Intestinal bacteria trigger T cell-independent immunoglobulin A(2) class switching by inducing epithelial-cell secretion of the cytokine APRIL

Bacteria colonize the intestine shortly after birth and thereafter exert several beneficial functions, including induction of protective immunoglobulin A (IgA) antibodies. The distal intestine contains IgA(2), which is more resistant to bacterial proteases than is IgA(1). The mechanism by which B cells switch from IgM to IgA(2) remains unknown. We found that human intestinal epithelial cells (IECs) triggered IgA(2) class switching in B cells, including IgA(1)-expressing B cells arriving from mucosal follicles, through a CD4(+) T cell-independent pathway involving a proliferation-inducing ligand (APRIL). IECs released APRIL after sensing bacteria through Toll-like receptors (TLRs) and further increased APRIL production by activating dendritic cells via thymic stromal lymphopoietin. Our data indicate that bacteria elicit IgA(2) class switching by linking lamina propria B cells with IECs through a TLR-inducible signaling program requiring APRIL. Thus, mucosal vaccines should activate IECs to induce more effective IgA(2) responses.

Early detection of cardiotoxicity during chemotherapy using biomarkers

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Cancer chemotherapy (CHEMO), especially anthracycline-containing regimens, may result in heart failure and left ventricular dysfunction (LVD) due to cardiotoxicity (CVTx). The ability to detect CVTx currently utilizes techniques to assess LVD, such as MUGA or echocardiography (Echo), which have substantial limitations and only detect LVD well after it occurs. Cardiac biomarkers, troponin (Trop I) and B-Type Natriuretic Peptide (BNP) are well established for detecting myocardial injury and LVD in patients without cancer. Limited evidence suggests that these may be important predictors of subsequent CVTx during CHEMO, but these markers have not been systematically investigated prospectively. Methods: Patients undergoing anthracycline-containing combination CHEMO were evaluated at baseline with: history and physical; electrocardiogram; Echo; and BNP and Trop I. Biomarkers were repeated before and after up to 6 cycles of CHEMO. ECHO was repeated after 6 cycles or at 6 months from baseline. Cardiac events (heart failure, LVD, sudden death, or arrhythmia) were documented, if present. Results: To date, 111 (53M/58F) patients, age 56±14 (mean±SD), with either lymphoma (n=39, 35%), sarcoma (n=60, 54%), or breast cancer (n=12, 11%) were enrolled. At least one traditional cardiac risk factor was identified in 77 (69%) and 2 or more risk factors noted in 46 (41%). Baseline ECHO parameters including ejection fraction (EF) and biomarkers were normal. With CHEMO, the mean post CHEMO BNP value (pg/ml) for the group did not change significantly; however, in the 8 patients with cardiac events, the BNP post CHEMO was elevated. The Trop I values were not abnormal except in 2 patients with events. Conclusion: Preliminary data collected to date indicates that BNP values during CHEMO remain normal unless cardiac events occur. Additionally, elevated BNP levels appear to detect CVTx, but LVEF did not. Furthermore, patients receiving CHEMO frequently have cardiac risk factors that may promote CVTx.

[Table: see text]

No significant financial relationships to disclose.

Intestinal Bacteria Induce T Cell-Independent IgA2 Class Switching by Linking Epithelial Cells with Lamina Propria B Cells through APRIL (40.3)

Bacteria colonize the intestine shortly after birth and thereafter exert several beneficial functions, including induction of protective IgA antibodies. The distal intestine contains IgA2, which is more resistant to bacterial proteases than IgA1. The mechanism by which B cells undergo IgA2 class switching remains unknown. We found that human intestinal epithelial cells (IECs) triggered IgA2 class switching by activating B cells, including IgA1-expressing effector B cells, through a T cell-independent pathway involving a proliferation-inducing ligand (APRIL). IECs released APRIL after sensing whole bacteria or bacterial products, such as lipopolysaccharide or flagellin, through a Toll-like receptor (TLR)-mediated MyD88-dependent pathway. Bacteria-activated IECs further increased APRIL production by cross talking with dendritic cells via thymic stromal lymphopoietin (TSLP), an IL-7-like cytokine. Our findings indicate that bacteria and their products elicit IgA1-to-IgA2 diversification by linking lamina propria effector B cells arriving from mucosal lymphoid follicles with IECs through a TLR-inducible APRIL-dependent signaling program. Our data also suggest that vaccines should activate IECs to effectively induce protective IgA2 responses in the intestinal mucosa.

This work was supported by NIH grant AI057653 (to A.C.) and NIH T32 training grant AI07621.

