Intestinal Polymeric Immunoglobulin Receptor Is Affected by Type and Route of Nutrition

BACKGROUND

Secretory immunoglobulin A (SIgA) prevents adherence of pathogens at mucosal surfaces to prevent invasive infection. Polymeric immunoglobulin receptor (pIgR) is located on the basolateral surface of epithelial cells and binds dimeric immunoglobulin A (IgA) produced by plasma cells in the lamina propria. This IgA-pIgR complex is transported apically, where IgA is exocytosed as SIgA to the mucosal surface. Our prior work shows that mice fed intragastric (IG, an elemental diet model) and IV parenteral nutrition (PN) solution have reduced intestinal T and B cells, SIgA, and interleukin-4 (IL-4) compared with mice fed chow or a complex enteral diet (CED). Prior work also demonstrates a reduction in IgA transport to mucosal surfaces in IV PN-fed mice. Because IL-4 up-regulates pIgR production, this work studies the effects of these diets on intestinal pIgR.

METHODS

Male Institute of Cancer Research (ICR) mice were randomized to chow (n = 11) with IV catheter, CED (n = 10) or IG PN (n = 11) via gastrostomy and IV PN (n = 12) for 5 days. CED and PN were isocaloric and isonitrogenous. Small intestine was harvested for pIgR and IL-4 assays after mucosal washing for IgA. IgA and IL-4 levels were analyzed by enzyme-linked immunosorbent assay and pIgR by Western blot.

RESULTS

Small intestinal pIgR expression, IgA levels, and IL-4 levels decreased significantly in IV PN and IG PN groups.

CONCLUSIONS

Lack of enteral stimulation affects multiple mechanisms responsible for decreased intestinal SIgA levels, including reduced T and B cells in the lamina propria, reduced Th-2 IgA-stimulating cytokines, and impaired expression of the IgA transport protein, pIgR.

Lack of Enteral Nutrition Delays Nuclear Factor Kappa B Activation in Peritoneal Exudative Cells in a Murine Glycogen-Induced Peritonitis Model

BACKGROUND

Early enteral nutrition is associated with a lower incidence of intraabdominal abscess in severely injured patients than parenteral nutrition (PN). We explored the underlying mechanisms by examining the influence of nutrition route on nuclear factor kappaB (NFkappaB) activation in peritoneal exudative cells (PECs) and peritoneal cytokine levels.

METHODS

Thirty male Institute Cancer Research mice were randomized to chow (n = 10), IV PN (n = 10), or intragastric (IG) PN (n = 10) and fed for 5 days. PECs were harvested at 2 or 4 hours after intraperitoneal injection of 2 mL of 1% glycogen. Intranuclear NFkappaB activity in PECs was examined by laser scanning cytometry. Cytokine (tumor necrosis factor-alpha [TNF-alpha], macrophage inflammatory protein-2 [MIP-2], interleukin-10 [IL-10]) levels in peritoneal lavaged fluid were determined by enzyme-linked immunosorbent assay.

RESULTS

Intranuclear NFkappaB at 2 hours was significantly higher in the chow and IG-PN groups than in the IV-PN group. TNF-alpha and IL-10 levels of the chow group were significantly higher than those of IV-PN mice at 2 hours, whereas those of IG-PN mice were midway between those of the chow and IV-PN groups. MIP-2 was significantly higher in the chow group than in the IG-PN and IV-PN mice at 2 hours. TNF-alpha levels correlated positively with intranuclear NFkappaB activity in PECs.

CONCLUSIONS

Enteral nutrition may improve peritoneal defense by preserving early NFkappaB activation in PECs and cytokine responses.

5-Fluorouracil Infusion Reduces Gut-Associated Lymphoid Tissue Cell Number and Mucosal Immunoglobulin A Levels

BACKGROUND

Anticancer drugs have been demonstrated to affect gut mucosal morphology and cause gastrointestinal symptoms. We hypothesized that even small doses of 5-fluorouracil (5-FU) would reduce gut-associated lymphoid tissue (GALT) mass and function.

METHODS

Mice underwent IV cannulation and received continuous infusion of normal saline or 10 mg/kg of 5-FU for 5 days. GALT cell numbers, phenotypes, and mucosal immunoglobulin A (IgA) levels were measured.

RESULTS

During the infusion, there were no significant differences in food intake or body weight change between the 2 groups. Cell yields from the intraepithelial space and lamina propria of the small intestine were lower in the 5-FU than the control group. The lamina propria CD4/CD8 ratio was reduced in the 5-FU compared with the control group. Intestinal and respiratory tract IgA levels were lower in the 5-FU than in the control group.

CONCLUSIONS

A small dose of 5-FU reduces GALT cell number and mucosal IgA levels, regardless of food intake.

Influence of adding fish oil to parenteral nutrition on gut-associated lymphoid tissue

BACKGROUND

Lack of enteral nutrition reduces gut-associated lymphoid tissue (GALT) mass and function, a mechanism underlying the increased morbidity of infectious complications in severely injured or critically ill patients. Strategies to restore parenteral nutrition (PN)-induced changes of GALT mass and function have been pursued. However, the influences of adding fish oil to PN on gut immunity remain to be clarified.

