Eric Y. T. Chan

Mannose-Binding Lectin in Severe Acute Respiratory Syndrome Coronavirus Infection

Abstract Little is known about the innate immune response to severe acute respiratory syndrome (SARS) coronavirus (CoV) infection. Mannose-binding lectin (MBL), a key molecule in innate immunity, functions as an ante-antibody before the specific antibody response. Here, we describe a case-control study that included 569 patients with SARS and 1188 control subjects and used in vitro assays to investigate the role that MBL plays in SARS-CoV infection. The distribution of MBL gene polymorphisms was significantly different between patients with SARS and control subjects, with a higher frequency of haplotypes associated with low or deficient serum levels of MBL in patients with SARS than in control subjects. Serum levels of MBL were also significantly lower in patients with SARS than in control subjects. There was, however, no association between MBL genotypes, which are associated with low or deficient serum levels of MBL, and mortality related to SARS. MBL could bind SARS-CoV in a dose- and calcium-dependent and mannan-inhibitable fashion in vitro, suggesting that binding is through the carbohydrate recognition domains of MBL. Furthermore, deposition of complement C4 on SARS-CoV was enhanced by MBL. Inhibition of the infectivity of SARS-CoV by MBL in fetal rhesus kidney cells (FRhK-4) was also observed. These results suggest that MBL contributes to the first-line host defense against SARS-CoV and that MBL deficiency is a susceptibility factor for acquisition of SARS

Serum levels of IL-33 and soluble ST2 and their association with disease activity in systemic lupus erythematosus

OBJECTIVE IL-33 has recently been found to be the specific ligand of ST2, an IL-1 receptor family member that is selectively expressed in Th2 cells and mediates Th2 response. This study aims to measure the serum levels of soluble ST2 (sST2) and IL-33 in patients with SLE and to examine their association with disease activity. METHODS Seventy SLE patients were evaluated for disease activity, determined by SLEDAI, levels of anti-dsDNA antibody, C3 and C4. Fifty-seven patients were evaluated longitudinally on a second occasion. IL-33 and sST2 were measured by sandwich ELISA in the 127 SLE serum samples and compared with 28 age- and sex-matched healthy controls. RESULTS Serum sST2 level was significantly higher in active SLE patients [0.51 (0.18) ng/ml] compared with inactive patients [0.42 (0.08) ng/ml] (P = 0.006) and normal controls [0.36 (0.13) ng/ml] (P < 0.001). sST2 level correlated significantly with SLEDAI, anti-dsDNA antibody and prednisolone dosage, and negatively with C3. Linear regression analysis showed that serum sST2 level was an independent predictive factor for modified SLEDAI, excluding anti-dsDNA and complement score after controlling for age, sex, glomerular filtration rate and prednisolone dosage (regression coefficient: 8.5; 95% CI 2.6, 14.3) (P = 0.005). Serum sST2 level was sensitive to change in disease activity longitudinally, with an effect size of 0.29. Elevated serum IL-33 was comparable in frequency (4.3 vs 7.1%; P = 0.62) and levels (P = 0.53) between SLE patients and controls. CONCLUSIONS Elevated serum sST2 level in SLE patients was found to correlate with disease activity and was sensitive to change, suggesting a potential role as a surrogate marker of disease activity.

Quantitative Analysis of HIV-1 Infected CD4+ Cell Proteome: Dysregulated Cell Cycle Progression and Nuclear Transport Coincide with Robust Virus Production

ABSTRACT Relatively little is known at the functional genomic level about the global host response to human immunodeficiency virus type 1 (HIV-1) infection. Microarray analyses by several laboratories, including our own, have revealed that HIV-1 infection causes significant changes in host mRNA abundance and regulation of several cellular biological pathways. However, it remains unclear what consequences these changes bring about at the protein level. Here we report the expression levels of ∼3,200 proteins in the CD4+ CEMx174 cell line after infection with the LAI strain of human immunodeficiency virus type 1 (HIV-1); the proteins were assessed using liquid chromatography-mass spectrometry coupled with stable isotope labeling and the accurate mass and time tag approach. Furthermore, we found that 687 (21%) proteins changed in abundance at the peak of virus production at 36 h postinfection. Pathway analysis revealed that the differential expression of proteins was concentrated in select biological pathways, exemplified by ubiquitin-conjugating enzymes in ubiquitination, carrier proteins in nucleocytoplasmic transport, cyclin-dependent kinase in cell cycle progression, and pyruvate dehydrogenase of the citrate cycle pathways. Moreover, we observed changes in the abundance of proteins with known interactions with HIV-1 viral proteins. Our proteomic analysis captured changes in the host protein milieu at the time of robust virus production, depicting changes in cellular processes that may contribute to virus replication. Continuing analyses are expected to focus on blocking virus replication by targeting these pathways and their effector proteins.

