Active hexose correlated compound enhances the immune function of mice in the hindlimb-unloading model of spaceflight conditions

Active Hexose-Correlated Compound Restores Gene Expression and Protein Secretion of Protective Cytokines of Immune Cells in a Murine Stress Model during Chlamydia muridarum Genital Infection

Chlamydia trachomatis genital infection is the most common bacterial sexually transmitted disease worldwide. Previously, we reported that cold-induced stress results in immune suppression of mice that subsequently leads to increased intensity of Chlamydia muridarum genital infection. Furthermore, we demonstrated that stressed mice orally fed with active hexose-correlated compound (AHCC) have reduced shedding of C. muridarum from the genital tract. However, the mechanism of AHCC in reducing the organ load and changing the immune response in the stress model is not well known. This study evaluated infection and changes in immunological parameters of stressed AHCC-fed mice with or without C. muridarum genital infection. We hypothesized that AHCC feeding to stressed mice restores protective immune function and reduces susceptibility to C. muridarum genital infection. The results show that oral feeding of stressed mice with AHCC resulted in decreased shedding of C. muridarum from the genital tract, reduced production of plasma catecholamines, increased expression of T-bet and reduced GATA-3 in CD4⁺ T cells, increased production of interleukin-12 (IL-12) and interferon gamma (IFN-γ) and reduced production of IL-4 in CD4⁺ T cells, and enhanced expression of surface markers and costimulatory molecules of CD4⁺ T cells, bone marrow-derived dendritic cells (BMDCs), and natural killer cells. Coculturing of mature BMDCs with splenic CD4⁺ T cells led to the increased and decreased production of T helper 1 and T helper 2 cytokines, respectively. Overall, our results show that AHCC fosters the restoration of Th1 cytokine production while reducing Th2 cytokine production, which would promote C. muridarum clearance in the murine stress model.

The Effects of AHCC®, a Standardized Extract of Cultured Lentinura edodes Mycelia, on Natural Killer and T Cells in Health and Disease: Reviews on Human and Animal Studies

Mushrooms have been used for various health conditions for many years by traditional medicines practiced in different regions of the world although the exact effects of mushroom extracts on the immune system are not fully understood. AHCC® is a standardized extract of cultured shiitake or Lentinula edodes mycelia (ECLM) which contains a mixture of nutrients including oligosaccharides, amino acids, and minerals obtained through liquid culture. AHCC® is reported to modulate the numbers and functions of immune cells including natural killer (NK) and T cells which play important roles in host defense, suggesting the possible implication of its supplementation in defending the host against infections and malignancies via modulating the immune system. Here, we review in vivo and in vitro effects of AHCC® on NK and T cells of humans and animals in health and disease, providing a platform for the better understanding of immune-mediated mechanisms and clinical implications of AHCC®.

Effect of cold water-induced stress on immune response, pathology and fertility in mice during Chlamydia muridarum genital infection

Genital infection by Chlamydia trachomatis is the most common bacterial sexually transmitted disease worldwide. It causes serious reproductive health complications, including pelvic inflammatory disease and infertility. Stress is implicated as a risk factor for various infections; however, its effect on chlamydia genital infection is unknown. We previously showed that repeated exposure of mice to cold water results in increased severity of chlamydia genital infection. In this study, cold water-induced stress resulted in (i) elevated levels of norepinephrine (NE) and epinephrine in the spleen and genital tract of stressed mice; (ii) elevated IL-1β, TNF-α, IL-6 and nitric oxide production in macrophage-rich peritoneal cells of mice; (iii) supplement of NE in vitro exerts an immunosuppressive effect on splenic T-cell production of cytokines; (iv) decreased C. muridarum shedding in the genital tract of β1Adr/β2Adr receptor KO mice; and (v) a higher rate of infertility in infected mice. These results suggest that cold water stress induces the production of catecholamines, which may play a critical role in the modulation of the immune system leading to increased intensity of C. muridarum genital infection.

Hindlimb unloading: rodent analog for microgravity

The rodent hindlimb unloading (HU) model was developed in the 1980s to make it possible to study mechanisms, responses, and treatments for the adverse consequences of spaceflight. Decades before development of the HU model, weightlessness was predicted to yield deficits in the principal tissues responsible for structure and movement on Earth, primarily muscle and bone. Indeed, results from early spaceflight and HU experiments confirmed the expected sensitivity of the musculoskeletal system to gravity loading. Results from human and animal spaceflight and HU experiments show that nearly all organ systems and tissues studied display some measurable changes, albeit sometimes minor and of uncertain relevance to astronaut health. The focus of this review is to examine key HU results for various organ systems including those related to stress; the immune, cardiovascular, and nervous systems; vision changes; and wound healing. Analysis of the validity of the HU model is important given its potential value for both hypothesis testing and countermeasure development.