METHODS

Male Institute of Cancer Research (ICR) mice (n = 50) were randomized to 4 groups: ad libitum chow (chow), fat free PN (fat (-)-PN), PN + fish oil (FO-PN), and PN + safflower oil (SO-PN). The PN groups were given isocaloric and isonitrogenous PN solutions. The FO- and SO-PN groups received 20% of total calories from fat emulsions. After 5 days of feeding, lymphocytes from Peyer's patches (PPs), the intraepithelial space (IE), and the lamina propria (LP) of the entire small intestine were isolated. GALT lymphocyte numbers and phenotypes (CD4+, CD8+, alphabetaTCR+, gammadeltaTCR+, B220+ cells) were determined. Immunoglobulin A (IgA) levels of small intestinal washings were also measured by enzyme-linked immunosorbent assay. Another set of mice (n = 24) was used to determine plasma fatty acid compositions after feeding.

RESULTS

Lymphocyte numbers from PPs and the LP and intestinal IgA levels were significantly lower in the PN groups than in the chow group, with no significant differences between any 2 PN groups. The FO- and SO-PN groups showed moderate recovery of IE cell numbers compared with the fat (-)-PN group. Omega-3 and omega-6 fatty acid levels were increased with fish and safflower oil additions, respectively, compared with the fat (-)-PN group.

CONCLUSIONS

Adding fish oil to PN does not exacerbate PN-induced GALT changes but rather partially reverses these changes, with increased plasma omega-3 fatty acid levels.

Intraluminal Glutamine Administration During Ischemia Worsens Survival After Gut Ischemia-Reperfusion

BACKGROUND

Glutamine (GLN) treatment prior to gut ischemia-reperfusion (I/R) reportedly preserves gut glutathione levels and gut barrier function. We hypothesized that intraluminal GLN during ischemia would also protect against gut I/R.

MATERIAL AND METHODS

After randomization to control and GLN groups, mice were exposed to 75 min (Exp 1) or 50 min (Exp 2 and 3) gut I/R. One mL of 2% GLN solution was injected into the duodenal lumen at the onset of ischemia in the GLN group, whereas controls were given normal saline. In experiment 1, survival was monitored for 120 h (n = 38). In experiment 2, blood, small intestine, and liver samples were collected at 4 h after reperfusion (n = 13). Expressions of CD11a and CD11b on myeloid cells were measured. Reactive oxygen intermediate production by myeloid cells was determined with or without phorbol myristate acetate stimulation. Glutathione levels in the small intestine and liver were also evaluated. In experiment 3, hemodynamic parameters were measured before and after I/R (n = 6).

RESULTS

In experiment 1, survival time in the GLN group was reduced compared with the control group. In experiment 2, GLN increased expression of CD11b and reactive oxygen intermediate with phorbol myristate acetate, compared with controls. There were no significant differences in gut or liver glutathione levels between the two groups. In experiment 3, the GLN group showed a transient but significant reduction in systolic blood pressure after reperfusion compared with the control group.

CONCLUSION

Intraluminal GLN during severe gut ischemia worsens outcomes, possibly by enhancing circulating myeloid cell priming and activation, and by disturbing hemodynamics, without increasing organ glutathione levels.

Nutritional route affects ERK phosphorylation and cytokine production in hepatic mononuclear cells

OBJECTIVE

To clarify the influence of nutritional route on hepatic immunity in a murine model.

SUMMARY BACKGROUND DATA

Parenteral nutrition is disadvantageous for preventing infectious complications in critically ill and/or severely injured patients as compared with enteral nutrition. To date, lack of enteral nutrition has been demonstrated to impair mucosal immunity, gut barrier function, and the peritoneal defense system. However, influences of nutritional route on hepatic immunity, another important defense system against infection, have not been well studied.

METHODS

Male ICR mice were randomized to 3 groups: ad libitum chow (chow), intravenous (IV)-TPN and intragastric (IG)-TPN groups. The TPN groups were given isocaloric and isonitrogenous TPN solutions. After the mice had been fed for 5 days, hepatic mononuclear cells (MNCs) were isolated. Hepatic MNC numbers and functions (cytokine production, intracellular signaling, and LPS receptor expression) were determined. Moreover, 1.0 x 10 Pseudomonas aeruginosa were delivered by intraportal injection. Survival and histology were examined.

RESULTS

Hepatic MNC numbers were significantly lower in the IV-TPN group than in the chow and IG-TPN groups, without subpopulation changes. As compared with enterally fed mice, cytokine production (TNF-alpha, IFN-gamma, and IL-10) by hepatic MNCs in response to LPS was impaired in parenterally fed mice in association with blunted phosphorylation of ERK1/2, a MAPK. Hepatic MNCs from IV-TPN mice showed decreased expressions of CD14 and TLR4/MD2, as compared with enterally fed mice. Survival times were reduced in the IV-TPN group as compared with the chow and IG-TPN groups.

CONCLUSION

Preservation of hepatic immunity with enteral feeding is important for prevention of infectious complications in severely injured and/or critically ill patients.

Parenteral nutrition and fasting reduces mucosal addressin cellular adhesion molecule-1 (MAdCAM-1) mRNA in Peyer's patches of mice

BACKGROUND

Mucosal addressin cellular adhesion molecule-1 (MAdCAM-1) in Peyer's patches (PP) is the gateway molecule for cellular migration into the mucosal immune system. Lack of enteral feeding during parenteral nutrition (PN) rapidly decreases PP MAdCAM-1, leading to drops in mucosal T and B cells and intestinal and respiratory IgA. We determined the molecular events associated with MAdCAM-1 mRNA and protein during PN (short and long term) and fasting (1 and 2 days).

