Role for complement in mediating intestinal nitric oxide synthase-2 and superoxide dismutase expression

Integrated multi-omics of the gastrointestinal microbiome and ruminant host reveals metabolic adaptation underlying early life development

BACKGROUND

The gastrointestinal tract (GIT) microbiome of ruminants and its metabolic repercussions vastly influence host metabolism and growth. However, a complete understanding of the bidirectional interactions that occur across the host-microbiome axis remains elusive, particularly during the critical development stages at early life. Here, we present an integrative multi-omics approach that simultaneously resolved the taxonomic and functional attributes of microbiota from five GIT regions as well as the metabolic features of the liver, muscle, urine, and serum in sika deer (Cervus nippon) across three key early life stages.

RESULTS

Within the host, analysis of metabolites over time in serum, urine, and muscle (longissimus lumborum) showed that changes in the fatty acid profile were concurrent with gains in body weight. Additional host transcriptomic and metabolomic analysis revealed that fatty acid β-oxidation and metabolism of tryptophan and branched chain amino acids play important roles in regulating hepatic metabolism. Across the varying regions of the GIT, we demonstrated that a complex and variable community of bacteria, viruses, and archaea colonized the GIT soon after birth, whereas microbial succession was driven by the cooperative networks of hub populations. Furthermore, GIT volatile fatty acid concentrations were marked by increased microbial metabolic pathway abundances linked to mannose (rumen) and amino acids (colon) metabolism. Significant functional shifts were also revealed across varying GIT tissues, which were dominated by host fatty acid metabolism associated with reactive oxygen species in the rumen epithelium, and the intensive immune response in both small and large intestine. Finally, we reveal a possible contributing role of necroptosis and apoptosis in enhancing ileum and colon epithelium development, respectively.

CONCLUSIONS

Our findings provide a comprehensive view for the involved mechanisms in the context of GIT microbiome and ruminant metabolic growth at early life. Video Abstract.

Targeting the Complement Pathway in Malignant Glioma Microenvironments

Malignant glioma is a highly fatal type of brain tumor, and its reoccurrence is largely due to the ordered interactions among the components present in the complex microenvironment. Besides its role in immune surveillance and clearance under physiological conditions, the complement system is expressed in a variety of tumor types and mediates the interactions within the tumor microenvironments. Recent studies have uncovered the broad expression spectrum of complement signaling molecules in the tumor microenvironment and various tumor cells, in particular, malignant glioma cells. Involvement of the complement system in tumor growth, immunosuppression and phenotype transition have also been elucidated. In this review, we enumerate the expression and function of complement molecules in multiple tumor types reported. Moreover, we elaborate the complement pathways in glioma cells and various components of malignant glioma microenvironments. Finally, we summarize the possibility of the complement molecules as prognostic factors and therapeutic targets in the treatment of malignant glioma. Specific targeting of the complement system maybe of great significance and value in the future treatment of multi-type tumors including malignant glioma.

Effect of atherosclerosis and the protective effect of the antioxidant vitamin E on the rabbit cerebellum

BACKGROUND

Atherosclerosis is a major cardiovascular disease and one of the commonest causes of mortality in the world. Speech, balance, fine motor control and cognition are affected by atherosclerosis of cerebellar arteries. This study investigated the protective role of vitamin E against induced atherosclerosis in the rabbit cerebellum.

MATERIALS AND METHODS

Forty Rex New Zealand adult male rabbits were randomly divided into four groups (10 rabbits each). Group I was designated as the control and received an ordinary diet. Group II received an ordinary diet, but with vitamin E (12 mg/kg/day) added. Group III were given an ordinary diet along with 1% cholesterol powder for 6 weeks. Finally, group IV received an ordinary diet with both 1% cholesterol powder and vitamin E (12 mg/kg/day). Cerebellum samples were stained with haematoxylin and eosin and examined using light microscopy, along with quantitative immunohistochemical assessments of the expression of caspase-3, glial fibrillary acidic protein (GFAP) and inducible nitric oxide synthase (iNOS).

