Citrus pectin attenuates endotoxin shock via suppression of Toll-like receptor signaling in Peyer's patch myeloid cells

Pectin, a water-soluble dietary fiber, has been found to improve survival in endotoxin shock. However, the underlying mechanism by which pectin exerts its protective effect against endotoxin shock remains unknown. Apart from its prebiotic effects, it has been suggested that pectin directly affects immune cells to regulate inflammatory responses. In this study, we investigated the direct effect of pectin in murine model of endotoxin shock. Citrus pectin solution was administered to male C57BL/6 mice for 10 days. Thereafter, hypothermia was induced in the mice with intraperitoneal injection of lipopolysaccharide (LPS). The pectin-treated mice showed attenuation of both the decrease in rectal temperature and increase in serum IL-6 level as compared to vehicle control mice. Simultaneously, the pectin-treated mice showed reduced levels of inflammatory cytokine mRNA in Peyer's patches and mesenteric lymph nodes, but not in the spleen. Peyer's patch cells from the pectin-treated mice were sorted and their levels of IL-6 production on LPS stimulation were measured. The results of ex vivo analysis indicated that IL-6 secretion from CD11c⁺ cells was suppressed by oral administration of pectin. Furthermore, IL-6 secretion from Toll-like receptor (TLR)-activated RAW264.7 cells was suppressed by pretreatment with pectin in vitro. This suppression was observed even with degraded pectin pretreatment but not with polygalacturonic acid, as the principal constituent of the pectin backbone. Taken together, these results suggest that pectin intake suppresses TLR-induced inflammatory cytokine expression in Peyer's patch myeloid cells, presumably through inhibition of TLR signaling by the pectin side chains.     

Bone marrow-derived cells contribute to contractile dysfunction in endotoxic shock

How infection precipitates depressed contractility is incompletely understood but may involve the immune, nervous, and endocrine systems as well as the heart itself. In this study, we examined the role of Toll-like receptor 4 (TLR4) in LPS-induced myocardial contractile depression. Eighteen hours following endotoxin challenge, we compared contractile responses in hearts from wild-type (WT) and TLR4-deficient mice using modified Langendorff preparations. Unlike hearts from WT mice, TLR4-deficient hearts did not reveal significant contractile dysfunction following LPS administration, as measured by decreased responses in maximal left ventricular pressure, +dP/dtmax, and -dP/dtmax in ex vivo Langendorff preparations. These findings indicate a requirement for TLR4 in LPS-induced contractile depression. To determine the contribution of bone marrow-derived TLR4 function to LPS-induced myocardial dysfunction, we generated TLR4 chimeras using adoptive transfer between histocompatible mouse strains: either TLR4-deficient mice with TLR4+/+ bone marrow-derived cells or TLR4+/+ animals lacking TLR4 in their hematopoietic cells. We then compared the contractile responses of engrafted animals after LPS challenges. Engraftment of TLR4-deficient mice with WT marrow restored sensitivity to the myocardial depressant effects of LPS in TLR4-deficient hearts (P < 0.05). Inactivation of bone marrow-derived TLR4 function, via transplantation of WT mice with TLR4-/- marrow, however, did not protect against the depressant effect of endotoxin. These findings indicate that bone marrow-derived TLR4 activity is sufficient to confer sensitivity to mice lacking TLR4 in all other tissues. However, because inactivation of marrow-derived TLR4 function alone does not protect against endotoxin-triggered contractile dysfunction, TLR4 function in other tissues may also contribute to this response.     

Thermoregulatory responses of rats to conventional preparations of lipopolysaccharide are caused by lipopolysaccharide per se-- not by lipoprotein contaminants