METHODS

Experiment 1: Cannulated mice received PN for 8 hours (short-term PN, n = 6) or chow + saline (chow, n = 6). Experiment 2: Cannulated mice received PN (long-term PN, n = 4) or chow (n = 3) for 5 days. Experiment 3: Noncannulated chow mice were fasted for 1 and 2 days (n = 2/time). Total cellular RNA from the PP was quantified for MAdCAM-1 mRNA by real-time polymerase chain reaction (PCR). MAdCAM-1 protein was measured by Western blot.

RESULTS

PN rapidly down-regulated MAdCAM-1 gene expression. After 8 hours of PN with lack of enteral feeding, MAdCAM-1 mRNA levels dropped 20% (0.8-fold vs chow, p > .05); 5 days of PN reduced MAd-CAM-1 levels 64% (0.34-fold vs chow, p < .05). PN reduced MAdCAM-1 protein levels by 30% (chow: 329 +/- 14 vs PN: 230 +/- 35, p < .05) after 5 days. Fasting of uncannulated mice decreased MAdCAM-1 mRNA levels by 16% (0.84-fold, p < .05) at day 1 and 30% (0.7-fold, p < .05) by day 2 compared with chow.

CONCLUSIONS

Both PN with lack of enteral feeding and fasting down-regulate MAdCAM-1 mRNA and protein levels in PP. The MAdCAM-1 changes are due to lack of enteral stimulation rather than toxic effects of PN.

LACK OF ENTERAL NUTRITION BLUNTS EXTRACELLULAR-REGULATED KINASE PHOSPHORYLATION IN GUT-ASSOCIATED LYMPHOID TISSUE

The mitogen-activated protein kinase (MAPK) family (extracellular-regulated kinase [ERK], p38, etc.) of signal transduction proteins includes important intracellular mediators of inflammation, playing critical roles in host defense. Phosphorylations of ERK and p38 are responsible for cell proliferation, cell differentiation, and cell death. We hypothesized that impaired gut-associated lymphoid tissue (GALT) function in the absence of enteral nutrition is associated with reduced MAPK phosphorylation in GALT cells. Fifty-three male Institute of Cancer Research mice were randomized into 3 groups; ad libitum chow, intragastric (i.g.)-TPN, and intravenous (i.v.)-TPN. TPN groups were administered a standard TPN solution. After 5 days of feeding, lymphocytes from Peyer patches (PPs), the lamina propria (LP) cells, and intraepithelial (IE) spaces in the small intestine were isolated. GALT lymphocyte numbers were determined. The lymphocytes were incubated with or without 50 ng/mL of phorbol myristate acetate (PMA) for 15 min, and phosphorylated ERK (p-ERK) and p38 (p-p38) levels were determined using laser scanning cytometry. In PP (GALT inductive site) lymphocytes, p-ERK was increased after PMA in all three groups. However, ERK phosphorylation in GALT effector sites (IE and LP) was enhanced only in the enteral groups. p38 phosphorylation was not increased in any GALT sites, in any of the three groups, in response to PMA. In another set of mice (n = 33), in vitro LP lymphocyte proliferation was assessed with BrdU with or without PMA. Cell proliferation was increased or maintained at high level with PMA in the i.g.-TPN and chow group, but remained low in the i.v.-TPN group. In conclusion, lack of enteral feeding blunts ERK activation and cell proliferation in response to PMA stimulation in GALT effector sites, which may be an important mechanism underlying reduced GALT function. The influence of nutrition on GALT p38 phosphorylation must be assessed with other types and dosages of stimulants.

Influences of long-term antibiotic administration on Peyer's patch lymphocytes and mucosal immunoglobulin A levels in a mouse model

BACKGROUND

Long-term antibiotic administration is sometimes necessary to control bacterial infections during the perioperative period. However, antibiotic administration may alter gut bacterial flora, possibly impairing gut mucosal immunity. We hypothesized that 1 week of subcutaneous (SC) antibiotic injections would affect Peyer's patch (PP) lymphocyte numbers and phenotypes, as well as mucosal immunoglobulin A (IgA) levels.

METHODS

Sixty-one male Institute of Cancer Research mice were randomized to CMZ (cefmetazole 100 mg/kg, administered SC twice a day), IPM (imipenem/cilastatin 50 mg/kg x 2), and control (saline 0.1 mL x 2) groups. After 7 days of treatment, the mice were killed and their small intestines removed. Bacterial numbers in the small intestine were determined using sheep blood agar plates under aerobic conditions (n = 21). PP lymphocytes were isolated to determine cell numbers and phenotypes (CD4, CD8, alphabetaTCR, gammadeltaTCR, B220; n = 40). IgA levels in the small intestinal and bronchoalveolar washings were also measured with ELISA.

RESULTS

Antibiotic administration decreased both bacterial number and the PP cell yield compared with the control group. There were no significant differences in either phenotype percentages or IgA levels at any mucosal sites among the 3 groups.

CONCLUSIONS

Long-term antibiotic treatment reduces PP cell numbers while decreasing bacterial numbers in the small intestine. It may be important to recognize changes in gut mucosal immunity during long-term antibiotic administration.

Parenteral nutrition impairs gut-associated lymphoid tissue and mucosal immunity by reducing lymphotoxin Beta receptor expression

OBJECTIVE

To determine the effects of parenteral nutrition (PN) on LTbetaR in gut-associated lymphoid tissue (GALT), particularly the intestine and Peyer's patches (PP).