RESULTS

Cerebellum sections from cholesterol-treated rabbits showed ischaemic changes as fibre density decreased, with vacuolation of the molecular layer, and deformed and shrunken Purkinje cells. A significant increase in caspase-3, GFAP and iNOS immunoreactivity was found. However, vitamin E administration reduced these ischaemic manifestations.

CONCLUSIONS

The results demonstrate the neurological protective role of vitamin E therapy in atherosclerosis.

The complement system in glioblastoma multiforme

The human complement system is represents the main effector arm of innate immunity and its ambivalent function in cancer has been subject of ongoing dispute. Glioma stem-like cells (GSC) residing in specific niches within glioblastomas (GBM) are capable of self-renewal and tumor proliferation. Recent data are indicative of the influence of the complement system on the maintenance of these cells. It appears that the role of the complement system in glial tumorigenesis, particularly its influence on GSC niches and GSC maintenance, is significant and warrants further exploration for therapeutic interventions.

Inducible Nitric Oxide Synthase (iNOS) Is a Novel Negative Regulator of Hematopoietic Stem/Progenitor Cell Trafficking

Nitric oxide (NO) is a gaseous free radical molecule involved in several biological processes related to inflammation, tissue damage, and infections. Based on reports that NO inhibits migration of granulocytes and monocytes, we became interested in the role of inducible NO synthetase (iNOS) in pharmacological mobilization of hematopoietic stem/progenitor cells (HSPCs) from bone marrow (BM) into peripheral blood (PB). To address the role of NO in HSPC trafficking, we upregulated or downregulated iNOS expression in hematopoietic cell lines. Next, we performed mobilization studies in iNOS^-/- mice and evaluated engraftment of iNOS^-/- HSPCs in wild type (control) animals. Our results indicate that iNOS is a novel negative regulator of hematopoietic cell migration and prevents egress of HSPCs into PB during mobilization. At the molecular level, downregulation of iNOS resulted in downregulation of heme oxygenase 1 (HO-1), and, conversely, upregulation of iNOS enhanced HO-1 activity. Since HO-1 is a negative regulator of cell migration, the inhibitory effects of iNOS identified by us can be at least partially explained by its enhancing the HO-1 level in BM cells.

Evolution and Function of Thioester-Containing Proteins and the Complement System in the Innate Immune Response

The innate immune response is evolutionary conserved among organisms. The complement system forms an important and efficient immune defense mechanism. It consists of plasma proteins that participate in microbial detection, which ultimately results in the production of various molecules with antimicrobial activity. Thioester-containing proteins (TEPs) are a superfamily of secreted effector proteins. In vertebrates, certain TEPs act in the innate immune response by promoting recruitment of immune cells, phagocytosis, and direct lysis of microbial invaders. Insects are excellent models for dissecting the molecular basis of innate immune recognition and response to a wide range of microbial infections. Impressive progress in recent years has generated crucial information on the role of TEPs in the antibacterial and antiparasite response of the tractable model insect Drosophila melanogaster and the mosquito malaria vector Anopheles gambiae. This knowledge is critical for better understanding the evolution of TEPs and their involvement in the regulation of the host innate immune system.

The Isothiocyanate Isolated from Moringa oleifera Shows Potent Anti-Inflammatory Activity in the Treatment of Murine Subacute Parkinson's Disease

