The Novel α-glucan YCP And Curcumin Ameliorate Inflammatory Diseases Through Modulating The Expansion And Immunosuppressive Function Of MDSCs

Part I YCP and curcumin modulate the immuosuppressive function of MDSCs(completed in China)Myeloid-derived suppressor cells(MDSCs)are a heterogeneous population of immature myeloid cells(IMCs)composed of two subsets:monocytic MDSCs(M-MDSCs)and granulocytic MDSCs(G-MDSCs).In pathological conditions,such as inflammation,infection and cancer,inflammatory factors and tumor-derived cytokines block the differentiation of IMCs into mature myeloid cells hence that results in the expansion of this population,which has a remarkable ability to suppress T-cell responses.The expansion and immnosuppresive function of MDSCs are regulated by several signaling pathways including JAK/STAT,NF-κb and PI3K/Akt.And the levels of arginase-1(Arg-1),inducible nitric oxide synthase(iNOS)and reactive oxygen species(ROS)are essential for MDSC-mediated immunosuppression.Recently,many studies have reported MDSCs not only are immunosuppressive cells,but also are immune regulatory cells.Various natural polysaccharides possess the ability to activate the immune system.It has been reported that a novel natural a-glucan,YCP,could enhance host immune responses though Toll like receptor(TLR)2 and TLR4.Sepsis is initially characterized by systemic uncontrolled inflammation,and later transitions to persistent immunosuppression.The number of MDSCs gradually increases and remains dramatically elevated in the patients and mouse model of sepsis.Thus,we are wondering if YCP could ameliorate septic symptoms by regulating MDSCs in mice.Curcumin is a highly pleiotropic molecule with anti-oxidant and anti-inflammatory effects.Curcumin possess anti-proliferative and pro-apoptotic abilities in lung cancer cells.Several recent studies have shown curcumin could inhibit the growth of tumor through reducing the number of MDSCs.But it is not clear how curcumin modulates the suppressive function of MDSCs.In this study,we have investigated the therapeutic effect of YCP on CLP-induced septic mice and defined the underlying mechanisms,and explored the function of curcumin on LLCs isogenic tumor model.The novel a-glucan YCP ameliorates septic symptoms by regulating MDSCs in miceSepsis is a life-threatening health condition initially characterized by uncontrolled inflammation and followed by the development of persistent immunosuppression.We have previously reported a novel natural a-glucan,YCP,with antitumor potential via enhancing host immune responses.In this study,we investigated the functions of YCP,using the cecal ligation and puncture(CLP)-induced sepsis model in mice.We found that YCP significantly improved the survival rate of mice while also inhibiting the production of pro-inflammatory cytokines IL-6 and TNFa.YCP decreased the overall percentage of MDSCs,which were dramatically altered,in the lung and liver during sepsis.Further in vitro studies confirmed that YCP indeed led to the decreased MDSC population.Moreover,YCP reduced signal transducer and activator of transcription 3(STAT3)phosphorylation and induced interferon regulatory factor-8(IRF-8)expression,whereas it enhanced Arg-1 and iNOS production and activated the NF-κB pathway in MDSCs.Additionally,YCP-treated TLR4-/-MDSCs expressed much lower levels of iNOS and Arg-1 compared with those in both normal and TLR2-/-MDSCs.Together,these results suggest a mechanism by which YCP inhibits the expansion of MDSCs via STAT3 while enhancing their immunosuppressive function,partially through NF-κB.The effects of YCP on MDSCs appear to be dependent on TLR4.Our findings suggest that YCP protects mice against sepsis by regulating MDSCs.Thus,YCP may be a potential therapeutic agent for sepsis.Inhibition of curcumin on the expansion and activation of MDSCs through interleukin-6 is requisite for controlling lung cancerLung cancer remains the leading cause of cancer mortality in the worldwide.MDSCs,which are a heterogeneous population of immature myeloid cells,are potent immune-suppressive cells and expand in most cancer patients.Curcumin possess anti-proliferative and pro-apoptotic abilities in lung cancer cells.Recently,several studies have shown curcumin inhibits the expansion of MDSCs.But it is not clear whether curcumin achieves anti-tumor effects via regulating the expansion of MDSCs in lung cancer,and how curcumin modulates the suppressive function of MDSCs.Here,our results showed that curcumin significantly inhibited tumor growth in LLC isogenic tumor model.Curcumin reduced the accumulation of MDSCs in spleen and tumor tissue in LLC isogenic model.And curcumin promoted the maturation and differentiation of MDSCs in tumor tissue.Notably,curcumin inhibited the expression level of immune suppressive