Resistance and augmentation of innate immunity in mice exposed to starvation.

Mice were exposed to starvation for 3 days. Body temperature and various parameters were examined. By starvation, body temperature, blood glucose and ACTH decreased, especially on days 2 and 3. The level of corticosterone increased at this time. On the other hand, the number of lymphocytes yielded by the liver, spleen and thymus decreased from day 1 to 3. The change of the distribution of lymphocyte subsets was unique because NK, NKT and extrathymic T cells were stress-resistant in the liver. Conventional T and B cells were stress-sensitive. Reflecting the increased proportion of NK and NKT cells, NK and NKT activities were augmented. The increased proportion of NKT cells produced both IFNgamma and IL-4 (Th0-type profile). The proportion and some functions of granulocytes and macrophages increased on Day 1 after starvation. These results suggest that starvation has a potential to increase the functions of unconventional lymphocytes and myeloid cells.

Role of alpha-adrenergic stimulus in stress-induced modulation of body temperature, blood glucose and innate immunity.

Mice were exposed to restraint stress for 3h. During this period, low body temperature (hypothermia, 39 degrees C-->less than 37 degrees C) and high blood glucose levels (hyperglycemia, 150 mg/dl-->up to 220 mg/dl) were simultaneously induced. Reflecting a stress-induced phenomenon, blood levels of catecholamines increased at that time. Administration of adrenaline (alpha-stimulus), but neither noradrenaline (alpha but less than adrenaline) nor isoproterenol (beta), induced a similar stress-induced pattern of body temperature and blood glucose variations. This alpha-adrenergic effect was confirmed using alpha- and beta-blockers in adrenaline-induced hypothermia and hyperglycemia. By applying this alpha-stimulus, the effect on immunoparameters was then investigated. Stress-resistant lymphocyte populations were found to be NK cells, extrathymic T cells and NKT cells, especially in the liver. Functional assays showed that both NK-cell cytotoxicity and NKT-cell cytotoxicity were augmented by alpha-stimulus. These results suggest that alpha-stimulus is one of the important factors in the stress-induced phenomenon and that it eventually produces hypothermia, hyperglycemia and innate-immunity activation seen during stress.

Malaria protection in beta 2-microglobulin-deficient mice lacking major histocompatibility complex class I antigens: essential role of innate immunity, including gammadelta T cells.

It is still controversial whether malaria protection is mediated by conventional immunity associated with T and B cells or by innate immunity associated with extrathymic T cells and autoantibody-producing B cells. Given this situation, it is important to examine the mechanism of malaria protection in beta(2)-microglobulin-deficient (beta(2)m(-/-)) mice. These mice lack major histocompatibility complex class I and CD1d antigens, which results in the absence of CD8(+) T cells and natural killer T (NKT) cells. When C57BL/6 and beta(2)m(-/-) mice were injected with parasitized (Plasmodium yoelii 17XNL) erythrocytes, both survived from the infection and showed a similar level of parasitaemia. The major expanding T cells were NK1.1(-) alphabeta T-cell receptor(int) cells in both mice. The difference was a compensatory expansion of NK and gammadelta T cells in beta(2)m(-/-) mice, and an elimination experiment showed that these lymphocytes were critical for protection in these mice. These results suggest that malaria protection might be events of the innate immunity associated with multiple subsets with autoreactivity. CD8(+) T and NKT cells may be partially related to this protection.

Relationship between diseases accompanied by tissue destruction and granulocytes with surface adrenergic receptors.

It is well-known that physiological phenomena and certain diseases, including neonatal granulocytosis, age-associated granulocytosis, periodontitis, pancreatitis, Crohn's disease, ulcerative colitis, hemorrhoids, endometriosis, and NSADs-enteritis, are accompanied by tissue destruction and granulocytosis. We investigated what is a key factor connecting tissue destruction and granulocytosis, attention being focused on adrenergic receptors on granulocytes and stress-induced sympathetic nerve stimulation. If we introduce the concept that "granulocytosis and subsequent tissue destruction are induced by sympathetic nerve stimulation," the mechanisms underlying many physiological phenomena and the etiology of several uncurable diseases in humans can be clearly understood.

Modulation of the endocrine and immune systems by well-controlled hyperthermia equipment.