The present study was aimed at estimating a possible neuroprotective effect of glucomoringin (GMG) [4-(α-L-rhamnopyranosyloxy)benzyl glucosinolate] bioactivated with the enzyme myrosinase to form the corresponding isothiocyanate [4-(α-L-rhamnopyranosyloxy)benzyl C; moringin] in the treatment or prevention of Parkinson's disease (PD). In this study, the beneficial effects of moringin were compared with those of pure GMG, not enzymatically activated, in an in vivo experimental mouse model of subacute PD. Subacute PD was induced in C57BL/6 mice by administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Mice were pretreated daily for 1 week with moringin (10 mg/kg +5 μL myrosinase/mouse) and with GMG (10 mg/kg). Behavioral evaluations were also performed to assess motor deficits and bradykinesia in MPTP mice. Besides, assuming that pretreatment with moringin could modulate the triggering of inflammatory cascade with a correlated response, we tested its in vitro anti-inflammatory activity by using a model of RAW 264.7 macrophages stimulated with lipopolysaccharide. Achieved results in vivo showed a higher efficacy of moringin compared with GMG not only to modulate the inflammatory pathway but also oxidative stress and apoptotic pathways. In addition, the greater effectiveness of moringin in countering mainly the inflammatory pathway has been corroborated by the results obtained in vitro. The relevance and innovation of the present study lie in the possible use of a safe formulation of a bioactive compound, resulting from exogenous myrosinase hydrolysis of the natural phytochemical GMG, which can be used in clinical practice as a useful drug for the treatment or prevention of PD.

Tuscan black kale sprout extract bioactivated with myrosinase: a novel natural product for neuroprotection by inflammatory and oxidative response during cerebral ischemia/reperfusion injury in rat

Background

Cerebral ischemia and reperfusion (CIR) is a pathological condition characterized by a first blood supply restriction to brain followed by the consequent restoration of blood flow and simultaneous reoxygenation.

The aim of this study was to evaluate the neuroprotective effects of Tuscan black kale sprout extract (TBK-SE) bioactivated with myrosinase enzyme, assessing its capability to preserve blood–brain barrier (BBB), in a rat model of CIR.

Methods

CIR was induced in rats according to a classic model of carotid artery occlusion for a time period of 1 h and the reperfusion time was prolonged for seven days.

Results

By immunohistochemical evaluation and western blot analysis of brain and cerebellum tissues, our data have clearly shown that administration of bioactive TBK-SE is able to restore alterations of tight junction components (claudin-5 immunolocalization). Also, bioactive TBK-SE reduces some inflammatory key-markers (p-selectin, GFAP, Iba-1, ERK1/2 and TNF-α), as well as the triggering of neuronal apoptotic death pathway (data about Bax/Bcl-2 balance, p53 and cleaved-caspase 3) and the generation of radicalic species by oxidative stress (results focused on iNOS, nitrotyrosine and Nrf2).

Conclusion

Taken together, our findings lead to believe that bioactive TBK-SE exerts pharmacological properties in protecting BBB integrity through a mechanism of action that involves a modulation of inflammatory and oxidative pathway as well into control of neuronal death.

(RS)-glucoraphanin purified from Tuscan black kale and bioactivated with myrosinase enzyme protects against cerebral ischemia/reperfusion injury in rats

Ischemic stroke is the result of a transient or permanent reduction in cerebral blood flow caused by the occlusion of a cerebral artery via an embolus or local thrombosis. Restoration of blood supply to ischemic tissues can cause additional damage known as reperfusion injury that can be more damaging than the initial ischemia. This study was aimed to examine the possible neuroprotective role of (RS)-glucoraphanin, bioactivated with myrosinase enzyme (bioactive RS-GRA), in an experimental rat model of brain ischemia/reperfusion injury (I/R). RS-GRA is a thiosaccharidic compound found in Brassicaceae, notably in Tuscan black kale (Brassica oleracea L. var. acephala sabellica). The mechanism underlying the inhibitory effects of bioactive RS-GRA on inflammatory and apoptotic responses, induced by carotid artery occlusion in rats, was carefully examined. Cerebral I/R was induced by the clamping of carotid artery for 1h, followed by 40 min of reperfusion through the release of clamp. Our results have clearly shown that administration of bioactive RS-GRA (10 mg/kg, i.p.) 15 min after ischemia, significantly reduces proinflammatory parameters, such as inducible nitric oxide synthase expression (iNOS), intercellular adhesion molecule 1 (ICAM-1), nuclear factor (NF)-kB traslocation as well as the triggering of the apoptotic pathway (TUNEL and Caspase 3 expression). Taken together our data have shown that bioactive RS-GRA possesses beneficial neuroprotective effects in counteracting the brain damage associated to I/R. Therefore, bioactive RS-GRA, could be a useful treatment in the cerebral ischemic stroke.