Active Hexose Correlated Compound Activates Immune Function to Decrease Chlamydia trachomatis Shedding in a Murine Stress Model

A cold-induced stress mouse model for investigating chlamydia genital infection and immune response analysis was established in our laboratory. Previous results showed that cold-induced stress results in suppression of the immune response and increased intensity of chlamydia genital infection in the mouse model. The purpose of the present study was to evaluate the potential therapeutic value of active hexose correlated compound (AHCC) against chlamydia genital infection in mice. AHCC is an extract of mushroom commonly used as a dietary supplement is known to boost the immune system. Mice were infected intravaginally with Chlamydia trachomatis after a 24-day cold-stress application. Oral administration of AHCC to stressed or non-stressed mice was carried out seven days before infection and during the course of infection along with cervicovaginal swabbing. Cytokine production by peritoneal and splenic T cells isolated from AHCC-fed stressed mice and non-stressed mice was measured ELISA. Splenic T cells from both animal groups were co-cultured with mouse monocyte J774.2 cell line or cultured by addition of supernatants of AHCC-treated J774.2 cell line for 24 hours. Infection studies showed that AHCC-feeding compared to phosphate buffered saline (PBS)-feeding to stressed mice resulted in reduced Chlamydia trachomatis shedding from the genital tract. Levels of tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) were significantly increased in stressed mice receiving AHCC compared to stressed mice receiving PBS. Production of interferon gamma (IFN-γ) and interleukin 2 (IL-2) in the AHCC group was significantly high compared to production in PBS-fed group. Splenic T cells from stressed and non-stressed cultured with supernatants of AHCC-treated J774.2 cell line resulted in significantly increased TNF-α or IFN-γ production. Results obtained in this study show that AHCC improves the function of immune cells as indicated by the restoration of levels of cytokines production that were suppressed under cold induced-stress conditions. This is the first report showing that oral administration of AHCC enhances the function of the immune system, which could result in increased resistance of the host to chlamydia genital infection.

Broad-spectrum antibiotic or G-CSF as potential countermeasures for impaired control of bacterial infection associated with an SPE exposure during spaceflight

A major risk for astronauts during prolonged space flight is infection as a result of the combined effects of microgravity, situational and confinement stress, alterations in food intake, altered circadian rhythm, and radiation that can significantly impair the immune system and the body’s defense systems. We previously reported a massive increase in morbidity with a decrease in the ability to control a bacterial challenge when mice were maintained under hindlimb suspension (HS) conditions and exposed to solar particle event (SPE)-like radiation. HS and SPE-like radiation treatment alone resulted in a borderline significant increase in morbidity. Therefore, development and testing of countermeasures that can be used during extended space missions in the setting of exposure to SPE radiation becomes a serious need. In the present study, we investigated the efficacy of enrofloxacin (an orally bioavailable antibiotic) and Granulocyte colony stimulating factor (G-CSF) (Neulasta) on enhancing resistance to Pseudomonas aeruginosa infection in mice subjected to HS and SPE-like radiation. The results revealed that treatment with enrofloxacin or G-CSF enhanced bacterial clearance and significantly decreased morbidity and mortality in challenged mice exposed to suspension and radiation. These results establish that antibiotics, such as enrofloxacin, and G-CSF could be effective countermeasures to decrease the risk of bacterial infections after exposure to SPE radiation during extended space flight, thereby reducing both the risk to the crew and the danger of mission failure.

Active hexose correlated compound potentiates the antitumor effects of low-dose 5-fluorouracil through modulation of immune function in hepatoma 22 tumor-bearing mice

BACKGROUND/OBJECTIVES

A variety of immunomodulators can improve the efficacy of low-dose chemotherapeutics. Active hexose correlated compound (AHCC), a mushroom mycelia extract, has been shown to be a strong immunomodulator. Whether AHCC could enhance the antitumor effect of low-dose 5-fluorouracil (5-FU) via regulation of host immunity is unknown.

MATERIALS/METHODS

In the current study Hepatoma 22 (H22) tumor-bearing mice were treated with PBS, 5-FU (10 mg·kg^-1·d^-1, i.p), or AHCC (360 mg·kg^-1·d^-1, i.g) plus 5-FU, respectively, for 5 d. CD3⁺, CD4⁺, CD8⁺, and NK in peripheral blood were detected by flow cytometry. ALT, AST, BUN, and Cr levels were measured by biochemical assay. IL-2 and TNFα in serum were measured using the RIA kit and apoptosis of tumor was detected by TUNEL staining. Bax, Bcl-2, and TS protein levels were measured by immunohistochemical staining and mRNA level was evaluated by RT-PCR.

