Airway Epithelial Cell-Derived Colony Stimulating Factor-1 Promotes Allergen Sensitization.

Airway epithelial cells (AECs) secrete innate immune cytokines that regulate adaptive immune effector cells. In allergen-sensitized humans and mice, the airway and alveolar microenvironment is enriched with colony stimulating factor-1 (CSF1) in response to allergen exposure. In this study we found that AEC-derived CSF1 had a critical role in the production of allergen reactive-IgE production. Furthermore, spatiotemporally secreted CSF1 regulated the recruitment of alveolar dendritic cells (DCs) and enhanced the migration of conventional DC2s (cDC2s) to the draining lymph node in an interferon regulatory factor 4 (IRF4)-dependent manner. CSF1 selectively upregulated the expression of the chemokine receptor CCR7 on the CSF1R+ cDC2, but not the cDC1, population in response to allergen stimuli. Our data describe the functional specification of CSF1-dependent DC subsets that link the innate and adaptive immune responses in T helper 2 (Th2) cell-mediated allergic lung inflammation.

Tumor immunogenicity regulates host immune responses, and conventional dendritic cell type 2 uptakes the majority of tumor antigens in an orthotopic lung cancer model.

Human lung cancer carries high genetic alterations, expressing high tumor-specific neoantigens. Although orthotopic murine lung cancer models recapitulate many characteristics of human lung cancers, genetically engineered mouse models have fewer somatic mutations than human lung cancer, resulting in scarce immune cell infiltration and deficient immune responses. The endogenous mouse lung cancer model driven by Kras mutation and Trp53 deletion (KP model) has minimal immune infiltration because of a scarcity of neoantigens. Fine-tuning tumor antigenicity to trigger the appropriate level of antitumor immunity would be key to investigating immune responses against human lung cancer. We engineered the KP model to express antigens of OVA peptides (minOVA) as neoantigens along with ZsGreen, a traceable fluorescent conjugate. The KP model expressing minOVA exhibited stronger immunogenicity with higher immune cell infiltration comprised of CD8+ T cells and CD11c+ dendritic cells (DCs). Consequently, the KP model expressing minOVA exhibits suppressed tumor growth compared to its origin. We further analyzed tumor-infiltrated DCs. The majority of ZsGreen conjugated with minOVA was observed in the conventional type 2 DCs (cDC2), whereas cDC1 has minimal. These data indicate that tumor immunogenicity regulates host immune responses, and tumor neoantigen is mostly recognized by cDC2 cells, which may play a critical role in initiating antitumor immune responses in an orthotopic murine lung cancer model.

ROCK2 regulates microglia proliferation and neuronal survival after traumatic brain injury.

Traumatic brain injury (TBI) results in prolonged and non-resolving activation of microglia. Forced turnover of these cells during the acute phase of TBI aids recovery, but the cell-intrinsic pathways that underpin the pro-repair phenotype of these repopulating microglia remain unclear. Here, we show that selective targeting of ROCK2 with the small molecule inhibitor KD025 impairs the proliferative response of microglia after TBI as well as during genetically induced turnover of microglia. KD025 treatment abolished the substantial neuroprotective and cognitive benefits conferred by repopulating microglia, preventing these cells from replenishing the depleted niche during the early critical time window post-injury. Delaying KD025 treatment to the subacute phase of TBI allowed microglial repopulation to occur, but this did not enhance the benefits conferred by repopulating microglia. Taken together, our data indicate that ROCK2 mediates neuronal survival and microglial population dynamics after TBI, including the emergence of repopulating microglia with a pro-repair phenotype.

CX3CR1+ Macrophage Facilitates the Resolution of Allergic Lung Inflammation via Interacting CCL26.

