N.M. Pellegrino

Enteric bacteria, lipopolysaccharides and related cytokines in inflammatory bowel disease: biological and clinical significance.

Ulcerative colitis (UC) and Crohns disease (CD) [inflammatory bowel disease (IBD)] are both characterized by an exaggerated immune response at the gut associated lymphoreticular tissue level. Such an abnormal and dysregulated immune response may be directed against luminal and/or enteric bacterial antigens, as also supported by murine models of inflammatory bowel disease (IBD) caused by organisms such as Citrobacter rodentium and Helicobacter hepaticus. Bacterial endotoxins or lipopolysaccharides (LPS) have been detected in the plasma of IBD patients and an abnormal microflora and/or an increased permeability of the intestinal mucosa have been invoked as cofactors responsible for endotoxemia. At the same time, the evidence that phagocytosis and killing exerted by polymorphonuclear cells and monocytes and the T-cell dependent antibacterial activity are decreased in IBD patients may also explain the origin of LPS in these diseases. In IBD, pro-inflammatory cytokines and chemokines have been detected in elevated amounts in mucosal tissue and/or in peripheral blood, thus suggesting a monocyte/macrophage stimulation by enteric bacteria and/or their constituents (e.g. LPS). On these grounds, in experimental models and in human IBD, anti-cytokine monoclonal antibodies and interleukin receptor antagonists are under investigation for their capacity to neutralize the noxious effects of immune mediators. Finally, the administration of lactobacilli is beneficial in human IBD and, in murine colitis, this treatment leads to a normalization of intestinal flora, reducing the number of colonic mucosal adherent and translocated bacteria.

Antimicrobial and immunoregulatory functions of lactoferrin and its potential therapeutic application.

Lactoferrin is an iron-binding glycoprotein present in various secretions (e.g. milk, tears, saliva, pancreatic juice, etc.). It is also stored in specific granules of polymorphonuclear granulocytes from which it is released following activation. Lactoferrin exerts a bactericidal activity by damagingthe outer membrane of Gram-negative bacteria, as well as immunoregulatory functions by decreasing the release of interleukin-1 (IL-1), IL-2 and tumor necrosis factor- (TNF-) and enhancing monocyte and natural killer cell cytotoxicity. Lactoferrin binds with high affinity to lipid A, the toxic moiety of the lipopolysaccharide, or endotoxin from Gram-negative bacteria. Lipopolysaccharide interaction with monocytes/macrophages results in the production and release of TNF- , that plays an important role in inducing septic shock. In this respect, it has recently been demonstrated that lactoferrin inhibits the lipopolysaccharide interaction with CD14 on monocytes/macrophages by competition with the lipopolysaccharide binding protein. Therefore, besides its bactericidal activity, lactoferrin may also act by neutralizing the toxic effects of lipopolysaccharide and this protective role against endotoxin lethal shock has been demonstrated in animal models. Moreover, in vitro and in vivo neutralization of endotoxin by a human lactoferrin-derived peptide was also reported and lactoferrin or lactoferrin-derived peptides could represent useful tools for the treatment of endotoxin-induced septic shock. The recent production and characterization of monoclonal antibodies against different epitopes of human lactoferrin, including monoclonal antibodies selectively neutralizinglactoferrin binding to lipid A, may allow a better elucidation of the consequence of lactoferrin-lipopolysaccharideinteraction.

SPLENECTOMY AND SEPSIS: THE ROLE OF THE SPLEEN IN THE IMMUNE-MEDIATED BACTERIAL CLEARANCE

Over the past few years, many observations of overwhelming post splenectomy bacterial infections have been reported. Streptococcus pneumoniae is the aetiologic agent in about 80% of cases, but also gram-negative bacteria are involved in the development of fatal infections in splenectomized patients. Functionally, the spleen plays a fundamental role in bacterial clearance either by antibody response or macrophage bactericidal capacity. At the same time, there is evidence that the spleen also contributes to bacterial endotoxin detoxification. Finally, the mechanisms responsible for gram-positive and gram-negative sepsis in the splenectomized host and possible therapeutical approaches able to neutralize bacterial products endowed with noxious effects are discussed.