RESULTS

Diet consumption and body weight showed that AHCC had no apparent toxicity. AHCC could reverse liver injury and myelosuppression induced by 5-FU (P < 0.05). Compared to mice treated with 5-FU, mice treated with AHCC plus 5-FU had higher thymus index, percentages of CD3⁺, CD4⁺, and NK cells (P < 0.01), and ratio of CD4⁺/CD8⁺ (P < 0.01) in peripheral blood. Radioimmunoassay showed that mice treated with AHCC plus 5-FU had the highest serum levels of IL-2 and TNFα compared with the vehicle group and 5-FU group. More importantly, the combination of AHCC and 5-FU produced a more potent antitumor effect (P < 0.05) and caused more severe apoptosis in tumor tissue (P < 0.05) compared with the 5-FU group. In addition, the combination of AHCC and 5-FU further up-regulated the expression of Bcl-2 associated X protein (Bax) (P < 0.01), while it down-regulated the expression of B cell lymphoma 2 (Bcl-2) (P < 0.01).

CONCLUSIONS

These results support the claim that AHCC might be beneficial for cancer patients receiving chemotherapy.

Effects of active hexose correlated compound on the seasonal variations of immune competence in healthy subjects

The aim of this study was to evaluate the effects of active hexose correlated compound intake on the immune competence in healthy volunteers. Thirty-four subjects were randomized to receive placebo or active hexose correlated compound at 1.0 g/d for 4 weeks in early winter. Natural killer cell activity was significantly increased in both groups during the study period, the natural killer cell number, however, was not altered in the active hexose correlated compound group while placebo group showed remarkable decline. In addition, the score of immunological vigor, an index of total immune competence, was maintained in the active hexose correlated compound group although that of placebo group lowered during the test period. These results suggested that the continuous active hexose correlated compound intake maintained the immune competence against the seasonal change.

Active hexose correlated compound exerts therapeutic effects in lymphocyte driven colitis

Active hexose correlated compound (AHCC) is a commercial extract of Basidiomycetes fungi enriched in oligosaccharides that is used as a human nutritional supplement for various purposes in humans. Our aim was to study the anti-inflammatory effect of AHCC in the CD4+ CD62L(+) T cell transfer model of colitis, considered one of the closest to the human disease. Colitis was induced by transfer of CD4(+) CD62L(+) T cells to recombination activating gene 1(-/-) mice. AHCC (75 mg/d) was administered by gavage as a post-treatment. Three groups were established: noncolitic, colitic (CD4(+) CD62L(+) transferred mice treated with vehicle), and AHCC (colitic treated with AHCC). AHCC improved colitis, as evidenced by a 24% lower colonic myeloperoxidase and a 21% lower alkaline phosphatase activity. In addition, a decreased secretion of proinflammatory genes assessed by RT-qPCR was observed, particularly TNF-α and IL-1β. Ex vivo mesenteric lymph node cells obtained from AHCC treated mice exhibited a fully normalized production of IL-6, IL-17, and IL-10 (p < 0.05). Also, AHCC treated mice exhibited decreased STAT4 and IκB-α phosphorylation in splenic CD4(+) cells. Our data provide validation of AHCC colonic anti-inflammatory activity in a chronic, T cell driven model of inflammatory bowel disease.

Terrestrial stress analogs for spaceflight associated immune system dysregulation

Recent data indicates that dysregulation of the immune system occurs and persists during spaceflight. Impairment of immunity, especially in conjunction with elevated radiation exposure and limited clinical care, may increase certain health risks during exploration-class deep space missions (i.e. to an asteroid or Mars). Research must thoroughly characterize immune dysregulation in astronauts to enable development of a monitoring strategy and validate any necessary countermeasures. Although the International Space Station affords an excellent platform for on-orbit research, access may be constrained by technical, logistical vehicle or funding limitations. Therefore, terrestrial spaceflight analogs will continue to serve as lower cost, easier access platforms to enable basic human physiology studies. Analog work can triage potential in-flight experiments and thus result in more focused on-orbit studies, enhancing overall research efficiency. Terrestrial space analogs generally replicate some of the physiological or psychological stress responses associated with spaceflight. These include the use of human test subjects in a laboratory setting (i.e. exercise, bed rest, confinement, circadian misalignment) and human remote deployment analogs (Antarctica winterover, undersea, etc.) that incorporate confinement, isolation, extreme environment, physiological mission stress and disrupted circadian rhythms. While bed rest has been used to examine the effects of physical deconditioning, radiation and microgravity may only be simulated in animal or microgravity cell culture (clinorotation) analogs. This article will characterize the array of terrestrial analogs for spaceflight immune dysregulation, the current evidence base for each, and interpret the analog catalog in the context of acute and chronic stress.