Rationale: The resolution of inflammation is an active process coordinated by mediators and immune cells to restore tissue homeostasis. However, the mechanisms for resolving eosinophilic allergic lung inflammation triggered by inhaled allergens have not been fully elucidated. Objectives: Our objectives were to investigate the cellular mechanism of tissue-resident macrophages involved in the resolution process of eosinophilic lung inflammation. Methods: For the study, we used the institutional review board-approved protocol for human subsegmental bronchoprovocation with allergen, mouse models for allergic lung inflammation, and novel transgenic mice, including a conditional CCL26 knockout. The samples were analyzed using mass cytometry, single-cell RNA sequencing, and biophysical and immunological analyses. Measurements and Main Results: We compared alveolar macrophage (AM) subsets in the BAL before and after allergen provocation. In response to provocation with inhaled allergens, the subsets of AMs are dynamically changed in humans and mice. In the steady state, the AM subset expressing CX3CR1 is a relatively small fraction in bronchoalveolar space and lung tissue but drastically increases after allergen challenges. This subset presents unique patterns of gene expression compared with classical AMs, expressing high C1q family genes. CX3CR1+ macrophages are activated by airway epithelial cell-derived CCL26 via a receptor-ligand interaction. The binding of CCL26 to the CX3CR1+ receptor induces CX3CR1+ macrophages to secrete C1q, subsequently facilitating the clearance of eosinophils. Furthermore, the depletion of CX3CR1 macrophages or CCL26 in airway epithelial cells delays the resolution of allergic lung inflammation displaying prolonged tissue eosinophilia. Conclusions: These findings indicate that the CCL26-CX3CR1 pathway is pivotal in resolving eosinophilic allergic lung inflammation.

Complement C1q essential for aeroallergen sensitization via CSF1R+ conventional dendritic cells type 2.

BACKGROUND: Dendritic cells (DCs) are heterogeneous, comprising multiple subsets with unique functional specifications. Our previous work has demonstrated that the specific conventional type 2 DC subset, CSF1R+cDC2s, plays a critical role in sensing aeroallergens. OBJECTIVE: It remains to be understood how CSF1R+cDC2s recognize inhaled allergens. We sought to elucidate the transcriptomic programs and receptor-ligand interactions essential for function of this subset in allergen sensitization. METHODS: We applied single-cell RNA sequencing to mouse lung DCs. Conventional DC-selective knockout mouse models were employed, and mice were subjected to inhaled allergen sensitization with multiple readouts of asthma pathology. Under the clinical arm of this work, human lung transcriptomic data were integrated with mouse data, and bronchoalveolar lavage (BAL) specimens were collected from subjects undergoing allergen provocation, with samples assayed for C1q. RESULTS: We found that C1q is selectively enriched in lung CSF1R+cDC2s, but not in other lung cDC2 or cDC1 subsets. Depletion of C1q in conventional DCs significantly attenuates allergen sensing and features of asthma. Additionally, we found that C1q binds directly to human dust mite allergen, and the C1q receptor CD91 (LRP1) is required for lung CSF1R+cDC2s to recognize the C1q-allergen complex and induce allergic lung inflammation. Lastly, C1q is enriched in human BAL samples following subsegmental allergen challenge, and human RNA sequencing data demonstrate close homology between lung IGSF21+DCs and mouse CSF1R+cDC2s. CONCLUSIONS: C1q is secreted from the CSF1R+cDC2 subset among conventional DCs. Our data indicate that the C1q-LRP1 axis represents a candidate for translational therapeutics in the prevention and suppression of allergic lung inflammation.

CSF-1R inhibitor PLX3397 attenuates peripheral and brain chronic GVHD and improves functional outcomes in mice.

Graft-versus-host disease (GVHD) is a serious complication of otherwise curative allogeneic haematopoietic stem cell transplants. Chronic GVHD induces pathological changes in peripheral organs as well as the brain and is a frequent cause of late morbidity and death after bone-marrow transplantation. In the periphery, bone-marrow-derived macrophages are key drivers of pathology, but recent evidence suggests that these cells also infiltrate into cGVHD-affected brains. Microglia are also persistently activated in the cGVHD-affected brain. To understand the involvement of these myeloid cell populations in the development and/or progression of cGVHD pathology, we here utilized the blood-brain-barrier permeable colony stimulating factor-1 receptor (CSF-1R) inhibitor PLX3397 (pexidartinib) at varying doses to pharmacologically deplete both cell types. We demonstrate that PLX3397 treatment during the development of cGVHD (i.e., 30 days post-transplant) improves disease symptoms, reducing both the clinical scores and histopathology of multiple cGVHD target organs, including the sequestration of T cells in cGVHD-affected skin tissue. Cognitive impairments associated with cGVHD and neuroinflammation were also attenuated by PLX3397 treatment. PLX3397 treatment prior to the onset of cGVHD (i.e., immediately post-transplant) did not change in clinical scores or histopathology. Overall, our data demonstrate significant benefits of using PLX3397 for the treatment of cGVHD and associated organ pathologies in both the periphery and brain, highlighting the therapeutic potential of pexidartinib for this condition.

