Downregulation of TREM2 expression exacerbates neuroinflammatory responses through TLR4-mediated MAPK signaling pathway in a transgenic mouse model of Alzheimer's disease.

Activation of glial cells and neuroinflammation play an important role in the onset and development of Alzheimer's disease (AD). Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglia-specific receptor in the brain that is involved in regulating neuroinflammation. However, the precise effects of TREM2 on neuroinflammatory responses and its underlying molecular mechanisms in AD have not been studied in detail. Here, we employed a lentiviral-mediated strategy to downregulation of TREM2 expression on microglia in the brain of APPswe/PS1dE9 (APP/PS1) transgenic mice and BV2 cells. Our results showed that downregulation of TREM2 significantly aggravated AD-related neuropathology including Aß accumulation, peri-plaque microgliosis and astrocytosis, as well as neuronal and synapse-associated proteins loss, which was accompanied by a decline in cognitive ability. The further mechanistic study revealed that downregulation of TREM2 expression initiated neuroinflammatory responses through toll-like receptor 4 (TLR4)-mediated mitogen-activated protein kinase (MAPK) signaling pathway and subsequent stimulating the production of pro-inflammatory cytokines in vivo and in vitro. Moreover, blockade of p38, JNK, and ERK1/2 inhibited the release of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) induced by Aß1-42 in TREM2-knocked down BV2 cells. Taken together, these findings indicated that TREM2 might be a potential therapeutic target for AD and other neuroinflammation-related diseases.

Hepatitis C Virus Subtypes Novel 6g-Related Subtype and 6w Could Be Indigenous in Southern Taiwan with Characteristic Geographic Distribution.

Hepatitis C virus (HCV) genotype (GT) 6 is the most genetically diverse GT and mainly distributed in Southeast Asia and south China but not Taiwan. Earlier studies showed the major HCV GTs in Taiwan were GT 1b and 2 with very rare GT 6 except in injection drug users (IDUs), and subtype 6a is the main GT 6 subtype among IDUs. Recently, we reported a much higher prevalence (18.3%) of GT 6 in Tainan City, southern Taiwan. This study was designed to clarify the subtypes of GT 6 in this endemic area. A total of 3022 (1343 men and 1679 women) HCV viremic patients were enrolled. Subtypes of GT 6 were determined by sequencing of core/E1 and nonstructural protein 5B in 322 of 518 GT 6 patients. The overall GT 6 prevalence rate was 17.1% (518/3022), with higher prevalence districts (>25%) located in northern Tainan. A novel 6g-related subtype is the most prevalent subtype (81.0%), followed by 6w (10.8%), 6a (7.5%), and 6n (0.7%). The high GT 6 prevalence in Tainan was mainly due to a novel 6g-related subtype and 6w. These two subtypes could be indigenous in Tainan with characteristic geographic distribution.

Tanshinone IIA attenuates neuroinflammation via inhibiting RAGE/NF-κB signaling pathway in vivo and in vitro.

BACKGROUND: Glial activation and neuroinflammation play a crucial role in the pathogenesis and development of Alzheimer's disease (AD). The receptor for advanced glycation end products (RAGE)-mediated signaling pathway is related to amyloid beta (Aß)-induced neuroinflammation. This study aimed to investigate the neuroprotective effects of tanshinone IIA (tan IIA), a natural product isolated from traditional Chinese herbal Salvia miltiorrhiza Bunge, against Aß-induced neuroinflammation, cognitive impairment, and neurotoxicity as well as the underlying mechanisms in vivo and in vitro. METHODS: Open-field test, Y-maze test, and Morris water maze test were conducted to assess the cognitive function in APP/PS1 mice. Immunohistochemistry, immunofluorescence, thioflavin S (Th-S) staining, enzyme-linked immunosorbent assay (ELISA), real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and western blotting were performed to explore Aß deposition, synaptic and neuronal loss, microglial and astrocytic activation, RAGE-dependent signaling, and the production of pro-inflammatory cytokines in APP/PS1 mice and cultured BV2 and U87 cells. RESULTS: Tan IIA treatment prevented spatial learning and memory deficits in APP/PS1 mice. Additionally, tan IIA attenuated Aß accumulation, synapse-associated proteins (Syn and PSD-95) and neuronal loss, as well as peri-plaque microgliosis and astrocytosis in the cortex and hippocampus of APP/PS1 mice. Furthermore, tan IIA significantly suppressed RAGE/nuclear factor-κB (NF-κB) signaling pathway and the production of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1ß) in APP/PS1 mice and cultured BV2 and U87 cells. CONCLUSIONS: Taken together, the present results indicated that tan IIA improves cognitive decline and neuroinflammation partly via inhibiting RAGE/NF-κB signaling pathway in vivo and in vitro. Thus, tan IIA might be a promising therapeutic drug for halting and preventing AD progression.