Plasma cytokine concentrations indicate that in vivo hormonal regulation of immunity is altered during long-duration spaceflight

Aspects of immune system dysregulation associated with long-duration spaceflight have yet to be fully characterized and may represent a clinical risk to crewmembers during deep space missions. Plasma cytokine concentration may serve as an indicator of in vivo physiological changes or immune system mobilization. The plasma concentrations of 22 cytokines were monitored in 28 astronauts during long-duration spaceflight onboard the International Space Station. Blood samples were collected 3 times before flight, 3-5 times during flight (depending on mission duration), at landing, and 30 days after landing. Analysis was performed by bead array immunoassay. With few exceptions, minimal detectable mean plasma concentrations were observed at baseline (launch minus 180) for innate inflammatory cytokines or adaptive regulatory cytokines; however, interleukin (IL)-1ra and several chemokines and growth factors were constitutively present. An increase in the plasma concentration, tumor necrosis factor-α (TNFα), IL-8, IL-1ra, thrombopoietin (Tpo), vascular endothelial growth factor (VEGF), C-C motif chemokine ligand 2 (CCL2), chemokine ligand 4/macrophage inhibitory protein 1b (CCL4), and C-X-C motif chemokine 5/epithelial neutrophil-activating protein 78 (CXCL5) was observed associated with spaceflight. No significant alterations were observed during or following spaceflight for the inflammatory or adaptive/T-regulatory cytokines: IL-1α, IL-1β, IL-2, interferon-gamma (IFN-γ), IL-17, IL-4, IL-5, IL-10, G-CSF, GM-CSF, FGF basic, CCL3, or CCL5. This pattern of cytokine dysregulation suggests multiple physiological adaptations persist during flight, including inflammation, leukocyte recruitment, angiogenesis, and thrombocyte regulation.

Three weeks of murine hindlimb unloading induces shifts from B to T and from th to tc splenic lymphocytes in absence of stress and differentially reduces cell-specific mitogenic responses

Extended space missions are known to induce stress and immune dysregulation. Hindlimb unloading is a ground-based model used to reproduce most spaceflight conditions. The aim of this study was to better characterize the consequences of prolonged exposure to hindlimb unloading on murine splenic lymphocyte sub-populations. To ensure that the observed changes were not due to tail restraint but to the antiorthostatic position, three groups of mice were used: control (C), orthostatic restrained (R) and hindlimb unloaded (HU). After 21 days of exposure, no difference in serum corticosterone levels nor in thymus and spleen weights were observed between HU mice and their counterparts, revealing a low state of stress. Interestingly, flow cytometric analyses showed that B cells were drastically reduced in HU mouse spleens by 59% and, while the T cells number did not change, the Th/Tc ratio was decreased. Finally, the use of a fluorescent dye monitoring lymphoproliferation demonstrated that lymphocyte response to mitogen was reduced in Th and Tc populations and to a greater extent in B cells. Thus, we showed for the first time that, even if restraint has its own effects on the animals and their splenic lymphocytes, the prolonged antiorthostatic position leads, despite the absence of stress, to an inversion of the B/T ratio in the spleen. Furthermore, the lymphoproliferative response was impaired with a strong impact on B cells. Altogether, these results suggest that B cells are more affected by hindlimb unloading than T cells which may explain the high susceptibility to pathogens, such as gram-negative bacteria, described in animal models and astronauts.

An evidence-based systematic review of active hexose correlated compound (AHCC) by the Natural Standard Research Collaboration

An evidence-based systematic review of active hexose correlated compound (AHCC) by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated, reproducible grading rationale. This article includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

A natural immune modulator attenuates stress hormone and catecholamine concentrations in polymicrobial peritonitis

BACKGROUND

Activated hexose correlated compound (AHCC), derived from shiitake mushrooms, increases resistance to infection in immunocompromised hosts with positive effects on dendritic cells, natural killer cell function and interleukin 12 production. It may also be attenuating the systemic inflammatory response by regulating the secretion of cortisol and norepinephrine (NE).