LPS preparations cause a variety of body temperature (T(b)) responses: monophasic fever, different phases of polyphasic fever, and hypothermia. Conventional (c) LPS preparations contain highly active lipoprotein contaminants (endotoxin proteins). Whereas LPS signals predominantly via the Toll-like receptor (TLR) 4, endotoxin proteins signal via TLR2. Several TLR2-dependent responses of immunocytes to cLPS in vitro are triggered by endotoxin proteins and not by LPS itself. We tested whether any T(b) response to cLPS from Escherichia coli 055:B5 is triggered by non-TLR4-signaling contaminants. A decontaminated (d) LPS preparation (free of endotoxin proteins) was produced by subjecting cLPS to phenol-water reextraction. The presence of non-TLR4-signaling contaminants in cLPS (and their absence in dLPS) was confirmed by showing that cLPS (but not dLPS) induced IL-1beta expression in the spleen and increased serum levels of TNF-alpha and IL-1beta of C3H/HeJ mice; these mice bear a nonfunctional TLR4. Yet, both cLPS and dLPS caused cytokine responses in C3H/HeOuJ mice; these mice bear a fully functional TLR4. We then studied the T(b) responses to cLPS and dLPS in Wistar rats preimplanted with jugular catheters. At a neutral ambient temperature (30 degrees C), a low (0.1 microg/kg iv) dose of cLPS caused a monophasic fever, whereas a moderate (10 microg/kg iv) dose produced a polyphasic fever. In the cold (20 degrees C), a high (500 microg/kg iv) dose of cLPS caused hypothermia. All T(b) responses to dLPS were identical to those of cLPS. We conclude that all known T(b) responses to LPS preparations are triggered by LPS per se and not by non-TLR4-signaling contaminants of such preparations.     

Effects of IL-10 and age on IL-6, IL-1beta, and TNF-alpha responses in mouse skeletal and cardiac muscle to an acute inflammatory insult.

Exaggerated proinflammatory cytokine responses can be observed with aging, and reduced levels of the anti-inflammatory cytokine IL-10 may contribute to these responses. IL-10 can reduce IL-6, IL-1beta, and TNF-alpha expression in nonmuscle tissues; however, no studies have examined the combined effects of IL-10 and age on cytokine responses in skeletal and cardiac muscle. These experiments tested the hypothesis that the absence of IL-10, in vivo, is associated with greater IL-6, TNF-alpha, and IL-1beta responses to an inflammatory challenge in skeletal and cardiac muscle and that aging exaggerates these responses. We compared IL-6, IL-1beta, and TNF-alpha mRNA and protein levels in skeletal and cardiac muscle of young (4 mo) and mature (10-11 mo) wild-type (IL-10(+/+)) and IL-10 deficient (IL-10(-/-)) mice following LPS. Skeletal and cardiac IL-6 mRNA and protein were elevated by LPS for IL-10(+/+) and IL-10(-/-) mice with greater responses in the IL-10(-/-) mice (P < 0.01). In skeletal muscle these effects were greater in mature than young mice (P < 0.01). IL-1beta mRNA and protein responses to LPS were greater in cardiac muscle of young but not mature IL-10(-/-) mice compared with IL-10(+/+) (P < 0.01). However, IL-1beta responses were greater in mature than young mice, but only in IL-10(+/+) groups (P < 0.05). The absence of IL-10 was associated with higher TNF-alpha protein levels in cardiac muscle (P < 0.05). The results provide the first in vivo evidence that the absence of IL-10 is associated with a greater IL-6 response to LPS in skeletal and cardiac muscles, and in skeletal muscle aging further exaggerates these responses.     

Reduced Lipopolysaccharide (LPS)-Induced Nitric Oxide Production in Peritoneal Macrophages and Inhibited LPS-Induced Lethal Shock in Mice by a Sugar Cane (Saccharum officinarum L.) Extract

A sugar cane extract (SCE) has been found to have an immunostimulating effect in several animals. Lipopolysaccharide (LPS) is known to induce endotoxin shock via the production of inflammatory modulators such as tumor necrosis factor (TNF)-α and nitric oxide (NO). We examined in the present study the effects of SCE on the TNF-α and NO production in LPS-stimulated mice peritoneal cells and the endotoxin shock in mice. The supplementation of SCE to peritoneal macrophages cultured with LPS resulted in a significant decrease in NO production. All the mice injected intraperitoneally with LPS and D-galactosamine (LPS+GalN) died within 24 h. However, a peritoneal injection, but no intravenous or oral administration, of SCE (500–1,000 mg/kg) at 3 to 48 h before the LPS+GalN-challenge resulted in a significantly improved survival rate. These results suggest that SCE had a protective effect on LPS-induced endotoxin shock via one of possible mechanisms involving the suppression of NO production in the mouse peritoneal cavity.     

