Amir A. Qamar

Asymptomatic Carriage of Clostridium difficile and Serum Levels of IgG Antibody against Toxin A

BACKGROUND Clostridium difficile infection can result in asymptomatic carriage, mild diarrhea, or fulminant pseudomembranous colitis. We studied whether antibody responses to C. difficile toxins affect the risks of colonization, diarrhea, and asymptomatic carriage. METHODS We prospectively studied C. difficile infections in hospitalized patients who were receiving antibiotics. Serial stool samples were tested for C. difficile colonization by cytotoxin assay and culture. Serum antibody (IgA, IgG, and IgM) levels and fecal antibody (IgA and IgG) levels against C. difficile toxin A, toxin B, and nontoxin antigens were measured by an enzyme-linked immunosorbent assay (ELISA). RESULTS Of 271 patients, 37 (14 percent) were colonized with C. difficile at the time of admission, 18 of whom were asymptomatic carriers. An additional 47 patients (17 percent) became infected in the hospital, 19 of whom remained asymptomatic. The baseline antibody levels were similar in the patients who later became colonized and those who did not. After colonization, those who became asymptomatic carriers had significantly greater increases in serum levels of IgG antibody against toxin A than did the patients in whom C. difficile diarrhea developed (P<0.001). The adjusted odds ratio for diarrhea was 48.0 (95 percent confidence interval, 3.4 to 678) among patients with colonization who had a serum level of IgG antibody against toxin A of 3.00 ELISA units or less, as compared with patients with colonization who had a level of more than 3.00 ELISA units. CONCLUSIONS We find no evidence of immune protection against colonization by C. difficile. However, after colonization there is an association between a systemic anamnestic response to toxin A, as evidenced by increased serum levels of IgG antibody against toxin A, and asymptomatic carriage of C. difficile.

Association between antibody response to toxin A and protection against recurrent Clostridium difficile diarrhoea

BACKGROUND We have reported that symptom-free carriers of Clostridium difficile have a systemic anamnestic immune response to toxin A. The aim of this study was to determine whether an acquired immune response to toxin A, during an episode of C. difficile diarrhoea, influences risk of recurrence. METHODS We prospectively studied 63 patients with nosocomial C. difficile diarrhoea. Serial serum IgA, IgG, and IgM concentrations against C. difficile toxin A, toxin B, or non-toxin antigens were measured by ELISA. Individuals were followed for 60 days. FINDINGS 19 patients died (30%). Of the 44 who survived, 22 had recurrent C. difficile diarrhoea. Patients with a single episode of C. difficile diarrhoea (n=22) had higher concentrations of serum IgM against toxin A on day 3 of their first episode of diarrhoea than those with recurrent diarrhoea (n=22, p=0.004). On day 12, serum IgG values against toxin A were higher in patients who had a single episode of diarrhoea (n=7) than in those who subsequently had recurrent diarrhoea (n=9, p=0.009). The odds ratio for recurrence associated with a low concentration of serum IgG against toxin A, measured 12 days after onset of C. difficile diarrhoea, was 48.0 (95% CI 3.5-663). INTERPRETATION A serum antibody response to toxin A, during an initial episode of C. difficile diarrhoea, is associated with protection against recurrence.

p38 MAP kinase activation by Clostridium difficile toxin A mediates monocyte necrosis, IL-8 production, and enteritis