Silencing of LRP1 Exacerbates Inflammatory Response Via TLR4/NF-κB/MAPKs Signaling Pathways in APP/PS1 Transgenic Mice.

Activation of glial cells (including microglia and astrocytes) appears central to the initiation and progression of neuroinflammation in Alzheimer's disease (AD). The low-density lipoprotein receptor-related protein 1 (LRP1) is a major receptor for amyloid-ß (Aß), which plays a critical role in AD pathogenesis. LRP1 regulates inflammatory response by modulating the release of pro-inflammatory cytokines and phagocytosis. However, the effects of LRP1 on microglia- and astrocytic cell-mediated neuroinflammation and their underlying mechanisms in AD remain unclear. Therefore, using APP/PS1 transgenic mice, we found that LRP1 is downregulated during disease progression. Silencing of brain LRP1 markedly exacerbated AD-related neuropathology including Aß deposition, neuroinflammation, and synaptic and neuronal loss, which was accompanied by a decline in spatial cognitive ability. Further mechanistic study revealed that silencing of LRP1 initiated neuroinflammation by increasing microgliosis and astrogliosis, enhancing pro-inflammatory cytokine production, and regulating toll-like receptor 4 (TLR4)-mediated activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Taken together, these findings indicated that LRP1 suppresses microglia and astrocytic cell activation by modulating TLR4/NF-κB/MAPK signaling pathways. Our results further provide insights into the role of LRP1 in AD pathogenesis and highlight LRP1 as a potential therapeutic target for the treatment of AD.

Site-specific mortality in native joint septic arthritis: a national population study.

OBJECTIVE: This national cohort study investigated the incidence, site-specific mortality and prognostic factors of native septic arthritis (SA). METHODS: Tapping Taiwan's National Health Insurance Research Database, we identified inpatients with newly diagnosed SA between 1998 and 2012. They were categorized by site of infection and followed to calculate 30-day, 90-day and 1-year mortality. Predictors of mortality were calculated using Cox models. RESULTS: A total of 31 491 patients were identified as having SA, the most common site of infection being the knee (50.1%), followed by the hip (14.4%), other sites (26.8%), the shoulder (5.5%) and multiple sites (1.2%). Knee joint involvement was the most common site for all subgroups. Incidence increased from 9.8/105 in 1998 to 13.3/105 in 2012. The 30-day, 90-day and 1-year mortality rates were 4.3, 8.6 and 16.4% respectively. Predictors for mortality were hip infection, shoulder infection, multiple-site infection, being male, age ≥65 years old and comorbidities. We derived a mortality scoring model over age/SA site/comorbidity, and age ≥65 years old had the greatest risk contribution to mortality. No matter whether 1-month, 3-month or 1-year mortality was being considered, patients with the higher risk scores had the higher mortality rates (P < 0.0001). CONCLUSION: SA is an emerging infectious disease with a rising incidence, long duration of hospital stay and high mortality rate. The most common affected joint was knee for all subgroups. Patients aged ≥65 years old had a high SA incidence and the greatest risk contribution.

Effect of Chronic Pancreatitis on Complications and Mortality in DM Patients: A 10-year Nationwide Cohort Study.

CONTEXT: Chronic pancreatitis (CP), is a long-term inflammation of the pancreatic parenchyma, and might increase risk of a hyperglycemia crisis or hypoglycemia in patients with diabetes mellitus (DM); however, the relationship has not been previously investigated. OBJECTIVE: To investigate the risk of diabetic ketoacidosis (DKA), hyperglycemic hyperosmolar state (HHS), hypoglycemia, and long-term outcomes in DM patients with CP. DESIGN: A population-based cohort study. SETTING AND PARTICIPANTS: Tapping Taiwan's National Health Insurance Research Database, we identified 506 DM patients with newly diagnosed CP from 1999 to 2010 and created a control cohort consisting of 5060 age- and sex-matched DM patients without CP from the same time period. We followed those 2 cohorts from the index date to occurrence of outcomes, the date of death or 31 December 2012. MAIN OUTCOME MEASURES: DKA, HHS, hypoglycemia and mortality. RESULTS: DM patients with CP, who were predominantly male (88%) and younger (60% < 45 years old), had a 9.5-, 5.0-, and 3.0-fold higher risk for DKA (95% confidence interval [CI]: 6.51-13.91), HHS (95% CI: 2.85-8.62), and hypoglycemia (95% CI: 2.23-4.08), respectively. They also had lower 1-, 5-, and 10-year cumulative survival rates (98.4% vs 99.0%, 87.7% vs 96.6%, and 78.7% vs 93.6%, respectively) (log-rank test: P < .001), and a 2.43-fold higher risk for death (HR: 2.43, 95% CI: 1.82-3.27). CONCLUSIONS: In Taiwan, DM patients with CP have a higher incidence of DKA, HHS, hypoglycemia, and mortality. More attention is needed for preventing hyperglycemia crisis and hypoglycemia prevention in this population.

