Therapeutics for sickle cell disease intravascular hemolysis.

Sickle cell disease (SCD) is a genetic disorder predominantly affecting individuals of African descent, with a significant global health burden. SCD is characterized by intravascular hemolysis, driven by the polymerization of mutated hemoglobin within red blood cells (RBCs), leading to vascular inflammation, organ damage, and heme toxicity. Clinical manifestations include acute pain crises, hemolytic anemia, and multi-organ dysfunction, imposing substantial morbidity and mortality challenges. Current therapeutic strategies mitigate these complications by increasing the concentration of RBCs with normal hemoglobin via transfusion, inducing fetal hemoglobin, restoring nitric oxide signaling, inhibiting platelet-endothelium interaction, and stabilizing hemoglobin in its oxygenated state. While hydroxyurea and gene therapies show promise, each faces distinct challenges. Hydroxyurea's efficacy varies among patients, and gene therapies, though effective, are limited by issues of accessibility and affordability. An emerging frontier in SCD management involves harnessing endogenous clearance mechanisms for hemolysis products. A recent work by Heggland et al. showed that CD-36-like proteins mediate heme absorption in hematophagous ectoparasite, a type of parasite that feeds on the blood of its host. This discovery underscores the need for further investigation into scavenger receptors (e.g., CD36, SR-BI, SR-BII) for their possible role in heme uptake and detoxification in mammalian species. In this review, we discussed current SCD therapeutics and the specific stages of pathophysiology they target. We identified the limitations of existing treatments and explored potential future developments for novel SCD therapies. Novel therapeutic targets, including heme scavenging pathways, hold the potential for improving outcomes and reducing the global burden of SCD.

Relative Adrenal Insufficiency Is a Risk Factor for Pediatric Sepsis: A Proof-of-Concept Study.

Glucocorticoid (GC) therapy had been strongly recommended for pediatric sepsis (grade 1A). However, the recommendation was changed to grade 2C in 2020 due to weak evidence. About 32.8% of patients with pediatric septic develop relative adrenal insufficiency (RAI). But whether GC therapy should be determined by RAI status is controversial. This study utilized 21-day-old SF1CreSRBIfl/fl mice as the first pediatric RAI mouse model to assess the pathogenesis of RAI and evaluate GC therapy. RAI mice exhibited a substantially higher mortality rate in cecal ligation and puncture and cecal slurry-induced sepsis. These mice featured persistent inflammatory responses and were effectively rescued by GC therapy. RNA sequencing analysis revealed persistent inflammatory responses in RAI mice, caused by transcriptional dysregulation of AP-1 and NF-κB, and cytokine-induced secondary inflammatory response. Our findings support a precision medicine approach to guide GC therapy for pediatric patients based on the status of RAI.

Deficiency of Acute-Phase Serum Amyloid A Exacerbates Sepsis-Induced Mortality and Lung Injury in Mice.

Serum amyloid A (SAA) is a family of proteins, the plasma levels of which may increase >1000-fold in acute inflammatory states. We investigated the role of SAA in sepsis using mice deficient in all three acute-phase SAA isoforms (SAA-TKO). SAA deficiency significantly increased mortality rates in the three experimental sepsis mouse models: cecal ligation and puncture (CLP), cecal slurry (CS) injection, and lipopolysaccharide (LPS) treatments. SAA-TKO mice had exacerbated lung pathology compared to wild-type (WT) mice after CLP. A bulk RNA sequencing performed on lung tissues excised 24 h after CLP indicated significant enrichment in the expression of genes associated with chemokine production, chemokine and cytokine-mediated signaling, neutrophil chemotaxis, and neutrophil migration in SAA-TKO compared to WT mice. Consistently, myeloperoxidase activity and neutrophil counts were significantly increased in the lungs of septic SAA-TKO mice compared to WT mice. The in vitro treatment of HL-60, neutrophil-like cells, with SAA or SAA bound to a high-density lipoprotein (SAA-HDL), significantly decreased cellular transmigration through laminin-coated membranes compared to untreated cells. Thus, SAA potentially prevents neutrophil transmigration into injured lungs, thus reducing exacerbated tissue injury and mortality. In conclusion, we demonstrate for the first time that endogenous SAA plays a protective role in sepsis, including ameliorating lung injury.