Prevalence and Related Factors of Depression Before and During the COVID-19 Pandemic: Findings From the Korea National Health and Nutrition Examination Survey.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has greatly altered the daily lives of people in unprecedented ways, causing a variety of mental health problems. In this study, we aimed to evaluate the prevalence of depression among Korean adults during the COVID-19 pandemic and explore the factors associated with depressive mood using data from the Korea National Health and Nutrition Survey (KNHANES). METHODS: We analyzed participants aged ≥ 19 years from KNHANES 2018 (n = 5,837) and 2020 (n = 5,265) to measure and compare the prevalence of depression before and during the COVID-19 pandemic. Depression was defined as a score ≥ 10 on the Patient Health Questionnaire-9. Furthermore, we performed a multivariate logistic regression analysis to investigate the independent predictors of depressive mood during the COVID-19 pandemic. RESULTS: The prevalence of depression was notably higher during the COVID-19 pandemic than in the pre-pandemic period (5.2% vs. 4.3%, P = 0.043). In a multivariate model, female sex (adjusted odds ratio [aOR], 1.63; 95% confidence interval [CI], 1.10-2.41), age < 50 years (19-29 years: aOR, 7.31; 95% CI, 2.40-22.21; 30-39 years: aOR, 7.38; 95% CI, 2.66-20.47; 40-49 years: aOR, 4.94; 95% CI, 1.84-13.31 compared to ≥ 80 years), unemployment (aOR, 2.00; 95% CI, 1.41-2.85), upper-middle class household income (aOR, 1.83; 95% CI, 1.18-2.85 compared to upper-class income), being a beneficiary of Medicaid (aOR, 2.35; 95% CI, 1.33-4.14), poor self-rated health (aOR, 4.99; 95% CI, 1.51-3.47 compared to good self-rated health), and current smoking (aOR, 2.29; 95% CI, 1.51-3.47) were found to be significant risk factors for depression during the pandemic. CONCLUSION: Depression was significantly more prevalent among Korean adults during the COVID-19 pandemic than in the pre-pandemic era. Therefore, more attention should be paid to individuals vulnerable to depression during pandemics. Implementing psychological support public policies and developing interventions to prevent the adverse outcomes of COVID-19-related depression should be considered.

Visual Aura in Non-Migraine Headaches: A Population Study.

BACKGROUND: Visual aura (VA) occurs mostly in migraine with aura (MA), but some case studies have reported aura in non-migraine headaches. Thus, information of VA in non-migraine headaches is scarce. Aim of this study was to investigate the prevalence and impact of VA in non-migraine headache and compare it with that of migraine headache. METHODS: This study was a nationwide population-based study. We used an internet-based headache diagnosis questionnaire to diagnose headache, and various modules to evaluate clinical features and comorbidities of participants with headache. We defined migraine headache as migraine and probable migraine (PM), whereas non-migraine headache was defined as a headache but not migraine or PM. VA was defined as a self-reporting VA rating scale score ≥ 3. RESULTS: Of the 3,030 participants, 1,431 (47.2%) and 507 (16.7%) had non-migraine headache and migraine headache, respectively. VA prevalence was much lower in the non-migraine headache group than in the migraine headache group (14.5% [207/1,431] vs. 26.0% [132/507], P < 0.001). In subjects with non-migraine headache, those with VA had a markedly higher number of headache days per 30 days (median [25th-75th percentiles]: 2.0 [1.0-5.0] vs. 2.0 [1.0-3.0], P < 0.001), and headache-related disability (6.0 [3.0-16.0] vs. 2.0 [0.0-7.0], P < 0.001) than those without VA. VA prevalence did not differ significantly according to age and sex. CONCLUSION: Non-migraine headache with VA patients had more severe symptoms than those without VA. These findings may improve the understanding of VA and the management of individuals with non-migraine headache.

Prevalence and associated factors of premature discontinuation of antiplatelet therapy after ischemic stroke: a nationwide population-based study.