Complement component 3 inhibition by an antioxidant is neuroprotective after cerebral ischemia and reperfusion in mice

Oxidative stress after stroke is associated with the inflammatory system activation in the brain. The complement cascade, especially the degradation products of complement component 3, is a key inflammatory mediator of cerebral ischemia. We have shown that pro-inflammatory complement component 3 is increased by oxidative stress after ischemic stroke in mice using DNA array. In this study, we investigated whether up-regulation of complement component 3 is directly related to oxidative stress after transient focal cerebral ischemia in mice and oxygen-glucose deprivation in brain cells. Persistent up-regulation of complement component 3 expression was reduced in copper/zinc-superoxide dismutase transgenic mice, and manganese-superoxide dismutase knock-out mice showed highly increased complement component 3 levels after transient focal cerebral ischemia. Antioxidant N-tert-butyl-α-phenylnitrone treatment suppressed complement component 3 expression after transient focal cerebral ischemia. Accumulation of complement component 3 in neurons and microglia was decreased by N-tert-butyl-α-phenylnitrone, which reduced infarct volume and impaired neurological deficiency after cerebral ischemia and reperfusion in mice. Small interfering RNA specific for complement component 3 transfection showed a significant increase in brain cells viability after oxygen-glucose deprivation. Our study suggests that the neuroprotective effect of antioxidants through complement component 3 suppression is a new strategy for potential therapeutic approaches in stroke.

The complement system in ischemia-reperfusion injuries

Tissue injury and inflammation following ischemia and reperfusion of various organs have been recognized for many years. Many reviews have been written over the last several decades outlining the role of complement in ischemia/reperfusion injury. This short review provides a current state of the art knowledge on the complement pathways activated, complement components involved and a review of the clinical biologics/inhibitors used in the clinical setting of ischemia/reperfusion. This is not a complete review of the complement system in ischemia and reperfusion injury but will give the reader an updated view point of the field, potential clinical use of complement inhibitors, and the future studies needed to advance the field.

The pig as a preclinical model for intestinal ischemia-reperfusion and transplantation studies

Small bowel transplantation has become an established procedure for treatment of irreversible intestinal failure. In this procedure, primary ischemia and reperfusion is inevitable and will lead to some level of tissue injury. Both clinical and experimental data demonstrate that events occurring at the time of transplantation, called ischemia reperfusion injury (IRI), may have deleterious short- and long-term effects, manifesting as increased episodes of acute rejection and chronic allograft dysfunction. Recently, the acute phase of IRI has been increasingly viewed as part of the innate immune response to the lack of vascular perfusion and oxygen. Research on intestinal IRI that aims to understand its mechanisms and the means to reduce its impact on morbidity and mortality related to intestinal transplantations is considered important because a link has been suggested between innate immunity, adaptive immune responses and organ regeneration, and thus long-term graft function. This article provides an overview of porcine models commonly used to study intestinal reperfusion injury and to evaluate intestinal transplant protocols. It also updates the current knowledge obtained from this model, establishing the pig as a reference standard in intestinal transplantation research.

