Interleukin-11 improves survival and reduces bacterial translocation and bone marrow suppression in burned mice

Burn-Induced Local and Systemic Immune Response: Systematic Review and Meta-Analysis of Animal Studies

As burn injuries are often followed by a derailed immune response and excessive inflammation, a thorough understanding of the occurring reactions is key to prevent secondary complications. This systematic review, that includes 247 animal studies, shows the post-burn response of 14 different immune cell types involved in immediate and long-term effects, in both wound tissue and circulation. Peripheral blood neutrophil and monocyte numbers increased directly after burns, whereas thrombocyte numbers increased near the end of the first week. Lymphocyte numbers, however, were decreased for at least two weeks. In burn wound tissue, neutrophil and macrophage numbers accumulated during the first three weeks. Burns also altered cellular functions as we found increased migratory potential of leukocytes, impaired antibacterial activity of neutrophils and enhanced inflammatory mediator production by macrophages. Neutrophil surges were positively associated with burn size and were highest in rats. Altogether, this comprehensive overview of the temporal immune cell dynamics shows that unlike normal wound healing, burn injury induces a long-lasting inflammatory response. It provides a fundamental research basis to improve experimental set-ups, burn care and outcome.

CsIL-11, a teleost interleukin-11, is involved in promoting phagocytosis and antibacterial immune defense

Interleukin (IL)-11 is a multifunctional cytokine belonging to the IL-6 family, which plays essential roles in immune response. However, much less is known about the immunological functions of IL-11 in teleost. In this study, we investigated the immune properties of a teleost IL-11 homologue (CsIL-11) from tongue sole Cynoglossus semilaevis. CsIL-11 possesses four conserved α-helices and conserved CsIL-11 receptor binding residues L86 and R187, and shares 23.3%-80.1% identities with other IL-11 homologues. CsIL-11 expression was constitutive in tissues, with most abundant in blood and least abundant in spleen, and upregulated by bacterial challenge in blood, spleen, and head kidney. Recombinant CsIL-11 (rCsIL-11) in the native form of monomer, could bind to peripheral blood leukocytes (PBLs) membrane and enhance the activation and phagocytosis of PBLs. When administered in vivo, rCsIL-11 could markedly promote the host to defend against microbial infection. Overall, our findings show that CsIL-11 plays a pivotal role in regulating PBLs phagocytosis and antibacterial immunity.

Experimental stem cell therapies on burn wound: do source, dose, timing and method matter?

Stem cell therapy has been introduced as a new and promising modality of wound covering in recent decade. It has been used for improvement of burn wound, post burn scar and saving stasis zone of burn with good results. However, there have been some differences between the various experimental burn wound trials in stem cell source, therapeutic dose, delivery method and timing of stem cell delivery. In our study, we aimed to review stem cell biology and investigate discrepancies in animal trials of use of stem cells in burn wound account for the variation in, stem cell source, therapeutic dose, delivery method and timing of stem cell delivery.

Analysis of systemic interleukin-11 after major trauma

Recent data have shown that anti-inflammatory responses to major injury occur immediately after trauma. Interleukin 11 (IL-11), a member of the IL-6 family, is a pleiotropic cytokine with hematopoietic, osteotrophic, and mucosa protective properties, as well as anti-inflammatory functions. IL-11 inhibits synthesis of proinflammatory cytokines, promotes a Th2-type immune response, and improves outcome after shock and sepsis in different animal models. To further investigate the role of IL-11 in the human posttraumatic immune response, we measured plasma levels of IL-11 in 216 multiple-injured patients (mean age of 40 +/- 16 [range 11-81] years; Injury Severity Score [ISS] of 31 +/- 11 [range 16-66] points; 52 women and 164 men) after injury and correlated this with demographics, clinical course, and other laboratory parameters. IL-11 was significantly elevated in polytraumatized patients compared with healthy donors (P <0.0001). The time course of IL-11 in surviving patients was an initial increase after trauma with a decrease during the first 4 weeks, whereas nonsurvivors (n=34) had a significant increase later after injury (4 weeks). IL-11 was significantly higher after abdominal trauma and in men. No correlation between systemic IL-11 and ISS or age was detected. IL-11 correlated significantly with other pro- and anti-inflammatory cytokines such as IL-18. Our data demonstrate elevated levels of systemic IL-11 after multiple injuries; however, the role of a posttraumatic increase of IL-11 has to be further analyzed. In contrast to IL-6, IL-11 in plasma does not correlate with trauma severity and seems to have no clinical relevance to outcome prediction after trauma.