Portosystemic shunts in a large cohort of patients with liver cirrhosis: detection rate and clinical relevance

BackgroundThis study aimed to determine the detection rate and clinical relevance of portosystemic collaterals.MethodsWe studied 326 cirrhotics. Portosystemic collaterals, portal vein diameter, and splenic area were evaluated by color Doppler sonography; esophageal varices were detected by endoscopy.ResultsOf the cirrhotics, 130 had portosystemic collaterals (39.9% total, left gastric vein 11%, paraumbilical vein 7.4%, splenorenal shunts 13.8%, and combined shunts 7.7%). Cirrhotics without portosystemic collaterals or with a paraumbilical vein had a significantly narrower portal vein diameter than cirrhotics with a left gastric vein (P < 0.001). Cirrhotics with a paraumbilical vein had a significantly smaller splenic area than cirrhotics with a left gastric vein (P < 0.001), splenorenal shunts (P < 0.001), combined shunts (P < 0.001), or without portosystemic collaterals (P < 0.05). A significant association between portosystemic collaterals and Child’s classes or presence and type of esophageal varices was found (P < 0.0001 and P = 0.0004, respectively). The highest prevalence of Child’s class C and large (F-3) esophageal varices was found in cirrhotics with a left gastric vein (41.7% and 36.1%, respectively), whereas esophageal varices were absent in 47.4% of cirrhotics without portosystemic collaterals and in 58.3% of cirrhotics with a paraumbilical vein.ConclusionsThe left gastric vein is associated with some sonographic and clinical markers of disease severity, whereas the absence of portosystemic collaterals or the presence of paraumbilical veins seems to identify cirrhotics with markers predictive of a more favorable clinical course.

Immune Abnormalities and Endotoxemia in Patients with Ulcerative Colitis and in Their First Degree Relatives: Attempts at Neutralizing Endotoxin- Mediated Effects

Proinflammatory cytokines released from monocytes/macrophages, in particular tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6, and IL-8 seem to play an important role in Inflammatory Bowel Disease (ulcerative colitis and Crohns disease). Endotoxins or lipopolysaccharides, derived from the outer membrane of Gram-negative bacteria interact with CD14 on surface membrane of macrophages, thus triggering a signal cascade, which leads to the production and release of proinflammatory cytokines, particularly TNF-alpha. Therefore, in IBD, lipopolysaccharides could play a pathogenic role. In this respect, plasma endotoxins have been demonstrated in a not negligible percentage of patients with ulcerative colitis and in their unaffected relatives. The presence of circulating endotoxins could be due, at least in part, to the impaired natural immunity in either patients with ulcerative colitis or in their first degree unaffected relatives. Lactoferrin is an iron-binding glycoprotein, which binds to the lipid A region of lipopolysaccharide with a high affinity and this interaction prevents the binding of lipopolysaccharide to CD14, thus inhibiting the release of proinflammatory cytokines. Therefore, based on the possible pathogenic role exerted by endotoxins in ulcerative colitis, lactoferrin may deserve attention as a possible therapeutical agent in experimental models of Inflammatory Bowel Disease.

Increased Spontaneous Release of Tumor Necrosis Factor-α/Cachectin in Headache Patients. A Possible Correlation with Plasma Endotoxin and Hypothalamic-Pituitary-Adrenal Axis

Tumor Necrosis Factor-alpha/cachectin (TNF-alpha/cachectin), Lipopolysaccharide (LPS), ACTH, beta-Endorphin (beta-EPH), and Cortisol (F) levels were determined in 33 Headache patients: 22 patients were affected with Migraine (M) and 11 patients with Chronic Type Tension Headache (CTTH). TNF-alpha/cachectin serum level was detected in 15 out of 22 migraneous patients and in no CTTH patients. Plasma LPS was observed in 11 out of 15 TNF-alpha/cachectin positive migraneous patients (73%) and in 3 out of 11 CTTH patients (27%). A negative correlation was observed between TNF-alpha/cachectin values and either ACTH or beta-EPH. In the group of migraneous patients the presence of serum TNF-alpha/cachectin showed a sensibility of .6 and a specificity of 1. The endocrine and immunological implications concerning these data are discussed.

HELICOBACTER PYLORI INFECTION AND HOST CELL RESPONSES

It is well known that Helicobacter pylori is able to colonize the gastric mucosa, causing a chronic and persistent infection with complications, such as peptic ulcer and gastric cancer. This review places emphasis on some epidemiological aspects of Helicobacter pylori infection and its mode of transmission. At the same time, invasive and non-invasive methods of diagnosis of Helicobacter pylori infection are illustrated. More space is devoted to the host response following invasion of the stomach. In this respect, the role played by different growth factors and polyamines in the course of Helicobacter pylori disease is discussed also in relation to the result of eradicating treatment. On the other hand, an accurate description of the host immune responses against Helicobacter pylori organism and/or their components (e.g. lipopolysaccharides) is reported. Finally, since Helicobacter pylori has been classified as a class I carcinogen, current researches are focussed on the Helicobacter pylori-induced carcinogenesis.