METHODS

Female Swiss-Weber mice were pretreated with AHCC (Amino Up Chemical Co., Sapporo, Japan) or water by gavage for 10 days before undergoing cecal ligation and puncture (CLP). Peritoneal exudate cells and blood samples were harvested at 4 hours and 24 hours following CLP. Plasma and peritoneal concentrations of cortisol and NE were obtained using enzyme-linked immunosorbent assay. Peritoneal bacteria were quantified by colony counts after 4 hours and 24 hours. Significance was denoted by a p < 0.05.

RESULTS

Plasma and peritoneal cortisol concentrations were increased 4 hours after CLP compared with normal controls, with no difference between the pretreated groups. Concentrations of cortisol decreased from 4 hours to 24 hours after CLP with AHCC (plasma, p = 0.009; peritoneal, p < 0.001), and peritoneal cortisol at 24 hours was lower with AHCC as compared with water (p = 0.028). There was no change in plasma or peritoneal NE concentrations at 4 hours. At 24 hours, higher concentrations of NE were detected in both plasma and peritoneal fluid, with lower plasma concentrations in those gavaged with AHCC (p = 0.015). There was no significant difference in peritoneal bacteria counts.

CONCLUSION

Enhanced immune function observed with AHCC could be caused by attenuated concentrations of stress hormones and catecholamines.

The nutritional supplement Active Hexose Correlated Compound (AHCC) has direct immunomodulatory actions on intestinal epithelial cells and macrophages involving TLR/MyD88 and NF-κB/MAPK activation

Active Hexose Correlated Compound (AHCC) is an immunostimulatory nutritional supplement. AHCC effects and mechanism of action on intestinal epithelial cells or monocytes are poorly described. AHCC was added to the culture medium of intestinal epithelial cells (IEC18 and HT29 cells) and monocytes (THP-1 cells) and assessed the secretion of proinflammatory cytokines by ELISA. Inhibitors of NFκB and MAPKs were used to study signal transduction pathways while TLR4 and MyD88 were silenced in IEC18 cells using shRNA. It was found that AHCC induced GROα and MCP1 secretion in IEC18 and IL-8 in HT29 cells. These effects depended on NFκB activation, and partly on MAPKs activation and on the presence of MyD88 and TLR4. In THP-1 cells AHCC evoked IL-8, IL-1β and TNF-α secretion. The induction of IL-8 depended on JNK and NFκB activation. Therefore, AHCC exerts immunostimulatory effects on intestinal epithelial cells and monocytes involving TLR4/MyD88 and NFκB/MAPK signal transduction pathways.

Active Hexose Correlated Compound promotes T helper (Th) 17 and 1 cell responses via inducing IL-1β production from monocytes in humans

The differentiation of T helper (Th) cells is critically dependent on cytokine milieu. The innate immune monocytes produce IL-1β which can affect the development of Th17 and Th1 cells that predominantly produce IL-17 and IFN-γ, respectively. Oligosaccharides from microorganisms, crops and mushrooms can stimulate innate immune cells. Active Hexose Correlated Compound (AHCC) that contains a large amount of oligosaccharides is a natural extract prepared from the mycelium of the edible Basidiomycete fungus. This compound is reported to modulate immune responses against pathogens although the mechanisms for this effect are largely unknown. Here we show that AHCC could induce high levels of IL-1β production from human monocytes. Furthermore, AHCC-treated monocytes increased the production of IL-17 and IFN-γ from autologous CD4(+) T cells, which was blocked by adding IL-1 receptor antagonist. These finding provide new insight into how food supplements like AHCC could enhance human immunity by modulating monocytes and Th cells.

Innate immune responses of Drosophila melanogaster are altered by spaceflight

Alterations and impairment of immune responses in humans present a health risk for space exploration missions. The molecular mechanisms underpinning innate immune defense can be confounded by the complexity of the acquired immune system of humans. Drosophila (fruit fly) innate immunity is simpler, and shares many similarities with human innate immunity at the level of molecular and genetic pathways. The goals of this study were to elucidate fundamental immune processes in Drosophila affected by spaceflight and to measure host-pathogen responses post-flight. Five containers, each containing ten female and five male fruit flies, were housed and bred on the space shuttle (average orbit altitude of 330.35 km) for 12 days and 18.5 hours. A new generation of flies was reared in microgravity. In larvae, the immune system was examined by analyzing plasmatocyte number and activity in culture. In adults, the induced immune responses were analyzed by bacterial clearance and quantitative real-time polymerase chain reaction (qPCR) of selected genes following infection with E. coli. The RNA levels of relevant immune pathway genes were determined in both larvae and adults by microarray analysis. The ability of larval plasmatocytes to phagocytose E. coli in culture was attenuated following spaceflight, and in parallel, the expression of genes involved in cell maturation was downregulated. In addition, the level of constitutive expression of pattern recognition receptors and opsonins that specifically recognize bacteria, and of lysozymes, antimicrobial peptide (AMP) pathway and immune stress genes, hallmarks of humoral immunity, were also reduced in larvae. In adults, the efficiency of bacterial clearance measured in vivo following a systemic infection with E. coli post-flight, remained robust. We show that spaceflight altered both cellular and humoral immune responses in Drosophila and that the disruption occurs at multiple interacting pathways.