Ischemic post-conditioning to counteract intestinal ischemia/reperfusion injury

Intestinal ischemia is a severe disorder with a variety of causes. Reperfusion is a common occurrence during treatment of acute intestinal ischemia but the injury resulting from ischemia/reperfusion (IR) may lead to even more serious complications from intestinal atrophy to multiple organ failure and death. The susceptibility of the intestine to IR-induced injury (IRI) appears from various experimental studies and clinical settings such as cardiac and major vascular surgery and organ transplantation. Whereas oxygen free radicals, activation of leukocytes, failure of microvascular perfusion, cellular acidosis and disturbance of intracellular homeostasis have been implicated as important factors in the pathogenesis of intestinal IRI, the mechanisms underlying this disorder are not well known. To date, increasing attention is being paid in animal studies to potential pre- and post-ischemia treatments that protect against intestinal IRI such as drug interference with IR-induced apoptosis and inflammation processes and ischemic pre-conditioning. However, better insight is needed into the molecular and cellular events associated with reperfusion-induced damage to develop effective clinical protection protocols to combat this disorder. In this respect, the use of ischemic post-conditioning in combination with experimentally prolonged acidosis blocking deleterious reperfusion actions may turn out to have particular clinical relevance.

The protective effects of resveratrol and L-NAME on visceral organs following aortic clamping

BACKGROUND

This study investigated the effect of temporary occlusion of the aorta on the development of ischemia-reperfusion (I/R) injury of the visceral organs, the optimal timing of administration of resveratrol, and its mechanism of protection via inhibiting nitric oxide (NO) release with an NO synthase inhibitor.

METHODS

Rabbits were divided into seven groups according to the administration period of resveratrol and/or N(G)-nitro-L-arginine methyl ester (L-NAME): control group; group 1, resveratrol during ischemic period; group 2, resveratrol during reperfusion period; group 3, L-NAME during ischemic period; group 4, L-NAME during reperfusion period; group 5, resveratrol during ischemic period and L-NAME during reperfusion period; group 6, L-NAME during ischemic period and resveratrol during reperfusion period. The infrarenal aorta was clamped for 30 min. Blood samples were taken for the biochemical assessment, and organ specimens were taken for pathological assessment at 24hr of reperfusion.

RESULTS

In groups 5 and 6, the renal I/R injury was comparatively milder (I/R injury score 1.04+/-0.29 in control group, 0.25+/-0.17 in group 5, and 0.33+/-0.13 in group 6 [p<0.05]). The I/R injury of bowel was milder in group 5 (I/R injury score 1.8+/-0.80 in control group vs. 0.0+/-0.0 in group 5 [p<0.05]).

CONCLUSION

The protective effects of resveratrol on organs that have high metabolic rate like kidney and bowel was proven histopathologically. It may be beneficial to use different pharmacological medications in different periods of the I/R damage as they represent different characteristics with and without oxygen. The combination of resveratrol and L-NAME against I/R injury appears to be an effective option in the near future.

Low-density lipoproteins oxidized after intestinal ischemia/reperfusion in rats

BACKGROUND

Intestinal ischemia/reperfusion (I/R) is a complex phenomenon causing destruction of both local and remote tissues, as well as multiple-organ failure. We investigated the role of lipid peroxidation in damage to intestinal, liver, and lung tissues in this pathology.

MATERIALS AND METHODS

The superior mesenteric artery was blocked for 30 min followed by 24 h of reperfusion. Tissues were removed and the presence of oxidized LDL, the activities of the superoxide dismutase enzyme, malondialdehyde levels, and inducible nitric oxide synthase expression were each evaluated in the intestinal, liver, and lung tissues.

RESULTS

While there was no staining in the control group tissues, ischemia/reperfusion resulted in positive oxidized LDL staining in all of the I/R test group tissue samples. Inducible nitric oxide synthase expression was significantly increased in the ischemia/reperfusion group tissues. Compared with those of the control group rats, the ischemia/reperfusion group tissues showed significantly higher malondialdehyde levels and lower superoxide dismutase activities.

