The glutathione disulfide mimetic NOV-002 inhibits cyclophosphamide-induced hematopoietic and immune suppression by reducing oxidative stress

Immunomodulatory effects and mechanisms of Tiepishihu Xiyangshen granules on cyclophosphamide induced immuno-suppression via TLR4/MAPKs and PI3K/AKT/FOXO3a signal pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Tiepishihu Xiyangshen granules (TXG) is a traditional Chinese medicine formula composed of Panax quinquefolius L, Dendrobium officinale Kimura & Migo and Ganoderma lucidum (Curtis) P. Karst. It has long been used as a nutritional supplement and an immune enhancer in China. However, the immunomodulatory effects and the underlying mechanisms of TXG have not been clarified.

AIM OF THE STUDY

This study aims to investigate the immunomodulatory effects of TXG and clarify the underlying mechanism.

MATERIALS AND METHOD

TXG was administered by gavage for 18 days. From the 15th day, the immunosuppression model was induced by intraperitoneally injecting 80 mg/kg CTX for 3 days. The immune regulatory effects of TXG on immune organs were verified by calculating the organ index and observing the spleen tissue structure through HE staining. The effects of TXG on immune cells were examined by recording the PBWC, the proliferation rate of lymphocyte and the T lymphocyte phenotype. The effects of TXG on immune molecules were measured by detecting serum hemolysin and the content of cytokines. In parallel, kit was utilized to detect its antioxidant capacity. RNA seq and Western blot were used to analyze the possible immune regulation mechanism of TXG. HPLC and UPLC-Q-TOF-MS were used to identify the chemical components in TXG.

RESULTS

At the level of immune organs, TXG effectively reduced the adverse reaction to the body and the substantial damage to the spleen after chemotherapy by improving the spleen damage. At the level of immune molecules, TXG upregulated the expression of cytokines and antibodies. At the level of immune cells, TXG antagonized bone marrow suppression by increasing the PBWC of immunosuppressed mice. Meanwhile, TXG upregulated the ratio of CD4⁺/CD8⁺ lymphocytes and ameliorated the proliferation of T and B lymphocytes. And the mechanism of TXG to improve immunity might be through TLR4/MAPKs and PI3K/AKT/FOXO3a signaling pathways.

CONCLUSION

The results of this study confirmed that TXG has prominent immunomodulatory activities, and the immunity regulations of TXG may be achieved by regulating TLR4/MAPKs and PI3K/AKT/FOXO3a signal pathways.

Chemotherapy-Induced Oxidative Stress in Pediatric Acute Lymphoblastic Leukemia

Introduction Plasma antioxidant capacity in children receiving chemotherapy decreases due to the effect of the disease and chemotherapy. Increased oxidative stress (OS) predisposes to an increased risk for chemotherapy-related toxicity and febrile neutropenic episodes. Materials and methods We conducted this case-control study in the hematology-oncology unit of the department of pediatrics of a tertiary hospital in Delhi, India, from November 2017 to March 2019 to compare OS between children with acute lymphoblastic leukemia (ALL) and healthy controls. We estimated the trends in OS as measured by the plasma total antioxidant capacity (TAC) and thiobarbituric acid reactive substance (TBARS) levels at baseline and at the completion of induction I (four weeks), induction II (eight weeks), and induction IIA-consolidation (16 weeks) phases of chemotherapy in children with ALL. We also assessed the change in OS during different phases of initial treatment and studied the association between OS and the hematological toxicity of chemotherapy (determined by the need for blood component therapy and the number of febrile neutropenic episodes) and serum cobalamin and folate levels. Results OS was significantly higher in children with ALL at diagnosis (n=23) compared to controls (n=19). The median (interquartile range (IQR)) TAC levels (mM) were significantly lower (1.21 (1.05-1.26) versus 1.28 (1.26-1.32), P=0.006), and TBARS levels (nmol/mL) were significantly higher (312.0 (216.6-398.0) versus 58.5 (46.2-67.2), P<0.001) in children with ALL at diagnosis compared to controls. OS was highest at the end of the induction I phase (four weeks) despite the patients being in clinical and hematological remission. OS at the completion of intensive chemotherapy (16 weeks) was higher than at diagnosis. A significant correlation was found between serum folate levels and TAC levels at baseline (P=0.03). Serum cobalamin levels, the need for blood component therapy, and the number of febrile neutropenic episodes did not have any association with OS. Conclusion Children with ALL had significantly higher OS compared to controls, indicating that underlying disease affects the oxidative balance unfavorably. Chemotherapy itself increases oxidative stress.