The effects of in vivo administration of endotoxin on the functions and interaction of hepatocytes and Kupffer cells

It was the purpose of this study to determine the effects of the in vivo administration of endotoxin on certain in vitro hepatocyte and Kupffer cell functions. An Alzet osmotic pump that contained endotoxin (LPS, 2.5 mg/100g) was implanted into the peritoneal cavity of 300g guinea pigs and delivered the endotoxin over a period of four days. In vivo administration of LPS did not cause a change in the in vitro release of albumin by isolated hepatocytes. However, when hepatocytes were co-cultured with Kupffer cells there was a significant decrease in albumin release for both control and LPS-treated animals. There was no difference between control and LPS-treated animals in the release of C3 by hepatocytes. However, there was a significant increase over the control group in C3 release by Kupffer cells from LPS-treated animals. When hepatocytes and Kupffer cells were cultured together, their release of C3 was not additive. Kupffer cells from LPS-treated animals released significantly greater amounts of PGE2 than control animals when stimulated in vitro with LPS. Thus, these Kupffer cells appeared to be primed to respond to an in vitro challenge of LPS. Kupffer cells from LPS-treated animals had significantly depressed antibody dependent cellular cytotoxicity (ADCC). This endotoxin model is useful for determining the in vivo effects of endotoxin on cellular function and gives some indirect evidence for the detrimental effects of LPS on the immune system and host defense.     

Role of nitric oxide in tolerance to lipopolysaccharide in mice.

The injection of repeated doses of lipopolysaccharide (LPS) results in attenuation of the febrile response, which is called endotoxin tolerance. We tested the hypothesis that nitric oxide (NO) arising from inducible NO synthase (iNOS) plays a role in endotoxin tolerance, using not only pharmacological trials but also genetically engineered mice. Body core temperature was measured by biotelemetry in mice treated with NG-monomethyl-L-arginine (L-NMMA, 40 mg/kg; a nonselective NO synthase inhibitor) or aminoguanidine (AG, 10 mg/kg; a selective iNOS inhibitor) and in mice deficient in the iNOS gene (iNOS KO) mice. Tolerance to LPS was induced by means of three consecutive LPS (100 microg/kg) intraperitoneal injections at 24-h intervals. In wild-type mice, we observed a significant reduction of the febrile response to repeated administration of LPS. Injection of L-NMMA and AG markedly enhanced the febrile response to LPS in tolerant animals. Conversely, iNOS-KO mice repeatedly injected with LPS did not become tolerant to the pyrogenic effect of LPS. These data are consistent with the notion that NO modulates LPS tolerance in mice and that iNOS isoform is involved in NO synthesis during LPS tolerance.     

Interleukin-1 (IL-1) depresses cytochrome P450 levels and activities in mice

Endotoxin depresses cytochrome P450 levels when injected into animals. The purpose of this study was to determine whether endotoxin itself, or monokine(s) released in response to endotoxin administration are responsible for this effect. Cytochrome P450 levels and drug metabolizing activities were measured in endotoxin resistant C3H/HeJ mice 24h after single intraperitoneal injections of either lipopolysaccharide (LPS), a semipurified murine monokine preparation containing interleukin-1 (IL-1), or murine recombinant IL-1. In endotoxin sensitive C3H/HeN mice, LPS (0.5 mg/Kg) decreased total cytochrome P450 levels, benzphetamine demethylase activities, and ethoxyresorufin-0-deethylase activities. This dose of LPS did not alter cytochrome P450 levels or activities in the C3H/HeJ mice. However, after injection of the semipurified monokine preparation or the recombinant IL-1, there were significant decreases in cytochrome P450 levels and activities similar to the decreases observed with LPS in the C3H/HeN mice. These findings suggest that the alterations in hepatic cytochrome P450 seen with endotoxin injection are mediated, at least in part, by IL-1.     

