NTR1 role in tissue healing, mucosal inflammatory injury was established administering 3% DSS for 5 days. After DSS discontinuation, mice rapidly gained weight, ulcers were healed, and colonic NT, NTR1, and cyclooxygenase (COX)-2 mRNA levels were upregulated, whereas SR-48642 treatment caused a further body weight loss, ulcer enlargement, and a blunted colonic COX-2 mRNA upregulation. In a wound-healing model in vitro, NT-induced cell migration in the denuded area was inhibited by indomethacin but not by an antitransforming growth factor-beta neutralizing antibody. Furthermore, NT significantly increased COX-2 mRNA levels by 2.4-fold and stimulated PGE(2) release in HT-29 cells. These findings suggest that NT and NTR1 are part of the network activated after mucosal injuries and that NT stimulates epithelial restitution at least, in part, through a COX-2 dependent pathway.

Nonpeptide corticotropin-releasing hormone receptor type 1 antagonists and their applications in psychosomatic disorders

Overproduction of corticotropin-releasing hormone (CRH) and stress system abnormalities are seen in psychiatric diseases such as depression, anxiety, eating disorders, and addiction. Investigations of CRH type 1 receptor (CRHR1) nonpeptide antagonists suggest therapeutic potential for treatment of these and other neuropsychiatric diseases. However, overproduction of CRH in the brain and on its periphery and disruption of the hypothalamic-pituitary-adrenal axis are also found in 'somatic' disorders. Some rare forms of Cushing's disease and related pituitary/adrenal disorders are obvious applications for CRHR1 antagonists. In addition, however, these antagonists may also be effective in treating more common somatic diseases. Patients with obesity and metabolic syndrome who often have subtle, but chronic hypothalamic-pituitary-adrenal hyperactivity, which may reflect central dysregulation of CRH and consequently glucocorticoid hypersecretion, could possibly be treated by administration of CRHR1 antagonists. Hormonal, autonomic, and immune aberrations are also present in chronic inflammatory, autoimmune, and allergic diseases, with considerable evidence linking CRH with the observed abnormalities. Furthermore, autonomic dysregulation is a prominent feature of common gastrointestinal disorders, such as irritable bowel syndrome and peptic ulcer disease. Patients with irritable bowel syndrome and other gastrointestinal disorders frequently develop altered pain perception and affective symptoms. CRH acts peripherally to modulate bowel activity both directly through the autonomic system and centrally by processing viscerosensory and visceromotor neural signals. This review presents clinical and preclinical evidence for the role of CRH in the pathophysiology of these disorders and for potential diagnostic and therapeutic applications of CRHR1 antagonists. Recognition of a dysfunctional stress system in these and other diseases will alter the understanding and treatment of 'psychosomatic' disorders.

Propagation of lewis rat encephalitogenic T cell lines: T-cell-growth-factor is superior to recombinant IL-2

This study was designed to test the process of selecting encephalitogenic T cell lines in the Lewis rat using recombinant human IL-2 (rhIL-2) in comparison to TCGF. The lines were tested for growth, antigen induced proliferation, cytokine production, V-beta 8.2 expression and pathogenicity. We now report that rhIL-2 and TCGF were equally effective in supporting short-term pathogenic T-cell lines with similar proportion of V-beta 8.2 usage. For the maintenance of long term lines, however, TCGF was superior to IL-2. The concentration of rhIL-2 influenced the cultures: 10 units/ml led to more T-cell proliferation than either 2 or 50 units/ml. However, 50 units/ml of IL-2 led to enhanced Th1 polarization. Thus, the type and concentration of growth factors can influence both the propagation of T cells and their phenotype.