Chemotherapy-induced thrombocytopenia: literature review

Chemotherapy-induced thrombocytopenia (CIT) is a common condition that frequently results in reduced chemotherapy dosages, postponed treatment, bleeding, and unfavorable oncological outcomes. At present, there is no clear suggestions for preventing or treating CIT. Thrombopoietin (TPO) replacement therapy has been invented and used to treat CIT to promote the production of megakaryocytes and stimulate the formation of platelets. However, this treatment is limited to the risk of immunogenicity and cancer progression. Therefore, an unmet need exists for exploring alternatives to TPO to address the clinical issue of CIT. Application of appropriate therapeutic drugs may be due to understanding the potential mechanisms of CIT. Studies have shown that chemotherapy significantly affects various cells in bone marrow (BM) microenvironment, reduces their ability to support normal hematopoiesis, and may lead to BM damage, including CIT in cancer patients. This review focuses on the epidemiology and treatment of cancer patients with CIT. We also introduce some recent progress to understand the cellular and molecular mechanisms of chemotherapy inhibiting normal hematopoiesis and causing thrombocytopenia.

Characterization of Purified Mulberry Leaf Glycoprotein and Its Immunoregulatory Effect on Cyclophosphamide-Treated Mice

Mulberry leaf protein is a potentially functional food component and health care agent with antioxidant and anti-inflammatory properties. However, its composition, immunoregulatory effects, and gut microbial regulatory effects are unclear. Herein, ultra-filtrated and gel-fractionated mulberry leaf protein (GUMP) was characterized. Its effects on cyclophosphamide-induced immunosuppressed mice were further investigated. The results indicated that GUMP is a glycoprotein mainly containing glucose, arabinose, and mannose with 9.23% total sugar content. Its secondary structure is mainly β-sheet. LC–MS/MS analysis showed that GUMP closely matched with a 16.7 kDa mannose-binding lectin and a 52.7 kDa Rubisco’s large subunit. GUMP intervention significantly improved serous TNF-α, IL-6, and IL-2 contents; increased serum immunoglobulins (IgA and IgG) levels; and reversed splenic damage prominently. Moreover, GUMP administration increased fecal shot-chain fatty acid concentration and up-regulated the relative abundance of Odoribacter, which was positively correlated with SCFAs and cytokine contents. Overall, GUMP alleviated immunosuppression through the integrated modulation of the gut microbiota and immune response. Therefore, GUMP could be a promising dietary supplement to help maintain gut health.

Immunosuppressive cells in cancer: mechanisms and potential therapeutic targets

Immunotherapies like the adoptive transfer of gene-engineered T cells and immune checkpoint inhibitors are novel therapeutic modalities for advanced cancers. However, some patients are refractory or resistant to these therapies, and the mechanisms underlying tumor immune resistance have not been fully elucidated. Immunosuppressive cells such as myeloid-derived suppressive cells, tumor-associated macrophages, tumor-associated neutrophils, regulatory T cells (Tregs), and tumor-associated dendritic cells are critical factors correlated with immune resistance. In addition, cytokines and factors secreted by tumor cells or these immunosuppressive cells also mediate the tumor progression and immune escape of cancers. Thus, targeting these immunosuppressive cells and the related signals is the promising therapy to improve the efficacy of immunotherapies and reverse the immune resistance. However, even with certain success in preclinical studies or in some specific types of cancer, large perspectives are unknown for these immunosuppressive cells, and the related therapies have undesirable outcomes for clinical patients. In this review, we comprehensively summarized the phenotype, function, and potential therapeutic targets of these immunosuppressive cells in the tumor microenvironment.

