Neuroendocrine-immune correlates of circadian physiology: studies in experimental models of arthritis, ethanol feeding, aging, social isolation, and calorie restriction

Influence of Environmental Exposure to Steel Waste on Endocrine Dysregulation and PER3 Gene Polymorphisms

OBJECTIVE

To evaluate the association between environmental exposure to the following chemical substances: cadmium (Cd), lead (Pb), nickel (Ni), manganese (Mn), benzene (BZN), and toluene (TLN), and Period Circadian Regulator 3 (PER3) gene variable number of tandem repeats (VNTR) polymorphisms, according to chronotype in a population living in a steel residue-contaminated area.

METHODS

This assessment comprises a study conducted from 2017 to 2019 with 159 participants who completed health, work, and Pittsburgh sleep scale questionnaires. Cd, Pb, Ni, Mn, BZN, and TLN concentrations in blood and urine were determined by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and Headspace Gas Chromatography (GC), and genotyping was carried out using Polymerase Chain Reaction (PCR).

RESULTS

A total of 47% of the participants were afternoon chronotype, 42% were indifferent, and 11% were morning chronotype. Insomnia and excessive sleepiness were associated with the indifferent chronotype, while higher urinary manganese levels were associated with the morning chronotype (Kruskal-Wallis chi-square = 9.16; p < 0.01). In turn, the evening chronotype was associated with poorer sleep quality, higher lead levels in blood, and BZN and TLN levels in urine (χ² = 11.20; p < 0.01) in non-occupationally exposed individuals (χ² = 6.98; p < 0.01) as well as the highest BZN (χ² = 9.66; p < 0.01) and TLN (χ² = 5.71; p < 0.01) levels detected in residents from the influence zone 2 (far from the slag).

CONCLUSION

Mn, Pb, benzene, and toluene contaminants may have influenced the different chronotypes found in the steel residue-exposed population.

PER1 promotes functional recovery of mice with hindlimb ischemia by inducing anti-inflammatory macrophage polarization

Hindlimb ischemia (HLI) is an arterial occlusive disease that exposes the patients to the risk of limb gangrene and loss. Polarization of macrophages is related to HLI-induced inflammation. Period circadian regulator 1 (PER1) is a core component of the circadian clock. We first showed, based upon bioinformatics analysis of microarray data, that PER1 expression was reduced in monocytes from patients with critical limb ischemia. The proximal femoral artery in the left hindlimb of male mice was ligated and then the femoral artery and its collateral branches were removed to establish the HLI mouse model. After modeling, a single intramuscular injection of 1 × 10⁹ pfu Ad-PER1 was performed at the adductor and gastrocnemius muscles. The gastrocnemius muscle tissues were collected at day 0, 3, 7, 14, 21 post-HLI. There was obvious pathological necrosis, accompanied with reduced expression of PER1 in the muscle tissues of HLI mice. Expression of CD68 and CD31 seemed to be corresponded to PER1 in gastrocnemius muscle, implying the potential of PER1 in regulating macrophage-related inflammation and angiogenesis. PER1 overexpression diminished myocyte damage, promoted blood flow restoration and improved behavioral scores of HLI mice. Immunostaining of CD31 and α-SMA revealed that PER1 upregulation reversed HLI-induced decreases in capillary and arteriole density. In vitro, RAW264.7 cells were cultured in hypoxia (1% O₂) for 24 h. The percentage of pro-inflammatory CD86⁺ macrophages (M1 type) was decreased and that of anti-inflammatory CD206+ macrophages (M2 type) was increased when PER1 was overexpressed. Moreover, the expression levels of TNF-α, IL-6 and M1-type marker iNOS were decreased, and levels of IL-10 and M2-type marker Arg-1 were increased by PER1 in gastrocnemius muscle of HLI mice and hypoxia-treated RAW264.7 cells. PER1 might reduce M1 macrophage polarization and promote M2 macrophage polarization, and thus exert anti-inflammatory and pro-angiogenic actions. Our findings suggest that PER1 overexpression promotes functional recovery of mice with HLI through regulating macrophage polarization.