BACKGROUND: We tried to evaluate the prevalence of premature discontinuation of antiplatelets and its affecting factors after ischemic stroke using large-sized representative national claims data. METHODS: Patients aged 20 years or older with newly confirmed ischemic stroke who started aspirin or clopidogrel for the first time were selected from 2003 to 2010 National Health Insurance Service-National Sample Cohort (NHIS-NSC) of South Korea (n = 4621), a randomly collected sample which accounts for 2.2% (n = 1,017,468) of total population (n = 46,605,433). The prevalence of discontinuation of antiplatelets was measured every 6 months until the 24 months since the first prescription. Then we classified the participants into 2 groups according to the discontinuation status at 12 months and assessed the factors influencing premature discontinuation of antiplatelets within 12 months. RESULTS: Among total participants, 35.5% (n = 1640) discontinued antiplatelets within 12 months and 58.5% (n = 2704) discontinued them within 24 months. The remaining 41.5% (n = 1917) continued them for 24 months or more. In the multivariate logistic regression analysis, initiating treatment with aspirin monotherapy [adjusted OR (aOR), 2.66, 95% CI 2.17-3.25] was the most prominent determinant of premature discontinuation within 12 months followed by CCI score ≥ 6 (aOR 1.50, 95% CI 1.31-1.98), and beginning treatment with clopidogrel monotherapy (aOR 1.41, 95% CI 1.15-1.72). Rural residency (aOR 1.36, 95% CI 1.14-1.62), < 4 total prescribed drugs (aOR 1.24, 95% CI 1.05-1.47), lower income (aOR 1.20, 95% CI 1.03-1.40 for middle income class and OR 1.21, 95% CI 1.02-1.45 for low income class), and ages ≥70 years (aOR 1.15, 95% CI 1.00-1.31) were also significantly associated with premature discontinuation of antiplatelets within 12 months. CONCLUSIONS: The prevalence of premature discontinuation of antiplatelets after ischemic stroke was quite high. Thus, by understanding factors associated with premature discontinuation, a more strategic approach is required for the physicians to improve persistence with antiplatelets.

Prevalence, awareness, treatment, and control of dyslipidemia among diabetes mellitus patients and predictors of optimal dyslipidemia control: results from the Korea National Health and Nutrition Examination Survey.

BACKGROUND: This study aimed to investigate the prevalence, awareness, treatment, and control rates of dyslipidemia and identify the predictors of optimal control (low-density lipoprotein cholesterol < 100 mg/dL) among patients with diabetes mellitus (DM). METHODS: A cross-sectional study was conducted using the representative Korea National Health and Nutrition Examination Survey (2014-2018). Overall, 4311 patients with DM, aged ≥19 years, and without cardiovascular diseases were selected, and the prevalence, awareness, treatment, and control rates of dyslipidemia were calculated. Univariate and multivariate logistic regression analyses were conducted to evaluate the factors influencing the optimal control of dyslipidemia. RESULTS: Dyslipidemia was prevalent in 83.3% of patients with DM, but the awareness and treatment rates were 36.5 and 26.9%, respectively. The control rate among all patients with dyslipidemia was 18.8%, whereas it was 61.1% among those being treated. Prevalence and awareness rates were also significantly higher in women than in men. Dyslipidemia was most prevalent in those aged 19-39 years, but the rates of awareness, treatment, and control among all patients with dyslipidemia in this age group were significantly lower than those in other age groups. The predictors of optimal control were age ≥ 40 years [range 40-49 years: adjusted odds ratio (aOR) 3.73, 95% confidence interval (CI) 1.43-9.72; 50-59 years: aOR 6.25, 95% CI 2.50-15.65; 60-69 years: aOR 6.96, 95% CI 2.77-17.44; 70-79 years: aOR 9.21, 95% CI 3.58-23.74; and ≥ 80 years: aOR 4.43, 95% CI 1.60-12.27]; urban living (aOR 1.44, 95% CI 1.15-1.80); higher body mass index (aOR 1.27, 95% CI 1.13-1.42); lower glycated hemoglobin levels (aOR 0.71, 95% CI 0.67-0.76); hypertension (aOR 1.53, 95% CI 1.22-1.92); poorer self-rated health status (aOR 0.72, 95% CI 0.62-0.84); and receiving regular health check-ups (aOR 1.58, 95% CI 1.25-2.00). CONCLUSIONS: Most patients with DM were diagnosed with dyslipidemia, but many were unaware of or untreated for their condition. Therefore, their control rate was suboptimal. Thus, by understanding factors influencing optimal control of dyslipidemia, physicians should make more effort to encourage patients to undergo treatment and thus, adequately control their dyslipidemia.