Myeloid-derived suppressor cells as immunosuppressive regulators and therapeutic targets in cancer

Myeloid-derived suppressor cells (MDSCs) are a heterogenic population of immature myeloid cells with immunosuppressive effects, which undergo massive expansion during tumor progression. These cells not only support immune escape directly but also promote tumor invasion via various non-immunological activities. Besides, this group of cells are proved to impair the efficiency of current antitumor strategies such as chemotherapy, radiotherapy, and immunotherapy. Therefore, MDSCs are considered as potential therapeutic targets for cancer therapy. Treatment strategies targeting MDSCs have shown promising outcomes in both preclinical studies and clinical trials when administrated alone, or in combination with other anticancer therapies. In this review, we shed new light on recent advances in the biological characteristics and immunosuppressive functions of MDSCs. We also hope to propose an overview of current MDSCs-targeting therapies so as to provide new ideas for cancer treatment.

The Role of Reactive Oxygen Species in Tumor Treatment and its Impact on Bone Marrow Hematopoiesis

Reactive oxygen species (ROS), an important molecule inducing oxidative stress in organisms, play a key role in tumorigenesis, tumor progression and recurrence. Recent findings on ROS have shown that ROS can be used to treat cancer as they accelerate the death of tumor cells. At present, pro-oxidant drugs that are intended to increase ROS levels of the tumor cells have been widely used in the clinic. However, ROS are a double-edged sword in the treatment of tumors. High levels of ROS induce not only the death of tumor cells but also oxidative damage to normal cells, especially bone marrow hemopoietic cells, which leads to bone marrow suppression and (or) other side effects, weak efficacy of tumor treatment and even threatening patients' life. How to enhance the killing effect of ROS on tumor cells while avoiding oxidative damage to the normal cells has become an urgent issue. This study is a review of the latest progress in the role of ROS-mediated programmed death in tumor treatment and prevention and treatment of oxidative damage in bone marrow induced by ROS.

Calf thymus polypeptide improved hematopoiesis via regulating colony-stimulating factors in BALB/c mice with hematopoietic dysfunction

Calf thymus polypeptide (CTP) is prepared from calf thymus. It has a molecular mass of <10 kilodalton (kDa) and contains 17 types of amino acids. This study investigated the hematopoietic function-improvement effect of CTP in CHRF, K562, and bone marrow mononuclear cells; mice with immunosuppression; and with hematopoietic dysfunction. In mice with immunosuppression, CTP enhanced the cytotoxic activity of natural killer cells and the proliferation of lymphocytes and regulated the levels of immunoglobulins. It also enhanced the proliferation and differentiation of CHRF and K562 cells by upregulating the expression of proliferation- and differentiation-related proteins. In mice with hematopoietic dysfunction, CTP restored white blood cell, neutrophil, and hemoglobin proportions in the peripheral blood and enhanced the levels of B lymphocytes and hematopoietic stem cells and progenitor cells in the bone marrow. CTP effectively regulated the levels of hematopoiesis-related cytokines, such as granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating factor (M-CSF), interleukin 2, and interferons-γ, and enhanced the expression of hematopoiesis-related proteins in both primary bone marrow cells and mice with hematopoietic dysfunction. These results indicate that CTP has hematopoietic function-improvement effect and this effect may be related to the modulation of colony-stimulating factors (CSFs) and related signaling pathways.

Hematopoietic Stem Cells: Normal Versus Malignant

SIGNIFICANCE

The long-term hematopoietic stem cell (LT-HSC) demonstrates characteristics of self-renewal and the ability to manage expansion of the hematopoietic compartment while maintaining the capacity for differentiation into hematopoietic stem/progenitor cell (HSPC) and terminal subpopulations. Deregulation of the HSPC redox environment results in loss of signaling that normally controls HSPC fate, leading to a loss of HSPC function and exhaustion. The characteristics of HSPC exhaustion via redox stress closely mirror phenotypic traits of hematopoietic malignancies and the leukemic stem cell (LSC). These facets elucidate the HSC/LSC redox environment as a druggable target and a growing area of cancer research. Recent Advances: Although myelosuppression and exhaustion of the hematopoietic niche are detrimental side effects of classical chemotherapies, new agents that modify the HSPC/LSC redox environment have demonstrated the potential for protection of normal HSPC function while inducing cytotoxicity within malignant populations.

