Functional Brain Imaging Reveals Rapid Blockade of Abdominal Pain Response Upon Anti-TNF Therapy in Crohn's Disease

Abdominal Pain in Inflammatory Bowel Disease-Epidemiology, Pathophysiology, and Management: A Narrative Review

Abdominal pain is a major symptom of inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, and has a significant impact on patients' quality of life. Given the evolving understanding of IBD pathology and management strategies, there is an urgent need to review the recent research findings. In this review, we have analyzed the epidemiology, pathophysiology, and management of abdominal pain in IBD over the past decade. We draw on the current literature and highlight emerging trends, challenges, and advances in this field. By synthesizing key findings, this review provides insights into the complex interplay between abdominal pain, disease progression, and therapeutic interventions for IBD.

Reversing the Inflammatory Process-25 Years of Tumor Necrosis Factor-α Inhibitors

Immune-mediated inflammatory diseases, such as rheumatoid arthritis, psoriatic arthritis, peripheral and/or axial spondyloarthritis, Crohn's disease, and ulcerative colitis, are characterized by molecular and cellular changes in the immune system. Due to the systemic nature of these diseases, organs such as the liver or cardiovascular system are often affected by the inflammatory process. Tumor necrosis factor-α inhibitor therapy reduces the activation of pro-inflammatory signaling cascades, mitigates the chronic inflammatory process by restoring cellular balance, and alleviates clinical consequences, such as pain and tissue damage.

Special Focus on the Cellular Anti-Inflammatory Effects of Several Micro-Immunotherapy Formulations: Considerations Regarding Intestinal-, Immune-Axis-Related- and Neuronal-Inflammation Contexts

INTRODUCTION

Chronic inflammation is a pernicious underlying status, well-known for its contribution to the progressive development of various diseases. In this regard, Micro-immunotherapy (MI) might be a promising therapeutic strategy. MI employs low doses (LD) and ultra-low doses (ULD) of immune regulators in their formulations. In particular, as both IL-1β and TNF-α are often used at ULD in MI medicines (MIM), a special emphasis has been made on formulations that include these factors in their compositions.

METHODS

Several in vitro models have been employed in order to assess the effects of two unitary MIM consisting of ULD of IL-1β and TNF-α (u-MIM-1 and u-MIM-2, respectively), and four complex MIM (c-MIM-1, -2, -3 and -4) characterized by the presence of ULD of IL-1β and TNF-α amongst other factors. Thus, we first investigated the anti-inflammatory effects of u-MIM-1 and u-MIM-2 in a model of inflamed colon carcinoma cells. In addition, the anti-inflammatory potential of c-MIM-1, -2, -3 and -4, was assessed in in vitro models of intestinal and neuronal inflammation.

RESULTS

The results revealed that u-MIM-1 and u-MIM-2 both induced a slight decrease in the levels of IL-1β and TNF-α transcripts. Regarding the c-MIMs' effects, c-MIM-1 displayed the capability to restore the altered transepithelial electrical resistance in inflamed-HCoEpiC cells. Moreover, c-MIM-1 also slightly increased the expression of the junction-related protein claudin-1, both at the mRNA and protein levels. In addition, our in vitro investigations on c-MIM-2 and c-MIM-3 revealed their immune-modulatory effects in LPS-inflamed human monocytes, macrophages, and granulocytes, on the secretion of cytokines such as TNF-α, PGE2, and IL-6. Finally, c-MIM-4 restored the cell viability of LPS/IFN-γ-inflamed rat cortical neurons, while reducing the secretion of TNF-α in rat glial cells.

DISCUSSION

Our results shed the light on the potential role of these MIM formulations in managing several chronic inflammation-related conditions.

The Gut-Immune-Brain Axis: An Important Route for Neuropsychiatric Morbidity in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) comprises Crohn's disease (CD) and ulcerative colitis (UC) and is associated with neuropsychiatric symptoms like anxiety and depression. Both conditions strongly worsen IBD disease burden. In the present review, we summarize the current understanding of the pathogenesis of depression and anxiety in IBD. We present a stepwise cascade along a gut-immune-brain axis initiated by evasion of chronic intestinal inflammation to pass the epithelial and vascular barrier in the gut and cause systemic inflammation. We then summarize different anatomical transmission routes of gut-derived peripheral inflammation into the central nervous system (CNS) and highlight the current knowledge on neuroinflammatory changes in the CNS of preclinical IBD mouse models with a focus on microglia, the brain-resident macrophages. Subsequently, we discuss how neuroinflammation in IBD can alter neuronal circuitry to trigger symptoms like depression and anxiety. Finally, the role of intestinal microbiota in the gut-immune-brain axis in IBD will be reviewed. A more comprehensive understanding of the interaction between the gastrointestinal tract, the immune system and the CNS accounting for the similarities and differences between UC and CD will pave the path for improved prediction and treatment of neuropsychiatric comorbidities in IBD and other inflammatory diseases.