Reduced lipopolysaccharide (LPS)-induced nitric oxide production in peritoneal macrophages and inhibited LPS-induced lethal shock in mice by a sugar cane (Saccharum officinarum L.) extract

A sugar cane extract (SCE) has been found to have an immunostimulating effect in several animals. Lipopolysaccharide (LPS) is known to induce endotoxin shock via the production of inflammatory modulators such as tumor necrosis factor (TNF)-alpha and nitric oxide (NO). We examined in the present study the effects of SCE on the TNF-alpha and NO production in LPS-stimulated mice peritoneal cells and the endotoxin shock in mice. The supplementation of SCE to peritoneal macrophages cultured with LPS resulted in a significant decrease in NO production. All the mice injected intraperitoneally with LPS and D-galactosamine (LPS+GalN) died within 24 h. However, a peritoneal injection, but no intravenous or oral administration, of SCE (500-1,000 mg/kg) at 3 to 48 h before the LPS+GalN-challenge resulted in a significantly improved survival rate. These results suggest that SCE had a protective effect on LPS-induced endotoxin shock via one of possible mechanisms involving the suppression of NO production in the mouse peritoneal cavity.     

Sickness and Aggressive Behavior in Dominant and Subordinate Mice*

Sick animals show a set of organized behavioral changes (sickness behavior), which is the result of a motivational re‐organization of the behavior as a whole. Sickness behavior display can be influenced by the social context. In this work, we sought to investigate the regulation of sickness behavior within a pair of mice in the presence of an intruder mouse. Dominant and subordinate mice were treated with the bacterial endotoxin lipopolysaccharide (LPS) and were challenged with the presence of an intruder mouse. LPS effects depended on ranking and social context. Even though dominant mice displayed more agonistic interaction towards the intruder, subordinate mice displayed agonistic behavior towards the intruder when their dominant companion was treated with LPS. The results show that, not only sickness behavior is differentially expressed among different social ranks, but also that sickness behavior is related to different reactions among surrounding animals. These data are relevant for a biological approach to the relation between sickness behavior and social behavior.     

Developmental differences in hyperoxia-induced oxidative stress and cellular responses in the murine lung

Exposure of newborn mice to high inspired oxygen elicits a distinct phenotype of compromised alveolar and vascular development, although lethality during long-term exposure is lower in newborns compared to adults. As the effects of hyperoxia are mediated by excessive reactive oxygen species (ROS) generation, we hypothesized that newborn mice may exhibit enhanced expression of antioxidant defenses or attenuated ROS generation compared with adults. We measured subcellular oxidant responses to acute hyperoxia in lung slices and alveolar epithelial cells at varying time points during postnatal murine lung development. Oxidant stress was assessed using RoGFP, a ratiometric protein thiol redox sensor, targeted to the cytosol or the mitochondrial matrix. In contrast to newborn resistance to oxygen-induced mortality, cells of lung slices from younger mice demonstrated exaggerated mitochondrial matrix oxidant stress compared to adults, whereas oxidant stress responses in the cytosol were absent. Cell death in lung slices from newborn mice exposed to 48 h of hyperoxia was also greater than for adults. Consistent with these findings, expression of antioxidant enzymes in newborn lungs was lower than in adults, and induction of antioxidant levels and activity during 24 h of in vivo exposure was absent. However, expression of the reactive oxygen species-generating enzyme NADPH oxidase 1 was increased with hyperoxic exposure in the young but not the adult lung. Collectively, these results suggest that the greater lethality in adult animals may be more likely attributed to processes such as inflammation than to differences in antioxidant defenses. Therapies for neonatal and adult oxidative lung injury should therefore consider and address developmental differences in oxidative stress responses.     

Differential COX-2 induction by viral and bacterial PAMPs: Consequences for cytokine and interferon responses and implications for anti-viral COX-2 directed therapies