Impaired intestinal immunity and barrier function: a cause for enhanced bacterial translocation in alcohol intoxication and burn injury

Alcohol intoxication is being recognized increasingly as the major factor in pathogenesis after burn injury. Findings from multiple studies support the suggestion that, in comparison with burn-injured patients who sustained injury in the absence of alcohol intoxication, burn-injured patients who sustained injury under the influence of alcohol exhibit higher rates of infection and are more likely to die. Thus, infection becomes the primary cause of death in burn-injured patients. Because the intestine is considered to be a major source of bacteria, studies in experimental animals have been designed to examine whether alcohol intoxication before burn injury enhances bacterial translocation from the intestine. Results of these studies have shown a several-fold increase in bacterial translocation from the intestine in the group of animals receiving combined insult of alcohol intoxication and burn injury compared with findings for the groups receiving either insult alone. Alcohol intoxication and burn injury independent of each other have also been shown to cause an increase in bacterial translocation. The gastrointestinal tract normally maintains a physical mucosal and immunologic barrier that provides an effective defense in keeping bacteria within the intestinal lumen. However, in injury conditions these defense mechanisms are impaired. Intestinal bacteria consequently gain access to extraintestinal sites. Intestine-derived bacteria are implicated in causing systemic infection and in subsequent multiple organ dysfunction in both immunocompromised patients and patients with injury, such as burn and trauma. In this article, we discuss three potential mechanisms that are likely to contribute to the increase in bacterial translocation in alcohol intoxication and burn injury: (1) increase in bacterial growth in the intestine, (2) physical disruption of mucosal barrier of the intestine, and (3) suppression of the immune defense in the intestine.

Gastrointestinal disorders of the critically ill. Bacterial translocation in the gut

The human gastrointestinal tract is colonized by a dense population of microorganisms, referred to as the bacterial flora. Although the gut provides a functional barrier between these organisms and the host, bacterial translocation is a common event in the healthy person. However, in critically ill patients, with various underlying diseases, this bacterial translocation may lead to infections and consequently to a further reduction in general health status. The mechanism of bacterial translocation is widely, and somehow controversially investigated in vitro and in animal models. In human studies, several diseases have been associated with bacterial translocation. However, methodological shortcomings, insufficient populations and conflicting results leave many open questions. This is also reflected in the various published therapeutic strategies. To overcome this problem more investigations in humans are needed, especially in techniques for detecting bacterial translocation.

Effects of interleukin-1alpha administration on intestinal ischemia and reperfusion injury, mucosal permeability, and bacterial translocation in burn and sepsis

OBJECTIVE

To evaluate the effect of interleukin-1alpha (IL-1alpha) on the mesenteric circulation, intestinal mucosal integrity, and bacterial translocation in a burn/endotoxemia chronic porcine model.

SUMMARY BACKGROUND DATA

Major burn and sepsis are associated with a high mortality, ischemia/reperfusion injury to the intestine, and an increased rate of bacterial translocation. Pathologic alterations of IL-1 synthesis, degradation, and binding to receptors have been reported. Manipulation of IL-1-mediated effects might be of therapeutic utility.

METHODS

Twenty-one female pigs were instrumented with an ultrasonic flow probe on the superior mesenteric artery and a catheter into the superior mesenteric vein. After 5 days, all animals were anesthetized, and 14 received 40% total body surface area third-degree burn. IL-1alpha was administered intravenously at 1,000 ng/kg to seven pigs immediately after burn. Eighteen hours after burn, 100 microg/kg lipopolysaccharide (LPS) was administered intravenously. Systemic and splanchnic hemodynamics were measured and blood samples were drawn for blood gas analysis. Intestinal permeability was assessed every 6 hours by measuring the lactulose/mannitol (L/M) excretion ratio. At the end of the study (42 hours), tissue samples were harvested for bacteriologic cultures.

