Chronotherapy with low-dose modified-release prednisone for the management of rheumatoid arthritis: a review

Artificial Intelligence/Machine Learning-Driven Small Molecule Repurposing via Off-Target Prediction and Transcriptomics

The process of discovering small molecule drugs involves screening numerous compounds and optimizing the most promising ones, both in vitro and in vivo. However, approximately 90% of these optimized candidates fail during trials due to unexpected toxicity or insufficient efficacy. Current concepts with respect to drug-protein interactions suggest that each small molecule interacts with an average of 6-11 targets. This implies that approved drugs and even discontinued compounds could be repurposed by leveraging their interactions with unintended targets. Therefore, we developed a computational repurposing framework for small molecules, which combines artificial intelligence/machine learning (AI/ML)-based and chemical similarity-based target prediction methods with cross-species transcriptomics information. This repurposing methodology incorporates eight distinct target prediction methods, including three machine learning methods. By using multiple orthogonal methods for a "dataset" composed of 2766 FDA-approved drugs targeting multiple therapeutic target classes, we identified 27,371 off-target interactions involving 2013 protein targets (i.e., an average of around 10 interactions per drug). Relative to the drugs in the dataset, we identified 150,620 structurally similar compounds. The highest number of predicted interactions were for drugs targeting G protein-coupled receptors (GPCRs), enzymes, and kinases with 10,648, 4081, and 3678 interactions, respectively. Notably, 17,283 (63%) of the off-target interactions have been confirmed in vitro. Approximately 4000 interactions had an IC50 of <100 nM for 1105 FDA-approved drugs and 1661 interactions had an IC50 of <10 nM for 696 FDA-approved drugs. Together, the confirmation of numerous predicted interactions and the exploration of tissue-specific expression patterns in human and animal tissues offer insights into potential drug repurposing for new therapeutic applications.

Chrono-moxibustion adjusts circadian rhythm of CLOCK and BMAL1 in adjuvant-induced arthritic rats

OBJECTIVE

The clinical symptoms of rheumatoid arthritis (RA) have significant circadian rhythms, with morning stiffness and joint pain. Moxibustion is effective in the treatment of RA, while the underlying therapeutic mechanisms remain limited. Thus, we explored whether moxibustion could adjust the circadian rhythm of RA by modulating the core clock genes CLOCK and BMAL1 at the molecular level.

METHODS

144 Sprague Dawley rats were randomly divided into four groups: control group (group A), model group (group B), 7-9 am moxibustion treatment group (group C), and 5-7 pm moxibustion treatment group (group D). Each group was divided into 6 time points (0 am, 4 am, 8 am, 12 N, 6 pm, and 8 pm) with an equal number of rats at each time point. Except for group A, all rats were injected with Freund's Complete Adjuvant (FCA) 0.15 ml on the right foot pad to establish the RA model. The rats of the two moxibustion treatment groups were respectively subjected to moxibustion at 7-9 am and 5-7 pm. After 3 weeks of treatment, the tissues were collected at 6 time points during the next 24 hours. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to test the mRNA expression of CLOCK and BMAL1 in the hypothalamus and synovial tissues. CLOCK and BMAL1 protein expression in synovial tissues were detected with western blot.

RESULTS

Compared to group A, group B showed significantly down-regulated expression levels of CLOCK and BMLA1 at synovial tissue (P < 0.05), while no statistically significant difference was found in the hypothalamus (P > 0.05). The expression levels of CLOCK and BMLA1 were up-regulated in the moxibustion treatment groups in different tissues, especially in synovial tissue (P < 0.05) compared to group B. Nevertheless, no difference was observed between groups C and D (P > 0.05).

CONCLUSIONS

Moxibustion could treat RA by modulating clock core genes CLOCK and BMAL1 to regulate the circadian rhythm. However, there was no significant difference between the 7-9 am moxibustion treatment group and the 5-7 pm moxibustion treatment group. This study provides a basis for research on moxibustion in the treatment of RA.

Role of the Immune System and the Circadian Rhythm in the Pathogenesis of Chronic Pancreatitis: Establishing a Personalized Signature for Improving the Effect of Immunotherapies for Chronic Pancreatitis

Pancreatitis, in both acute and chronic forms, poses a major therapeutic challenge and is associated with great morbidity and several complications. The nature of pancreatic injury in chronic pancreatitis (CP) and the wide range of causative processes that lead to CP have made effective therapy a true unmet need. Multiple physiological, genetic, environmental, and behavioral factors contribute to the development of CP. As a result, several fields of research are aimed at identifying and addressing the factors that contribute to pancreatic injury. In this article, we review the current understanding of the pathogenesis and natural history of CP. We focus on the autonomous nervous system, immune system, and role of a chronobiological therapeutic approach to alleviate symptoms and prevent or reverse pancreatic injury associated with CP. We aim to demonstrate that individualizing chronopharmacological treatments for CP is a promising direction for future treatment using immune, nervous, and circadian systems.