A pilot study to evaluate the impact of involving breast cancer patients in the multidisciplinary discussion of their disease and treatment plan

Multidisciplinary care is the accepted best model of management of breast cancer patients. Current evidence suggests that multidisciplinary care has the potential to reduce mortality, improve quality of life, and reduce health care costs. We investigated the impact of patient involvement in the multidisciplinary meeting. A pilot study was conducted to assess the feasibility and acceptability of directly involving patients diagnosed with breast cancer in multidisciplinary clinic discussions and treatment planning. 30 consecutive breast cancer patients presenting for surgery were invited to attend our weekly multidisciplinary breast meeting at the time of receiving their results of surgery. Patients completed questionnaires before and after the meeting, and participated in a tape-recorded interview with the breast care nurse after the meeting. Members of the multi-disciplinary team also completed a short survey at the end of the study. The intervention was highly valued by most of the participating patients; and acceptable to and welcomed by most health professionals in the multidisciplinary team. Change in anxiety scores was not affected by participation. Patient attendance at the breast multidisciplinary meeting was shown to be potentially acceptable to both patients and health professionals, without unduly raising patient anxiety. A national survey exploring attitudes towards patient involvement in the multidisciplinary team meeting is currently in progress.

HIV-1 induces targeted down-regulation of the Ig gene-diversifying enzyme AID in the germinal center of infected lymphoid follicles (45.1)

Class switching from IgM to IgG and IgA is essential for antiviral immunity and requires activation-induced cytidine deaminase (AID), an APOBEC family member with DNA-editing activity. Germinal center (GC) B cells express AID upon activation by CD4+ T cells through CD40 ligand (CD40L) and IL-4. HIV-1 is thought to impair IgG and IgA responses to viral antigens, opportunistic pathogens and vaccines by causing progressive loss of CD4+ T cells and by rendering B cells poorly responsive to CD4+ T cell help. It remains unknown whether HIV-1 targets AID to hamper protective IgG and IgA responses. We found that infected GCs contained less AID, but normal APOBEC3G, an AID-related RNA-editing protein. AID down-regulation was not associated with local loss of CD4+ T cells and CD40L, but rather correlated with decreased activation of AID-inducing transcription factors, such as NF-κB and STAT6, and with increased expression of feedback inhibitors of NF-κB and STAT6, including IκBα, SOCS1 and SOCS3. AID down-regulation also correlated with accumulation of the viral protein Nef in the GC and with trafficking of Nef within membrane channels connecting infected myeloid cells to B cells. Together with our recent in vitro studies showing that Nef penetrates B cells and inhibits class, the present in vivo data suggest that HIV-1 evades protective IgG and IgA responses by targeting the class switch recombinase machinery.

Epithelial cells trigger frontline immunoglobulin class switching through an SLPI-regulated pathway (41.7)

Epithelial cells (ECs) recruit B cells expressing class-switched IgG and IgA into mucosal effector sites and transport IgG and IgA antibodies across mucous membranes. Whether ECs initiate IgG and IgA class switching remains unknown. We found that ECs lining tonsillar crypts formed pockets populated by B cells expressing activation-induced cytidine deaminase (AID), a DNA-editing enzyme associated with ongoing class switch DNA recombination (CSR). ECs released AID- and CSR-inducing factors, such as B cell-activating factor of the TNF family (BAFF), after sensing microbial products through Toll-like receptors (TLRs). EC-induced IgG and IgA CSR was further amplified by thymic stromal lymphopoietin (TSLP), an epithelial IL-7-like cytokine that enhanced BAFF production by dendritic cells. Conversely, EC-induced IgG and IgA CSR was restrained by secretory leukocyte protease inhibitor (SLPI), an epithelial homeostatic protein that inhibited BAFF signaling in B cells. Our findings indicate that ECs function as mucosal guardians that orchestrate frontline IgG and IgA class switching through a TLR-inducible SLPI-regulated signaling program.

This work was supported by NIH grants AI057653 (to A.C.) and by NIH T32 training grant AI07621 (to W. X.).

Establishment of a stroke unit in a district hospital: review of experience

BACKGROUND

The experience and outcomes of co-locating acute stroke and stroke rehabilitation care in a district hospital were reviewed.

METHOD

Information for patients admitted to Blacktown and Mt Druitt Hospitals before and after setting up an acute stroke unit (SU) (12 months data for each period), including mortality and length of stay (LOS) at the hospital were obtained from various sources, including the diagnosis-related group and subacute and non-acute casemix databases.

RESULTS

There was a significant reduction of mortality (18 vs 10%; P = 0.01) and reduced total LOS (46 vs 39 days; P = 0.01) with similar functional outcomes in the post-SU period. Fifty per cent of patients were unable to access the acute SU. Patients admitted into the SU had lower mortality (5 vs 14%; P = 0.01) and were also discharged from hospital earlier (35 vs 54 days; P = 0.01) than patients admitted into general wards during the post-SU period. Thirty-four per cent of patients received rehabilitation within the rehabilitation facility in the post-SU period compared with 19% in the pre-SU period.

CONCLUSION

The Blacktown experience showed the feasibility of establishing a co-located SU within rehabilitation facility with good outcomes as illustrated by the significant reduction in the stroke mortality, a reduction in the total LOS and an increase in the number of patients receiving rehabilitation post-stroke.