Since high levels of hyperthermia induce immunosuppression to a certain extent (i.e., granulocytosis and lymphocytopenia) in patients, we applied mild hyperthermia in volunteers using equipment enabling well-controlled hyperthermia. Restricted control of rectal temperature at 39.4 (+/- 0.2) degrees C for 30 min was conducted and various parameters of the body were examined. The most prominent change observed during exposure to hyperthermia was elevated levels of pH and PO(2) in the blood, even in the venous blood. A transient elevation of ACTH, cortisol and growth hormone in the blood was also seen during this time. In parallel with this phenomenon, the number of total lymphocytes and those of its subsets (especially CD57(+) or CD56(+) NK cells and NKT cells) increased. More interestingly, the proportion of HLA-DR (MHC class II antigens) increased in NK and NKT cells, and their intensity on the surface of CD20(+) B cells increased. These results suggest that mild hyperthermia is important for modulation of the functions of the circulatory, endocrine and immune systems.

Potentiation of intestinal immunity by micellary mushroom extracts.

Mushroom (shiitake) extracts were dispersed with lecithin micelles to prepare superfine particles (0.05 to 0.2 microm in diameter) of beta-1,3-glucan (micellary mushroom extracts). When mice were fed with these micelles of beta-glucan (0.75 mg/day/mouse, smaller amounts of beta-glucan), the number of lymphocytes yielded by the small intestine increased by up to 40%. More interestingly, the ratio of CD8alphabeta(+)TCRalphabeta(+) cells/CD8alphaalpha(+)TCRalphabeta(+) cells increased prominently. In parallel with this deviation in the distribution of lymphocyte subsets, tumor cytotoxicity against P815 cells and cytokine productions were also augmented. In other words, phylogenetically developed lymphocytes (CD8alphabeta(+), TCRalphabeta(+)) were much more effectively activated by the oral administration of micellary beta-glucan. These results suggest that smaller amounts of micellary beta-glucan might be useful for the potentiation of intestinal immunity.

Research on stress-induced apoptosis of natural killer cells and the alteration of their killing activity in mouse liver.

AIM: To investigate the stress-induced apoptosis of natural killer (NK) cells and the changes in their killing activity in mouse livers. METHODS: A restraint stress model was established in mice. Flow cytometry was employed to measure the percentage of NK cells and the changes in their absolute number in mouse liver. The cytotoxicity of hepatic and splenic NK cells was assessed against YAC-1 target cells via a 4 h 51Cr-release assay. RESULTS: The restraint stress stimulation induced the apoptosis of NK cells in the liver and the spleen, which decreased the cell number. The number and percentage of NK cells in the spleen decreased. However, the number of NK cells in the liver decreased, whereas the percentage of NK cells was significantly increased. The apoptosis of NK cells increased gradually with prolonged stress time, and the macrophage-1 (Mac-1)(+) NK cells were more susceptible to apoptosis than Mac-1(-) NK cells. Large numbers of Mac-1(-) NK cells in the liver, which are more resistant to stress-induced apoptosis, were observed than the Mac-1(-) NK cells in the spleen. The stress stimulation diminished the killing activity of NK cells in the spleen was significantly decreased, but the retention of numerous Mac-1(-) NK cells in the liver maintained the killing ability. CONCLUSION: Significant stress-induced apoptosis was observed among Mac-1(+) NK cells, but not Mac-1(-) NK cells in the mouse liver. Stress stimulation markedly decreased the killing activity of NK cells in the spleen but remained unchanged in the liver.

Proposal of alternative mechanism responsible for the function of high-speed swimsuits.

Since many top swimmers wearing Speedo LZR Racer swimsuits have broken world records, it is considered that the corset-like grip of suit supports the swimmers to maintain flexibility of movement and reducing water resistance. We propose an alternative mechanism to explain this phenomenon. The suits are so tight that the blood circulation of swimmers is suppressed. This effect accelerates the anaerobic glycolysis system but rather suppresses the aerobic mitochondrial respiration system. Because of the prompt production of ATP in the glycolysis system, the swimmers, especially in short distance competitions, obtain instantaneous force in white fibers of the skeletal muscles.

Alkalization of blood pH is responsible for survival of cancer patients by mild hyperthermia.

The effect of mild hyperthermia on venous blood pH was examined in 6 cancer patients. Mild hyperthermia was induced by continuation of a rectal temperature of 39.5 degrees C for 30 min. All 6 patients were diagnosed as suffering from advanced cancer with or without surgery and chemotherapy pretreatments. In Cases 1 to 5, but not Case 6, venous blood pH was alkalized up to pH 7.7 by this mild hyperthermia and the effect was reproduced depending on the application of hyperthermia. At this time, alkalized pH was accompanied by increased PO2 and decreased PCO2 in the blood. These patients showed good physical conditions and improved clinical data. On the other hand, hyperthermia could not be continued in Case 6 due to his worsened physical condition. The present data suggest that mild hyperthermia is a useful method to improve circulation failure, physical condition and clinical data.