CONCLUSIONS

This study demonstrated for the first time that oxidized LDL accumulated in the terminal ileum, liver, and lung tissues after intestinal ischemia/reperfusion. This occurrence (or the presence of oxidized LDL) may be an indicator of ongoing oxidative stress and enhanced lipid peroxidation. Augmentation of inducible nitric oxide synthase expression may play a role in progression of inflammation and LDL oxidation. These data support the hypothesis that cellular oxidative stress is a critical step in reperfusion-mediated injury in both the intestine and end organs, and that antioxidant strategies may provide organ protection in patients with reperfusion injury, at least through affecting interaction with free radicals, nitric oxide, and oxidized LDL.

Association of serum nitrate and nitrite levels with longitudinal assessments of disease activity and damage in systemic lupus erythematosus and lupus nephritis

OBJECTIVE

Reactive intermediate production is an essential component of the innate immune response that is induced during disease activity in murine lupus. This study was undertaken to determine whether a marker of systemic nitric oxide (NO) production correlates with prospectively studied disease activity in human systemic lupus erythematosus (SLE) and lupus nephritis patients.

METHODS

Eighty-three SLE patients and 40 control subjects were studied longitudinally. The SLE group included 23 patients with lupus nephritis documented by renal biopsy and 26 with a history of lupus nephritis. During each visit, following a 24-hour low-nitrate diet, traditional markers of disease activity and damage were determined. Serum nitrate plus nitrite (NOx) levels were determined by chemiluminescence detection.

RESULTS

NOx levels were higher in SLE patients than in controls during the first visit. In univariate longitudinal analyses, NOx levels were associated with SLE Disease Activity Index scores. In multivariate analyses, NOx levels were associated with serum levels of C3 and creatinine and the urinary protein:creatinine ratio. Among patients with lupus nephritis, those with proliferative lesions had higher NOx levels, and higher NOx levels were associated with accumulation of renal damage and lack of response to therapy.

CONCLUSION

This is the first study to prospectively demonstrate longitudinal associations between serum NOx levels and markers of SLE and lupus nephritis disease activity. The more pronounced association with proliferative lupus nephritis and with longitudinal response to lupus nephritis therapy provides a rationale for the study of reactive intermediates as biomarkers of disease activity and therapeutic targets in proliferative lupus nephritis.

Natural IgM-mediated innate autoimmunity: a new target for early intervention of ischemia-reperfusion injury

Recent studies showed that innate autoimmunity is an early mechanism for ischemia-reperfusion (I/R) injury. Results from different animal models showed that reperfusion of ischemic tissues elicits an acute inflammatory response involving a complement system, which is activated by autoreactive natural IgM. Moreover, ischemia-specific self-targets were identified. In contrast to the unsuccessful attempts in the past to treat I/R injury, targeting natural IgM-mediated innate autoimmunity may open a new avenue for early intervention.

Anti-inflammatory properties of Lactobacillus gasseri expressing manganese superoxide dismutase using the interleukin 10-deficient mouse model of colitis

Emerging evidence has implicated reactive oxygen species (ROS) in the pathogenesis of inflammatory bowel disease (IBD). Although intestinal epithelial cells produce the ROS-neutralizing enzyme superoxide dismutase (SOD), the protein and activity levels of copper/zinc (Cu/Zn) and manganese (Mn) SOD are perturbed in inflamed tissues of IBD patients. Thus we investigated the ability of MnSOD from Streptococcus thermophilus to reduce colitis symptoms in interleukin (IL) 10-deficient mice using Lactobacillus gasseri as a delivery vehicle. Cohorts of 13-15 IL-10-deficient mice were left untreated or supplemented with native L. gasseri or L. gasseri expressing MnSOD for 4 wk. Colonic tissue was collected and inflammation was histologically scored. The presence of innate immune cells was investigated by immunohistochemistry and the host antioxidant response was determined by quantitative PCR. It was demonstrated that L. gasseri was stably maintained in mice for at least 3 days. L. gasseri producing MnSOD significantly reduced inflammation in IL-10-deficient mice compared with untreated controls (P < 0.05), whereas the anti-inflammatory effects of both native and MnSOD producing L. gasseri were more pronounced in males. The anti-inflammatory effects of L. gasseri were associated with a reduction in the infiltration of neutrophils and macrophages. Transcripts of antioxidant genes were equivalent in colonic tissues obtained from control and probiotic-treated IL-10-deficient mice. This study demonstrates that L. gasseri producing MnSOD has significant anti-inflammatory activity that reduces the severity of colitis in the IL-10-deficient mouse.