The adrenal stress response is an essential host response against therapy-induced lethal immune activation.

Cytokine release syndrome (CRS) is a systemic inflammatory syndrome associated with infection- or drug-induced T cell activation and can cause multiple organ failure and even death. Because current treatments are ineffective in some patients with severe CRS, we set out to identify risk factors and mechanisms behind severe CRS that might lead to preventive therapies and better clinical outcomes in patients. In mice, we found that deficiency in the adrenal stress response-with similarities to such in patients called relative adrenal insufficiency (RAI)-conferred a high risk for lethal CRS. Mice treated with CD3 antibodies were protected against lethal CRS by the production of glucocorticoids (GC) induced by the adrenal stress response in a manner dependent on the scavenger receptor B1 (SR-BI), a receptor for high-density lipoprotein (HDL). Mice with whole-body or adrenal gland-specific SR-BI deficiency exhibited impaired GC production, more severe CRS, and increased mortality in response to CD3 antibodies. Pretreatment with a low dose of GC effectively suppressed the development of CRS and rescued survival in SR-BI-deficient mice without compromising T cell function through apoptosis. Our findings suggest that RAI may be a risk factor for therapy-induced CRS and that pretreating RAI patients with GC may prevent lethal CRS.

Phospholipids impact the protective effects of HDL-mimetic nanodiscs against lipopolysaccharide-induced inflammation.

Aim: The impacts of synthetic high-density lipoprotein (sHDL) phospholipid components on anti-sepsis effects were investigated. Methods: sHDL composed with ApoA-I mimetic peptide (22A) and different phosphatidylcholines were prepared and characterized. Anti-inflammatory effects were investigated in vitro and in vivo on lipopolysaccharide (LPS)-induced inflammation models. Results: sHDLs composed with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (22A-DMPC) most effectively neutralizes LPS, inhibits toll-like receptor 4 recruitment into lipid rafts, suppresses nuclear factor κB signaling and promotes activating transcription factor 3 activating. The lethal endotoxemia animal model showed the protective effects of 22A-DMPC. Conclusion: Phospholipid components affect the stability and fluidity of nanodiscs, impacting the anti-septic efficacy of sHDLs. 22A-DMPC presents the strongest LPS binding and anti-inflammatory effects in vitro and in vivo, suggesting a potential sepsis treatment.

Sepsis is triggered by endotoxins released by bacteria. These endotoxins trigger an exaggerated inflammatory response, leading to widespread inflammation and organ damage. Synthetic high-density lipoprotein (sHDL) is a potential treatment of sepsis by neutralizing endotoxins and regulating inflammatory responses. The phospholipid components of sHDL may affect the effectiveness of sHDL against sepsis. In this study, we prepared sHDLs with different phospholipids and compared their anti-septic effects on cells and in animal models. We found that sHDL made from DMPC presented the best anti-septic effects, possibly because DMPC-sHDL had the best fluidity at body temperature.

Replenishing HDL with synthetic HDL has multiple protective effects against sepsis in mice.

Sepsis is a major health issue with mortality exceeding 30% and few treatment options. We found that high-density lipoprotein cholesterol (HDL-C) abundance was reduced by 45% in septic patients compared to that in nonseptic patients. Furthermore, HDL-C abundance in nonsurviving septic patients was substantially lower than in those patients who survived. We therefore hypothesized that replenishing HDL might be a therapeutic approach for treating sepsis and found that supplementing HDL with synthetic HDL (sHDL) provided protection against sepsis in mice. In mice subjected to cecal ligation and puncture (CLP), infusing the sHDL ETC-642 increased plasma HDL-C amounts and improved the 7-day survival rate. Septic mice treated with sHDL showed improved kidney function and reduced inflammation, as indicated by marked decreases in the plasma concentrations of blood urea nitrogen (BUN) and the cytokines interleukin-6 (IL-6) and IL-10, respectively. We found that sHDL inhibited the ability of the endotoxins LPS and LPA to activate inflammatory pathways in RAW264.7 cells and HEK-Blue cells expressing the receptors TLR4 or TLR2 and NF-κB reporters. In addition, sHDL inhibited the activation of HUVECs by LPS, LTA, and TNF-α. Together, these data indicate that sHDL treatment protects mice from sepsis in multiple ways and that it might be an effective therapy for patients with sepsis.