Effect of antiplatelet persistence on long-term mortality and predictors of non-persistence in ischemic stroke patients 75 years and older: a nationwide cohort study.

BACKGROUND: We aimed to provide real-world evidence on the benefit of persistence with antiplatelet therapy (APT) on long-term all-cause mortality (ACM) in ischemic stroke patients aged 75 years and older. METHODS: Newly diagnosed ischemic stroke patients aged 75 years and older who initiated aspirin or clopidogrel for the first time were chosen from 2003 to 2010 National Health Insurance Service-National Sample Cohort (NHIS-NSC) of Korea (n = 887), a random cohort sample accounting for 2.2% (n = 1,017,468) of total population (n = 46,605,433). Then subjects were divided into persistent (n = 556) and non-persistent (n = 321) groups according to the persistent status at 6 months. Survivor analysis was performed between the two groups and predictors of non-persistence were analyzed by multivariate logistic regression analysis. Patients were followed up until death or December 31, 2013. RESULTS: Non-persistence with APT was significantly associated with increased risk of ACM (adjusted hazard ration [aHR] 2.13, 95% confidence interval [CI] 1.72-2.65), cerebro-cardiovascular disease (CVD) mortality (aHR 2.26, 95% CI 1.57-3.24), and non-CVD mortality (aHR 2.06, 95% CI 1.5702.70). More comorbidities (Charlson comorbidity index score ≥ 6) (adjusted odds ratio [aOR], 2.56, 95% CI 1.43-4.55), older age (aOR 1.52, 95% CI 1.11-2.09 for 80-84 years, aOR 1.73, 95% CI 1.17-2.57 for ≥85 years), and less than 4 total prescribed drugs (aOR 1.54, 95% CI 1.08-2.21) were independent predictors of non-persistence. CONCLUSIONS: Persistent with APT after ischemic stroke featured long-term mortality benefit even in patients aged 75 years and older. Thus, improving APT persistence for ischemic stroke patients in this age group is also recommended by understanding factors associated with non-persistence.

Colony-stimulating factor 1 and its receptor are new potential therapeutic targets for allergic asthma.

BACKGROUND: A new approach targeting aeroallergen sensing in the early events of mucosal immunity could have greater benefit. The CSF1-CSF1R pathway has a critical role in trafficking allergens to regional lymph nodes through activating dendritic cells. Intervention in this pathway could prevent allergen sensitization and subsequent Th2 allergic inflammation. OBJECTIVE: To examine the therapeutic effectiveness of CSF1 and CSF1R inhibition for blocking the dendritic cell function of sensing aeroallergens. METHODS: We adopted a model of chronic asthma induced by a panel of three naturally occurring allergens and novel delivery system of CSF1R inhibitor encapsulated nanoprobe. RESULTS: Selective depletion of CSF1 in airway epithelial cells abolished the production of allergen-reactive IgE, resulting in prevention of new asthma development as well as reversal of established allergic lung inflammation. CDPL-GW nanoprobe containing GW2580, a selective CSF1R inhibitor, showed favorable pharmacokinetics for inhalational treatment and intranasal insufflation delivery of CDPL-GW nanoprobe ameliorated asthma pathologies including allergen-specific serum IgE production, allergic lung and airway inflammation and airway hyper-responsiveness (AHR) with minimal pulmonary adverse reaction. CONCLUSION: The inhibition of the CSF1-CSF1R signaling pathway effectively suppresses sensitization to aeroallergens and consequent allergic lung inflammation in a murine model of chronic asthma. CSF1R inhibition is a promising new target for the treatment of allergic asthma.

Sympathoexcitation following intermittent hypoxia in rat is mediated by circulating angiotensin II acting at the carotid body and subfornical organ.