RESULTS

Mesenteric blood flow was significantly decreased after burn and endotoxin. Administration of IL-1alpha significantly improved mesenteric blood flow postburn and post-LPS. Mesenteric oxygen supply and consumption showed a significant reduction after burn. In contrast, animals treated with IL-1alpha showed an increase in postburn mesenteric oxygen supply and consumption. LPS-induced mesenteric hypoxia was also ameliorated by IL-1alpha treatment. Intestinal permeability, as assessed by the L/M ratio, showed a 7- and 10-fold elevation after thermal injury and LPS, respectively. In contrast, IL-1alpha-treated animals showed an increase of only three- and fourfold in the L/M ratio, respectively. Bacterial translocation was significantly increased in the burn/endotoxin group. IL-1alpha significantly reduced the rates of bacterial translocation.

CONCLUSIONS

IL-1alpha treatment attenuates mesenteric ischemia and reperfusion injury induced by thermal injury and endotoxemia by improving mesenteric blood flow and oxygenation. Subsequently, IL-1alpha reduces intestinal permeability and bacterial translocation after burn and sepsis.

Factors enhancing intestinal adaptation after bowel compensation

Intestinal failure (IF) refers to the condition in which certain causes lead to derangements in nutrient absorption capacity. Gut adaptation occurs in response to IF and it is both morphologic and physiologic in nature and can be mediated by growth factors and nutrients. Our paper reviews certain trophic growth factors that have important interactions relevant for intestinal growth, function and adaptation.

DATA SOURCE

The literature was reviewed (data from both animal and human studies) and certain trophic factors that modulate intestinal adaptation are summarized. The factors reviewed are: epidermal growth factor, insulin-like growth factor I and II, transforming growth factor alpha and beta, neurotensin, interleukin-11, glucagon-like peptide-2, keratinocyte growth factor, human growth hormone, short-chain fatty acids, and glutamine.

CONCLUSIONS

Growth factors augment intestinal proliferation, diminish programmed apoptosis, and modulate the adaptive process. They also have the potential to improve nutrient absorption in some bowel disease. The enhancement of gut adaptation may allow patients to transition of parenteral/enteral to normal nutrition, in a shorter period of time, which reduce the rate of adverse effects caused by artificial nutrition and improve quality of life.

Administration of recombinant human IL11 after supralethal radiation exposure promotes survival in mice: interactive effect with thrombopoietin

In the present study, we evaluated the therapeutic potential of recombinant human IL11 in lethally irradiated C57BL6/J mice exposed to gamma rays. IL11 administered for 5 consecutive days beginning 2 h after total-body irradiation with 8 or 9 Gy 60Co gamma rays resulted in a significant increase in 30-day survival. When IL11 was administered, only a slight improvement in the hematopoietic status (both blood cell counts and progenitor cells) was observed after an 8-Gy exposure, and no improvement in hematopoietic reconstitution was observed after 9 Gy total-body irradiation. The enhancement of fibrinogen in the plasma of irradiated animals suggested the importance of infections in the death of animals. IL11 was able to limit the increase in fibrinogen levels. However, prevention of bacterial infections by antibiotic treatment, although it delayed death, was ineffective in promoting survival either in placebo-treated and IL11-treated mice. IL11 was administered along with thrombopoietin (TPO) or bone marrow transplantation to limit the hematopoietic syndrome, in addition to antibiotic treatment. When IL11 was combined with TPO, a potent stimulator of hematopoiesis, the survival of animals which had been irradiated with 10 Gy 137Cs gamma rays was increased significantly compared to those treated with IL11 or TPO alone. Furthermore, an interactive effect of TPO and IL11 on hematopoietic reconstitution was observed. Similarly, IL11 in combination with bone marrow transplantation enhanced survival after 15 Gy 137Cs gamma rays. These data suggest that the effect of IL11 on the hematopoietic system is only moderate when it is used alone in supralethally irradiated mice but that the effect is improved in the presence of a hematopoietic growth factor or bone marrow transplantation.