Association of glucocorticoid with stress-induced modulation of body temperature, blood glucose and innate immunity.

To know the details of the mechanism on stress-associated responses, attention was first focused on body temperature and blood glucose after stress. Mice were exposed to restraint stress for 6 h. Under this condition, hypothermia (39 degrees C --> 33 degrees C) and hyperglycemia (150 mg/dl --> 350 mg/dl) were induced. Reflecting a stress-associated response, an increase of serum corticosterone (200 ng/ml --> up to 600 ng/ml) was observed. It was examined whether an administration of glucocorticoid induced a similar response. An injection of hydrocortisone (5.0 and 10.0 mg/mouse) simultaneously induced hypothermia and hyperglycemia. The effect on immunoparameters by an injection of hydrocortisone was examined. Although immunosuppression was seen as thymic atrophy and a decrease in the proportion of B cells in the liver, extrathymic T cells and NKT cells were found to be stress-resistant lymphocyte populations, especially in the liver. HSP70 mRNA was indicated to increase in the adrenal glands in response to the hydrocortisone injection. All these responses, including hypothermia, hyperglycemia and immunomodulation, induced by the hydrocortisone injection were suppressed by pre-administration of a glucocorticoid receptor antagonist (RU-486). These results suggest that glucocorticoid is one of the important mediators of the stress-associated responses.

Acute stress augments innate immunity in the liver and increases hyaluronan levels in the tissues and blood of mice.

The effect of acute stress on the immune system was examined in mice. Restraint stress decreased the number of lymphocytes in the liver, whereas the number of lymphocytes remained unchanged in the spleen and thymus. In the liver, the decrease in number appeared at 1.5 h and fell to a third of he control level at 3 h. The proportions of IL-2Rbeta(+)CD3(int) cells, NKT cells, CD44(+) T cells and B cells were changed in the liver. The absolute numbers of IL-2Rbeta(+)CD3(int) cells, NKT cells and CD3(+)CD44(+) cells remained constant in the liver under the stress, while those of total T cells and NK cells decreased. The levels of hyaluronan (HA) in various tissues and sera were then examined. The expression of hyaluronan binding protein (HABP) was found to increase in the skin, liver and kidney as shown by immunohistochemical staining. An increase of HA in sera due to stress was seen at 3 h. The present results suggest that the activation of CD44(+) T cells and unconventional T cells (i.e., innate immunity) in the blood and the elevated levels of HA (ligand for CD44) in the tissues and blood are crucial responses to acute stress exposure.

Reasons why DBA/2 mice are resistant to malarial infection: expansion of CD3int B220+ gammadelta T cells with double-negative CD4- CD8- phenotype in the liver.

DBA/2 (H-2(d)) mice are known to be more resistant than C57BL/6 (B6, H-2(b)) mice to the non-lethal 17XNL strain of Plasmodium yoelii. This is a very strange phenomenon because the functions of conventional T cells, especially CD8(+) T cells, are known to be somewhat lower in DBA/2 mice than in other strains of mice. We examined herein how immune responses differed between DBA/2 mice and B6 mice during malarial infection. DBA/2 mice and (DBA/2 x B6)F(1) (BDF(1), H-2(b/d)) mice were found to have milder parasitaemia and to recover more quickly from malarial infection than B6 mice. These DBA/2 and BDF(1) mice were also found to experience a marked expansion of interleukin (IL)-2Rbeta(+) CD3(int) cells and gammadelta T cells in the liver, especially in the recovery phase. The expansion of unconventional T cells (i.e. B220(+) T cells) was also marked in DBA/2 and BDF(1) mice. The majority of B220(+) T cells were gammadelta T cells and these T cells were double-negative CD4(-) CD8(-). More importantly, the production of immunoglobulin M (IgM)-type anti-DNA autoantibody was also higher in DBA/2 and BDF(1) mice than in B6 mice. In conjunction with data on cytokine production, these results indicate that primitive T and B cells, namely autoreactive extrathymic T cells and autoantibody-producing B cells, may be much more activated in DBA/2 mice and therefore resistant to the non-lethal 17XNL strain of P. yoelii.