factors of MDSCs,Arg-1 and ROS,in purified MDSCs from tumor tissue.Expectedly,curcumin also inhibited the immunosuppressive function of bone marrow-derived MDSCs(BM-derived MDSCs)in vitro.Moreover,curcumin decreased the level of IL-6 in the tumor tissue and serum from LLC-bearing mice.Taken together,curcumin indeed possesses anti-cancer effect and inhibits the expansion and activation of MDSCs.Curcumin reduces the level of IL-6 in tumor-bearing mice to impair the function of MDSCs,suggesting that inhibition of MDSCs in tumor is requisite for controlling lung cancer.Part II Protective function of calcium channel blockers against noise-induced hearing loss and high resolution three dimensional imaging of intact cochlea(completed in USA)Noise is the most common occupational and environmental hazard.Occupational noise-induced hearing loss(NIHL)is one of the most prevalent occupational disease.Unfortunately,there are no reliable medications are available for NIHL currently.Our previous studies have indicated that modulation of calcium signaling may have protective effect against NIHL.Three dimensional imaging of the whole cochlea at high resolution are in high demand in the study of hearing.However,the cochlea is a specific and complex organ that poses several obstacles that may be problematic for its intact imaging at high resolution.In this study,we have explored the protective function of calcium channel blocks against NIHL and developed a new technique that providing unsurpassed image quality for the whole cochlea and could be used in the research of cochlear damage.Protective function of calcium channel blockers against noise-induced loss of synapse between inner hair cell and spiral ganglion neuronsNIHL is the second most common form of sensorineural hearing deficit,after presbycusis.The prevention programs for reducing NIHL are focused on minimizing environmental noise production and use of personal hearing protective devices.Currently,there are no drug therapies available for NIHL.The mechanism underlying NIHL is quite complex in both cellular and molecular levels.Calcium signaling pathway is one of the pathways that involved in NIHL.Our previous studies have indicated that modulation of calcium signaling may have protective effect against NIHL.Thus,in this study,we established an extensive noise exposure model to invesgate whether calcium channel blockers,zonisamide(a blocker for T-type calcium channels)or diltiazem(a blocker for L-type calcium channels),could protect hearing.In this model,two-month old CBA/CaJ mice were exposed to 120 dB octave band noise(8-16k Hz)for two hours.But there was no auditory functional recovery from drug treatments.However,a significant protection of SGNs by these drugs was observed three month after the noise exposure.Since the hearing of mice was almost totally lost and the organ of Corti was destroyed under this extensive noise exposure condition,we changed the noise intensity to 96 dB,which did not affect the number of hair cell and the function of outer hair cells(OHCs).We discovered that the auditory brainstem response threshold shift was decreased by zonisamide in this model.Moreover,further studies found that zonisamide protected the synapse between inner hair cells(IHCs)and spiral ganglion neurons(SGNs)in cochleae.Thus,we suggested calcium channel blockers could protect hearing against NIHL through improving the survival of synapses.High resolution three dimensional imaging of cochlear synaptic connectiosUnderstanding the precise arrangement of cells within a thick complex tissue at high resolution can be accomplished through non-destructive optical sectioning with three dimensional reconstructions.Using confocal microscopy,multiple fluorophores can be used to visualize various cell types varying in size,location,and function within the same tissue and at the same time.While non-destructive optical sectioning shows great promise,the inner ear poses multiple obstacles not encountered elsewhere in the body.A number of techniques have been employed to image thick tissues at high resolution but have focused on brain cortex(CLARITY and 3DISCO).Unfortunately,the cochlea is thicker than the sections of brain used in these studies,is calcified,and is a complex three dimensional shape.Several groups have successfully imaged the inner ear,but they could not reach the resolution of synapse.Here,we developed a new technique which named 3Dimensonal Imaging of Thick Tissues by Laser microscopy(3DITTL),and we compared 3DITTL with CLARITY and 3DISCO method.We show that 3DITTL is quick,easy,reliable and inexpensive while providing unsurpassed image quality for the inner ear and preservation of endogenous fluorescent proteins.Most importantly,3DITTL could reach the resolution of synapse between IHCs and SGNs.