CRITICAL ISSUES

New therapies must preserve, or only slightly disturb normal HSPC redox balance and function, while simultaneously altering the malignant cellular redox state. The cascade nature of redox damage makes this a critical and delicate line for the development of a redox-based therapeutic index.

FUTURE DIRECTIONS

Recent evidence demonstrates the potential for redox-based therapies to impact metabolic and epigenetic factors that could contribute to initial LSC transformation. This is balanced by the development of therapies that protect HSPC function. This pushes toward therapies that may alter the HSC/LSC redox state but lead to initiation cell fate signaling lost in malignant transformation while protecting normal HSPC function. Antioxid. Redox Signal.

SEP enhanced the antitumor activity of 5-fluorouracil by up-regulating NKG2D/MICA and reversed immune suppression via inhibiting ROS and caspase-3 in mice

Chemotherapy and immunotherapy are the main remedies used in cancer treatment. Because immunotherapy can not only reduce the toxicity of chemotherapeutics but also enhance antitumor effects in vivo, combining these two therapies is a trend that continues to gain more attention in clinic. SEP, a polysaccharide isolated from Strongylocentrotus nudus egg, has been reported to display antitumor activity by stimulating immune cells, including NK and T cells, via TLR2 and TLR4. In the present study, the synergistic effect between SEP and 5-fluorouracil (5-FU), a traditional cytotoxic drug, in vitro and in vivo was investigated. The results obtained indicated that SEP alone stimulated NK-92 cytotoxicity and coordinated with 5-FU to augment the cytotoxicity of NK-92 cells against HepG-2 or A549 cells in vitro. SEP promoted NK-92 activity by stimulating NKG2D and its downstream DAP10/PI3K/Erk signaling pathway. Additionally, 5-FU could increase MICA expression on HepG-2 or A549 cells and prevent membrane MICA from shedding as soluble MICA, which were abrogated in the tumor cells transfected with ADAM 10 overexpression plasmid. Moreover, in H22- or Lewis lung cancer (LLC)-bearing mouse models, SEP reversed 5-FU-induced atrophy and apoptosis in both the spleen and bone marrow in vivo by suppressing ROS generation and caspase-3 activation. All of these results highlight the potential for the combination of SEP and 5-FU in cancer therapy in the future.

Improvement of icaritin on hematopoietic function in cyclophosphamide-induced myelosuppression mice

CONTEXT

Icaritin (ICT), an intestinal metabolite of prenylflavonoids from Herba Epimedii, has been known to regulate many immune processes. But there are little studies of ICT on hematopoietic function.

OBJECTIVE

We aimed to investigate the improvement of ICT on hematopoietic function in cyclophosphamide (CTX)-induced myelosuppression mice.

METHODS

Mice were given CTX (50 mg/kg) by i.p. for five days to produce bone marrow depression model. 48 h after last treated with CTX, ICT was administrated at 10 mg/kg/d by p.o. for five days. Blood routine, body weight, thymus index and spleen index were tested. The bone marrow hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs), cell cycle and apoptosis of HSCs were quantified by flow cytometry. The bone marrow nucleated cells were counted by an automated cell counter. The histology of femoral bone was examined by Haemotoxylin and Eosin (H&E) staining. Serum erythropoietin (EPO), granulocyte colony-stimulating factor (G-CSF) and thyroperoxidase (TPO) were tested by ELISA kit.

RESULTS

ICT (10 mg/kg) protected against CTX-induced myelosuppression, is evidenced by increased blood cell numbers, body weight, thymus index, spleen index and improved femoral bone morphology. ICT corrected the reduction of bone marrow HSCs and HPCs, promoted bone marrow HSCs entering the proliferative cycle phase and prevented cells proceeding to the apoptosis phase. Meanwhile, ICT increased the release of G-CSF and TPO in model mice serum.