Effects of active hexose correlated compound on frequency of CD4+ and CD8+ T cells producing interferon-γ and/or tumor necrosis factor-α in healthy adults

Active hexose correlated compound (AHCC) is a natural compound with the potential to be used as an immunoenhancer in cases in which the immune system is compromised. The purpose of this study was to evaluate the effects of this compound on the immune function of healthy adults aged 50 years or more. The production of interferon (IFN)-γ and tumor necrosis factor (TNF)-α by CD4(+) and CD8(+) T cells was measured by flow cytometry in peripheral blood obtained from subjects at different time points after AHCC intake. The frequency of CD4(+) and CD8(+) T cells producing IFN-γ alone, TNF-α alone, or both increased during AHCC intake compared with baseline values. Furthermore, the frequency of such cells remained high even 30 days after discontinuing AHCC. Overall, these findings suggest that AHCC enhances CD4(+) and CD8(+) T cell immune responses in healthy elderly persons taking at least 30 days to obtain such effect, which remained up to 30 days after discontinuing treatment with this compound.

Low-dose supplementation with active hexose correlated compound improves the immune response to acute influenza infection in C57BL/6 mice

Supplementation with mushroom-derived active hexose correlated compound (AHCC) modulates immunity and increases survival in response to a broad spectrum of acute infections, including influenza virus infection. However, dose-response data are nonexistent. Therefore, the aims of this study were to evaluate AHCC supplementation at various doses and determine the effects of low-dose supplementation on the immune response in a mouse model of influenza virus infection. We hypothesized that AHCC supplementation would influence the immune response to influenza infection in a dose-dependent manner. Male C57BL/6 mice were supplemented with AHCC at daily doses of 0.05, 0.1, 0.5, and 1 g/kg and infected intranasally with influenza A virus (H1N1, PR8). Supplemented mice demonstrated a dose-dependent increase in survival and reduction in the loss of body weight. To further evaluate the effects of low-dose AHCC supplementation on the immune response to influenza infection, mice were supplemented with 0.1 g/kg per day and infected with a sublethal dose of influenza virus. Supplemented mice exhibited enhanced virus clearance and decreased weight loss compared to controls. Low-dose supplementation did not influence total natural killer (NK) cell cytotoxicity, although lytic efficiency was increased in the spleens of AHCC-supplemented mice, indicating enhanced NK cell function per cell. In conclusion, these data suggest that the effects of AHCC on the immune response to influenza infection are dose dependent and that low-dose AHCC supplementation improves the response to influenza infection despite no effect on total NK cell cytotoxicity.

Effects of exposure of mice to hindlimb unloading on leukocyte subsets and sympathetic nervous system activity

The hindlimb unloading (HU) rodent model was developed to simulate some of the aspects of spaceflight conditions. Our previous studies showed that exposure to HU for 48 h (h) followed by bacterial challenge, reduces the ability of mice to resist infection. The purpose of this study was to investigate the physiological changes in mice during the 48 h of exposure to HU to understand the mechanisms involved in the increased susceptibility to infection observed in mice subjected to these conditions. Female Swiss Webster mice were hindlimb-unloaded during 48 h. Blood samples, spleen and peritoneal cells were removed before and after 18 or 48 h of HU-exposure. Leukocyte subset analysis was performed in spleen and peritoneal cells by flow cytometry, and catecholamine levels were measured in plasma and whole spleen by a catecholamine enzyme immunoassay. Catecholamine levels measured in plasma and spleen were significantly greater in mice exposed to HU compared to control. This increase coincided with significant reductions in spleen size in the HU group. Flow cytometric analyses showed a significant reduction of splenic CD19 + B-cells and NK1.1+ cells in mice exposed to HU with a concomitant increase in T-cells. These results suggest that exposure to HU increases the activity of the sympathetic nervous system (SNS) and induces lymphocyte sub-population changes that may contribute to the deregulation of immunity seen in mice exposed to HU and, more importantly may predispose the otherwise healthy host to the subsequent reduced ability to resist infections.