Clostridium difficile toxin A causes acute neutrophil infiltration and intestinal mucosal injury. In cultured cells, toxin A inactivates Rho proteins by monoglucosylation. In monocytes, toxin A induces IL-8 production and necrosis by unknown mechanisms. We investigated the role of mitogen-activated protein (MAP) kinases in these events. In THP-1 monocytic cells, toxin A activated the 3 main MAP kinase cascades within 1 to 2 minutes. Activation of p38 was sustained, whereas stimulation of extracellular signal-regulated kinases and c-Jun NH(2)-terminal kinase was transient. Rho glucosylation became evident after 15 minutes. IL-8 gene expression was reduced by 70% by the MEK inhibitor PD98059 and abrogated by the p38 inhibitor SB203580 or by overexpression of dominant-negative mutants of the p38-activating kinases MKK3 and MKK6. SB203580 also blocked monocyte necrosis and IL-1beta release caused by toxin A but not by other toxins. Finally, in mouse ileum, SB203580 prevented toxin A-induced neutrophil recruitment by 92% and villous destruction by 90%. Thus, in monocytes exposed to toxin A, MAP kinase activation appears to precede Rho glucosylation and is required for IL-8 transcription and cell necrosis. p38 MAP kinase also mediates intestinal inflammation and mucosal damage induced by toxin A.

Saccharomyces boulardii stimulates intestinal immunoglobulin A immune response to Clostridium difficile toxin A in mice.

ABSTRACT Saccharomyces boulardii is a nonpathogenic yeast that protects against antibiotic-associated diarrhea and recurrentClostridium difficile colitis. The administration ofC. difficile toxoid A by gavage to S. boulardii-fed BALB/c mice caused a 1.8-fold increase in total small intestinal immunoglobulin A levels (P = 0.003) and a 4.4-fold increase in specific intestinal anti-toxin A levels (P < 0.001). Enhancing host intestinal immune responses may be an important mechanism for S. boulardii-mediated protection against diarrheal illnesses.

Incidence, Prevalence, and Clinical Significance of Abnormal Hematologic Indices in Compensated Cirrhosis

BACKGROUND & AIMS Patients with cirrhosis develop abnormal hematologic indices (HI) from multiple factors, including hypersplenism. We aimed to analyze the sequence of events and determine whether abnormal HI has prognostic significance. METHODS We analyzed a database of 213 subjects with compensated cirrhosis without esophageal varices. Subjects were followed for approximately 9 years until the development of varices or variceal bleeding or completion of the study; 84 subjects developed varices. Abnormal HI was defined as anemia at baseline (hemoglobin, < or =13.5 g/dL for men and 11.5 g/dL for women), leukopenia (white blood cell counts, < or =4000/mm3), or thrombocytopenia (platelet counts, < or =150,000/mm3). The primary end points were death or transplant surgery. RESULTS Most subjects had thrombocytopenia at baseline. Kaplan-Meier analysis showed that leukopenia occurred by 30 months (95% confidence interval, 18.5-53.6), and anemia occurred by 39.6 months (95% confidence interval, 24.1-49.9). Baseline thrombocytopenia (P = .0191) and leukopenia (P = .0383) were predictors of death or transplant, after adjusting for baseline hepatic venous pressure gradient (HVPG), and Child-Pugh scores. After a median of 5 years, a significant difference in death or transplant, mortality, and clinical decompensation was observed in patients who had leukopenia combined with thrombocytopenia at baseline compared with patients with normal HI (P < .0001). HVPG correlated with hemoglobin and white blood cell count (hemoglobin, r = -0.35, P < .0001; white blood cell count, r = -0.31, P < .0001). CONCLUSIONS Thrombocytopenia is the most common and first abnormal HI to occur in patients with cirrhosis, followed by leukopenia and anemia. A combination of leukopenia and thrombocytopenia at baseline predicted increased morbidity and mortality.

Platelet count is not a predictor of the presence or development of gastroesophageal varices in cirrhosis.