Case Report: Brachydactyly Type A1 Induced by a Novel Variant of in-Frame Insertion in the IHH Gene

Brachydactyly type A1 (BDA1) is an autosomal dominant inherited disease characterized by the shortness/absence of the middle phalanges, which can be induced by mutations in the Indian hedgehog gene (IHH). Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease characterized by joint destruction, synovitis, and the presence of autoantibodies. In this study, the proband was diagnosed with both BDA1 and RA. We performed whole-exome sequencing in a four-generation Chinese family to investigate their inherited causal mutation to BDA1. A novel in-frame insertion variant in IHH: NM_002,181.4: c.383_415dup/p.(R128_H138dup) was identified in the BDA1 pedigree. This insertion of 11 amino acids was located in the highly conserved amino-terminal signaling domain of IHH and co-segregated with the disease status. This adds one to the total number of different IHH mutations found to cause BDA1. Moreover, we found a potential causal germline variant in CRY1 for a molecular biomarker of RA (i.e., a high level of anti-cyclic citrullinated peptide). Collectively, we identified novel variants in IHH for inherited BDA1, which highlights the important role of this gene in phalange development.

The effect of a complex of melatonin, aluminum oxide and polymethylsiloxane on the cellular composition of the mice spleen kept in round-the-clock lighting conditions

It is known that the circadian rhythm of melatonin production depends on the intensity of illumination. Violation of the light regime leads to suppression of melatonin synthesis and the development of desynchronosis, which increases the risk of developing a number of pathologies. In this regard, it is relevant to search for opportunities to restore disturbed circadian rhythms and, especially, to correct immune dysfunctions that occur in these situations.The aim of this study was to examine the effect of a complex of melatonin, aluminum oxide and polymethylsiloxane on the lymphocytes of the spleen of mice kept under round-the-clock lighting.Materials and methods. Mice of the C57Bl/6J line were kept under round-the-clock lighting for 14 days, against which they were intragastrically injected with distilled water, aluminum oxide with polydimethylsiloxane, melatonin and a complex of melatonin, aluminum oxide and polymethylsiloxane (a new drug developed by the Research Institute of Clinical and Experimental Lymphology – Branch of the Federal Research Center Institute of Cytology and Genetics SB RAS; Patent of Russian Federation No. 2577580, 2016), represented by a complex of porous material (aluminum oxide with polydimethylsiloxane) and melatonin, immobilized in the pores, from which it is gradually released in a liquid medium. Intact animals kept under the light regime of ST 12/12 and under round-the-clock lighting served as a control. Immunophenotyping of spleen B- and T-lymphocytes was performed on a flow cytofluorimeter with monoclonal antibodies APC CD3 and FITC CD19. For studying the distribution of cells by stages of the cell cycle in splenocytes, the amount of intracellular DNA was measured by the level of inclusion of propidium iodide.Results. Flow cytometry of the distribution of B- and T-lymphocytes of the spleen in male mice of the C57Bl/6J line kept under round-the-clock lighting conditions (KO 24/0 h) revealed a decrease in the percentage of B-lymphocytes and an increase in the number of T-lymphocytes, compared with animals kept under standard lighting conditions (the light/dark photoperiod – 14/10 hours). The ratio of CD19+/CD3+ lymphocytes of the spleen in mice under the conditions of KO significantly decreases (1.5 times) compared to intact animals (p ≤ 0.001). The administration of pure and modified melatonin (Complex M) to animals kept under round-the-clock lighting conditions has an equally pronounced normalizing effect on the cellular composition of B- (CD19) and T- (CD3) lymphocytes of the spleen, bringing the values of the studied parameters to the control values of the intact animals (p ≤ 0.001) Round-the-clock lighting affects the proliferative potential of splenocytes, reducing the number of cells in the G2/M phase, compared with animals treated with melatonin (p ≤ 0.050). The introduction of melatonin leads to an increase in the percentage of cells in the G2/M phase relative to the placebo group (p ≤ 0.050). In the group of mice treated with Complex M, the greatest increase in cells at the S + G2/M phases and the highest percentage of cells at the G2/M phase were revealed compared to the placebo control group (p ≤ 0.050).Conclusion. The complex of melatonin, aluminum oxide and polymethylsiloxane has additional immunotropic properties in relation to the modifier molecule, which, apparently, are due to the joint immunostimulating effect of melatonin and the lymphostimulating effect of the sorbent. Melatonin in the composition of the complex shows its properties more stably.