CONCLUSION

These results demonstrated that ICT improves myelosuppression by improving bone marrow hematopoietic microenvironment, promoting the proliferation and differentiation of HSCs, inhibiting the apoptosis of HSCs and stimulating the expression of G-CSF and TPO.

Investigation on the immunomodulatory activities of Sarcodon imbricatus extracts in a cyclophosphamide (CTX)-induced immunosuppressanted mouse model

Aims: Sarcodon imbricatus, an edible fungus, is widely used in Asian medicine because of its significant pharmacological activities. In the present study, we investigated the immunomodulatory effects of polysaccharide-enriched S. imbricatus extracts (SP) in cyclophosphamide (CTX)-induced immunosuppressed mice. Results: Astragalus polysaccharide (AP) was used as a positive control. Compared with CTX-induced immunosuppressed mice, thirty-day SP treatment strongly enhanced the organ indexes of spleen and thymus and suppressed hind paw swelling. Both AP and SP increased the serum levels of immunoglobulin (IgA, IgG, and IgM), and suppressed the overproduction of interleukin-2 (IL-2). Moreover, SP reduced methane dicarboxylic aldehyde levels, and increased the total antioxidant capacity, superoxide dismutase, and glutathione peroxidase in both serum and liver tissues of CTX-induced immunosuppressed mice. Conclusion: S. imbricatus extracts significantly improved immune function in CTX-induced immunosuppressed mice via modulation of oxidative systems.

Clinically Evaluated Cancer Drugs Inhibiting Redox Signaling

SIGNIFICANCE

There are a number of redox-active anticancer agents currently in development based on the premise that altered redox homeostasis is necessary for cancer cell's survival. Recent Advances: This review focuses on the relatively few agents that target cellular redox homeostasis to have entered clinical trial as anticancer drugs.

CRITICAL ISSUES

The success rate of redox anticancer drugs has been disappointing compared to other classes of anticancer agents. This is due, in part, to our incomplete understanding of the functions of the redox targets in normal and cancer tissues, leading to off-target toxicities and low therapeutic indexes of the drugs. The field also lags behind in the use biomarkers and other means to select patients who are most likely to respond to redox-targeted therapy.

FUTURE DIRECTIONS

If we wish to derive clinical benefit from agents that attack redox targets, then the future will require a more sophisticated understanding of the role of redox targets in cancer and the increased application of personalized medicine principles for their use. Antioxid. Redox Signal. 26, 262-273.

Activation of Nrf2-ARE signaling mitigates cyclophosphamide-induced myelosuppression

Myelosuppression is the most common dose-limiting adverse effect of chemotherapies. In the present study, we investigated the involvement of nuclear erythroid 2-related factor 2 (Nrf2) in cyclophosphamide-induced myelosuppression in mice, and evaluated the potential of activating Nrf2 signaling as a preventive strategy. The whole blood from Nrf2^-/- mice exhibited decreased antioxidant capacities, while the bone marrow cells, peripheral blood mononuclear cells and granulocytes from Nrf2^-/- mice were more susceptible to acrolein-induced cytotoxicity than those from wild type mice. Single dosage of cyclophosphamide induced significantly severer acute myelosuppression in Nrf2^-/- mice than in wild type mice. Furthermore, Nrf2^-/- mice exhibited greater loss of peripheral blood nucleated cells and recovered slower from myelosuppression nadir upon multiple consecutive dosages of cyclophosphamide than wild type mice did. This was accompanied with decreased antioxidant and detoxifying gene expressions and impaired colony formation ability of Nrf2^-/- bone marrow cells. More importantly, activation of Nrf2 signaling by CDDO-Me significantly alleviated cyclophosphamide-induced myelosuppression, while this alleviation was diminished in Nrf2^-/- mice. In conclusion, the present study shows that Nrf2 plays a protective role in cyclophosphamide-induced myelosuppression and activation of Nrf2 is a promising strategy to prevent or treat chemotherapy-induced myelosuppression.