A Point of View: The Need to Identify an Antigen in Psyconeuroimmunological Disorders

Several lines of evidence support a mutual relationship between the nervous system and the immune system. Therefore, it is not surprising that some neuropsychiatric disorders are also characterized by immune abnormalities. In patients with phobic disorders and in patients with migraine without aura some common immune abnormalities have been detected and, in particular, natural immunity deficits, exaggerated release of proinflammatory cytokines and circulating bacterial endotoxins have been found. In other neurological disease, some etiologic factors have been detected as in the case of Guillain-Barrè syndrome in which molecular mimicry between Campylobacter jejuni endotoxin and GM1 ganglioside may cause an acute inflammatory polyneuropathy. On the other hand, attempts to identify an antigen have been made in patients with Alzheimers disease and schizophrenia. Finally, the chronic fatigue syndrome, an old illness in search for an antigen, risk factors and precipitating agents have been described but evidence for a specific antigen is still lacking.

Antibodies to carbonic anhydrase in patients with connective tissue diseases: relationship with lung involvement.

The aim of this study is to evaluate the presence of antibodies to carbonic anhydrase I and/or II (ACAI and ACAII) in patients affected by connective tissue diseases (CTD) and to investigate their association with lung involvement evaluated by High resolution CT scan (HRCT). Ninety-six patients affected by CTD were studied, i.e. 33 rheumatoid arthritis (RA), 8 psoriatic arthritis (PA), 8 ankylosing spondilitis (AS), 23 Systemic Lupus Erythematosus (SLE), 10 Sjogren Syndrome (SS), and 14 Systemic Sclerosis (SSc). ACA were detected by ELISA. The lung involvement was evaluated by means of a previously described HRCT score. According to a receiver operator characteristic curve, patients were divided into those with HRCT score ≥ 10 and those with HRCT score < 10, where HRCT score ≥ 10 was predictive of interstitial lung disease. ACAI and/or ACAII were detected in 30/96 patients (31.2%) (P<0.0001 in comparison with controls). In particular, the prevalence of ACAI and/or ACAII was significantly higher in patients with RA (P = 0.002), PA (P < 0.0001), SLE (P = 0.0003) and SSc (P<0.0001). A positive correlation was found between HRCT scores and CRP or ACAI levels (P=<0.0001 and P=0.004, respectively). Thirty-nine of 96 patients (40.6%) showed a HRCT score ≥ 10 and both their CRP and ACAI levels were significantly higher when compared with patients showing a HRCT score < 10 (P<0.0006 and P = 0.0009, respectively). Moreover, C3 and C4 complement fractions inversely correlated with HRCT scores (P = 0.0004 and P<0.0001, respectively) and lower values of C3 and C4 complement fractions were found in patients with HRCT score ≥ 10 than in those with HRCT score < 10 (P = 0.014 and P = 0.007, respectively). Due to the lower levels of complement fractions detected in patients with HRCT score ≥ 10, a possible immune-complex-mediated pathogenic mechanism of lung involvement could be suggested.

Variability in anticardiolipin antibody detection: role of nonspecific IgG binding and different microtiter plates.

There are many studies that are available on the Internet that attempt to standardize the assay for anticardiolipin antibody evaluation because of the variability of results. The aim of this study was to evaluate simultaneously the role of different microplates and the importance of sample nonspecific binding in determining different results in anticardiolipin antibody detection. Sera from 8 patients with raised levels of IgG anticardiolipin antibodies and 10 control sera were assayed by enzyme-linked immunosorbent assay in the presence (specific binding) or in the absence of cardiolipin (sample blank) with four different microplates, that is, NUNC PolySorp, FALCON ProBIND, Greiner 655061 (high binding), and Greiner 655001 (medium binding). Results were expressed as optical densities or net-optical densities (following sample blank subtraction) as well as international IgG anticardiolipin units (GPL) or net-GPL. A wide interplate variability of optical densities was found. When results were expressed as GPL, significant differences were only found between Greiner 655061, FALCON ProBIND, and NUNC PolySorp (P < .05 and P < .001, respectively) whereas differences were not statistically significant if interplate variability was analyzed as net-GPL. Results expressed as categorical variables (ie, positive/negative, according to a GPL cut-off and net-GPL cut-off, obtained with sera from 100 apparently healthy blood donors) showed a good or excellent Cohens κ coefficient of concordance among plates when positivity was evaluated on net-GPL. Our data strongly suggest that quantification and subtraction of sample blank may improve both interlaboratory agreement and reliability of anticardiolipin assay and minimize false-positive results.