Bidirectional association between alopecia areata and sleep disorders: a population-based cohort study in Taiwan

BACKGROUND

The relationship between alopecia areata (AA) and sleep disorders remains uncertain. This study aims to investigate the bidirectional association between AA and sleep disorders.

METHODS

To assess the risk of developing sleep disorders, we recruited 5648 patients with AA and 22,592 matched controls from the National Health Insurance Research Database (NHIRD) in Taiwan. Similarly, risk of developing AA was assessed in 93,130 patients with sleep disorders (including 7310 patients with obstructive sleep apnea [OSA] and 85,820 patients with non-apnea insomnia) and 372,520 matched controls. Cox regression model was used for the analysis.

RESULTS

AA patients had a significantly increased risk of developing OSA (adjusted hazard ratio [aHR] 3.80; 95% confidence interval [CI] 2.53-5.71) and non-apnea insomnia (aHR 4.20; 95% CI 3.68-4.79). Conversely, presence of sleep disorders significantly increased the risk of AA development (aHR 4.70; 95% CI 3.99-5.54). Both OSA (aHR 3.89; 95% CI 2.46-6.16) and nonapnea insomnia (aHR 4.77; 95% CI 4.03-5.64) were associated an increased risk of developing AA.

CONCLUSIONS

Patients with AA have a higher risk of developing sleep disorders compared to controls, and vice versa. Further studies are needed to investigate the shared pathogenic mechanism underlying these two conditions.

Circadian disruption of core body temperature in trauma patients: a single-center retrospective observational study

Background

Circadian clock alterations were poorly reported in trauma patients, although they have a critical role in human physiology. Core body temperature is a clinical variable regulated by the circadian clock. Our objective was to identify the circadian temperature disruption in trauma patients and to determine whether these disruptions were associated with the 28-day mortality rate.

Methods

A retrospective and observational single-center cohort study was conducted. All adult severe trauma patients admitted to the intensive care unit of Aix Marseille University, North Hospital, from November 2013 to February 2018, were evaluated. The variations of core body temperature for each patient were analyzed between days 2 and 3 after intensive care unit admission. Core body temperature variations were defined by three parameters: mesor, amplitude, and period. A logistic regression model was used to determine the variables influencing these three parameters. A survival analysis was performed assessing the association between core body temperature rhythm disruption and 28-day mortality rate. A post hoc subgroup analysis focused on the patients with head trauma.

Results

Among the 1584 screened patients, 248 were included in this study. The period differed from 24 h in 177 (71%) patients. The mesor value (°C) was associated with body mass index and ketamine use. Amplitude (°C) was associated with ketamine use only. The 28-day mortality rate was 18%. For all trauma patients, age, body mass index, intracranial hypertension, and amplitude were independent risk factors. The patients with a mesor value < 36.9 °C (p < 0.001) and an amplitude > 0.6 °C (p < 0.001) had a higher 28-day mortality rate. Among the patients with head trauma, mesor and amplitude were identified as independent risk factors (HR = 0.40, 95% CI [0.23–0.70], p = 0.001 and HR = 4.73, 95% CI [1.38–16.22], p = 0.01).

Conclusions

Our results highlight an association between core body temperature circadian alteration and 28-day mortality rate. This association was more pronounced in the head trauma patients than in the non-head trauma patients. Further studies are needed to show a causal link and consider possible interventions.

Determining rhythmicity and determinism of temperature curves in septic and non-septic critically ill patients through chronobiological and recurrence quantification analysis: a pilot study

BACKGROUND

A few studies have demonstrated that critically ill patients exhibit circadian deregulation and reduced complexity of different time series, such as temperature.