Protein Glycosylation and Gut Microbiota Utilization Can Limit the In Vitro and In Vivo Metabolic Cellular Incorporation of Neu5Gc.

SCOPE: Red meat intake is reported to be correlated with chronic diseases. A potential causal factor is N-glycolylneuraminic acid (Neu5Gc) which metabolically incorporates into diverse glycoconjugates in humans. This study aims to investigate the impact of exposure to Neu5Gc-rich red meat on healthy cytidine-5'-monophospho-N-acetylneuraminic acid hydroxylase (Cmah) knock-out mice and the underlying mechanisms. METHODS AND RESULTS: CMAH-/- mice are fed Neu5Gc-rich diet for short-term (4 months) and long-term (10 months). Health status and levels of inflammatory cytokines are assessed. Caco-2 cells are used to investigate the intestinal absorption of Neu5Gc-containing glycoprotein, and in vitro fermentation is used to investigate the Neu5Gc utilization by gut microbiota. Neu5Gc-rich diets show neither measurable abnormality in physio-biochemical and inflammatory indexes nor observable alterations of liver tissue in mice. Glycosylation of lactoferrin limits its intestinal epithelial absorption, and the absorption of Neu5Gc attach onto glycoprotein is thus limited. Neu5Gc is also simultaneously utilized by microorganisms under simulated gut conditions. CONCLUSION: The results indicate that the long-term intake of Neu5Gc-rich red meat has no adverse effect on the health of CMAH-/- mice, which may be related to the limited absorption of Neu5Gc that is regulated by protein glycosylation, and the metabolism of Neu5Gc by gut microorganisms.

Relative adrenal insufficiency is a risk factor and endotype of sepsis - A proof-of-concept study to support a precision medicine approach to guide glucocorticoid therapy for sepsis.

Introduction: 25-60% of septic patients experience relative adrenal insufficiency (RAI) and glucocorticoid (GC) is frequently used in septic patients. However, the efficacy of GC therapy and whether GC therapy should be based on the status of RAI are highly controversial. Our poor understanding about the pathogenesis of RAI and a lack of RAI animal model present significant barriers to address these critical issues. Methods: Scavenger receptor BI (SR-BI) regulates stress-induced GC (iGC) production in response to stress. We generated SF1CreSR-BIfl/fl mice and utilized the mice as a RAI model to elucidate the pathogenesis of RAI and GC therapy in sepsis. SF1CreSR-BIfl/fl mice did not express SR-BI in adrenal gland and lacked iGC production upon ACTH stimulation, thus, they are RAI. Results and Discussion: RAI mice were susceptible to cecal ligation and puncture (CLP)-induced sepsis (6.7% survival in SF1CreSR-BIfl/fl mice versus 86.4% in SR-BIfl/fl mice; p = 0.0001). Compared to a well-controlled systemic inflammatory response in SR-BIfl/fl mice, SF1CreSR-BIfl/fl mice featured a persistent hyperinflammatory response. Supplementation of a low stress dose of GC to SF1CreSR-BIfl/fl mice kept the inflammatory response under control and rescued the mice. However, SR-BIfl/fl mice receiving GC treatment exhibited significantly less survival compared to SR-BIfl/fl mice without GC treatment. In conclusions, we demonstrated that RAI is a risk factor for death in this mouse model of sepsis. We further demonstrated that RAI is an endotype of sepsis, which features persistent hyperinflammatory response. We found that GC treatment benefits mice with RAI but harms mice without RAI. Our study provides a proof of concept to support a precision medicine approach for sepsis therapy - selectively applying GC therapy for a subgroup of patients with RAI.

Ultrasound Monitoring of Thymus Involution in Septic Mice.