SUMMARY BACKGROUND DATA

Lack of enteral stimulation with PN impairs mucosal immunity and reduces IgA levels through depression of GALT cytokines (IL-4 and IL-10) and GALT specific adhesion molecules. We have shown that each is critical to intact mucosal immunity through effects on lymphocyte homing, IgA production, and resistance to antibacterial and antiviral immunity. IgA is the principal specific immunologic mucosal defense. LTbetaR stimulation controls production of IL-4, the adhesion molecule MAdCAM-1, and other key components of GALT, all of which are important in increasing IgA levels and maintaining mucosal defenses.

METHODS

Experiment 1: LTbetaR expression in intestine and PP was analyzed by Western blot after 5 days of chow, a complex enteral diet (CED), or PN. Diets were isocaloric and isonitrogenous except for chow. Experiment 2: After completing pilot experiments to determine the appropriate dose of the LTbetaR agonistic antibody, mice received chow, PN + 5 mug of anti-LTbetaR mAb (2 times/d, i.v.) or PN + isotype control antibody. PP lymphocytes and intestinal IgA levels were measured after 2 days.

RESULTS

Lack of enteral stimulation with PN significantly decreased LTbetaR expression in intestine and PP compared with chow and CED. LTbetaR stimulation with an agonistic anti-LTbetaR mAb significantly increased PP lymphocyte counts and intestinal IgA in PN fed-mice.

CONCLUSIONS

LTbetaR expression is critical for GALT control mechanisms and intact mucosal immunity. PN reduces LTbetaR expression, PP lymphocytes, and intestinal IgA production. Exogenous LTbetaR stimulation reverses PN-induced depression of gut mucosal immunity.

Dietary restriction compromises resistance to gut ischemia-reperfusion, despite reduction in circulating leukocyte activation

BACKGROUND

Gut ischemia-reperfusion (gut I/R) accompanying severe surgical insults leads to neutrophil-mediated injury and is regarded as a triggering event in early multiple-organ failure. Our previous study demonstrated dietary restriction to down-regulate leukocyte activation. Therefore, we hypothesized dietary restriction might be beneficial in terms of surviving I/R. We also evaluated leukocyte activation and the level of organ glutathione, an antioxidative substance.

METHODS

Institute of Cancer Research mice received chow, 170 (ad libitum), 119 (MR: mild restriction) or 68 (SR: severe restriction) g/kg per day for 7 days. Exp. 1: The mice (n = 59) underwent 15 or 45 minutes of gut ischemia and survival was observed. Exp. 2: The mice (n = 73) were killed before or 60 or 120 minutes after 15-minute ischemia. Reactive oxygen intermediate (ROI) production by circulating myeloid cells and CD11b expression was determined. Some mice were assessed for nuclear factor kappa B (NFkappaB) activation. Glutathione levels were measured in some of the small intestine and liver samples from each group.

RESULTS

Dietary restriction decreased survival. Circulating myeloid cell priming and activation, in terms of ROI production and CD11b expression, were enhanced in the ad libitum group but not in the restricted groups. NFkappaB was activated only in the ad libitum group. Gut and hepatic glutathione levels were lower in the SR than in the ad libitum group. Dietary restriction caused histologic damages in gut, liver, and lung 120 minutes after reperfusion.

CONCLUSIONS

Dietary restriction blunts leukocyte priming and activation after gut ischemic insult but worsens the outcome by, at least in part, decreasing antioxidative activities. Clinically, nutrition replenishment may be required to improve the outcome of gut hypoperfusion.

Route and type of nutrition influence nuclear factor kappaB activation in peritoneal resident cells

Morbidity of intra-abdominal abscess is increased when severely injured patients are fed parenterally. Lack of enteral nutrition appears to impair peritoneal cavity host defense. Because the transcription factor nuclear factor kappaB (NFkappaB) regulates various genes involved in inflammatory responses and its activation is important for host defense, we hypothesized that enteral nutrition would preserve appropriate NFkappaB activation in peritoneal resident cells (PRCs), the first defense line against peritoneal contamination. Mice (n = 105) were randomized to chow (n = 38), intravenous (IV)-total parenteral nutrition (TPN) (n = 34), or intragastric (IG)-TPN (n = 33) for 5 days' feeding. In experiment 1, PRCs were harvested for measurement of intranuclear NFkappaB activity with or without in vitro lipopolysaccharide (LPS) stimulation using laser scanning cytometry and enzyme-linked immunoabsorbant assay. PRC numbers tended to be higher in enterally fed mice than in IV-TPN mice. The main PRC subpopulation was macrophages in all groups. NFkappaB activation was increased in response to LPS in chow mice, whereas there was no increase in the IV-TPN group. IG-TPN mice demonstrated moderate NFkappaB activation. In experiment 2, mice underwent cecal ligation and puncture (CLP). Survival was observed up to 5 days. In another set of mice, tumor necrosis factor (TNF) alpha levels of peritoneal lavaged fluid were measured 4 h after CLP. Survival times after CLP improved in the chow and IG-TPN groups compared with the IV-TPN group. TNFalpha levels were significantly higher in the chow than in the IV-TPN group. In conclusion, parenteral nutrition decreases PRC number and blunts NFkappaB activation in PRCs. These changes may impair host defense in the peritoneal cavity.