RESULTS

In this prospective study, we enrolled 21 patients divided into three groups: group A (N = 10) included subjects who had septic shock at the time of ICU entry, group B (N = 6) included patients who developed septic shock during ICU stay, and group C consisted of 5 non-septic critically ill patients. Core body temperature (CBT) was recorded for 24 h at a rate of one sample per hour (average of CBT for that hour) and during different occasions: upon ICU entry and exit in groups A and C and upon entry, septic shock development, and exit in group B. Markers of circadian rhythmicity included mean values, amplitude that is the difference between peak and mean values, and peak time. Furthermore, recurrence quantification analysis (RQA) was employed for assessing different markers of complexity of temperature signals. Patients from group C exhibited higher temperature amplitude upon entry (0.45 ± 0.19) in relation with both groups A (0.28 ± 0.18, p < 0.05) and B (0.32 ± 0.13, p < 0.05). Circadian features did not differ within all groups. Temperature amplitude in groups B and C upon entry was negatively correlated with SAPS II (r = - 0.72 and - 0.84, p < 0.003) and APACHE II scores (r = - 0.70 and - 0.63, p < 0.003), respectively, as well as duration of ICU and hospital stay in group B (r = - 0.62 and - 0.64, p < 0.003) and entry SOFA score in group C (r = - 0.82, p < 0.003). Increased periodicity of CBT was found for all patients upon exit related to entry in the ICU. Different RQA features indicating periodic patterns of change of entry CBT were negatively correlated with severity of disease and length of ICU stay for all patients.

CONCLUSIONS

Increased temperature rhythmicity during ICU entry was related with lower severity of disease and better clinical outcomes, whereas the more deterministic CBT patterns were found in less critically ill patients with shorter ICU stay.

Enriched Physical Environment Attenuates Spatial and Social Memory Impairments of Aged Socially Isolated Mice

BACKGROUND

Social isolation in the elderly is one of the principal health risks in an aging society. Physical environmental enrichment is shown to improve sensory, cognitive, and motor functions, but it is unknown whether environmental enrichment can protect against brain impairments caused by social isolation.

METHODS

Eighteen-month-old mice were housed, either grouped or isolated, in a standard or enriched environment for 2 months, respectively. Behavioral tests were performed to evaluate cognitive functional and social interaction ability. Synaptic protein levels, myelination, neuroinflammation, brain derived neurotrophic factor, and NOD-like receptor protein 3 inflammasome signaling pathways were examined in the medial prefrontal cortex and hippocampus.

RESULTS

Isolated aged mice exhibited declines in spatial memory and social memory compared with age-matched littermates living within group housing. The aforementioned memory malfunctions were mitigated in isolated aged mice that were housed in a large cage with a running wheel and novel toys. Enriched housing prevented synaptic protein loss, myelination defects, and downregulation of brain derived neurotrophic factor, while also increasing interleukin 1 beta and tumor necrosis factor alpha in the medial prefrontal cortex and hippocampus of isolated mice. In addition, activation of glial cells and NOD-like receptor protein 3 inflammasomes was partially ameliorated in the hippocampus of isolated mice treated with physical environmental enrichment.

CONCLUSIONS

These results suggest that an enriched physical environment program may serve as a nonpharmacological intervention candidate to help maintain healthy brain function of elderly people living alone.

Altered Neuroendocrine Immune Responses, a Two-Sword Weapon against Traumatic Inflammation

During the occurrence and development of injury (trauma, hemorrhagic shock, ischemia and hypoxia), the neuroendocrine and immune system act as a prominent navigation leader and possess an inter-system crosstalk between the reciprocal information dissemination. The fundamental reason that neuroendocrinology and immunology could mix each other and permeate toward the field of traumatology is owing to their same biological languages or chemical information molecules (hormones, neurotransmitters, neuropeptides, cytokines and their corresponding receptors) shared by the neuroendocrine and immune systems. The immune system is not only modulated by the neuroendocrine system, but also can modulate the biological functions of the neuroendocrine system. The interactive linkage of these three systems precipitates the complicated space-time patterns for the courses of traumatic inflammation. Recently, compelling evidence indicates that the network linkage pattern that initiating agents of neuroendocrine responses, regulatory elements of immune cells and effecter targets for immune regulatory molecules arouse the resistance mechanism disorders, which supplies the beneficial enlightenment for the diagnosis and therapy of traumatic complications from the view of translational medicine. Here we review the alternative protective and detrimental roles as well as possible mechanisms of the neuroendocrine immune responses in traumatic inflammation.