Thymus involution is characterized by a progressive regression of thymus size and contributes to immunosuppression in sepsis. High-frequency ultrasonography is a non-invasive monitoring system in multiple organs, including the thymus, in mice. However, thymus involution has not been studied using ultrasonography in septic mice. This study reports ultrasound approaches to monitoring septic thymus involution in mice. Sepsis was induced by cecum ligation and puncture (CLP). Mice were euthanized at three time points: baseline and days 3 and 10 after CLP. Thymus areas and volumes were measured using 2-D and 3-D ultrasound approaches. Thymus weights were measured ex vivo. Compared with values at baseline, both thymus area and volume decreased significantly at days 3 and 10. In addition, thymus areas and volumes correlated positively with thymus weights. In conclusion, ultrasonography provides reliable thymus measurements and is an optimal technique for monitoring thymus involution in septic mice.

SR-BI (Scavenger Receptor BI), Not LDL (Low-Density Lipoprotein) Receptor, Mediates Adrenal Stress Response-Brief Report.

OBJECTIVE: Adrenal gland secretes stress-induced glucocorticoids (iGCs) to coping with stress. Previous study showed that SR-BI (scavenger receptor BI) null (SR-BI-/-) mice failed to generate iGC in stress conditions, suggesting that SR-BI-mediated cholesterol uptake from HDL (high-density lipoprotein) is a key regulator for iGC production. However, the LDL (low-density lipoprotein)/LDLr (LDL receptor) pathway can also provide cholesterol for iGC synthesis, but rodents have limited LDL levels in circulation. Here, we generated SR-BI-/-ApoBtg (apolipoprotein B transgenic) mice with normal LDL levels in circulation to determine the relative contribution of the HDL/SR-BI and LDL/LDLr pathways to iGC production in stress conditions. Approach and Results: To obtain mouse models with normal LDL levels, SR-BI-/- mice were bred to ApoBtg mice. Then, the F1 SR-BI±ApoBtg mice were backcrossed to SR-BI-/- to obtain SR-BI-/-ApoBtg, SR-BI-/-ApoBwt (apolipoprotein B wild type), and SR-BI+/+ApoBtg mice. We first examined the lipoprotein profile, which shows a 6.5-fold increase in LDL levels in SR-BI-/-ApoBtg mice compared with SR-BI-/-ApoBwt mice. Then, we induced stress with adrenocorticotropic hormone and cecal ligation and puncture. One hour after adrenocorticotropic hormone stimulation, SR-BI+/+ApoBtg control mice produced iGC (14.9-fold), but both SR-BI-/-ApoBwt and SR-BI-/-ApoBtg showed no iGC production (P<0.001). Three hours after cecal ligation and puncture treatment, SR-BI+/+ApoBtg control mice showed iGC production (6.4-fold), but both SR-BI-/-ApoBwt and SR-BI-/-ApoBtg mice showed no iGC production (P<0.001). CONCLUSIONS: SR-BI-/-ApoBtg mice fail to produce iGC in stress conditions even though with restored LDL levels in circulation. These findings clarify that the HDL/SR-BI, not LDL/LDLr, pathway is responsible for iGC production in stress conditions.

Inflammasome Activation Triggers Blood Clotting and Host Death through Pyroptosis.

Inflammasome activation and subsequent pyroptosis are critical defense mechanisms against microbes. However, overactivation of inflammasome leads to death of the host. Although recent studies have uncovered the mechanism of pyroptosis following inflammasome activation, how pyroptotic cell death drives pathogenesis, eventually leading to death of the host, is unknown. Here, we identified inflammasome activation as a trigger for blood clotting through pyroptosis. We have shown that canonical inflammasome activation by the conserved type III secretion system (T3SS) rod proteins from Gram-negative bacteria or noncanonical inflammasome activation by lipopolysaccharide (LPS) induced systemic blood clotting and massive thrombosis in tissues. Following inflammasome activation, pyroptotic macrophages released tissue factor (TF), an essential initiator of coagulation cascades. Genetic or pharmacological inhibition of TF abolishes inflammasome-mediated blood clotting and protects against death. Our data reveal that blood clotting is the major cause of host death following inflammasome activation and demonstrate that inflammasome bridges inflammation with thrombosis.