Gut ischemia-reperfusion affects gut mucosal immunity: A possible mechanism for infectious complications after severe surgical insults*

OBJECTIVE

To examine influences of gut ischemia/reperfusion (I/R) on gut-associated lymphoid tissue (GALT) mass and function.

DESIGN

Prospective, randomized controlled study.

SETTING

Research laboratory.

SUBJECTS

Male Institute of Cancer Research mice.

INTERVENTIONS

Ninety mice were randomized to three groups: I/R (60-min gut ischemia), sham (laparotomy only), and control (no operation). On days 1, 2, 4, 7, and 10, mice were killed to harvest lymphocytes from Peyer patches, the intraepithelial space, and the lamina propria (LP) of the small intestine. Respiratory tract and small intestinal washings were also obtained.

MEASUREMENTS AND MAIN RESULTS

Gut I/R significantly reduced lymphocyte numbers in Peyer patches, the intraepithelial space, and the LP. The reduction was prominent in GALT effector sites, that is, the intraepithelial space and LP, but numbers recovered quickly in LP. Changes in cell numbers in Peyer patches, GALT inductive sites, were subtle but persistent. Gut I/R reduced B cell numbers in Peyer patches; alphabeta T cell receptor (TCR)+, gammadeltaTCR+, CD8+, and B cell numbers in the intraepithelial space; and gammadeltaTCR+, CD8+, and B cell numbers in the LP, in comparison with the sham or control group. There were no significant differences in respiratory tract immunoglobulin A levels between the I/R and sham groups. Intestinal immunoglobulin A was elevated on day 1 in the I/R group, with no significant difference after day 2 in comparison with the sham group.

CONCLUSIONS

Despite the maintained mucosal immunoglobulin A level, gut I/R markedly reduces GALT cell numbers, with changes in lymphocyte phenotypes. These alterations may be associated with increased morbidity due to infectious complications after severe surgical insults.

T lymphocyte numbers in human gut associated lymphoid tissue are reduced without enteral nutrition

BACKGROUND

Clinically, in the absence of enteral nutrition, the morbidity of infectious complication is high. Although experiments using mice have shown alterations in gut-associated lymphoid tissue (GALT) to be an important mechanism underlying impaired host defense, there are no clinical studies on the effects of nutritional routes on GALT.

METHODS

A total of 27 colon cancer cases who underwent right colectomy or hemicolectomy were reviewed. Six patients did not receive enteral nutrition for 4 to 28 days before surgery because of bowel obstruction (parenteral nutrition [PNI group). Twenty-one patients were enterally fed before surgery (enteral nutrition [EN] group). The terminal ileum from resected specimens was examined microscopically. T-cell numbers in intraepithelial spaces (IE) and the lamina propria (LP) were determined immunohistochemically in blinded fashion.

RESULTS

There were no significant differences in baseline characteristics between the 2 groups. T-cell number in the LP was significantly lower in the PN group than in the EN group, with no difference in IE cell numbers.

CONCLUSIONS

Lack of enteral delivery of nutrients reduces GALT cell number in patients with colon cancer, as is the case in mice.

L-arginine-enriched parenteral nutrition affects lymphocyte phenotypes of gut-associated lymphoid tissue

BACKGROUND

Experimentally, total parenteral nutrition (TPN) diminishes gut-associated lymphoid tissue (GALT) cell numbers and function. Although glutamine supplementation is known to reverse TPN-induced changes in GALT, effects of another conditionally essential amino acid, L-arginine (ARG), on GALT remain unclear.

METHODS

Twenty-two male Institute of Cancer Research mice were randomized to standard TPN (0.3% arginine, STD-total parenteral nutrition) or 1% ARG-enriched TPN (ARG-total parenteral nutrition). After 5 days of feeding, lymphocytes were harvested from Peyer's patches (PP), the lamina propria, and intraepithelial (IE) spaces of the small intestine to determine cell yields. Lymphocyte phenotypes (alphabetaTCR, gammadeltaTCR, CD4, CD8, and B220 as a B cell marker) were determined using flow cytometry. IgA levels in washings of the small intestine, upper respiratory tract, and lungs were measured with ELISA.

RESULTS

ARG-total parenteral nutrition did not affect lymphocyte yields. The percentages of CD4+ cells in PP and IE, and alphabetaTCR+ cells in PP, were significantly higher in the ARG-total parenteral nutrition than in the STD-total parenteral nutrition mice, without marked differences in other phenotypes examined. There were no significant differences in intestinal and respiratory tract IgA levels between the 2 groups of mice.

CONCLUSIONS

One percent ARG supplementation of TPN does not improve GALT cell number or mucosal IgA level but benefits to increase CD4+ cell percentages in GALT.

Effects of L-arginine infusion during ischemia on gut blood perfusion, oxygen tension, and circulating myeloid cell activation in a murine gut ischemia/reperfusion model

BACKGROUND

Gut hypoperfusion is considered to be a mechanism for early multiple-organ failure after severe surgical insults. L-Arginine (ARG) may preserve gut microcirculation as a substrate of nitric oxide synthase, but simultaneously may enhance immune cell response. It remains unknown if ARG infusion during gut ischemia improves the outcome after gut ischemia-reperfusion (I/R).