Cytomegalovirus colitis in individuals without apparent cause of immunodeficiency.

Cytomegalovirus infection is usually reported inimmunocompromised patients. In this study, apparentlyimmunocompetent patients with cytomegaloviral colitiswere reviewed. Records with a diagnosis ofcytomegaloviral colitis from January 1989 to June 1996 wereretrieved for analysis. Ten patients were included(median age 70 yr). The major presenting symptoms werediarrhea and hematochezia. Ulceration was the mainmacroscopic finding. Rectal bleeding was mostlyself-limiting. Three patients developed localcomplications (rectovaginal fistula in two; rectalstricture in one). In the two patients with rectovaginalfistula, lymphocytes subsets and proliferative response wereentirely normal. In the other patient, low B lymphocytecount and low response to mitogen were demonstrated.However, the immunoglobulins were not suppressed and rectal biopsies revealed noncaseatinggranulomas, suggesting activated cell-mediated immunity.In conclusion, a high index of suspicion is crucial forearly diagnosis of cytomegaloviral colitis in patients with bloody diarrhea, even though obviousevidence of immunodeficiency is lacking.

Disseminated Penicilliosis, Recurrent Bacteremic Nontyphoidal Salmonellosis, and Burkholderiosis Associated with Acquired Immunodeficiency Due to Autoantibody against Gamma Interferon

ABSTRACT Acquired immunodeficiency due to autoantibody against gamma interferon has recently been associated with opportunistic nontuberculous mycobacteriosis, especially among Southeast Asians. We report another 8 cases, all except one apparently immunocompetent hosts who suffered from concomitant or sequential infections by other intracellular pathogens causing penicilliosis, extraintestinal nontyphoidal salmonellosis, and burkholderiosis. The only case with an underlying immunodeficiency syndrome had systemic lupus erythematosus that was quiescent throughout the multiple infective episodes. Eight out of 10 (80.0%) patients with serological evidence of penicilliosis, 5 out of 7 (71.4%) with culture-positive extraintestinal nontyphoidal salmonellosis, 5 out of 28 (17.9%) with serological evidence of melioidosis, and 7 out of 13 (53.8%) with culture-positive nontuberculous mycobacteriosis possessed autoantibody against gamma interferon, whereas only 1 out of 100 patients with systemic lupus erythematosus did. Our study represents the first and largest case series linking this emerging immunodeficiency syndrome with these atypical infections in apparently immunocompetent hosts. Thus, we advocate that any patient with unexplained recurrent or polymicrobial infections due to these intracellular pathogens should be screened for acquired immunodeficiency due to autoantibody against gamma interferon.

Carcinoma of the Esophagus. an Autopsy Study of 231 Cases

&NA; Summary Autopsy findings for 231 cases of carcinoma of the esophagus are presented. Cases with tumour resection constituted 57% of the series. Residual malignancy was present in 81% of all cases. Local residual or recurrent tumour was found in 53%, lymph node metastases in 65% and visceral metastases in 54% of cases. Intrathoracic lymph node metastases were present in 41% of patients after tumour resection and were probably significant in the failure of radical surgery. Adequate clearance of intrathoracic lymph nodes during radical surgery may reduce the incidence of tumour recurrence in this group of patients. Survival was poor in patients with or without resection of the primary tumour. Less than 12% were alive 1 yr after presentation. The average duration of dysphagia at presentation was 2.5 mth. The poor survival of our patients suggests that, by the time they presented clinically, the disease was already advanced. Early disease detection is important for a chance of cure in patients with esophageal cancer.

The Lower Serum Immunoglobulin G2 Level in Severe Cases than in Mild Cases of Pandemic H1N1 2009 Influenza Is Associated with Cytokine Dysregulation

ABSTRACT The majority of patients with pandemic influenza H1N1 2009 had mild illness, but some, including those with no risk factors for severe disease, may succumb to this infection. Besides viral factors such as the D222/225G substitution of the hemagglutinin, host factors such as IgG2 subclass deficiency recently was reported to be associated with severe disease in a cohort of Australian patients besides other known risk factors, including underlying chronic illness, extremes of age, and pregnancy. We conducted a case-control study of 38 Asian patients with respiratory failure due to severe pandemic influenza and compared the results to those for 36 mild cases. None had selective IgG2 deficiency, but the level of IgG2 subclass was significantly lower in the severe cases (3.55 g/liter versus 4.75 g/liter; P = 0.002), whereas the levels of IgG1, IgG3, and IgG4 were not significantly different from those of the mild cases. Previous studies suggested that some IgHG2 and FcγRIIa genotypes were associated with IgG2 deficiency. The allelic frequency of the IgHG2 genotypes in our severe cases was not correlated with their levels of IgG2, while that of FcγRIIa was not significantly different from that of the general Han Chinese population (P = 0.216). Only the overall cytokine/chemokine profile (P = 0.029) and serum globulin level (P = 0.005) were found to be independently associated with the IgG2 level by multivariate analysis. The lower IgG2 level in our severe group might be related to cytokine dysregulation rather than being a significant risk factor for severe pandemic influenza. The importance of this finding for therapeutic intervention will require further studies of larger cohorts of patients.