Incorporating hydrodynamics into spatiotemporal metabolic models of bubble column gas fermentation.

Gas fermentation has emerged as a technologically and economically attractive option for producing renewable fuels and chemicals from carbon monoxide (CO) rich waste streams. LanzaTech has developed a proprietary strain of the gas fermentating acetogen Clostridium autoethanogenum as a microbial platform for synthesizing ethanol, 2,3-butanediol, and other chemicals. Bubble column reactor technology is being developed for the large-scale production, motivating the investigation of multiphase reactor hydrodynamics. In this study, we combined hydrodynamics with a genome-scale reconstruction of C. autoethanogenum metabolism and multiphase convection-dispersion equations to compare the performance of bubble column reactors with and without liquid recycle. For both reactor configurations, hydrodynamics was predicted to diminish bubble column performance with respect to CO conversion, biomass production, and ethanol production when compared with bubble column models in which the gas phase was modeled as ideal plug flow plus axial dispersion. Liquid recycle was predicted to be advantageous by increasing CO conversion, biomass production, and ethanol and 2,3-butanediol production compared with the non-recycle reactor configuration. Parametric studies performed for the liquid recycle configuration with two-phase hydrodynamics showed that increased CO feed flow rates (more gas supply), smaller CO gas bubbles (more gas-liquid mass transfer), and shorter column heights (more gas per volume of liquid per time) favored ethanol production over acetate production. Our computational results demonstrate the power of combining cellular metabolic models and two-phase hydrodynamics for simulating and optimizing gas fermentation reactors.

Metabolic modeling of bacterial co-culture systems predicts enhanced carbon monoxide-to-butyrate conversion compared to monoculture systems.

We used metabolic modeling to computationally investigate the potential of bacterial coculture system designs for CO conversion to the platform chemical butyrate. By taking advantage of the native capabilities of wild-type strains, we developed two anaerobic coculture designs by combining Clostridium autoethanogenum for CO-to-acetate conversion with bacterial strains that offer high acetate-to-butyrate conversion capabilities: the environmental bacterium the human gut bacteriumEubacterium rectale. When grown in continuous stirred tank reactor on a 70/0/30 CO/H2/N2 gas mixture, the C. autoethanogenum-C Kluyveri co-culture was predicted to offer no mprovement in butyrate volumetric productivity compared to an engineered C. autoethanogenum monoculture despite utilizing vinyl acetate as a secondary carbon source for C. kluyveri growth enhancement. A coculture consisting of C. autoethanogenum and C. kluyveri engineered in silico to eliminate hexanoate synthesis was predicted to enhance both butyrate productivity and titer. The C. autoethanogenum-E. rectale coculture offered similar improvements in butyrate productivity without the need for metabolic engineering when glucose was provided as a secondary carbon source to enhance E. rectale growth. A bubble column model developed to assess the potential for large-scale butyrate production of the C. autoethanogenum-E. rectale design predicted that a 40/30/30 CO/H2/N2 gas mixture and a 5 m column length would be preferred to enhance C. autoethanogenum growth and counteract CO inhibitory effects on E. rectale.

HDL in Endocrine Carcinomas: Biomarker, Drug Carrier, and Potential Therapeutic.

High-density lipoprotein (HDL) have long been studied for their protective role against cardiovascular diseases, however recently relationship between HDL and cancer came into focus. Several epidemiological studies have shown an inverse correlation between HDL-cholesterol (HDL-C) and cancer risk, and some have even implied that HDL-C can be used as a predictive measure for survival prognosis in for specific sub-population of certain types of cancer. HDL itself is an endogenous nanoparticle capable of removing excess cholesterol from the periphery and returning it to the liver for excretion. One of the main receptors for HDL, scavenger receptor type B-I (SR-BI), is highly upregulated in endocrine cancers, notably due to the high demand for cholesterol by cancer cells. Thus, the potential to exploit administration of cholesterol-free reconstituted or synthetic HDL (sHDL) to deplete cholesterol in endocrine cancer cell and stunt their growth of use chemotherapeutic drug loaded sHDL to target payload delivery to cancer cell has become increasingly attractive. This review focuses on the role of HDL and HDL-C in cancer and application of sHDLs as endocrine cancer therapeutics.