Augmentation of innate immunity by low-dose irradiation.

The effect of low-dose irradiation on the immune system was investigated in mice. When a 0.2 Gy dose of X-ray irradiation was administered every other day for a total of four times, the number of lymphocytes yielded by the liver, spleen and thymus decreased at the initial stage (around day 10). At this stage, NK cells, extrathymic T cells and NKT cells were found to be radioresistant. In other words, conventional lymphocytes were radiosensitive, even in the case of low-dose irradiation. However, the number of lymphocytes in all tested immune organs increased beyond the control level at the recovery stage (around day 28). Enumeration of the absolute number of lymphocyte subsets showed that the most prominently expanding populations were NK cells, extrathymic T cells and NKT cells, especially in the liver where primordial lymphocytes are primarily present. Functional and phenotypic activation of these populations also occurred at the recovery stage. It raised a possibility that an initial activation of macrophages by low-dose irradiation then mediated the present phenomenon. These results suggest that low-dose irradiation eventually has the potential to induce a hormesis effect on the immune system.

Nontoxic Shiga toxin derivatives from Escherichia coli possess adjuvant activity for the augmentation of antigen-specific immune responses via dendritic cell activation.

Shiga toxin (Stx) derivatives, such as the Stx1 B subunit (StxB1), which mediates toxin binding to the membrane, and mutant Stx1 (mStx1), which is a nontoxic doubly mutated Stx1 harboring amino acid substitutions in the A subunit, possess adjuvant activity via the activation of dendritic cells (DCs). Our results showed that StxB1 and mStx1, but not native Stx1 (nStx1), resulted in enhanced expression of CD86, CD40, and major histocompatibility complex (MHC) class II molecules and, to some extent, also enhanced the expression of CD80 on bone marrow-derived DCs. StxB1-treated DCs exhibited an increase in tumor necrosis factor alpha and interleukin-12 (IL-12) production, a stimulation of DO11.10 T-cell proliferation, and the production of both Th1 and Th2 cytokines, including gamma interferon (IFN-gamma), IL-4, IL-5, IL-6, and IL-10. When mice were given StxB1 subcutaneously, the levels of CD80, CD86, and CD40, as well as MHC class II expression by splenic DCs, were enhanced. The subcutaneous immunization of mice with ovalbumin (OVA) plus mStx1 or StxB1 induced high titers of OVA-specific immunoglobulin M (IgM), IgG1, and IgG2a in serum. OVA-specific CD4+ T cells isolated from mice immunized with OVA plus mStx1 or StxB1 produced IFN-gamma, IL-4, IL-5, IL-6, and IL-10, indicating that mStx1 and StxB1 elicit both Th1- and Th2-type responses. Importantly, mice immunized subcutaneously with tetanus toxoid plus mStx1 or StxB1 were protected from a lethal challenge with tetanus toxin. These results suggest that nontoxic Stx derivatives, including both StxB1 and mStx1, could be effective adjuvants for the induction of mixed Th-type CD4+ T-cell-mediated antigen-specific antibody responses via the activation of DCs.

Protection against malaria by anti-erythropoietin antibody due to suppression of erythropoiesis in the liver and at other sites.

We have previously reported that erythropoiesis commences in the liver and spleen after malarial infection, and that newly generated erythrocytes in the liver are essential for infection of malarial parasites as well as continuation of infection. At this time, erythropoietin (EPO) is elevated in the serum. In the present study, we administered EPO or anti-EPO antibody into C57BL/6 (B6) mice to modulate the serum level of EPO. When mice were infected with a non-lethal strain (17NXL) of Plasmodium yoelii (blood-stage infection of 10(4) parasitized erythrocytes per mouse), parasitemia continued for 1 month, showing a peak at day 17. Daily injection of EPO (200 IU/day per mouse) from day five to day 14 prolonged parasitemia, whereas injection of anti-EPO antibody (1.5 mg/day per mouse) every second day from day five to day 28 decreased it. Erythropoiesis was confirmed in the liver, spleen and bone marrow by the appearance of nucleated erythrocytes (TER119+). When anti-EPO antibody was injected by the same protocol into mice infected with a lethal strain (17XL) of P. yoelii, all mice showed decreased parasitemia and recovered from the infection. These results suggest that the use of anti-EPO antibody after malarial infection may be of therapeutic value in severe cases of malaria.

AIM inhibits apoptosis of T cells and NKT cells in Corynebacterium-induced granuloma formation in mice.