Modeling inter-sex and inter-individual variability in response to chronopharmacological administration of synthetic glucocorticoids

Endogenous glucocorticoids have diverse physiological effects and are important regulators of metabolism, immunity, cardiovascular function, musculoskeletal health and central nervous system activity. Synthetic glucocorticoids have received widespread attention for their potent anti-inflammatory activity and have become an important class of drugs used to augment endogenous glucocorticoid activity for the treatment of a host of chronic inflammatory conditions. Chronic use of synthetic glucocorticoids is associated with a number of adverse effects as a result of the persistent dysregulation of glucocorticoid sensitive pathways. A failure to consider the pronounced circadian rhythmicity of endogenous glucocorticoids can result in either supraphysiological glucocorticoid exposure or severe suppression of endogenous glucocorticoid secretion, and is thought be a causal factor in the incidence of adverse effects during chronic glucocorticoid therapy. Furthermore, given that synthetic glucocorticoids have potent feedback effects on the hypothalamic-pituitary-adrenal (HPA) axis, physiological factors which can give rise to individual variability in HPA axis activity such as sex, age, and disease state might also have substantial implications for therapy. We use a semi-mechanistic mathematical model of the rodent HPA axis to study how putative sex differences and individual variability in HPA axis regulation can influence the effects of long-term synthetic exposure on endogenous glucocorticoid circadian rhythms. Model simulations suggest that for the same drug exposure, simulated females exhibit less endogenous suppression than males considering differences in adrenal sensitivity and negative feedback to the hypothalamus and pituitary. Simulations reveal that homeostatic regulatory variability and chronic stress-induced regulatory adaptations in the HPA axis network can result in substantial differences in the effects of synthetic exposure on the circadian rhythm of endogenous glucocorticoids. In general, our results provide insight into how the dosage and exposure profile of synthetic glucocorticoids could be manipulated in a personalized manner to preserve the circadian dynamics of endogenous glucocorticoids during chronic therapy, thus potentially minimizing the incidence of adverse effects associated with long-term use of glucocorticoids.

Chronopharmacology of glucocorticoids

Glucocorticoids influence a wide array of metabolic, anti-inflammatory, immunosuppressive, and cognitive signaling processes, playing an important role in homeostasis and preservation of normal organ function. Synthesis is regulated by the hypothalamic-pituitary-adrenal (HPA) axis of which cortisol is the primary glucocorticoid in humans. Synthetic glucocorticoids are important pharmacological agents that augment the anti-inflammatory and immunosuppressive properties of endogenous cortisol and are widely used for the treatment of asthma, Crohn's disease, and rheumatoid arthritis, amongst other chronic conditions. The homeostatic activity of cortisol is disrupted by the administration of synthetic glucocorticoids and so there is interest in developing treatment options that minimize HPA axis disturbance while maintaining the pharmacological effects. Studies suggest that optimizing drug administration time can achieve this goal. The present review provides an overview of endogenous glucocorticoid activity and recent advances in treatment options that have further improved patient safety and efficacy with an emphasis on chronopharmacology.

Rheumatoid arthritis reprograms circadian output pathways

OBJECTIVE

We applied systems biology approaches to investigate circadian rhythmicity in rheumatoid arthritis (RA).

METHODS

We recruited adults (age 16-80 years old) with a clinical diagnosis of RA (active disease [DAS28 > 3.2]). Sleep profiles were determined before inpatient measurements of saliva, serum, and peripheral blood mononuclear leukocytes (PBML). Transcriptome and proteome analyses were carried out by RNA-SEQ and LC-MS/MS. Serum samples were analysed by targeted lipidomics, along with serum from mouse collagen induced-arthritis (CIA). Bioinformatic analysis identified RA-specific gene networks and rhythmic processes differing between healthy and RA.

RESULTS

RA caused greater time-of-day variation in PBML gene expression, and ex vivo stimulation identified a time-of-day-specific RA transcriptome. We found increased phospho-STAT3 in RA patients, and some targets, including phospho-ATF2, acquired time-of-day variation in RA. Serum ceramides also gained circadian rhythmicity in RA, which was also seen in mouse experimental arthritis, resulting from gain in circadian rhythmicity of hepatic ceramide synthases.