Current guidelines recommend esophagogastroduodenoscopy (EGD) in patients with cirrhosis to screen for gastroesophageal varices (GEV). Thrombocytopenia has been proposed as a noninvasive test to predict the presence of GEV. There is no agreement regarding a specific platelet count (PLT) that can reliably predict GEV. The present longitudinal study aims to (1) further investigate the relationship between varices and PLT at the time of endoscopy, (2) investigate whether changes in PLT from the baseline over time can predict the development of GEV, and (3) investigate whether changes in PLT correlate with the hepatic venous pressure gradient (HVPG). A secondary analysis was conducted for 213 subjects with compensated cirrhosis with portal hypertension but without GEV enrolled in a randomized, placebo‐controlled, double‐blind trial of a nonselective beta‐blocker used to prevent GEV. PLTs were obtained every 3 months, and HVPG measurements and EGD were done annually. The PLTs were compared between subjects who did and did not develop GEV. In a median follow‐up of 54.9 months, 84 patients developed GEV. PLT was greater than 150,000 in 15% of patients at the development of GEV. A receiver operating curve did not show any PLT with high sensitivity or specificity for the presence of GEV. Subjects with clinically insignificant portal hypertension (HVPG < 10 mm Hg) whose PLT remained greater than 100,000 had a 2‐fold reduction in the occurrence of GEV (P = 0.0374). A significant correlation was found between HVPG and PLT at the baseline, year 1, and year 5 (P < 0.0001). Conclusion: Cross‐sectional or longitudinal evaluations of PLTs are inadequate noninvasive markers for GEV. Patients with mild portal hypertension whose PLT remains greater than 100,000 have significantly less risk of GEV. Although HVPG correlates somewhat with PLT, changes in PLT cannot be used as a surrogate for HVPG changes. (HEPATOLOGY 2008;47:153–159.)

Recommendations for Probiotic Use--2015 Update: Proceedings and Consensus Opinion

This paper describes the consensus opinion of the participants in the 4th Triennial Yale/Harvard Workshop on Probiotic Recommendations. The recommendations update those of the first 3 meetings that were published in 2006, 2008, and 2011. Recommendations for the use of probiotics in necrotizing enterocolitis, childhood diarrhea, inflammatory bowel disease, irritable bowel syndrome and Clostridium difficile diarrhea are reviewed. In addition, we have added recommendations for liver disease for the first time. As in previous publications, the recommendations are given as A, B, or C ratings.

In vitro and in vivo protection of stellate cells from apoptosis by leptin.

Hepatic fibrogenesis is reduced in the absence of leptin. We hypothesized that leptin protects hepatic stellate cells (HSCs) from apoptosis and tested this in in vitro and in vivo systems. (i) Fas ligand (fas-L)-mediated apoptosis was induced in vitro in activated HSCs in the absence and presence of leptin. (ii) HSC apoptosis was also induced by UV irradiation in the absence and presence of leptin. (iii) Fas-L-mediated apoptosis was induced in vitro in HSCs from db/db mice in the absence and presence of leptin. (iv) Liver fibrosis was induced in wt and db/db mice. (v) Liver fibrosis was induced in wild-type mice with TAA, and mice received additional leptin or a control solution. HSC apoptosis was assessed by TUNEL staining. Western blot for α-SMA was used to determine differences in HSC activation. Results were as follows. (i) Fas-L induced significant apoptosis of HSC, and preincubation with leptin reduced this approximately threefold. (ii) Leptin provided no protection from UV-induced apoptosis. (iii) HSCs from db/db mice were not protected by leptin against fas-L-induced apoptosis. (iv) TAA-induced fibrosis was significantly less in db/db mice compared to wild type. (v) Wild-type mice receiving leptin had less apoptosis and more α-SMA than controls. We conclude that leptin protects HSC from in vitro and in vivo apoptosis. The antiapoptotic effect of leptin requires the long form of the leptin receptor and interacts with the apoptotic pathway proximal to mitochondrial activation.

Associated comorbidities in psoriasis and inflammatory bowel disease.

Background  The association between psoriasis and inflammatory bowel disease (IBD) has been previously reported although a great deal remains unknown about associated comorbidities.

Abnormal hematological indices in cirrhosis

Abnormalities in hematological indices are frequently encountered in cirrhosis. Multiple causes contribute to the occurrence of hematological abnormalities. Recent studies suggest that the presence of hematological cytopenias is associated with a poor prognosis in cirrhosis. The present article reviews the pathogenesis, incidence, prevalence, clinical significance and treatment of abnormal hematological indices in cirrhosis.