Active hexose correlated compound activates immune function to decrease bacterial load in a murine model of intramuscular infection

BACKGROUND

Infection is a serious, costly, and common complication of surgery and constitutes the principal cause of late death in patients undergoing surgery. The objective of this study was to clarify the mechanisms by which active hexose correlated compound (AHCC) increases survival in a murine model of intramuscular infection.

METHODS

Food-deprived mice receiving either AHCC or excipient were infected with bacteria. Kinetics of bacterial load, white blood cell counts, cytokine levels, and antibody levels were compared between groups.

RESULTS

AHCC-treated mice had reduced bacterial load at day 5 and cleared bacteria entirely at day 6. Levels of interleukin-12, tumor necrosis factor-alpha, and interleukin-6 peaked earlier in this group (day 3) compared with controls (day 5). Increased percentages of peripheral lymphocytes and monocytes and decreased numbers of polymorphonuclear cells were detected in the AHCC group.

CONCLUSIONS

AHCC appears to induce an early activation of the immune response, leading to an effective clearance of bacteria and rapid recovery.

Active hexose correlated compound acts as a prebiotic and is antiinflammatory in rats with hapten-induced colitis

Active hexose correlated compound (AHCC) is a product prepared from the mycelium of edible Basidiomycete fungi that contains oligosaccharides. Here we have studied the antiinflammatory effect of AHCC in the trinitrobenzenesulfonic acid (TNBS) model of colitis in rats. Rats received AHCC (100 or 500 mg/kg) daily starting 2 d before (pretreatment) colitis induction and were killed 6 d after the TNBS challenge. The status of the rats was assessed by morphological and biochemical methods. The effect of AHCC on the colonic microflora was also assessed by studying the bacteria profile in feces by standard culture techniques. AHCC administration attenuated colonic inflammation, improving rat weight, food intake, damage score, extension of necrosis, colonic weight, colonic weight-to-length ratio, myeloperoxidase and alkaline phosphatase activities, glutathione concentration, and the expression of proinflammatory cytokines and chemokines (IL-1beta, IL-1 receptor antagonist, TNF, and monocyte chemoattractant protein-1) and of mucins 2-4 and trefoil factor 3. The magnitude of the antiinflammatory effect of AHCC was similar to that of sulfasalazine (200 mg/kg). The study of colonic microflora indicated that rats treated with AHCC had higher aerobic and lactic acid bacteria counts as well as higher bifidobacteria counts, whereas clostridia were reduced when compared with the TNBS group. Therefore, our results indicate that AHCC is antiinflammatory and could be useful as a prebiotic to design functional foods for inflammatory bowel disease patients.

Active hexose correlated compound (AHCC) enhances resistance to infection in a mouse model of surgical wound infection

BACKGROUND

Infection is the most common postoperative complication within the surgical wound and during severe trauma. In spite of the use of modern sterile techniques and prophylaxis, infection continues to be a leading cause of death in these patients. Therefore, it has become crucial to develop new alternatives to prevent the effects of trauma and other complications on the immune system and improve resistance to infection. The objective of this study was to test the prophylactic effects of oral administration of active hexose correlated compound (AHCC), a natural immunoenhancer, on survival in a mouse model of surgical soft tissue infection.

METHODS

The model involves the intramuscular administration of a 50% lethal dose (LD50) of K. pneumoniae to mice that have restricted food intake for 24 hours prior to and six hours after infection and simulates local infection and food deprivation that often occur during trauma or surgical procedures. In the present study, AHCC was administrated orally to Swiss Webster mice for eight days prior to and during the infection period. Survival, time of death, LD50, and clearance of bacteria of this group were compared with those control mice receiving the excipient alone.

RESULTS

Survival and mean time to death were increased significantly in the AHCC-treated group; the LD50 was greater in mice receiving AHCC than in mice receiving the excipient. Mice receiving AHCC were better able to clear bacteria from their systems than were control animals.

CONCLUSIONS

The results suggest that AHCC protects mice in this model by restoring the immune and other systems negatively affected by trauma, infection, and food deprivation. More studies are necessary to determine the intrinsic mechanisms involved in this model and whether AHCC can prevent infection or improve survival in human beings with severe trauma or undergoing surgical procedures.