METHODS

Male Institute of Cancer Research mice were randomized to control and ARG groups. After i.v. cannulation, mice underwent 90 (Exp. 1) or 60 (Exp. 2 and 3) minutes of gut I/R. Control mice received normal saline infusion at 1 mL/h for 60 minutes during ischemia, whereas the ARG group was given 1% ARG hydrochloride solution. In Exp. 1, survival was observed for 72 hours (n = 35). In Exp. 2, blood perfusion and oxygen tension of the small intestine were measured (n = 9). In Exp. 3, peripheral blood was obtained at 2 or 4 hours after reperfusion (n = 22). Reactive oxygen intermediate (ROI) production by myeloid cells with or without phorbol myristate acetate (PMA) stimulation and expression of CD11a and CD11b on myeloid cells were examined using flow cytometry.

RESULTS

Exp. 1: There was no significant difference in survival times (log rank test, p = .2). However, survival rates at 12 hours were 72% (13/18) for the control group and 35% (6/17) for the ARG group (p < .05 Fisher). Exp. 2: ARG infusion significantly improved gut blood perfusion ratio during ischemia but had no effect on oxygen tension. Exp. 3: In the ARG group, ROI production with PMA and CD11b expression at 4 hours were higher than those at 2 hours, whereas there were no significant changes in the control mice.

CONCLUSIONS

ARG infusion improves intestinal blood perfusion during ischemia but primes and activates circulating myeloid cells excessively. Consequently, i.v. infusion of ARG during ischemia reduces survival rate.

Interleukin-12 and -18 induce severe liver injury in mice recovered from peritonitis after sublethal endotoxin challenge

BACKGROUND

Postoperative intraabdominal abscess is the major complication after abdominal surgery, and additional infection is often observed and becomes the leading cause of death in septic patients who survive initial resuscitation. Sepsis is initiated and perpetuated by the overzealous systemic production of proinflammatory cytokines-such as tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-12, and IL-18-sometimes resulting in excessive tissue injury and death. The purpose of this study was to assess the correlation between liver and spleen innate cytokine responses and organ dysfunction in sepsis syndrome.

METHODS

Peritonitis was induced by cecal ligation and puncture (CLP). All CLP mice survived more than 7 days after the procedure, and serum cytokine (TNF-alpha, IL-12, IL-18, and IL-10) levels peaked 12 hours after CLP; thereafter, they returned to basal levels 7 days after CLP. The mice were injected with a sublethal dose of lipopolysaccharide (LPS) 7 days after CLP. Survival rates, tissue damage, serum cytokine levels, and cytokine production of liver or spleen mononuclear cells (MNCs) were evaluated.

RESULTS

All CLP mice died within 6 hours from liver injury 7 days after LPS challenge, but all sham mice survived. IL-12, IL-18, and IFN-gamma levels in supernatants of the liver MNCs stimulated with LPS in CLP mice were significantly higher than those in sham mice 7 days after the procedure. Furthermore, serum IL-12 and IL-18 levels and liver MNCs IL-12, IL-18, and IFN-gamma production were significantly increased in CLP mice compared with sham mice after LPS challenge. Thereafter, effects of anti-IL-12 and/or anti-IL-18 antibody were evaluated in LPS-injected CLP mice. The survival rate of LPS-injected CLP mice treated with both anti-IL-12 and anti-IL-18 antibody was significantly better than that of untreated mice. Furthermore, liver damage was improved.

CONCLUSION

Mice recovered from mild peritonitis died of severe liver injury by subsequent injection of a sublethal dose of LPS, and this liver injury was related to the collaborating production of IL-12 and IL-18 by liver MNCs.

Glutamine infusion during ischemia is detrimental in a murine gut ischemia/reperfusion model

BACKGROUND

Gut ischemia/reperfusion (I/R) frequently occurs in clinical settings as a result of disproportionate splanchnic hypoperfusion during shock. Glutamine (GLN) supplementation of total parenteral nutrition (TPN) before gut I/R improves survival after gut I/R compared with standard TPN. However, it is unknown whether GLN treatment after the occurrence of the insult is beneficial or not. The aims of this study were to examine effects of GLN infusion during gut ischemia on survival, myeloid cell (neutrophils + monocytes) activation, and vascular permeability in organs.

METHODS

Male Institute of Cancer Research (ICR) mice were randomized to control and GLN groups. After IV cannulation, mice underwent 90 (experiments 1 and 2) or 60 (experiment 3) minutes of gut I/R. Control mice received normal saline infusion at 1 mL/h for 60 minutes during ischemia, whereas the GLN group was given 3% GLN solution. In experiment 1, survival rates were monitored for 72 hours (n = 25). In experiment 2, peripheral blood was obtained at 2 or 4 hours after reperfusion (n = 17). Reactive oxygen intermediate (ROI) production by myeloid cells was determined by flow cytometry using dihydrorhodamine 123 with or without phorbol myristate acetate stimulation. Expression of CD11a and CD11b on myeloid cells was also measured. Myeloperoxidase (MPO) activity in the lung was evaluated. In experiment 3, vascular permeability in organs was measured using Evans blue at 2 or 4 hours.

RESULTS

In experiment 1, survival time in the GLN group was significantly reduced compared with the control group (p = .02, log-rank test). The survival rates were 92% (12/13) and 42% (5/12) for the control and GLN groups at 12 hours (p = .01) and 38% (5/13) and 0% (0/12) at 48 hours (p = .02), respectively. In experiment 2, ROI production was significantly higher in the GLN group than in the control group after PMA stimulation both at 2 and 4 hours. CD11b expression was significantly higher in the GLN group than in the control group at 4 hours. There was no difference in pulmonary MPO activity at either time point. In experiment 3, GLN infusion significantly increased hepatic vascular permeability compared with saline infusion at 4 hours.