Cyclooxygenase 2 (COX)-2 is induced by bacterial and viral infections and has complex, poorly understood roles in anti-pathogen immunity. Here, we use a knock-in luciferase reporter model to image Cox2 expression across a range of tissues in mice following treatment with the either the prototypical bacterial pathogen-associated molecular pattern (PAMP), LPS, which activates Toll-like receptor (TLR)4, or with poly(I:C), a viral PAMP, which activates TLR3. LPS induced Cox2 expression in all tissues examined. In contrast, poly(I:C) elicited a milder response, limited to a subset of tissues. A panel of cytokines and interferons was measured in plasma of wild-type, Cox1^−/− and Cox2^−/− mice treated with LPS, poly(I:C), MALP2 (TLR2/6), Pam3CSK4 (TLR2/1), R-848 (TLR7/8) or CpG ODN (TLR9), to establish whether/how each COX isoform modulates specific PAMP/TLR responses. Only LPS induced notable loss of condition in mice (inactivity, hunching, piloerection). However, all TLR agonists produced cytokine responses, many of which were modulated in specific fashions by Cox1 or Cox2 gene deletion. Notably we observed opposing effects of Cox2 gene deletion on the responses to the bacterial PAMP, LPS, and the viral PAMP, poly(I:C), consistent with the differing abilities of the PAMPs to induce Cox2 expression. Cox2 gene deletion limited the plasma IL-1β and interferon-γ responses and hypothermia produced by LPS. In contrast, in response to poly(I:C), Cox2^−/− mice exhibited enhanced plasma interferon (IFNα,β,γ,λ) and related cytokine responses (IP-10, IL-12). These observations suggest that a COX-2 selective inhibitor, given early in infection, may enhance and/or prolong endogenous interferon responses, and thereby increase anti-viral immunity.     

Lipopolysaccharide Does Not Alter Small Airway Reactivity in Mouse Lung Slices

The bacterial endotoxin, lipopolysaccharide (LPS) has been associated with occupational airway diseases with asthma-like symptoms and in acute exacerbations of COPD. The direct and indirect effects of LPS on small airway reactivity have not been fully elucidated. We tested the hypothesis that both in vitro and in vivo LPS treatment would increase contraction and impair relaxation of mouse small airways. Lung slices were prepared from naïve Balb/C mice and cultured in the absence or presence of LPS (10 μg/ml) for up to 48 h for measurement of TNFα levels in conditioned media. Alternatively, mice were challenged with PBS or LPS in vivo once a day for 4 days for preparation of lung slices or for harvest of lungs for Q-PCR analysis of gene expression of pro-inflammatory cytokines and receptors involved in airway contraction. Reactivity of small airways to contractile agonists, methacholine and serotonin, and bronchodilator agents, salbutamol, isoprenaline and rosiglitazone, were assessed using phase-contrast microscopy. In vitro LPS treatment of slices increased TNFα release 6-fold but did not alter contraction or relaxation to any agonists tested. In vivo LPS treatment increased lung gene expression of TNFα, IL-1β and ryanodine receptor isoform 2 more than 5-fold. However there were no changes in reactivity in lung slices from these mice, even when also incubated with LPS ex vivo. Despite evidence of LPS-induced inflammation, neither airway hyperresponsiveness or impaired dilator reactivity were evident. The increase in ryanodine receptor isoform 2, known to regulate calcium signaling in vascular smooth muscle, warrants investigation. Since LPS failed to elicit changes in small airway reactivity in mouse lung slices following in vitro or in vivo treatment, alternative approaches are required to define the potential contribution of this endotoxin to altered small airway reactivity in human lung diseases.     

Changes in the superoxide production and other macrophage functions could be related to the mortality of mice with endotoxin-induced oxidative stress

Free radicals and proinflammatory cytokines from phagocytes have been implicated in the pathogenesis of endotoxic shock, a disease with high mortality caused by Gram-negative bacterial endotoxin. In the present study, male BALB/c and Swiss mice received intraperitoneally lipopolysaccharide (LPS) at 100 mg/kg and 150 mg/kg, respectively, that led to a lethal endotoxic shock (100 % of mortality before 30 h). Swiss mice injected with 100 mg/kg, that did not show lethal endotoxic shock, were also studied. Peritoneal macrophages were obtained from animals at 2, 4, 12 or 24 h after injection of LPS or saline (control) solutions. Superoxide anion and tumor necrosis factor (TNFalpha) production were determined in these cells as well as other functions such as adherence capacity, chemotaxis and phagocytosis. The increase in superoxide anion production after endotoxin injection was higher in cells from mice with lethal shock than in those with non-lethal shock. However, the enhancement of TNFalpha production was similar in all cases, although in Swiss mice the highest levels of TNFalpha were observed at 1.5 h after endotoxin injection, while in BALB/c mice they occurred at 2 h after LPS injection. This oxidative stress was also revealed by the other functions analyzed, since adherence to substrate and phagocytosis were stimulated and chemotaxis was decreased after endotoxin injection as compared to controls, the differences being even more significant in animals with lethal shock. These data suggest that these changes, mainly the increased production of free radicals even more than the TNFalpha release, could be involved in mouse mortality caused by LPS.     