Redox regulation of cancer metastasis: molecular signaling and therapeutic opportunities

Cancer metastasis is the major cause of cancer-related mortality. Accumulated evidence has shown that high-metastasis potential cancer cells have more reactive oxygen species (ROS) accumulation compared with low-metastasis potential cancer cells. ROS can function as second messengers to regulate multiple cancer metastasis-related signaling pathways via reversible oxidative posttranslational modifications of cysteine in key redox-sensitive proteins, which leads to the structural and functional change of these proteins. Because ROS can promote cancer metastasis, therapeutic strategies aiming at inducing/reducing cellular ROS level or targeting redox sensors involved in metastasis hold great potential in developing new efficient approaches for anticancer therapy. In this review, we summarize recent findings on regulation of tumor metastasis by key redox sensors and describe the potential of targeting redox signaling pathways for cancer therapy.

Possible modulating impact of glutathione disulfide mimetic on physiological changes in irradiated rats

Glutathione disulfide mimetic (NOV-002) is a complex of oxidized glutathione (GSSG) formulated with cisplatin at approximately 1000:1 molar ratio. Cisplatin serves to stabilize GSSG but does not assert any therapeutic effect. The objective of this study is to evaluate the impact of NOV-002 on hematological suppression, excessive free radical damage and DNA fragmentation in splenocytes, and metabolite disorders in whole-body γ-irradiated rats. The obtained data revealed that rats treated with 25 mg kg(-1) NOV-002 injected intraperitoneally (i.p.) for 5 days after whole-body γ-irradiation (IR) at 6.5 Gy attenuated the decrease of red blood cells, platelets, total white blood cells, absolute lymphocytes and neutrophils counts, hematocrit value, and hemoglobin content. NOV-002 treatment inhibits serum advanced oxidation protein products, malondialdehyde concentrations as well as cholesterol, triglycerides, urea, and creatinine levels, while enhances glutathione content and superoxide dismutase activity and improves DNA fragmentation in splenocytes. These findings provide a better understanding of the NOV-002 modulating impact in whole-body γ-rays-induced hematological toxicities, oxidative stress, and biological disturbances in γ-irradiated rats and could enhance the tolerance to high doses of ionizing IR utilized in radiotherapy.

Resveratrol, a natural antioxidant, has a protective effect on liver injury induced by inorganic arsenic exposure

Resveratrol (Rev) can ameliorate cytotoxic chemotherapy-induced toxicity and oxidative stress. Arsenic trioxide (As₂O₃) is a known cytotoxic environmental toxicant and a potent chemotherapeutic agent. However, the mechanisms by which resveratrol protects the liver against the cytotoxic effects of As₂O₃ are not known. Therefore, in the present study we investigated the mechanisms involved in the action of resveratrol using a cat model in which hepatotoxicity was induced by means of As₂O₃ treatment. We found that pretreatment with resveratrol, administered using a clinically comparable dose regimen, reversed changes in As₂O₃-induced morphological and liver parameters and resulted in a significant improvement in hepatic function. Resveratrol treatment also improved the activities of antioxidant enzymes and attenuated As₂O₃-induced increases in reactive oxygen species and malondialdehyde production. In addition, resveratrol attenuated the As₂O₃-induced reduction in the ratio of reduced glutathione to oxidized glutathione and the retention of arsenic in liver tissue. These findings provide a better understanding of the mechanisms whereby resveratrol modulates As₂O₃-induced changes in liver function and tissue morphology. They also provide a stronger rationale for the clinical utilization of resveratrol for the reduction of As₂O₃-induced hepatotoxicity.

Impact of myeloid cells on the efficacy of anticancer chemotherapy

Tumors are not immunologically silent but evolve and respond to therapy in the context of a continuous, bi-directional interaction with the host immune system. In line with this notion, several clinically successful chemotherapeutics have been shown to mediate antineoplastic effects as they (re)activate an anticancer immune response that is generally executed by lymphoid cells. Myeloid cells play a central role in this process, not only because they critically regulate the activity of T and B lymphocytes, but also because they exert direct tumoricidal effects, at least in some settings. Here, we discuss the impact of various myeloid cell populations, including macrophages, dendritic cells and myeloid-derived suppressor cells, on the efficacy of anticancer chemotherapy.