SR-BI (Scavenger Receptor Class B Type 1) Is Critical in Maintaining Normal T-Cell Development and Enhancing Thymic Regeneration.

Objective- Continuous T-cell production from thymus is essential in replenishing naïve T-cell pool and maintaining optimal T-cell functions. However, the underlying mechanisms regulating the T-cell development in thymus remains largely unknown. Approach and Results- We identified SR-BI (scavenger receptor class B type 1), an HDL (high-density lipoprotein) receptor, as a novel modulator in T-cell development. We found that SR-BI deficiency in mice led to reduced thymus size and decreased T-cell production, which was accompanied by narrowed peripheral naïve T-cell pool. Further investigation revealed that SR-BI deficiency impaired progenitor thymic homing, causing a dramatic reduction in the percentage of earliest thymic progenitors, but did not affect other downstream T-cell developmental steps inside the thymus. As a result of the impaired progenitor thymic homing, SR-BI-deficient mice displayed delayed thymic regeneration postirradiation. Using a variety of experimental approaches, we revealed that the impaired T-cell development in SR-BI-deficient mice was not caused by hematopoietic SR-BI deficiency or SR-BI deficiency-induced hypercholesterolemia, but mainly attributed to the SR-BI deficiency in adrenal glands, as adrenal-specific SR-BI-deficient mice exhibited similar defects in T-cell development and thymic regeneration with SR-BI-deficient mice. Conclusions- This study demonstrates that SR-BI deficiency impaired T-cell development and delayed thymic regeneration by affecting progenitor thymic homing in mice, elucidating a previously unrecognized link between SR-BI and adaptive immunity.

Dioxin-like PCB 126 Increases Systemic Inflammation and Accelerates Atherosclerosis in Lean LDL Receptor-Deficient Mice.

Exposure to dioxins and related persistent organic pollutants likely contributes to cardiovascular disease (CVD) risk through multiple mechanisms including the induction of chronic inflammation. Epidemiological studies have shown that leaner individuals may be more susceptible to the detrimental effects of lipophilic toxicants because they lack large adipose tissue depots that can accumulate and sequester these pollutants. This phenomenon complicates efforts to study mechanisms of pollutant-accelerated atherosclerosis in experimental animal models where high-fat feeding and adipose expansion limit the bioavailability of lipophilic pollutants. Here, we investigated whether a model dioxin-like pollutant, PCB 126, could increase inflammation and accelerate atherosclerosis in Ldlr-/- mice fed a low-fat atherogenic diet. We fed Ldlr-/- mice the Clinton/Cybulsky diet (10% kcal fat, 0.15% cholesterol) and sacrificed mice at 8, 10, or 12 weeks postPCB (2 doses of 1 µmol/kg) or vehicle gavage. To characterize this novel model, we examined the effects of PCB 126 on markers of systemic inflammation, hematological indices, fatty livers, and atherosclerotic lesion size. Mice exposed to PCB 126 exhibited significantly increased plasma inflammatory cytokine levels, increased circulating biomarkers of CVD, altered platelet, and red blood cell counts, increased accumulation of hepatic fatty acids, and accelerated atherosclerotic lesion formation in the aortic root. PCB 126 also increased circulating neutrophils, monocytes, and macrophages as determined by flow cytometry analysis. Exposure to dioxin-like PCB 126 increases inflammation and accelerates atherosclerosis in mice. This low-fat atherogenic diet may provide a useful tool to study the mechanisms linking exposure to lipophilic pollutants to increased risk of CVD.

Up-regulated expression of scavenger receptor class B type 1 (SR-B1) is associated with malignant behaviors and poor prognosis of breast cancer.