Measurement and comparison of the proliferative and antibody response of neonatal, immature and adult murine spleen cells to T-dependent and T-independent antigens.

Mouse spleen cell antigenic responses to the thymic-dependent antigen sheep red blood cells (SRBC), and the thymic-independent antigens, E. Coli lipopolysaccharide (LPS) and pneumococcal polysaccharides Type I and II (SI, SII) were studied as as a function of age, employing both in vitro spleen cell stimulation and plaque-forming cell (PFC) assay systems. Primary spleen cell proliferative and PFC responses to SRBC, were either absent or meager in comparison to adult (8–12 weeks) values for the first 3 weeks of life. Thereafter responses rose achieving adult values between 4 and 8 weeks of age. The inability of young mice to respond to SRBC was not because of a different immunizing dose requirement for SRBC, since immunization with SRBC over a 200-fold range did not enhance their capability to respond. Also, addition of adherent cells or macrophages from adult mice did not enhance the immune responses of young mice. Furthermore, immunization of 2–4 week old mice with SRBC inhibited the secondary response to SRBC. In contrast, young murine spleen cell proliferative and PFC responses to SI, SII, and LPS were approximately the same as the adult by 7–14 days of life. These data suggest that B-cell immunologic activity, as measured by immunologic assays utilized in this study, develops much earlier than does T-cell responsiveness.     

Maternal fever at parturition and its effects on the newborn rabbit.

The febrile response to administration of endotoxin has been reported to be suppressed in both pregnant animals at term and in their newborn. In a previous study we found that newborn rabbits under appropriate conditions to develop a febrile reaction to injected endotoxin. In this investigation we sought to discover whether pregnant rabbits at term had a febrile response to endotoxin, and if so, its effect on thermoregulation in their newborn. Endotoxin (E. Coli LPS) was injected into 19 pregnant rabbits at term. Six delivered spontaneously within an hour. At one hour, 13 were given oxytocin, and a further 8 delivered within five minutes. The colonic temperature (Tc) of the mothers before endotoxin administration and at delivery, and of their young, was measured. The results were compared with those of 10 pregnant rabbits not given endotoxin, and their young. Within 15 min of delivery newborn rabbits from each litter were placed on a thermal gradient to assess their thermoregulatory responses. Pregnant rabbits at term developed an impressive febrile response to injected endotoxin and their young were born with high colonic temperatures. Newborn rabbits from febrile mothers selected higher thermal environments and maintained a higher colonic temperature than the newborn of non-febrile mothers. We conclude that fever is sustained in the first hours of life in the newborn of mothers injected with endotoxin. The possible mechanisms are of considerable interest. None of the pregnant rabbits died after endotoxin administration, but the stillbirth rate was 50% compared with 10% in non-febrile does.     

Enhanced susceptibility to lipopolysaccharide-induced arthritis and endotoxin shock in interleukin-32 alpha transgenic mice through induction of tumor necrosis factor alpha

Introduction

The present study assessed the potential functions of interleukin (IL)-32α on inflammatory arthritis and endotoxin shock models using IL-32α transgenic (Tg) mice. The potential signaling pathway for the IL-32-tumor necrosis factor (TNF)α axis was analyzed in vitro.

Methods

IL-32α Tg mice were generated under control of a ubiquitous promoter. Two disease models were used to examine in vivo effects of overexpressed IL-32α: Toll-like receptor (TLR) ligand-induced arthritis developed using a single injection of lipopolysaccharide (LPS) or zymosan into the knee joints; and endotoxin shock induced with intraperitoneal injection of LPS and D-galactosamine. TNFα antagonist etanercept was administered simultaneously with LPS in some mice. Using RAW264.7 cells, in vitro effects of exogenous IL-32α on TNFα, IL-6 or macrophage inflammatory protein 2 (MIP-2) production were assessed with or without inhibitors for nuclear factor kappa B (NFκB) or mitogen-activated protein kinase (MAPK).