Mechanism of the antiulcerogenic effect of IL-11 on acetic acid-induced gastric ulcer in rats

The purpose of this study was to evaluate the healing effect of interleukin-11 (IL-11) on acetic acid-induced gastric ulcer in rats. Gastric ulcers were induced in male Wistar rats by applying acetic acid to the fundus of the stomach. Recombinant human interleukin-11 (rhIL-11 100 microg/kg/twice daily, subcutaneously) was administered starting on the 2nd day before ulcer induction up through the 7th day after ulcer induction. Control rats were injected with bovine serum albumin. At 12 hours and 7 days after ulcer induction, the animals were sacrificed, and the ulcer index, proliferating cell nuclear antigen (PCNA) expression, and IL-11alpha receptor expression in the gastric tissues were studied. The ulcer index of the rhIL-11-treated rats was significantly lower than that of the control rats at the 7th day. The expression of PCNA as evaluated by Western blotting and immunohistochemistry, was enhanced in both the mucosal proliferative zone and proper muscle layer of the rhIL-11-treated rats in comparison with that in the control rats. IL-11alpha receptor expression was observed in the mucosal neck cells of the rhIL-11-treated rats and control rats. These findings suggest that IL-11 accelerates ulcer healing by inducing the proliferation of mucosal and muscular cells.

Role of epidermal growth factor and its receptor in chemotherapy-induced intestinal injury

Several growth factors are trophic for the gastrointestinal tract and able to reduce the degree of intestinal damage caused by cytotoxic agents. However, studies of epidermal growth factor (EGF) for chemotherapy-induced intestinal injury are conflicting. The development of a transgenic mouse that specifically overexpresses EGF in the small intestine provided a unique opportunity to assess the contribution of EGF in mucositis. After a course of fluorouracil, transgenic mice fared no better than control mice. Weight recovery was inferior, and mucosal architecture was not preserved. Apoptosis was not decreased and proliferation was not increased in the crypts. To corroborate the findings in transgenic mice, ICR mice were treated with exogenous EGF after receiving fluorouracil. Despite ileal upregulation of native and activated EGF receptor, the mice were not protected from intestinal damage. No benefits were observed with different EGF doses or schedules or routes of EGF administration. Finally, mucositis was induced in mutant mice with specific defects of the EGF signaling axis. Compared with control mice, clinical and histological parameters of intestinal injury after fluorouracil were no different in waved-2 mice, which have functionally diminished EGF receptors, or waved-1 mice, which lack transforming growth factor-alpha, another major ligand for the EGF receptor. These findings do not support a critical role for EGF or its receptor in chemotherapy-induced intestinal injury.

Inflammatory cytokines and mucosal injury

The cause of mucosal injury in inflammatory bowel disease (IBD) is not clear but likely involves infectious agents or other toxins followed by an abnormal immune response in genetically susceptible individuals. The inflammatory cytokines appear to play a key role in both the susceptibility of some individuals and the tissue damage that accompanies IBD. The generation of transgenic and gene-targeted (knockout) animals has provided invaluable information regarding the cytokines and cellular immune effectors that are important in IBD. Information from these and other preclinical animal models, such as those involving interleukin 11, has led to human trials testing novel therapies for IBD and other diseases in which inflammation of the gut mucosa is an important component. Thus, expression of inflammatory cytokines appears to be an important target for the development of novel therapies for IBD and other diseases in which intestinal mucosal damage occurs, such as mucositis and graft-versus-host disease.

Characterization of conditions for the primary culture of human small intestinal epithelial cells

Intestinal epithelial cells (IECs) are important for many aspects of gut physiology and pathology. Different approaches have been tried for the primary culture of human IECs, with varying degrees of success, as apoptosis easily occurs. Our aim was to develop a method for primary culture of human IECs from biopsy material. IECs and Lamina propria (LP) cells were liberated from duodenal biopsies obtained from subjects undergoing routine endoscopy for clinical investigations, whose small bowel was macroscopically normal. IECs were cultured on collagen membranes in a 12-well tissue culture cluster, with LP cells and allogeneic Epstein-Barr Virus (EBV)-transformed B lymphocytes (allo-B cells) underneath, in the well. Cultured IECs were characterized by light and confocal microscopy. Cytokine levels in culture supernatants were measured by ELISA. Cells showed the columnar morphology of IECs, even after several days in culture. Best results were obtained from IECs cultured above both LP and allo-B cells. IECs did not form monolayers as do transformed epithelial cell lines, but they did preserve their original cell-cell contacts. Analysis of culture supernatants showed that IL-10 was produced by IECs initially, but IL-1ra was produced by LP cells in the underlying wells with increasing time in culture. Very little IL-1 beta was produced from any cultures. These results show that IECs can be isolated and maintained in primary culture for a short while, which could open new possibilities for research using patient material instead of cell lines.