Hematopoietic stem cell injury induced by ionizing radiation

SIGNIFICANCE

Exposure to ionizing radiation (IR) as the result of nuclear accidents or terrorist attacks is a significant threat and a major medical concern. Hematopoietic stem cell (HSC) injury is the primary cause of death after accidental or intentional exposure to a moderate or high dose of IR. Protecting HSCs from IR should be a primary goal in the development of novel medical countermeasures against radiation.

RECENT ADVANCES

Significant progress has been made in our understanding of the mechanisms by which IR causes HSC damage. The mechanisms include (i) induction of HSC apoptosis via the p53-Puma pathway; (ii) promotion of HSC differentiation via the activation of the G-CSF/Stat3/BATF-dependent differentiation checkpoint; (iii) induction of HSC senescence via the ROS-p38 pathway; and (iv) damage to the HSC niche.

CRITICAL ISSUES

Induction of apoptosis in HSCs and hematopoietic progenitor cells is primarily responsible for IR-induced acute bone marrow (BM) injury. Long-term BM suppression caused by IR is mainly attributable to the induction of HSC senescence. However, the promotion of HSC differentiation and damage to the HSC niche can contribute to both the acute and long-term effects of IR on the hematopoietic system.

FUTURE DIRECTIONS

In this review, we have summarized a number of recent findings that provide new insights into the mechanisms whereby IR damages HSCs. These findings will provide new opportunities for developing a mechanism-based strategy to prevent and/or mitigate IR-induced BM suppression. Antioxid.

Beneficial effects of hyaluronic acid

Biomaterials are playing a vital role in our day-to-day life. Hyaluronan (hyaluronic acid), a biomaterial, receives special attention among them. Hyaluronic acid (HA) is a polyanionic natural polymer occurring as linear polysaccharide composed of glucuronic acid and N-acetylglucosamine repeats via a β-1,4 linkage. It is the most versatile macromolecule present in the connective tissues of all vertebrates. Hyaluronic acid has a wide range of applications with its excellent physicochemical properties such as biodegradability, biocompatibility, nontoxicity, and nonimmunogenicity and serves as an excellent tool in biomedical applications such as osteoarthritis surgery, ocular surgery, plastic surgery, tissue engineering, and drug delivery. It plays a key role in cushioning and lubricating the body and is abundant in the eyes, joints, and heart valves. A powerful antioxidant, hyaluronic acid is perhaps best known for its ability to bond water to tissue. Hyaluronan production increases in proliferating cells, and the polymer may play a role in mitosis. This chapter gives an overview of hyaluronic acid and its physicochemical properties and applications. This chapter gives a deep understanding on the special benefits of hyaluronic acid in the fields of pharmaceutical, medical, and environmental applications. Hyaluronic acid paves the way for beneficial research and applications to the welfare of life forms.

Immunostimulatory and antiangiogenic activities of low molecular weight hyaluronic acid

The immunostimulatory activities of two low molecular weight hyaluronic acids (LMWHA-1 and LMWHA-2 with MW of 1.45×10(5) and 4.52×10(4) Da, respectively) and HA (MW, 1.05×10(6) Da) were evaluated by using in vitro cell models and in vivo animal models, and their effects on angiogenesis were measured in vivo by using the chick embryo chorioallantoic membrane (CAM) assay. The results demonstrated that LMWHA-1, LMWHA-2 and HA could promote the splenocyte proliferation, increase the activity of acid phosphatase in peritoneal macrophages and strengthen peritoneal macrophages to devour neutral red in vitro in a dose-dependent manner. Furthermore, LMWHA-1 and LMWHA-2 exhibited much stronger immunostimulatory activity than HA. For assay in vivo, LMWHA-1 and LMWHA-2 significantly increased the indices of spleen and thymus, the activity of lysozyme in serum and the swelling rate of earlap in delayed-type hypersensitivity in a dose-dependent manner. In the CAM model, the results showed that LMWHA-1, LMWHA-2 and HA suppressed angiogenesis in chicken embryos. Moreover, LMWHA-1 exhibited higher antiangiogenesis activity than LMWHA-2 and HA. All these results suggested that LMWHA might be a potential natural immunomodulator and a potential candidate compound for antiangiogenic.