Results

Single injection of LPS, but not zymosan, resulted in development of severe synovitis with substantial articular cartilage degradation in knees of the Tg mice. The expression of TNFα mRNA in inflamed synovia was highly upregulated in the LPS-injected Tg mice. Moreover, the Tg mice were more susceptive to endotoxin-induced lethality than the wild-type control mice 48 hours after LPS challenge; but blockade of TNFα by etanercept protected from endotoxin lethality. In cultured bone marrow cells derived from the Tg mice, overexpressed IL-32α accelerated production of TNFα upon stimulation with LPS. Of note, exogenously added IL-32α alone stimulated RAW264.7 cells to express TNFα, IL-6, and MIP-2 mRNAs. Particularly, IL-32α -induced TNFα, but not IL-6 or MIP-2, was inhibited by dehydroxymethylepoxyquinomicin (DHMEQ) and U0126, which are specific inhibitors of nuclear factor kappa B (NFκB) and extracellular signal regulated kinase1/2 (ERK1/2), respectively.

Conclusions

These results show that IL-32α contributed to the development of inflammatory arthritis and endotoxin lethality. Stimulation of TLR signaling with LPS appeared indispensable for activating the IL-32α-TNFα axis in vivo. However, IL-32α alone induced TNFα production in RAW264.7 cells through phosphorylation of inhibitor kappa B (IκB) and ERK1/2 MAPK. Further studies on the potential involvement of IL-32α-TNFα axis will be beneficial in better understanding the pathology of autoimmune-related arthritis and infectious immunity.     

Effects of vagotomy on serum endotoxin, cytokines, and corticosterone after intraperitoneal lipopolysaccharide

The vagus nerve appears to play a role in communicating cytokine signals to the central nervous system, but the exact extent of its involvement in cytokine-to-brain communication remains controversial. Recently, subdiaphragmatic vagotomy was shown to increase bacterial translocation across the gut barrier and thus may cause endotoxin tolerance. The current experiment tested whether or not vagotomized animals have similar systemic responses to endotoxin challenge as do sham-operated animals. Subdiaphragmatically vagotomized and sham-operated animals were injected intraperitoneally with one of three doses (10, 50, 100 microg/kg) of lipopolysaccharide (LPS) or vehicle, and blood samples were taken at 15, 30, 60, 90, and 120 min after the injection. The intraperitoneal injection of LPS increased circulating LPS levels at all time points examined. In addition, all three doses of LPS significantly increased serum interleukin (IL)-1beta, IL-6, and corticosterone in both control and vagotomized rats. In conclusion, vagotomy itself has no marked effect on circulating endotoxin levels or the production of IL-1beta, IL-6, or corticosterone in blood after an intraperitoneal injection of LPS.     

Complementation of the anti-TNP PFC response of N:NIH nude mice from nude dams by spleen cells of nude mice from heterozygous dams.

Type I and Type II nude (nu/nu) mice are borne and raised by nu/nu dams and +/nu dams, respectively, under SPF conditions. Splenocytes from Type I nude mice exhibit even smaller in vitro PFC responses to trinitrophenylated rabbit erythrocytes than splenocytes from Type II nude mice. Type II splenocytes complement the magnitude of the PFC response of Type I splenocytes. The helper cell-like activity contained in Type II splenocyte suspensions was increased by treating Type II nude donor mice with dibutyryl cyclic AMP, but was essentially unaffected by pretreatment of Type II donors with endotoxin (LPS). The helper-like activity of Type II splenocytes was suppressed by treatment with a rabbit antiserum (plus C′) raised against a mixture of neonatal mouse thymocytes (RAM-T). We interpret the data to indicate that Type II splenocytes contain a larger number of residual T cells and/or a more fully developed population of T precursor cells that initiate or that are capable of being induced to initiate a helper function.