The significance of circadian rhythms and dysrhythmias in critical illness

Many physiological and cellular processes cycle with time, with the period between one peak and the next being roughly equal to 24 h. These circadian rhythms underlie 'permissive homeostasis', whereby anticipation of periods of increased energy demand or stress may enhance the function of individual cells, organ systems or whole organisms. Many physiological variables related to survival during critical illness have a circadian rhythm, including the sleep/wake cycle, haemodynamic and respiratory indices, immunity and coagulation, but their clinical significance remains underappreciated. Critically ill patients suffer from circadian dysrhythmia, manifesting overtly as sleep disturbance and delirium, but with widespread covert effects on cellular and organ function. Environmental and pharmacological strategies that ameliorate or prevent circadian dysrhythmia have demonstrated clinical benefit. Harnessing these important biological phenomena to match metabolic supply to demand and bolster cell defenses at the apposite time may be a future therapeutic strategy in the intensive care unit.

Early-Life Social Isolation Impairs the Gonadotropin-Inhibitory Hormone Neuronal Activity and Serotonergic System in Male Rats

Social isolation in early life deregulates the serotonergic system of the brain, compromising reproductive function. Gonadotropin-inhibitory hormone (GnIH) neurons in the dorsomedial hypothalamic nucleus are critical to the inhibitory regulation of gonadotropin-releasing hormone neuronal activity in the brain and release of luteinizing hormone by the pituitary gland. Although GnIH responds to stress, the role of GnIH in social isolation-induced deregulation of the serotonin system and reproductive function remains unclear. We investigated the effect of social isolation in early life on the serotonergic-GnIH neuronal system using enhanced green fluorescent protein (EGFP)-tagged GnIH transgenic rats. Socially isolated rats were observed for anxious and depressive behaviors. Using immunohistochemistry, we examined c-Fos protein expression in EGFP-GnIH neurons in 9-week-old adult male rats after 6 weeks post-weaning isolation or group housing. We also inspected serotonergic fiber juxtapositions in EGFP-GnIH neurons in control and socially isolated male rats. Socially isolated rats exhibited anxious and depressive behaviors. The total number of EGFP-GnIH neurons was the same in control and socially isolated rats, but c-Fos expression in GnIH neurons was significantly reduced in socially isolated rats. Serotonin fiber juxtapositions on EGFP-GnIH neurons were also lower in socially isolated rats. In addition, levels of tryptophan hydroxylase mRNA expression in the dorsal raphe nucleus were significantly attenuated in these rats. These results suggest that social isolation in early-life results in lower serotonin levels, which reduce GnIH neuronal activity and may lead to reproductive failure.

'Chronomics' in ICU: circadian aspects of immune response and therapeutic perspectives in the critically ill

Complex interrelations exist between the master central clock, located in the suprachiasmatic nuclei of the hypothalamus, and several peripheral clocks, such as those found in different immune cells of the body. Moreover, external factors that are called ‘timekeepers’, such as light/dark and sleep/wake cycles, interact with internal clocks by synchronizing their different oscillation phases. Chronobiology is the science that studies biologic rhythms exhibiting recurrent cyclic behavior. Circadian rhythms have a duration of approximately 24 h and can be assessed through chronobiologic analysis of time series of melatonin, cortisol, and temperature. Critically ill patients experience severe circadian deregulation due to not only the lack of effective timekeepers in the intensive care unit (ICU) environment but also systemic inflammation. The latter has been found in both animal and human studies to disrupt circadian rhythmicity of all measured biomarkers. The aims of this article are to describe circadian physiology during acute stress and to discuss the effects of ICU milieu upon circadian rhythms, in order to emphasize the value of considering circadian-immune disturbance as a potential tool for personalized treatment. Thus, besides neoplastic processes, critical illness could be linked to what has been referred as ‘chronomics’: timing and rhythm. In addition, different therapeutic perspectives will be presented in association with environmental approaches that could restore circadian connection and hasten physical recovery.