The Gut-Brain Axis in Inflammatory Bowel Disease-Current and Future Perspectives

The gut–brain axis is a bidirectional communication system driven by neural, hormonal, metabolic, immunological, and microbial signals. Signaling events from the gut can modulate brain function and recent evidence suggests that the gut–brain axis may play a pivotal role in linking gastrointestinal and neurological diseases. Accordingly, accumulating evidence has suggested a link between inflammatory bowel diseases (IBDs) and neurodegenerative, as well as neuroinflammatory diseases. In this context, clinical, epidemiological and experimental data have demonstrated that IBD predisposes a person to pathologies of the central nervous system (CNS). Likewise, a number of neurological disorders are associated with changes in the intestinal environment, which are indicative for disease-mediated gut–brain inter-organ communication. Although this axis was identified more than 20 years ago, the sequence of events and underlying molecular mechanisms are poorly defined. The emergence of precision medicine has uncovered the need to take into account non-intestinal symptoms in the context of IBD that could offer the opportunity to tailor therapies to individual patients. The aim of this review is to highlight recent findings supporting the clinical and biological link between the gut and brain, as well as its clinical significance for IBD as well as neurodegeneration and neuroinflammation. Finally, we focus on novel human-specific preclinical models that will help uncover disease mechanisms to better understand and modulate the function of this complex system.

Prediction of response to Certolizumab-Pegol in rheumatoid arthritis (PreCePRA) by functional MRI of the brain - Study protocol for a randomized double-blind controlled study

Background

Tumor necrosis factor inhibitors (TNFi) signify a major advance in the treatment of rheumatoid arthritis (RA). However, treatment success initially remains uncertain as approximately half of the patients do not respond adequately to TNFi. Thus, an unmet need exists to better predict therapeutic outcome of biologicals.

Objectives

We investigated whether brain activity associated with arthritis measured by functional magnetic resonance imaging (fMRI) of the brain can serve as a predictor of response to TNFi in RA patients.

Methods

PreCePRA is a multi-center, randomized, double-blind, placebo-controlled fMRI trial on patients with RA [1] [2]. Active RA patients failing csDMARDs therapy with a DAS28 > 3.2 and at least three tender and/or swollen joints underwent a brain BOLD (blood-oxygen-level dependent) fMRI scan upon joint compression at screening. Patients were then randomized into a 12-week double-blinded treatment phase with 200 mg Certolizumab Pegol (CZP) every two weeks (arm 1: fMRI BOLD signal activated volume > 2000 voxel, i.e. 2 cm³; arm 2: fMRI BOLD signal activated volume <2000 voxel) or placebo (arm 3). DAS28 low disease activity at 12 weeks was assigned as primary endpoint. A 12-week follow-up phase in which patients were switched from the placebo to the treatment arm followed the blinded phase. fMRI was carried out at screening as well as after 12 and 24 weeks of receiving CZP or placebo.

Conclusion

We hypothesize that high-level central nervous representation of pain in patients with rheumatoid arthritis predicts response to the TNFi CZP which we further investigate in the PreCePRA trial.

Supraspinal Mechanisms of Intestinal Hypersensitivity

Gut inflammation or injury causes intestinal hypersensitivity (IHS) and hyperalgesia, which can persist after the initiating pathology resolves, are often referred to somatic regions and exacerbated by psychological stress, anxiety or depression, suggesting the involvement of both the spinal cord and the brain. The supraspinal mechanisms of IHS remain to be fully elucidated, however, over the last decades the series of intestinal pathology-associated neuroplastic changes in the brain has been revealed, being potentially responsible for the phenomenon. This paper reviews current clinical and experimental data, including the authors' own findings, on these functional, structural, and neurochemical/molecular changes within cortical, subcortical and brainstem regions processing and modulating sensory signals from the gut. As concluded in the review, IHS can develop and maintain due to the bowel inflammation/injury-induced persistent hyperexcitability of viscerosensory brainstem and thalamic nuclei and sensitization of hypothalamic, amygdala, hippocampal, anterior insular, and anterior cingulate cortical areas implicated in the neuroendocrine, emotional and cognitive modulation of visceral sensation and pain. An additional contribution may come from the pathology-triggered dysfunction of the brainstem structures inhibiting nociception. The mechanism underlying IHS-associated regional hyperexcitability is enhanced NMDA-, AMPA- and group I metabotropic receptor-mediated glutamatergic neurotransmission in association with altered neuropeptide Y, corticotropin-releasing factor, and cannabinoid 1 receptor signaling. These alterations are at least partially mediated by brain microglia and local production of cytokines, especially tumor necrosis factor α. Studying the IHS-related brain neuroplasticity in greater depth may enable the development of new therapeutic approaches against chronic abdominal pain in inflammatory bowel disease.