CONCLUSIONS

GLN infusion during ischemia is detrimental for survival after gut I/R. A possible mechanism is excessive priming of myeloid cells caused by GLN infusion. Timing of GLN administration is critical for outcome after gut ischemic insult.

Role of macrophage inflammatory protein 2 in acute lung injury in murine peritonitis

BACKGROUND

Acute lung injury is a frequent extraabdominal complication of bacterial peritonitis, and neutrophil plays an important role in this lung damage. Macrophage inflammatory protein 2 (MIP-2) serves the same chemotactic function as IL-8 which is a potent neutrophil chemotactic factor in humans, and we investigated the role of MIP-2 associated with neutrophil recruitment in the lung of murine peritonitis.

METHODS

Cecal ligation and puncture (CLP) were performed on mice. MIP-2 levels in blood and lung tissue, MIP-2 mRNA expression in lung tissue and bronchoalveolar lavage fluid (BALF), and CD11b expression on peripheral blood neutrophil and BALF cells were determined after CLP. In addition, we investigated the effect of anti-MIP-2 antibody on the lung injury associated with peritonitis.

RESULTS

MIP-2 mRNA expression was observed in lung tissue after CLP and numerous neutrophils were accumulated in the lung under those conditions. Anti-MIP-2 antibody contributed to the inhibition of the CD11b expression and chemotaxis of pulmonary neutrophils, lung edema, and thus the reduction in peritonitis-related mortality.

CONCLUSIONS

MIP-2 plays a pivotal role in neutrophil recruitment in the lung following peritonitis, and control of neutrophil accumulation in the lung by neutralizing MIP-2 is recommended as a new therapeutic approach to the lung damage associated with peritonitis.

Severe sepsis induces deficient interferon-gamma and interleukin-12 production, but interleukin-12 therapy improves survival in peritonitis

BACKGROUND

After severe sepsis, there is an increase of Th2 cytokine and a decrease in Th1 cytokine that may account for impaired cellular immunity. The aim of this study is to evaluate the Th1, Th2 cytokine balance in the serum, peritoneal lavage fluid (PLF) and liver mononuclear cells (MNC) of experimental peritonitis mice, and determine the effect of interleukin-12 (IL-12), a cytokine stimulating Th1 cytokine production, when administered to septic mice.

METHODS

Experimental bacterial peritonitis mice was induced by cecal ligation and puncture (21-gauge needle, mild peritonitis) or cut (5 mm, severe peritonitis). Serum and PLF levels and liver MNC production of interferon (IFN)-gamma, IL-10, and IL-12 were measured after the procedure. Mild and severe peritonitis mice were treated intraperitoneally with recombinant IL-12 (r-IL-12) either 6 hours before or 6 and 24 hours after the procedure. The survival rates were then compared with nontreated mice.

RESULTS

Serum and PLF IFN-gamma, IL-12 levels in severe peritonitis mice were significantly lower than those in mild peritonitis mice at 6 and 12 hours after the procedure. On the other hand, serum and PLF IL-10 levels in severe peritonitis mice were significantly higher than those in mild peritonitis mice at 6 hours after the procedure. Furthermore, liver MNC IFN-gamma production in severe peritonitis mice was significantly higher than that in mild peritonitis mice at 6 hours after the procedure, but liver MNC IL-12 production in severe peritonitis mice was significantly lower than that in mild peritonitis mice at 12 hours after the procedure. Severe peritonitis mice treated with r-IL-12 at 6 hours before the procedure improved survival rate, and mild peritonitis mice treated with r-IL-12 at 24 hours after the procedure showed significantly improved survival rates.

CONCLUSIONS

Change in the Th1, Th2 cytokine balance in peritonitis mice might induce a shift toward a Th2 dominant phenotype according to the severity of peritonitis, and the capacity to produce IFN-gamma and IL-12 by liver MNC is reduced. Therapies designed to augment the production of Th1 cytokines, such as IL-12, may thus prove to be beneficial in the treatment of severe sepsis after peritonitis.

Increased monocyte activation in elderly patients after surgical stress

OBJECTIVE

To investigate age-related changes in the host response to surgical stress. The clinical course, serum interleukin-6 (IL-6) levels, monocyte production of tumor necrosis factor-alpha (TNF-alpha), and monocyte expression of CD11b/CD18 were used as markers of the systemic response.

METHODS

Patients with gastric cancer, undergoing distal gastrectomy were divided into 2 groups: >75 years of age (elderly group) and < or =75 years of age (young group). Serum IL-6 levels, TNF-alpha production and CD11b/CD18 expression by monocytes, and the postoperative clinical course were compared between the 2 groups.

RESULTS

TNF-alpha production by lipopolysaccharide-stimulated monocytes and CD11b/CD18 expression on monocytes after surgical stress were significantly higher in the elderly than in the young group. Moreover, serum IL-6 levels on the first postoperative day in the elderly group were significantly higher than those in the young group. The incidence and duration of systemic inflammatory response syndrome (SIRS) were significantly greater in the elderly than in the young group.