Impaired leukocyte trafficking and skin inflammatory responses in hamsters lacking a functional circadian system

The immune system is under strong circadian control, and circadian desynchrony is a risk factor for metabolic disorders, inflammatory responses and cancer. Signaling pathways that maintain circadian rhythms (CRs) in immune function in vivo, and the mechanisms by which circadian desynchrony impairs immune function, remain to be fully identified. These experiments tested the hypothesis that the hypothalamic circadian pacemaker in the suprachiasmatic nucleus (SCN) drives CRs in the immune system, using a non-invasive model of SCN circadian arrhythmia. Robust CRs in blood leukocyte trafficking, with a peak during the early light phase (ZT4) and nadir in the early dark phase (ZT18), were absent in arrhythmic hamsters, as were CRs in spleen clock gene (per1, bmal1) expression, indicating that a functional pacemaker in the SCN is required for the generation of CRs in leukocyte trafficking and for driving peripheral clocks in secondary lymphoid organs. Pinealectomy was without effect on CRs in leukocyte trafficking, but abolished CRs in spleen clock gene expression, indicating that nocturnal melatonin secretion is necessary for communicating circadian time information to the spleen. CRs in trafficking of antigen presenting cells (CD11c(+) dendritic cells) in the skin were abolished, and antigen-specific delayed-type hypersensitivity skin inflammatory responses were markedly impaired in arrhythmic hamsters. The SCN drives robust CRs in leukocyte trafficking and lymphoid clock gene expression; the latter of which is not expressed in the absence of melatonin. Robust entrainment of the circadian pacemaker provides a signal critical to diurnal rhythms in immunosurveilliance and optimal memory T-cell dependent immune responses.

Laboratory models available to study alcohol-induced organ damage and immune variations: choosing the appropriate model

The morbidity and mortality resulting from alcohol-related diseases globally impose a substantive cost to society. To minimize the financial burden on society and improve the quality of life for individuals suffering from the ill effects of alcohol abuse, substantial research in the alcohol field is focused on understanding the mechanisms by which alcohol-related diseases develop and progress. Since ethical concerns and inherent difficulties limit the amount of alcohol abuse research that can be performed in humans, most studies are performed in laboratory animals. This article summarizes the various laboratory models of alcohol abuse that are currently available and are used to study the mechanisms by which alcohol abuse induces organ damage and immune defects. The strengths and weaknesses of each of the models are discussed. Integrated into the review are the presentations that were made in the symposium "Methods of Ethanol Application in Alcohol Model-How Long is Long Enough" at the joint 2008 Research Society on Alcoholism (RSA) and International Society for Biomedical Research on Alcoholism (ISBRA) meeting, Washington, DC, emphasizing the importance not only of selecting the most appropriate laboratory alcohol model to address the specific goals of a project but also of ensuring that the findings can be extrapolated to alcohol-induced diseases in humans.

Cadmium effects on 24h changes in glutamate, aspartate, glutamine, GABA and taurine content of rat striatum

This work evaluates the possible changes in 24 h variations of striatal aspartate, glutamate, glutamine, gamma-aminobutyric acid (GABA) and taurine content after oral cadmium treatment. Male rats were submitted to cadmium exposure at two doses (25 and 50 mg/L of cadmium chloride (CdCl(2))) in the drinking water for 30 days. Control rats received cadmium-free water. After the treatment, rats were killed at six different time intervals throughout a 24 h cycle. Differential effects of cadmium on 24 h amino acid fluctuations were observed. Metal exposure modified the daily pattern of the amino acids concentration found in control animals, except for GABA and taurine with the lowest dose used. Exposure to 25 mg/L of CdCl(2) decreased mean content of aspartate, as well as GABA concentration. These results suggest that cadmium exposure affects 24 h changes of the studied amino acids concentration in the striatum, and those changes may be related to alterations in striatal function.