CONCLUSION

RA drives a gain in circadian rhythmicity, both in immune cells, and systemically. The coupling of distant timing information to ceramide synthesis and joint inflammation points to a systemic re-wiring of the circadian repertoire. Circadian reprogramming in response to chronic inflammation has implications for inflammatory co-morbidities and time-of-day therapeutics.

Modeling the influence of chronopharmacological administration of synthetic glucocorticoids on the hypothalamic-pituitary-adrenal axis

Natural glucocorticoids, a class of cholesterol-derived hormones, modulate an array of metabolic, anti-inflammatory, immunosuppressive and cognitive signaling. The synthesis of natural glucocorticoids, largely cortisol in humans, is regulated by the hypothalamic-pituitary-adrenal (HPA) axis and exhibits pronounced circadian variation. Considering the central regulatory function of endogenous glucocorticoids, maintenance of the circadian activity of the HPA axis is essential to host survival and chronic disruption of such activity leads to systemic complications. There is a great deal of interest in synthetic glucocorticoids due to the immunosuppressive and anti-inflammatory properties and the development of novel dosing regimens that can minimize the disruption of endogenous activity, while still maintaining the pharmacological benefits of long-term synthetic glucocorticoid therapy. Synthetic glucocorticoids are associated with an increased risk of developing the pathological disorders related to chronic suppression of cortisol rhythmicity as a result of the potent negative feedback by synthetic glucocorticoids on the HPA axis precursors. In this study, a mathematical model was developed to explore the influence of chronopharmacological dosing of exogenous glucocorticoids on the endogenous cortisol rhythm considering intra-venous and oral dosing. Chronic daily dosing resulted in modification of the circadian rhythmicity of endogenous cortisol with the amplitude and acrophase of the altered rhythm dependent on the administration time. Simulations revealed that the circadian features of the endogenous cortisol rhythm can be preserved by proper timing of administration. The response following a single dose was not indicative of the response following long-term, repeated chronopharmacological dosing of synthetic glucocorticoids. Furthermore, simulations revealed the inductive influence of long-term treatment was only associated with low to moderate doses, while high doses generally led to suppression of endogenous activity regardless of the chronopharmacological dose. Finally, chronic daily dosing was found to alter the responsiveness of the HPA axis, such that a decrease in the amplitude of the cortisol rhythm resulted in a partial loss in the time-of-day dependent response to CRH stimulation, while an increase in the amplitude was associated with a more pronounced time-of-day dependence of the response.

Cancer chemotherapeutics in rheumatoid arthritis: A convoluted connection

Chemotherapy is one of the most popular therapeutic strategies to treat cancer. However, cancer chemotherapeutics have often been associated with impairment of the immune system, which might consequently lead to an augmented risk of autoimmune disorders, such as rheumatoid arthritis. Though the accurate mechanistic facets of rheumatoid arthritis induction have not been interpreted yet, a conglomeration of genetic and environmental factors might promote its etiology. What makes the scenario more challenging is that patients with rheumatoid arthritis are at a significantly elevated risk of developing various types of cancer. It is intriguing to note that diverse cancer chemotherapy drugs are also commonly used to treat symptoms of rheumatoid arthritis. However, a colossal multitude of such cancer therapeutics has demonstrated highly varied results in rheumatoid arthritis patients, including both beneficial and adverse effects. Herein, we attempt to present a holistic account of the variegated modalities of this complex tripartite cross-talk between cancer, rheumatoid arthritis and chemotherapy drugs in order to decode the sinuous correlation between these two appalling pathological conditions.

Glucocorticoid hormones are both a major circadian signal and major stress signal: How this shared signal contributes to a dynamic relationship between the circadian and stress systems

Glucocorticoid hormones are a powerful mammalian systemic hormonal signal that exerts regulatory effects on almost every cell and system of the body. Glucocorticoids act in a circadian and stress-directed manner to aid in adaptation to an ever-changing environment. Circadian glucocorticoid secretion provides for a daily waxing and waning influence on target cell function. In addition, the daily circadian peak of glucocorticoid secretion serves as a timing signal that helps entrain intrinsic molecular clock phase in tissue cells distributed throughout the body. Stress-induced glucocorticoid secretion also modulates the state of these same cells in response to both physiological and psychological stressors. We review the strong functional interrelationships between glucocorticoids and the circadian system, and discuss how these interactions optimize the appropriate cellular and systems response to stress throughout the day. We also discuss clinical implications of this dual aspect of glucocorticoid signaling, especially for conditions of circadian and HPA axis dysregulation.