Autoantibody formation after allogeneic bone marrow transplantation: Correlation with the reconstitution of CD5+ B cells and occurrence of graft-versus-host disease

Summary Manifestations of autoimmune diseases are common in patients who have received allogeneic bone marrow transplantation (BMT). Autoantibodies have been reported in these patients but the source and clinical significance of these autoantibodies are still obscure. In the present study the kinetics of autoantibody formation and the reconstitution of CD5+ B cells was followed in 21 patients who were submitted to allogeneic BMT. Anti‐nuclear, anti‐smooth muscle, anti‐neutrophil cytoplasmic antibodies, anti‐reticulin and rheumatoid factor were found at a frequency of 25%, 17%, 24%, 22% and 10% respectively after BMT. Anti‐double stranded DNA levels were mildly elevated in 15% of samples. The screening for anti‐extractable nuclear antigen, anti‐mitochondrial, anti‐gastric parietal cell, anti‐proteinase III, anti‐myeloperoxidase, anti‐lactoferrin antibodies was negative. The percentage and absolute count of CD5+ B cells increased with time after allogeneic BMT. Those patients with anti‐nuclear or anti‐smooth muscle antibodies had significantly higher CD5+ B cell counts than those without these two antibodies. Correlations of CD5+ B cell counts with other autoantibodies were negative. Acute graft‐versus‐host disease (GVHD) occurred in eight of the patients and chronic GVHD in four patients, but the frequency of autoantibodies had no relationship with the occurrence of acute or chronic GVHD.Abbreviations: BMT, bone marrow transplantation; GVHD, graft‐versus‐host disease; ANA, anti‐nuclear antibody; ANCA, anti‐neutrophilcytoplasmic antibody; SMA, anti‐smooth muscle antibody.

H5N1 virus causes significant perturbations in host proteome very early in influenza virus-infected primary human monocyte-derived macrophages.

H5N1 influenza viruses, which cause disease in humans, have unusually high pathogenicity. The temporal response of primary human monocyte-derived macrophages infected with highly pathogenic H5N1 and seasonal H1N1 influenza viruses was evaluated using mass spectrometry-based quantitative proteomic profiling. This was done in order to demonstrate significant perturbation of the host proteome upon viral infection, as early as 1 hour after infection. This early host response distinguished H5N1 infection from H1N1 infection, the latter inducing less of a response. The most pronounced effect was observed on the translational machinery, suggesting that H5N1 might gain advantage in replication by using the cell protein synthesis machinery early in the infection.

Expression of IL-2R, IL-4R, IL-6R on peripheral blood lymphocytes in systemic lupus erythematosus and correlation with disease activity: a prospective study.

AIMS: To study the expression of interleukin-2 receptor (IL-2R), interleukin-4 receptor (IL-4R) and interleukin-6 receptor (IL-6R) on peripheral blood lymphocytes (PBL) in patients with systemic lupus erythematosus (SLE); to correlate the level of expression of these receptors with SLE disease activity. METHODS: Peripheral blood lymphocytes were studied by a high sensitivity flow cytometry technique using monoclonal antibodies directed against CD25 (IL-2R alpha chain), CD122 (IL-2R beta chain), CD124 (IL-4R), and CD126 (IL-6R). SLE disease activity was scored using the SLE Disease Activity Index, C3 and C4 concentrations, anti-dsDNA level, and absolute lymphocyte count. RESULTS: Compared with normal controls, PBL from patients with SLE had a higher percentage of CD25+ cells (median 20.8% v 16.5%) and a lower percentage of CD122+ cells (median 13.1% v 22.4%). The difference in CD122+ cells was greater in the CD122weak population than the CD122strong (natural killer cell) population. The percentages of CD124+ and CD126+ PBLs in patients with SLE and controls were similar. On CD25+ cells, the relative antigenic level of the IL-2R alpha chain was significantly higher in patients with SLE (median 2.01 v 1.81). The relative antigenic levels of CD122+, CD124+ and CD126+ cells were similar in patients and controls. Neither the percentages nor the relative antigenic levels of all of these cytokine receptors were correlated with any of the parameters of disease activity. CONCLUSION: Lymphocyte activation in patients with SLE was evident from the increase in CD25 expression on PBL, with a reciprocal decrease in CD122 expression. As the expression of IL-2R, IL-4R, IL-6R did not correlate with disease activity, it seems that these cytokine/receptor systems do not play a direct role in disease activation in SLE.