KEY POINTS: In anaesthetized rats, acute intermittent hypoxia increases sympathetic nerve activity, sympathetic peripheral chemoreflex sensitivity and central sympathetic-respiratory coupling. Renin-angiotensin system inhibition prevents the sympathetic effects of intermittent hypoxia, with intermittent injections of angiotensin II into the systemic circulation replicating these effects. Bilateral carotid body denervation reduces the sympathetic effects of acute intermittent hypoxia and eliminates the increases in chemoreflex sensitivity and sympathetic-respiratory coupling. Pharmacological inhibition of the subfornical organ also reduces the sympathetic effects of acute intermittent hypoxia, although it has no effect on the increases in chemoreflex sensitivity and central sympathetic-respiratory coupling. Combining both interventions eliminates the sympathetic effects of both intermittent hypoxia and angiotensin II. ABSTRACT: Circulating angiotensin II (Ang II) is vital for arterial pressure elevation following intermittent hypoxia in rats, although its importance in the induction of sympathetic changes is unclear. We tested the contribution of the renin-angiotensin system to the effects of acute intermittent hypoxia (AIH) in anaesthetized and ventilated rats. There was a 33.7 ± 2.9% increase in sympathetic nerve activity (SNA), while sympathetic chemoreflex sensitivity and central sympathetic-respiratory coupling increased by one-fold following AIH. The sympathetic effects of AIH were prevented by blocking angiotensin type 1 receptors with systemic losartan. Intermittent systemic injections of Ang II (Int.Ang II) elicited similar sympathetic responses to AIH. To identify the neural pathways responsible for the effects of AIH and Int.Ang II, we performed bilateral carotid body denervation, which reduced the increase in SNA by 56% and 45%, respectively. Conversely, pharmacological inhibition of the subfornical organ (SFO), an established target of circulating Ang II, reduced the increase in SNA following AIH and Int.Ang II by 65% and 59%, respectively, although it did not prevent the sensitization of the sympathetic peripheral chemoreflex, nor the increase in central sympathetic-respiratory coupling. Combined carotid body denervation and inhibition of the SFO eliminated the enhancement of SNA following AIH and Int.Ang II. Repeated systemic injections of phenylephrine caused an elevation in SNA similar to AIH, and this effect was prevented by a renin inhibitor, aliskiren. Our findings show that the sympathetic effects of AIH are the result of RAS-mediated activations of the carotid bodies and the SFO.

IL-11 facilitates a novel connection between RA joint fibroblasts and endothelial cells.

IL-11 has been detected in inflamed joints; however, its role in the pathogenesis of arthritis is not yet clear. Studies were conducted to characterize the expression and functional significance of IL-11 and IL-11Rα in rheumatoid arthritis (RA). IL-11 levels were elevated in RA synovial fluid (SF) compared to osteoarthritis (OA) SF and plasma from RA, OA and normal individuals (NLs). Morphologic studies established that IL-11 was detected in lining fibroblasts and macrophages in addition to sublining endothelial cells and macrophages at higher levels in RA compared to NL synovial tissues. Since IL-11Rα was exclusively expressed in RA fibroblasts and endothelial cells, macrophages were not involved in IL-11 effector function. Ligation of IL-11 to IL-11Rα strongly provoked fibroblast infiltration into RA joint, while cell proliferation was unaffected by this process. Secretion of IL-8 and VEGF from IL-11 activated RA fibroblasts was responsible for the indirect effect of IL-11 on endothelial cell transmigration and tube formation. Moreover, IL-11 blockade impaired RA SF capacity to elicit endothelial cell transmigration and tube formation. We conclude that IL-11 binding to endothelial IL-11Rα can directly induce RA angiogenesis. In addition, secretion of proangiogenic factors from migrating fibroblasts potentiated by IL-11 can indirectly contribute to RA neovascularization.

Differential impact of obesity on the pathogenesis of RA or preclinical models is contingent on the disease status.

OBJECTIVE: Studies were performed to uncover the significance of obesity in rheumatoid arthritis (RA) and preclinical models. METHODS: Preclinical arthritis models were used to examine the impact of obesity on disease onset and remission. Conditioned media from RA adipose tissues were used to investigate the mechanism contributing to joint neutrophil influx and M1 macrophage differentiation observed in early and remission phases of arthritis. RESULTS: We report that mice fed with high fat diet (HFD) have an earlier onset of collagen-induced arthritis (CIA) compared with mice on regular diet. However, the differences in CIA joint swelling between the two diet groups are lost once disease is established. We found that early arthritis triggered by obesity is due to elevated joint MIP2/interleukin-8 levels detected in CIA as well as in the RA and mouse adipose tissues and the effect of this chemokine on neutrophil recruitment. Although active disease progression is similarly affected in both diet groups, arthritis resolution is accelerated in lean mice while joint inflammation is sustained in obese mice. We document that HFD can prolong toll-like receptor (TLR)4-induced arthritis by increasing joint monocyte migration and further remodelling the recruited cells into M1 macrophages. Consistently, we show that adipose condition media can transform RA and wild-type naïve myeloid cells into M1 macrophages; however, this function is impaired by TLR4 blockade or deficiency. CONCLUSIONS: We conclude that despite established disease being unaffected by obesity, the early and the resolution phases of RA are impacted by obesity through different mechanisms.