Apoptosis inhibitor expressed by macrophages (AIM) inhibits apoptosis of CD4(+)CD8(+) (CD4/CD8) double-positive thymocytes, and supports the viability of these cells on the thymic selection. However, pleiotropic functions of AIM have been suggested. In this study, heat-killed Corynebacterium parvum (C. parvum) was injected into mice carrying the homozygous mutation (AIM(-/-)) and wild-type (AIM(+/+)) mice, to investigate the role of AIM in the formation of hepatic granulomas. In AIM(-/-) mice, the size and the number of hepatic granulomas were larger, and the resorption of granulomas was more delayed than in AIM(+/+) mice. The production of interleukin-12 was more prominent in AIM(-/-) mice than in AIM(+/+) mice. In the liver of AIM(+/+) mice, expression of AIM messenger ribonucleic acid (mRNA) increased after C. parvum injection. In situ hybridization demonstrated that AIM mRNA was expressed in Kupffer cells and exudate macrophages in the liver, especially in granulomas. Larger numbers of T cells and natural killer T (NKT) cells underwent apoptosis in the granulomas of AIM(-/-) mice, suggesting that AIM prevents apoptosis of NKT cells and T cells in C. parvum-induced inflammation. Recombinant AIM (rAIM) protein significantly inhibited apoptosis of NKT cells and T cells obtained from C. parvum-stimulated livers in vitro. These results indicate that AIM functions to induce resistance to apoptosis within NKT cells and T cells, and supports the host defense in granulomatous inflammation.

Immunopotentiation of NKT cells by low-protein diet and the suppressive effect on tumor metastasis.

Mice were fed with a 5% low-protein diet for two weeks, at which point tumor inoculation was conducted. Following this inoculation, the 5% low-protein diet was continued. On the other hand, control mice were fed with a normal diet (25% protein) and such diet was continued after tumor inoculation. In comparison with control mice, mice fed with the 5% low-protein diet showed a prominent prolongation of survival rate when injected with both EL4 and 3LL tumors. Interestingly, CD1d(-/-) mice, which primarily lack natural killer T (NKT) cells, did not show the prolongation of survival rate even when they received a 5% low-protein diet. The most striking phenomenon seen in tumor-bearing mice fed with the 5% low-protein diet was the suppression of tumor metastasis to the liver and lung. Such suppression was not seen in CD1d(-/-) mice who were fed with a 5% low-protein diet. Phenotypic study revealed that the proportion of NKT cells after tumor inoculation decreased in the mice fed with a normal diet. However, such decrease did not occur in mice fed with the 5% low-protein diet. Reflecting the activation of NKT cells by feeding, tumor cytotoxicity and cytokine production were also augmented by the 5% low-protein diet. These results suggest that a low-protein diet has the potential to augment the innate immunity against tumors, especially mediated by the activation of NKT cells.

Age-dependent variation in the proportion and number of intestinal lymphocyte subsets, especially natural killer T cells, double-positive CD4+ CD8+ cells and B220+ T cells, in mice.

The age-dependent variation in the proportion and number of lymphocyte subsets was examined at various extrathymic sites, including the liver, small intestine, colon and appendix in mice. In comparison with young mice (4 weeks of age), the number of total lymphocytes yielded by all tested organs was greater in adult (9 weeks) and old (40 weeks) mice. The major lymphocyte subset that expanded with age was interleukin-2 receptor (IL-2R) beta+ CD3int cells (50% of them expressed NK1.1) in the liver, whereas it was CD3+ IL-2Rbeta- NK1.1- cells at all intraepithelial sites in the intestine. Although NK1.1+ CD3+ cells were present at intraepithelial sites in the intestine, the proportion of this subset was rather low. The ratio of CD4 to CD8 tended to decrease among natural killer T (NKT) cells and T cells at all intraepithelial sites in the intestine with age. A unique population of double-positive CD4+ CD8+ cells in the small intestine increased in old mice. B220+ T cells were found mainly in the appendix and colon, and the proportion of these T cells decreased in old mice. Conventional NKT cells were very few in Jalpha281-/- and CD1d-/- mice in the liver, while NKT cells which existed in the appendix remained unchanged even in these mice. This was because unconventional CD8+ NKT cells were present in the intestine. The present results suggest that despite the fact that both the liver and intraepithelial sites in the intestine carry many extrathymic T cells, the distribution of lymphocyte subsets and their age-associated variation are site-specific.