A Verbal Fluency Task-Based Brain Activation fMRI Study in Patients with Crohn's Disease in Remission

BACKGROUND AND PURPOSE

In this pilot study, we investigated functional brain activation changes in patients with Crohn's disease (CD) in remission compared to age and gender-matched healthy controls (HCs).

METHODS

Data from 20 patients with CD in remission (age range 19-63 years) and 20 HCs (matched in age and gender) were analyzed. Task functional MRI (fMRI) data were collected while participants performed a cognitive (phonemic verbal fluency) task in the scanner. All participants also performed the same task outside the scanner.

RESULTS

Task fMRI results showed greater bi-hemispheric activation in CD patients compared to controls. Because this pattern is commonly reported with normal aging, we performed further analyses to investigate fMRI responses in a subset of the younger CD patients (N = 12, age < = 35 years) compared to matched young HCs (age < = 35 years), and an older cohort of HCs (age > = 50 years). Results showed that task activation patterns were similar between young CD patients and older HCs, and that both groups differed significantly from younger HCs. Activation intensity in specific brain regions for patients was associated with disease duration.

CONCLUSIONS

These results suggest that CD patients in remission may show accelerated signs of aging in terms of brain responses to a typical cognitive task. Future work with larger sample size will need to replicate these results as well as investigate the influence of factors, such as chronicity of the disease and medication effects on task-associated brain activation patterns in this patient population.

[Research consortium Neuroimmunology and pain in the research network musculoskeletal diseases]

BACKGROUND

The research consortium Neuroimmunology and Pain (Neuroimpa) explores the importance of the relationships between the immune system and the nervous system in musculoskeletal diseases for the generation of pain and for the course of fracture healing and arthritis.

MATERIAL AND METHODS

The spectrum of methods includes analyses at the single cell level, in vivo models of arthritis and fracture healing, imaging studies on brain function in animals and humans and analysis of data from patients.

RESULTS

Proinflammatory cytokines significantly contribute to the generation of joint pain through neuronal cytokine receptors. Immune cells release opioid peptides which activate opioid receptors at peripheral nociceptors and thereby evoke hypoalgesia. The formation of new bone after fractures is significantly supported by the nervous system. The sympathetic nervous system promotes the development of immune-mediated arthritis. The studies show a significant analgesic potential of the neutralization of proinflammatory cytokines and of opioids which selectively inhibit peripheral neurons. Furthermore, they show that the modulation of neuronal mechanisms can beneficially influence the course of musculoskeletal diseases.

DISCUSSION

Interventions in the interactions between the immune system and the nervous system hold a great therapeutic potential for the treatment of musculoskeletal diseases and pain.

Anti-TNFα therapy in IBD alters brain activity reflecting visceral sensory function and cognitive-affective biases

Background

In inflammatory bowel disease (IBD), immune activation with increased circulating TNF-α is linked to the intensity of gastrointestinal symptoms and depression or anxiety. A central feature of depression is cognitive biases linked to negative attributions about self, the world and the future. We aimed to assess the effects of anti-TNFα therapy on the central processing of self-attribution biases and visceral afferent information in patients with Crohn’s disease.

Methods

We examined 9 patients with Crohn’s disease (age 26.1±10.6. yrs, 5 female, 5 ileocolonic, 2 colonic and 2 ileal disease) during chronic anti-TNFα therapy (5 adalimumab, 4 infliximab). Patients were studied twice in randomized order before and after anti-TNFα administration. On each occasion patients underwent functional magnetic resonance imaging (fMRI) of the brain during a test of implicit attribution biases regarding sickness/health and undertook a standardized nutrient challenge.