Supplementation with active hexose correlated compound increases the innate immune response of young mice to primary influenza infection

The emergence of H5N1 avian influenza and the threat of new or adapted viruses in bioterrorism have created an urgent interest in identifying agents to enhance the immune response to primary virus infection. Active hexose correlated compound (AHCC) is a natural mushroom extract reported to increase natural killer (NK) cell activity, survival, and bacterial clearance in young mice. However, the effects of AHCC on the response to viral infections have not been studied. In this study, young C57BL/6 mice were supplemented with 1 g AHCC/(kg body weight x d) for 1 wk prior to and throughout infection with influenza A (H1N1, PR8). Supplementation increased survival, decreased the severity of infection, and shortened recovery time following intranasal infection with flu, as determined by the recovery of body weight and epithelial integrity in the lungs. AHCC increased NK activity in lungs at d 1 (P < 0.05) and d 4 (P < 0.01) and in the spleen at d 2 postinfection (P < 0.01). Supplementation increased the percentage (P < 0.05) and number (P < 0.01) of NK1.1+ cells in the lung and reduced the infiltration of lymphocytes and macrophages compared with controls (P < 0.01). These data suggest that AHCC supplementation boosts NK activity, improves survival, and reduces the severity of influenza infection in young mice. Bolstering innate immunity with dietary bioactives may be one avenue for improving the immune response to primary flu infection.

Active hexose correlated compound enhances tumor surveillance through regulating both innate and adaptive immune responses

Active hexose correlated compound (AHCC) is a mixture of polysaccharides, amino acids, lipids and minerals derived from cocultured mycelia of several species of Basidiomycete mushrooms. AHCC has been implicated to modulate immune functions and plays a protective role against infection. However, the potential role of AHCC in tumor immune surveillance is unknown. In this study, C57BL/6 mice were orally administered AHCC or water, followed by tumor cell inoculation. We showed that compared to pure water-treated mice, AHCC treatment significantly delayed tumor development after inoculation of either melanoma cell line B16F0 or lymphoma cell line EL4. Treatment with AHCC enhanced both Ag-specific activation and proliferation of CD4(+) and CD8(+) T cells, increased the number of tumor Ag-specific CD8(+) T cells, and more importantly, increased the frequency of tumor Ag-specific IFN-gamma producing CD8(+) T cells. Interestingly, AHCC treatment also showed increased cell number of NK and gammadelta T cells, indicating the role of AHCC in activating these innate-like lymphocytes. In summary, our results demonstrate that AHCC can enhance tumor immune surveillance through regulating both innate and adaptive immune responses.

Inhibition of active lymph pump by simulated microgravity in rats

During spaceflight the normal head-to-foot hydrostatic pressure gradients are eliminated and body fluids shift toward the head, resulting in a diminished fluid volume in the legs and an increased fluid volume in the head, neck, and upper extremities. Lymphatic function is important in the maintenance of normal tissue fluid volume, but it is not clear how microgravity influences lymphatic pumping. We performed a detailed evaluation of the influence of simulated microgravity on lymphatic diameter, wall thickness, elastance, tone, and other measures of phasic contractility in isolated lymphatics. Head-down tail suspension (HDT) rats were used to simulate the effects of microgravity. Animals were exposed to HDT for 2 wk, after which data were collected and compared with the control non-HDT group. Lymphatics from four regional lymphatic beds (thoracic duct, cervical, mesenteric, and femoral lymphatics) were isolated, cannulated, and pressurized. Input and output pressures were adjusted to apply a range of transmural pressures and flows to the lymphatics. Simulated microgravity caused a potent inhibition of pressure/stretch-stimulated pumping in all four groups of lymphatics. The greatest inhibition was found in cervical lymphatics. These findings presumably are correlated to the cephalic fluid shifts that occur in HDT rats as well as those observed during spaceflight. Flow-dependent pump inhibition was increased after HDT, especially in the thoracic duct. Mesenteric lymphatics were less strongly influenced by HDT, which may support the idea that lymph hydrodynamic conditions in the mesenteric lymphatic during HDT are not dramatically altered.

Considerations for non-invasive in-flight monitoring of astronaut immune status with potential use of MEMS and NEMS devices

The dynamics of how astronauts' immune systems respond to space flight have been studied extensively, but the complex process has not to date been thoroughly characterized, nor have the underlying principles of what causes the immune system to change in microgravity been fully determined. Statistically significant results regarding overall immunological effects in space have not yet been established due to the relatively limited amount of experimental data available, and are further complicated by the findings not showing systematically reproducible trends. Collecting in vivo data during flight without affecting the system being measured would increase understanding of the immune response process. The aims of this paper are to briefly review the current knowledge regarding how the immune system is altered in space flight; to present a group of candidate biomarkers that could be useful for in-flight monitoring and give an overview of the current methods used to measure these markers; and finally, to further establish the need and usefulness of incorporating real-time analytical techniques for in-flight assessment of astronaut health, emphasizing the potential application of MEMS/NEMS devices.