Mammalian clock gene Cryptochrome regulates arthritis via proinflammatory cytokine TNF-alpha

The mammalian clock genes, Period and Cryptochrome (Cry), regulate circadian rhythm. We show that circadian rhythmicity and rhythmic expression of Period in the nuclei of inflammatory synovial cells and spleen cells are disturbed in mouse models of experimental arthritis. Expressions of other clock genes, Bmal1 and Dbp, are also disturbed in spleen cells by arthritis induction. Deletion of Cry1 and Cry2 results in an increase in the number of activated CD3(+) CD69(+) T cells and a higher production of TNF-alpha from spleen cells. When arthritis is induced, Cry1(-/-)Cry2(-/-) mice develop maximal exacerbation of joint swelling, and upregulation of essential mediators of arthritis, including TNF-alpha, IL-1beta and IL-6, and matrix metalloproteinase-3. Wee-1 kinase is solely upregulated in Cry1(-/-)Cry2(-/-) mice, in line with upregulation of c-Fos and Wee-1 kinase in human rheumatoid arthritis. The treatment with anti-TNF-alpha Ab significantly reduced the severity and halted the progression of the arthritis of Cry1(-/-)Cry2(-/-) mice and vice versa, ectopic expression of Cry1 in the mouse embryonic fibroblast from Cry1(-/-)Cry2(-/-) mice significantly reduced the trans activation of TNF-alpha gene. Thus, the biological clock and arthritis influence each other, and this interplay can influence human health and disease.

Elevation of Bombina variegata peptide 8 in mice with collagen-induced arthritis

Background

Bombina variegate peptide 8 (Bv8) is a small protein secreted by frog skin. Recently it has been shown to contribute to tumor angiogenesis in mouse model. The purpose of this study was to investigate Bv8 in mice with type II collagen-induced arthritis (CIA).

Methods

We induced CIA in male DBA/1J mice. The severity of arthritis was evaluated based on an arthritis score. RNA was extracted from the joint, and examined for Bv8 mRNA expression by RT-PCR and real-time RT-PCR. Synovial tissue and bone marrow were immunohistochemically examined using anti-Bv8 antibody.

Results

The level of Bv8 mRNA expression in the joint was below the detection limit in the control group, but was elevated in the CIA group, and was correlated with the arthritis score. In addition, an increase in Bv8-positive cells was observed in the synovium and bone marrow in the CIA group.

Conclusion

Bv8 was elevated in the synovium and bone marrow of CIA mice, suggesting that Bv8 plays an important role in the pathogenesis of arthritis.

Clock-cancer connection in non-Hodgkin's lymphoma: a genetic association study and pathway analysis of the circadian gene cryptochrome 2

Circadian genes have the potential to influence a variety of cancer-related biological pathways, including immunoregulation, which may influence susceptibility to non-Hodgkin's lymphoma (NHL). However, few studies have examined the role of circadian genes in lymphomagenesis. The current study examined Cryptochrome 2 (CRY2), a core circadian gene and transcriptional repressor, as a potential circadian biomarker for NHL. We first performed genetic association analyses of tagging single nucleotide polymorphisms (SNP) in CRY2 and NHL risk using DNA samples from a population-based case-control study (n = 455 cases and 527 controls). Three SNPs were found to be significantly associated with risk of NHL when combining all subtypes [dbSNP IDs, odds ratios (ORs), and 95% confidence intervals: rs11038689, OR, 2.34 (1.28-4.27), P = 0.006; rs7123390, OR, 2.40 (1.39-4.13), P = 0.002; and rs1401417, OR, 2.97 (1.57-5.63, P = 0.001)]. Each of these associations remained significant when restricting the analysis to B-cell cases and when further restricting to follicular lymphomas. An analysis of CRY2 diplotypes confirmed these significant findings. To further determine the functional effect of CRY2, we silenced the gene in vitro and performed a whole genome expression microarray. A pathway-based analysis showed that genes significantly altered by CRY2 knockdown formed networks associated with immune response and hematologic system development. In addition, these genes were predicted to have significant effects on several disease processes, including cancer (B-H P = 3.75E(-9)) and hematologic disease (B-H P = 8.01E(-8)). In conclusion, both genetic association and functional analyses suggest that the circadian gene CRY2 may play an important role in NHL development.