Scavenger receptor class B type 1 (SR-B1) is an integral membrane protein that is expressed in numerous cells and tissue types. The primary role of SR-B1 is to facilitate uptake of cholesteryl esters from high-density lipoproteins (HDL) in the liver. Altered SR-B1 expression contributes to human diseases. This study assessed association of SR-B1 expression in breast tissue specimens with breast cancer development and prognosis. Tissue specimens from 30 cases of adjacent normal breast tissues, ductal carcinoma in situ (DCIS) and invasive ductal breast cancer (IDCA) were subjected to Western blot analysis, and 135 cases of DCIS and IDCA were used for quantitative immunohistochemical analysis of SR-B1 expression. The data showed that SR-B1 was significantly overexpressed in IDCA tissues compared to normal breast and DCIS tissues. SR-B1 expression was associated with pre-menopausal status, tumor size, and worse overall survival of patients. The data from this ex vivo study suggests that up-regulated SR-B1 protein expression is associated with malignant behaviors of breast cancer and that SR-B1 is an independent predictor for poor survival in breast cancer patients.

PI(4)P Promotes Phosphorylation and Conformational Change of Smoothened through Interaction with Its C-terminal Tail.

In Hedgehog (Hh) signaling, binding of Hh to the Patched-Interference Hh (Ptc-Ihog) receptor complex relieves Ptc inhibition on Smoothened (Smo). A longstanding question is how Ptc inhibits Smo and how such inhibition is relieved by Hh stimulation. In this study, we found that Hh elevates production of phosphatidylinositol 4-phosphate (PI(4)P). Increased levels of PI(4)P promote, whereas decreased levels of PI(4)P inhibit, Hh signaling activity. We further found that PI(4)P directly binds Smo through an arginine motif, which then triggers Smo phosphorylation and activation. Moreover, we identified the pleckstrin homology (PH) domain of G protein-coupled receptor kinase 2 (Gprk2) as an essential component for enriching PI(4)P and facilitating Smo activation. PI(4)P also binds mouse Smo (mSmo) and promotes its phosphorylation and ciliary accumulation. Finally, Hh treatment increases the interaction between Smo and PI(4)P but decreases the interaction between Ptc and PI(4)P, indicating that, in addition to promoting PI(4)P production, Hh regulates the pool of PI(4)P associated with Ptc and Smo.

High scavenger receptor class B type I expression is related to tumor aggressiveness and poor prognosis in breast cancer.

Scavenger receptor class B type I (SR-BI) has been linked to the development and progression of breast cancer. However, its clinical significance in breast cancer remains unclear. Here, we evaluated SR-BI expression in a well-characterized breast cancer tissue microarray by immunohistochemistry. High SR-BI expression was observed in 54 % of all breast cancer cases and was significantly associated with advanced pTNM stage (P = 0.002), larger tumor size (P = 0.023), lymph node metastasis (P = 0.012), and the absence of ER (P = 0.014). The Kaplan-Meier survival analysis revealed that patients with high SR-BI expression had significantly shorter overall survival (OS) (P = 0.004). Moreover, multivariate analysis with adjustment for other prognostic factors confirmed that SR-BI was an independent prognostic factor for patient outcome (P = 0.017). Overall, our study demonstrated that high SR-BI expression was related to conventional parameters indicative of more aggressive tumor type and may serve as a new prognostic marker for poor clinical outcome in human breast cancer.

HDL in sepsis - risk factor and therapeutic approach.

High-density lipoprotein (HDL) is a key component of circulating blood and plays essential roles in regulation of vascular endothelial function and immunity. Clinical data demonstrate that HDL levels drop by 40-70% in septic patients, which is associated with a poor prognosis. Experimental studies using Apolipoprotein A-I (ApoAI) null mice showed that HDL deficient mice are susceptible to septic death, and overexpressing ApoAI in mice to increase HDL levels protects against septic death. These clinical and animal studies support our hypothesis that a decrease in HDL level is a risk factor for sepsis, and raising circulating HDL levels may provide an efficient therapy for sepsis. In this review, we discuss the roles of HDL in sepsis and summarize the efforts of using synthetic HDL as a potential therapy for sepsis.