Effects of Partial Absence of Visual Feedback Information on Gait Symmetry.

The incorporation of real-time visual feedback during gait rehabilitation can improve the efficacy of training. Our prior work demonstrated that the imposed distortion of simple visual feedback information of step lengths entails an unintentional adaptive process in the subjects' spatial gait pattern, thereby suggesting the important role of implicit learning in the context of gait rehabilitation that employs visual feedback. The purpose of this study was to investigate whether the removal of a portion of visual feedback information-after it had initially been provided-had any impact on gait symmetry. Eighteen healthy subjects walked on a treadmill for 10-min periods at their preferred walking speed and at a slower walking speed (1.3 mph) during the experimental trials, in which two simple vertical bars corresponding to subject's right and left step length were displayed on a computer screen. Halfway through the trial, one of the bars was removed from the visual feedback via random selection. Subjects were instructed to continually walk normally and also look at the visual feedback until the trials were completed. The changes in step length symmetry ratio were computed and analyzed. We found that displaying only one side of visual feedback influenced subjects to spontaneously modulate gait symmetry away from the baseline, and also that the amount of modulated gait symmetry slightly increased when their walking speed decreased. The changes in gait symmetry occurred by producing either longer right steps produced than left steps or vice versa, but we were unable to find any correlation between side of removal (right or left side) and the different types of trend in response. This warrants further investigation in a study with a larger population. Nonetheless, the results of this study demonstrated the effect of partial absence of visual feedback on changes in step symmetry, and that the perturbation of visual information caused implicit (unintentional) motor processes. A gait training procedure involving a novel way of perturbing visual feedback, such as partial absence of visual feedback tested in this study, may be of value in gait rehabilitation by driving more efficient motor adaptations.

Intrathecal Intermittent Orexin-A Causes Sympathetic Long-Term Facilitation and Sensitizes the Peripheral Chemoreceptor Response to Hypoxia in Rats.

Intermittent hypoxia causes a persistent increase in sympathetic nerve activity (SNA), which progresses to hypertension in conditions such as obstructive sleep apnea. Orexins (A and B) are hypothalamic neurotransmitters with arousal-promoting and sympathoexcitatory effects. We investigated whether the sustained elevation of SNA, termed sympathetic long-term facilitation, after acute intermittent hypoxia (AIH) is caused by endogenous orexin acting on spinal sympathetic preganglionic neurons. The role of orexin in the increased SNA response to AIH was investigated in urethane-anesthetized, vagotomized, and artificially ventilated Sprague-Dawley rats (n = 58). A spinally infused subthreshold dose of orexin-A (intermittent; 0.1 nmol × 10) produced long-term enhancement in SNA (41.4% ± 6.9%) from baseline. This phenomenon was not produced by the same dose of orexin-A administered as a bolus intrathecal infusion (1 nmol; 7.3% ± 2.3%). The dual orexin receptor blocker, Almorexant, attenuated the effect of sympathetic long-term facilitation generated by intermittent orexin-A (20.7% ± 4.5% for Almorexant at 30 mg∙kg(-1) and 18.5% ± 1.2% for 75 mg∙kg(-1)), but not in AIH. The peripheral chemoreflex sympathoexcitatory response to hypoxia was greatly enhanced by intermittent orexin-A and AIH. In both cases, the sympathetic chemoreflex sensitization was reduced by Almorexant. Taken together, spinally acting orexin-A is mechanistically sufficient to evoke sympathetic long-term facilitation. However, AIH-induced sympathetic long-term facilitation appears to rely on mechanisms that are independent of orexin neurotransmission. Our findings further reveal that the activation of spinal orexin receptors is critical to enhance peripheral chemoreceptor responses to hypoxia after AIH.

Ligation of TLR5 promotes myeloid cell infiltration and differentiation into mature osteoclasts in rheumatoid arthritis and experimental arthritis.