Results

Following anti-TNFα treatment, ratings of ‘fullness’ following nutrient challenge reduced compared to pre-treatment ratings (p<0.05). Reaction times revealed improved processing of self-related and positive health words, consistent with improved implicit sense of wellbeing that correlated with improvements in sensory function after treatment (r = 0.67, p<0.05). Treatment-associated improvements in implicit processing were mirrored by alterations of prefrontal, amygdala, posterior cingulate and visual regions. Between patients, the degree of functional amygdala change was additionally explained by individual differences in attention regulation and body awareness rankings.

Conclusion

In patients with Crohn’s disease, anti-TNFα administration reduces visceral sensitivity and improves implicit cognitive-affective biases linked to alterations in limbic (amygdala) function.

Structural Imaging Changes and Behavioral Correlates in Patients with Crohn's Disease in Remission

Background: Crohn’s disease (CD) is a subtype of inflammatory bowel disease caused by immune-mediated inflammation in the gastrointestinal tract. The extent of morphologic brain alterations and their associated cognitive and affective impairments remain poorly characterized.

Aims: We used magnetic resonance imaging to identify structural brain differences between patients with Crohn’s disease in remission compared to age-matched healthy controls and evaluated for structural-behavioral correlates.

Methods: Nineteen patients and 20 healthy, age-matched controls were recruited in the study. Group differences in brain morphometric measures and correlations between brain measures and performance on a cognitive task, the verbal fluency (VF) task, were examined. Correlations between brain measures and cognitive measures as well as self-reported measures of depression, personality, and affective scales were examined.

Results: Patients showed significant cortical thickening in the left superior frontal region compared to controls. Significant group differences were observed in sub-cortical volume measures in both hemispheres. Investigation of brain-behavior correlations revealed significant group differences in the correlation between cortical surface area and VF performance, although behavioral performance was equivalent between the two groups. The left middle temporal surface area was a significant predictor of VF performance with controls showing a significant positive correlation between these measures, and patients showing the opposite effect.

Conclusion: Our results indicate key differences in structural brain measures in patients with CD compared to controls. Additionally, correlation between brain measures and behavioral responses suggest there may be a neural basis to the alterations in patients’ cognitive and affective responses.

Immune response in irritable bowel syndrome: A systematic review of systemic and mucosal inflammatory mediators

OBJECTIVE

To systematically review the available data on cytokine and immune cells in the peripheral blood and mucosal biopsy samples from patients with irritable bowel syndrome (IBS).

METHODS

From a review of the literature, data on cytokines and immune cells that had been assayed in at least three independent studies were collated and trends examined.

RESULTS

Levels of interleukin (IL)-10 tended to be decreased and those of IL-6, IL-8, tumor necrosis factor-α and IL-1β increased in the systemic circulation in IBS, while in the mucosa, IL-10 was decreased and IL-8, mast cells, enterochromaffin cells and CD3⁺ T lymphocytes were increased. However, these findings were not consistent across all studies and, in some instances, were limited to certain IBS sub-populations.

CONCLUSIONS

The interpretation of this literature is limited by several factors, such as the intrinsic heterogeneity of IBS and a lack of standardization in study design. While a number of intriguing immunological observations have been made in IBS, more work is needed before a compelling case can be made for a role for immune-mediated events in the etiology of IBS.

Response to peripheral immune stimulation within the brain: magnetic resonance imaging perspective of treatment success

Chronic peripheral inflammation in diseases such as rheumatoid arthritis leads to alterations in central pain processing and consequently to mood disorders resulting from sensitization within the central nervous system and enhanced vulnerability of the medial pain pathway. Proinflammatory cytokines such as tumor necrosis factor (TNF) alpha play an important role herein, and therapies targeting their signaling (i.e., anti-TNF therapies) have been proven to achieve good results. However, the phenomenon of rapid improvement in the patients’ subjective feeling after the start of TNFα neutralization remained confusing, because it was observed long before any detectable signs of inflammation decline. Functional magnetic resonance imaging (fMRI), enabling visualization of brain activity upon peripheral immune stimulation with anti-TNF, has helped to clarify this discrepancy. Moreover, fMRI appeared to work as a reliable tool for predicting prospective success of anti-TNF therapy, which is valuable considering the side effects of the drugs and the high therapy costs. This review, which is mainly guided by neuroimaging studies of the brain, summarizes the state-of-the-art knowledge about communication between the immune system and the brain and its impact on subjective well-being, addresses in more detail the outcome of the abovementioned anti-TNF fMRI studies (rapid response to TNFα blockade within the brain pain matrix and differences in brain activation patterns between prospective therapy responders and nonresponders), and discusses possible mechanisms for the latter phenomena and the predictive power of fMRI.