CONCLUSIONS

The activation of monocytes and hypercytokinemia occur readily after surgical stress in the elderly and may therefore contribute to SIRS and increased susceptibility to postoperative complications.

Mechanism of the inhibitory effect of protease inhibitor on tumor necrosis factor alpha production of monocytes

If the inflammatory response becomes excessive or uncontrolled by some stimuli, inappropriate inflammatory responses occur. Monocytes are extremely important cells for regulating the cytokine network and tumor necrosis factor alpha (TNFalpha) and interleukin- (IL) 10, which are mainly synthesized by monocytes, are representative cytokines that play a central role in the cytokine network. Protease inhibitors such as gabexate mesilate (GM) and ulinastatin (UTI) have been shown to have various beneficial effects by inhibiting the activation of leukocytes, but the mechanism for this has yet to be fully elucidated. In this study we investigated the mechanism of the inhibitory effect of protease inhibitors on the proinflammatory cytokine production of lipopolysaccharide- (LPS) stimulated monocytes. LPS-stimulated monocytes were treated with GM or UTI. The value of TNFalpha and IL-10 in the culture medium of monocytes was measured and each mRNA expression was assayed. The inhibitory effect of protease inhibitors on the activity of intracellular signal transduction pathways such as protein kinase C (PKC) and nuclear factor kappa B (NFkappaB) were also evaluated. GM decreased the TNFalpha production of LPS-stimulated monocytes as shown by the inhibition of mRNA expression and increased the IL-10 production of LPS-stimulated monocytes. GM also suppressed the NFkappaB activity of LPS-stimulated monocytes. UTI decreased the TNFalpha production of LPS-stimulated monocytes, but did not inhibit the TNFalpha mRNA expression. The present study shows that the inhibitory effect of GM on the TNFalpha production of activated human monocytes is mediated by the suppression of NFkappaB activation, while the mechanism of UTI inhibiting TNFalpha production of human monocytes may be due to the inhibition of either the translation or secretion of TNFalpha.

Enhanced efficacy of nilvadipine in hypertensives whose raised ambulatory blood pressure is sustained during sleep

This study was designed to clarify the relationship between the antihypertensive effects of the calcium antagonist nilvadipine, and circadian changes in blood pressure. Based on measurements using an ambulatory blood pressure monitoring system (ABPM), 17 outpatients with untreated essential hypertension were divided into two groups: a sustained hypertensive group (with a fall in blood pressure during sleep < 10%, n = 7) and a waking time hypertensive group (with a fall in blood pressure during sleep > or = 10%, n = 10). During treatment with nilvadipine (8 mg/day, > or = 2 weeks), patients were reexamined by ABPM. The antihypertensive effect of nilvadipine was significantly and negatively correlated with the night time fall in blood pressure: this effect was significantly greater in the sustained hypertensive group than in the waking time hypertensive group. These data suggest that the long acting calcium antagonist nilvadipine has more potent antihypertensive effects in patients with sustained hypertension ("nondippers") than in those whose hypertension lessens during sleep ("dippers").

Cold activation of complement in sera from patients with persistent hepatitis C virus infection on interferon therapy

The loss of haemolytic activity in sera during storage at low temperature (the cold activation of complement) was observed in 136 of 184 (74%) patients with chronic liver disease associated with hepatitis C virus (HCV) infection. This was more frequent than observed in the three of 40 (8%) patients with chronic hepatitis B (P < 0.001) or none in 43 normal controls (P < 0.001). Of 103 patients with chronic hepatitis C who had completed a full course of recombinant interferon-alpha 2a therapy (total dose: 516 x 10(6) U), 40 responded completely and 21 responded partially, as judged by the normalization or decrease of alanine aminotransferase levels 6 months after the completion of therapy; 42 patients did not respond at all. The cold activation of complement persisted in five (13%) complete responders, less often than in 33 (79%) non-responders (P < 0.001). At the completion of interferon therapy, the cold activation of complement persisted in 12 of 54 patients despite the normalization of alanine aminotransferase. Spontaneous exacerbation of hepatitis occurred in seven of 12 (58%) patients with cold activation, which was more frequent than in the four of 42 patients (10%) without it (P < 0.01). The cold activation of complement disappeared along with the loss of HCV-RNA in five of six responders during the 6 month period after the completion of interferon therapy, while both cold activation and HCV-RNA persisted in all eight non-responders. These results indicate that the cold activation of complement may be useful as a marker of HCV viraemia for monitoring the response to interferon in patients with HCV infection.

Immunosuppression in dogs naturally infected with Babesia gibsoni

We examined lymphoproliferative response to phytohemagglutinin and anti-parasite antibody level in dogs naturally infected with Babesia gibsoni. The dogs with subclinical B. gibsoni infection exhibited suppressed lymphocyte blastogenesis. Prominent depression of lymphocyte blastogenesis and anti-parasite antibody production was observed in dogs suffering from relapses of clinical B. gibsoni infection.

Inherited thermostability variants of seven enzymes in a Japanese population

The frequency of inherited variations in thermostability was investigated in a series of seven enzymes in a Japanese population. Among a total of 5930 determinations, nine variants were encountered. In each instance one parent exhibited a similar finding. It is suggested that this procedure should detect a high proportion of the variants of these enzymes characterized by amino acid substitutions not altering molecular charge. Failure to detect more such thermostability variants is interpreted to mean that electrophoresis not only detects amino acid substitutions altering molecular charge but also a considerable proportion of those that do not alter charge.