Tanshinone IIA ameliorates cognitive deficits by inhibiting endoplasmic reticulum stress-induced apoptosis in APP/PS1 transgenic mice.

Our previous data indicated that tanshinone IIA (tan IIA) improves learning and memory in a mouse model of Alzheimer's disease (AD) induced by streptozotocin via restoring cholinergic function, attenuating oxidative stress and blocking p38 MAPK signal pathway activation. This study aims to estimate whether tan IIA inhibits endoplasmic reticulum (ER) stress-induced apoptosis to prevent cognitive decline in APP/PS1 transgenic mice. Tan IIA (10 mg/kg and 30 mg/kg) was intraperitoneally administered to the six-month-old APP/PS1 mice for 30 consecutive days. ß-amyloid (Aß) plaques were measured by immunohistochemisty and Thioflavin S staining, apoptotic cells were observed by TUNEL, ER stress markers and apoptosis signaling proteins were investigated by western blotting and RT-PCR. Our results showed that tan IIA significantly ameliorates cognitive deficits and improves spatial learning ability of APP/PS1 mice in the nest-building test, novel object recognition test and Morris water maze test. Furthermore, tan IIA significantly reduced the deposition of Aß plaques and neuronal apoptosis, and markedly prevented abnormal expression of glucose regulated protein 78 (GRP78), initiation factor 2α (eIF2α), inositol-requiring enzyme 1α (IRE1α), activating transcription factor 6 (ATF6), as well as suppressed the activation of C/EBP homologous protein (CHOP) and c-Jun N-terminal kinase (JNK) pathways in the parietal cortex and hippocampus. Moreover, tan IIA induced an up-regulation of the Bcl-2/Bax ratio and down-regulation of caspase-3 protein activity. Taken together, the above findings indicated that tan IIA improves learning and memory through attenuating Aß plaques deposition and inhibiting ER stress-induced apoptosis. These results suggested that tan IIA might become a promising therapeutic candidate drug against AD.

Epidemiology and outcome of acute pancreatitis in end-stage renal disease dialysis patients: a 10-year national cohort study.

BACKGROUND: The objective of this study is to determine the incidence and severity of acute pancreatitis (AP) in patients with end-stage renal disease (ESRD) on dialysis and whether the dialysis modality [hemodialysis (HD) versus peritoneal dialysis (PD)] confers a higher risk for AP as well as complications or mortality related to AP. METHODS: We analyzed national health insurance claims data of 67 078 ESRD patients initiating dialysis between 1999 and 2007 in Taiwan. All patients were followed up from the start of their dialysis to first AP diagnosis, death, end of dialysis or 31 December 2008. Cox proportional hazards models were used to identify risk factors. RESULTS: The cumulative incidence rates of AP were 0.6, 1.7, 2.6, 3.4 and 4% at 1, 3, 5, 7 and 9 years, respectively. ESRD patients on HD and PD had an AP incidence of 5.11 and 5.86 per 1000 person-years, respectively. Independent risk factors for AP in this population were being elderly, being female, having biliary stones or liver disease, and being on PD. Severe AP occurred in 44.9% of the HD patients and in 36% of the PD patients. Patients with AP on HD had a higher incidence of upper gastrointestinal (UGI) bleeding than those on PD (P = 0.002). In contrast, those with AP on PD had a higher incidence of need for total parenteral nutrition (TPN) support than those on HD (P = 0.072). Overall in-hospital mortality was 8.1%. The risk factors for mortality after an AP attack were male gender, increased age, AP severity, and the presence of diabetes mellitus or liver disease. CONCLUSIONS: ESRD patients on PD were at higher risk for AP than those on HD. HD patients with AP attacks had a greater incidence of UGI bleeding and PD patients with AP attacks a more frequent need for TPN support.