Necrotizing enterocolitis and hematopoietic cytokines

The names of the hematopoietic cytokines are misleading because in addition to their effects on bone marrow and bone marrow-derived cells, they have many diverse effects, including effects on the gastrointestinal tract. These effects may be directly mediated by interaction with specific receptors on gastrointestinal epithelial cells, or they may result from their effects on circulating or bowel wall leukocytes and the cytokines these cells produce. As might be expected of factors largely defined by their effects on inflammatory cells, the hematopoietic cytokines are intimately involved in the processes of bowel injury. Further investigations are needed to define the role of hematopoietic cytokines in the human neonate's balance between local gastrointestinal host defense and bowel wall injury. This could lead to effective strategies for the treatment and prevention of NEC.

Recombinant human interleukin-11 prevents mucosal atrophy and bowel shortening in the defunctionalized intestine

BACKGROUND

Mucosal atrophy and bowel shortening are the hallmark of proximal intestinal diversion for extensive necrotizing enterocolitis (NEC) or Thiry-Vella fistulas (TVF), in which the ends of a defunctionalized loop of intestine are exteriorized as stomas. Recombinant human interleukin-11 (rhIL-11) is a pleiotropic cytokine that promotes epithelial regeneration and enhances adaptation after bowel resection. The authors hypothesized that rhIL-11 may prevent mucosal atrophy and bowel shortening in rats with TVF METHODS: After creation of ileal TVF, Sprague-Dawley rats were selected randomly to receive either rhIL-11 or equal volume of 0.1% bovine serum albumin (BSA) subcutaneously daily. On day 14, the TVF were excised and examined morphologically. Enterocyte apoptosis was measured using the TUNEL assay. Mucosal DNA and protein content were measured.

RESULTS

Administration of rhIL-11 resulted in a significantly greater weight gain and less shortening of TVF than BSA treatment. TVF from the rhIL-11-treated group showed evidence of hyperplasia and hypertrophy and increased crypt to villus ratio. The BSA group had substantial mucosal atrophy. There was a qualitative decrease in the incidence of apoptosis in the rhIL-11 group.

CONCLUSIONS

Recombinant human IL-11 prevents mucosal atrophy and shortening of defunctionalized intestinal loops. It may help reduce the incidence of short gut syndrome in infants with extensive NEC.

Interleukin-11 enhances small intestine absorptive function and mucosal mass after intestinal adaptation

BACKGROUND/PURPOSE

Interleukin-11 (IL-11) recently has been shown to enhance mucosal mass after massive small bowel resection (MSBR). However, enhanced mucosal mass may not correlate with increased substrate absorption. This study was designed to examine the effect of systemic administration of increasing doses of IL-11 on small intestine absorptive function and mucosal mass after MSBR.

METHODS

Twenty-five Sprague-Dawley rats underwent an 80% small bowel resection and end-to-end jejunoileal anastomosis. Seven days after resection, all rats had placement of a jugular venous catheter connected to a subcutaneously placed osmotic pump. The rats were divided into 5 groups based on the content of the pump: group 1 (control, n = 5) received 0.1% bovine serum albumin (BSA) and groups 2 through 5 (n = 5 each) received IL-11 at 250, 500, 750, and 1,000 microg/kg/d, respectively. After a 14-day infusion period, [14C] galactose and [14C] glycine absorption was measured using an in vivo closed-recirculation technique. Mucosal DNA content also was determined for each group. Statistical analysis was performed by analysis of variance and expressed as mean +/-SEM.

RESULTS

IL-11 administered at 250 microg/kg/d, a dose used in previous studies, did not significantly affect substrate absorption. However, compared with the control group, administration of higher doses of IL-11 produced a significant increase in substrate absorption and mucosal mass. The dose of IL-11 producing the overall optimal response based on the parameters measured (galactose absorption, 72% increase over control; glycine absorption, 112% increase over control; and DNA content, 98% increase over control) was 750 microg/kg/d.