LAMOTRIGINE REDUCES INTESTINAL I/R INJURY IN THE RAT

I/R injury of the intestine is a life-threatening emergency with mortality rates still more than 60%. We have investigated the protective effect of lamotrigine (LTG), an antiepileptic drug, which has an established neuroprotective effect, on intestinal I/R injury in rats. Forty-eight Wistar albino rats were divided into three groups: a sham-operated group (no I/R injury; n = 16), an ischemic control group (I/R, n = 16), and an LTG-treated group (pretreatment 5 mg kg-1 LTG + IR; n = 16). A marker for lipid peroxidation, malondialdehyde, free radical scavengers, glutathione peroxidase, catalase, and superoxide dismutase levels, an index of polymorphonuclear neutrophils, myeloperoxidase activity, and mucosal damage were investigated. Malondialdehyde levels, myeloperoxidase activity, and the severity of mucosal damage were decreased in the LTG group. Moreover, in the LTG group, glutathione peroxidase and superoxide dismutase levels were higher compared with the I/R group. The pretreatment of rats with LTG before intestinal ischemia ameliorates the mucosal damage in intestinal I/R injury probably by altering lipid peroxidation, neutrophil accumulation, and antioxidant activity.

Peroxisome proliferator-activated receptors ligands and ischemia-reperfusion injury

Peroxisome proliferator-activated receptors (PPARs) belong to a subfamily of transcription nuclear factors. Three isoforms of PPARs have been identified: alpha, beta/delta and gamma, encoded by different genes and distributed in various tissues. They play important roles in metabolic processes like regulation of glucose and lipid redistribution. They also have anti-atherogenic, anti-inflammatory as well as antihypertensive functions. There is good evidence that ligands of PPARs reduce tissue injury associated with ischemia and reperfusion. The potential utility of PPAR ligands in ischemia and reperfusion will be discussed in this review.

Soluble complement receptor 1 preserves endothelial barrier function and microcirculation in postischemic pancreatitis in the rat

Components of the activated complement cascade are considered to play a pivotal role in ischemia-reperfusion-induced organ injury. With the use of intravital epifluorescence microscopy, we investigated the effect of complement inhibition by the recombinant soluble complement receptor 1 (sCR1; TP10) on the effect of macromolecular microvascular permeability, functional capillary perfusion, and leukocyte endothelium interaction in postischemic pancreatitis. Anaesthetized Sprague-Dawley rats were subjected to 60 min of normothermic pancreatic ischemia induced by microclipping of the blood-supplying arteries of the organ. Rats who received sCR1 (15 mg/kg body wt iv; n = 7) during reperfusion showed a significant reduction of permeability (1.77 +/- 1.34 x 10(-8) cm/s; n = 7) of tetramethylrhodamine isothiocyanate-labeled albumin injected 90 min after the onset of reperfusion compared with vehicle-treated animals (6.95 +/- 1.56 x 10(-8) cm/s; n = 7). At 120 min after the onset of reperfusion, the length of red blood cell-perfused capillaries (functional capillary density) was significantly improved (from 279 +/- 15.7 to 330 +/- 3.7 cm(-1); n = 7) and the number of leukocytes adherent to postcapillary venules was significantly reduced (from 314 +/- 87 to 163 +/- 71 mm(-2); n = 7) by sCR1 compared with vehicle treatment. Complement inhibition by sCR1 effectively ameliorates pancreatic ischemia-reperfusion-induced microcirculatory disturbances and might be considered for treatment of postischemic pancreatitis.