Our aim was to examine the impact of TLR5 ligation in rheumatoid arthritis (RA) and experimental arthritis pathology. Studies were conducted to investigate the role of TLR5 ligation on RA and mouse myeloid cell chemotaxis or osteoclast formation, and in addition, to uncover the significance of TNF-α function in TLR5-mediated pathogenesis. Next, the in vivo mechanism of action was determined in collagen-induced arthritis (CIA) and local joint TLR5 ligation models. Last, to evaluate the importance of TLR5 function in RA, we used anti-TLR5 Ab therapy in CIA mice. We show that TLR5 agonist, flagellin, can promote monocyte infiltration and osteoclast maturation directly through myeloid TLR5 ligation and indirectly via TNF-α production from RA and mouse cells. These two identified TLR5 functions are potentiated by TNF-α, because inhibition of both pathways can more strongly impair RA synovial fluid-driven monocyte migration and osteoclast differentiation compared with each factor alone. In preclinical studies, flagellin postonset treatment in CIA and local TLR5 ligation in vivo provoke homing and osteoclastic development of myeloid cells, which are associated with the TNF-α cascade. Conversely, CIA joint inflammation and bone erosion are alleviated when TLR5 function is blocked. We found that TLR5 and TNF-α pathways are interconnected, because TNF-α is produced by TLR5 ligation in RA myeloid cells, and anti-TNF-α therapy can markedly suppress TLR5 expression in RA monocytes. Our novel findings demonstrate that a direct and an indirect mechanism are involved in TLR5-driven RA inflammation and bone destruction.

Regulation of IGFBP-2 expression during fasting.

Insulin-like growth factor (IGF)-binding protein-2 (IGFBP-2), one of the most abundant circulating IGFBPs, is known to attenuate the biological action of IGF-1. Although the effect of IGFBP-2 in preventing metabolic disorders is well known, its regulatory mechanism remains unclear. In the present study, we demonstrated the transcriptional regulation of the Igfbp-2 gene by peroxisome-proliferator-activated receptor (PPAR) α in the liver. During fasting, both Igfbp-2 and PPARα expression levels were increased. Wy14643, a selective PPARα agonist, significantly induced Igfbp-2 gene expression in primary cultured hepatocytes. However, Igfbp-2 gene expression in Pparα null mice was not affected by fasting or Wy14643. In addition, through transient transfection and chromatin immunoprecipitation assay in fasted livers, we determined that PPARα bound to the putative PPAR-responsive element between -511 bp and -499 bp on the Igfbp-2 gene promoter, indicating that the Igfbp-2 gene transcription is activated directly by PPARα. To explore the role of PPARα in IGF-1 signalling, we treated primary cultured hepatocytes with Wy14643 and observed a decrease in the number of IGF-1 receptors (IGF-1Rs) and in Akt phosphorylation. No inhibition was observed in the hepatocytes isolated from Pparα null mice. These results suggest that PPARα controls IGF-1 signalling through the up-regulation of hepatic Igfbp-2 transcription during fasting and Wy14643 treatment.

Melatonin ameliorates ER stress-mediated hepatic steatosis through miR-23a in the liver.

The endoplasmic reticulum (ER) stress induces hepatic steatosis and inflammation in the liver. Although melatonin ameliorates ER stress-target genes, it remains unknown whether melatonin protects against hepatic steatosis as well as inflammation through regulation of miRNA. MicroRNAs have been identified as pivotal regulators in the field of gene regulation and their dysfunctions are a common feature in a variety of metabolic diseases. Especially, among miRNAs, miR-23a has been shown to regulate ER stress. Herein, we investigated the crucial roles of melatonin in hepatic steatosis and inflammation in vivo. Tunicamycin challenge caused increase of hepatic triglyceride and intracellular calcium levels through activation of ER stress, whereas these phenomena were partially disrupted by melatonin. We also demonstrated that expression of miR-23a stimulated with tunicamycin was rescued by melatonin treatment, resulting in reduced ER stress in primary hepatocytes. Overall, these results suggest a new function of melatonin that is involved in ameliorating ER stress-induced hepatic steatosis and inflammation by attenuating miR-23a. Melatonin may be useful as a pharmacological agent to protect against hepatic metabolic diseases due to its ability to regulate expression of miR-23a.