CONCLUSIONS

In addition to an increase in mucosal mass, these data show for the first time that IL-11 enhances absorptive function beyond the normal adaptive response after MSBR. Furthermore, the maximum effect of IL-11 on absorptive function was shown at 750 microg/kg/d, which is 3 times the dose used in previously reported studies. This study suggests that IL-11 may be useful clinically in patients with inadequate intestinal function.

Fixing the intestinal mucosa in the bone marrow transplant patient: lessons from other intestinal immunodeficiencies and inflammatory disorders

Gastrointestinal inflammation is common following bone marrow transplantation. Key pathogenetic events, such as major histocompatibility complex (MHC) expression on intestinal epithelial cells and local production of cytokines in the gastrointestinal mucosa, are common features of many gastrointestinal inflammatory disorders. Drawing from clinical experience of the treatment of other disorders associated with gastrointestinal inflammation, such as ulcerative colitis and Crohn's disease, a number of therapeutic alternatives may be relevant for the bone marrow transplant patient with significant graft-vs.-host disease (GvHD). Options to consider include therapeutics that alter inflammatory cell migration, anti-inflammatory cytokines, direct neutralization of proinflammatory cytokines, and cytokines that promote epithelial restitution in the gastrointestinal mucosa. In addition, a variety of nutritional and other novel treatments are available, which may improve epithelial function or which have anti-inflammatory actions. Prospective studies of combined nutrient and cytokine-modulating treatments for the bone marrow transplant patient are warranted.

Interleukin-11: its biology and prospects for clinical use

IL-11 is a multifunctional cytokine that has pleiotropic effects on a variety of tissue including the bone marrow and intestinal mucosa. IL-11 is useful in elevating the platelet count in cancer patients with chemotherapy-induced thrombocytopenia and has a cytoprotective effect on the bowel mucosa in a variety of causes of gut damage and a trophic effect on the villi after massive bowel resection.

Comparison of interleukin-11 and epidermal growth factor on residual small intestine after massive small bowel resection

BACKGROUND/PURPOSE

Interleukin-11 (IL-11) is a multifunctional cytokine derived from bone marrow, which has a trophic effect on small bowel epithelium. This study compares the effects of IL-11 with epidermal growth factor (EGF), a growth factor known to enhance small bowel adaptation.

METHODS

Forty Sprague-Dawley rats (90 to 100 g) underwent an 85% mid-small bowel resection with primary anastomosis on day 0. Rats were divided into four treatment groups: controls (group I) received bovine serum albumin (BSA), group II received IL-11, 125 microg/kg subcutaneously (SC) twice daily, group III received EGF, 0.10 microg/g SC bid, and group IV received EGF and IL-11 in the above doses. Half of the animals (five per group) were killed on day 4 of therapy, and the rest were killed on day 8. Animals were evaluated for weight, mucosal length, and bowel wall muscle thickness on days 4 and 8, and expression of proliferating cell nuclear antigen (PCNA) in intestinal crypt and smooth muscle cells on day 8.

RESULTS

There were two deaths; both were 8-day controls. Body weight was similar at day 4 and day 8. Mucosal thickness in groups II (IL-11) and group IV (IL-11 and EGF) was significantly increased at day 4 and 8 when compared with controls (group I) and EGF (group III, P < .001). Muscle thickness was significantly increased in the EGF and combined group IV compared with the BSA controls and IL-11 groups (P < .001). Thirty-two percent of the mucosal crypt cells in Group I stained positive for PCNA, whereas 51%, 53%, and 60% stained positive in groups II (IL-11), III (EGF), and IV (IL-11 and EGF), respectively. In groups I and II, 2% and 1.7% of the myocytes stained positive for PCNA, whereas 11.2% and 5.2% of the myocytes in group III and IV stained positive.

CONCLUSIONS

These data suggest that IL-11 has a trophic effect on small intestinal enterocytes, causing cell proliferation and increased mucosal thickness. EGF has a more generalized effect on intestine causing proliferation of both enterocytes and myocytes. IL-11, with or without EGF, may be a useful adjunct in instances of short bowel syndrome.