Epithelial cells trigger frontline immunoglobulin class switching through a pathway regulated by the inhibitor SLPI

Epithelial cells (ECs) transport class-switched immunoglobulin G (IgG) and IgA antibodies across mucous membranes. Whether ECs initiate class switching remains unknown. Here we found that ECs lining tonsillar crypts formed pockets populated by B cells expressing activation-induced cytidine deaminase (AID), an enzyme associated with ongoing class switching. ECs released B cell-activating AID-inducing factors after sensing microbial products through Toll-like receptors. The resulting class switching was amplified by thymic stromal lymphopoietin, an epithelial interleukin 7-like cytokine that enhanced the B cell 'licensing' function of dendritic cells, and was restrained by secretory leukocyte protease inhibitor, an epithelial homeostatic protein that inhibited AID induction in B cells. Thus, ECs may function as mucosal 'guardians' orchestrating frontline IgG and IgA class switching through a Toll-like receptor-inducible signaling program regulated by secretory leukocyte protease inhibitor.NOTE: In the version of this article initially published online, the middle label above Figure 6c is incorrect. The correct label should be 'BAFF'. The error has been corrected for all versions of the article.

MARS in the treatment of liver failure: controversies and evidence

Molecular Adsorbent Recirculation System (MARS) is a form of extracorporeal detoxification system used as an artificial liver support system. Numerous studies have been published on the topic, with the majority of them describing the capability of MARS in removing albumin-bound toxins and improving systemic hemodynamics. Whether such improvement could be translated into survival benefit is still uncertain, given the paucity of randomized controlled trials available. The outcome of patients receiving MARS treatment is difficult to analyze because liver failure patients constitute a heterogeneous population and different subgroups carry different prognoses. An evidence-based recommendation on the timing of MARS initiation is not available and currently MARS is usually commenced for hyperbilirubinemia or presence of complications of liver failure. MARS is in general a safe procedure, but there are still potential complications that need to be cautioned, along with various operative issues that are worth attention. The future prospects of MARS would rely on the completion of adequately powered randomized controlled trials.

Hodgkin lymphoma cells express TACI and BCMA receptors and generate survival and proliferation signals in response to BAFF and APRIL

Hodgkin lymphoma (HL) originates from the clonal expansion of malignant Hodgkin and Reed-Sternberg (HRS) cells. These B-cell-derived elements constitute less than 10% of the tumoral mass. The remaining tissue is comprised of an inflammatory infiltrate that includes myeloid cells. Myeloid cells activate B cells by producing BAFF and APRIL, which engage TACI, BCMA, and BAFF-R receptors on the B cells. Here, we studied the role of BAFF and APRIL in HL. Inflammatory and HRS cells from HL tumors expressed BAFF and APRIL. Unlike their putative germinal center B-cell precursors, HRS cells lacked BAFF-R, but expressed TACI and BCMA, a phenotype similar to that of plasmacytoid B cells. BAFF and APRIL enhanced HRS cell survival and proliferation by delivering nonredundant signals via TACI and BCMA receptors through both autocrine and paracrine pathways. These signals caused NF-kappaB activation; Bcl-2, Bcl-xL, and c-Myc up-regulation; and Bax down-regulation, and were amplified by APRIL-binding proteoglycans on HRS cells. Interruption of BAFF and APRIL signaling by TACI-Ig decoy receptor, which binds to and neutralizes BAFF and APRIL, or by small-interfering RNAs targeting BAFF, APRIL, TACI, and BCMA inhibited HRS cell accumulation in vitro and might attenuate HL expansion in vivo.

HIV-1 envelope triggers polyclonal Ig class switch recombination through a CD40-independent mechanism involving BAFF and C-type lectin receptors

Switching from IgM to IgG and IgA is essential for antiviral immunity and requires engagement of CD40 on B cells by CD40L on CD4(+) T cells. HIV-1 is thought to impair CD40-dependent production of protective IgG and IgA by inducing progressive loss of CD4(+) T cells. Paradoxically, this humoral immunodeficiency is associated with B cell hyperactivation and increased production of nonprotective IgG and IgA that are either nonspecific or specific for HIV-1 envelope glycoproteins, including gp120. Nonspecific and gp120-specific IgG and IgA are sensitive to antiretroviral therapy and remain sustained in infected individuals with very few CD4(+) T cells. One interpretation is that some HIV-1 Ags elicit IgG and IgA class switch DNA recombination (CSR) in a CD40-independent fashion. We show that a subset of B cells binds gp120 through mannose C-type lectin receptors (MCLRs). In the presence of gp120, MCLR-expressing B cells up-regulate the CSR-inducing enzyme, activation-induced cytidine deaminase, and undergo CSR from IgM to IgG and IgA. CSR is further enhanced by IL-4 or IL-10, whereas Ab secretion requires a B cell-activating factor of the TNF family. This CD40L-related molecule is produced by monocytes upon CD4, CCR5, and CXCR4 engagement by gp120 and cooperates with IL-4 and IL-10 to up-regulate MCLRs on B cells. Thus, gp120 may elicit polyclonal IgG and IgA responses by linking the innate and adaptive immune systems through the B cell-activating factor of the TNF family. Chronic activation of B cells through this CD40-independent pathway could impair protective T cell-dependent Ab responses by inducing immune exhaustion.

Stage specificity of novel growth factor expression during development of proliferative vitreoretinopathy

OBJECTIVE

To compare the relative levels of connective tissue growth factor (CTGF), platelet-derived growth factor alpha (PDGF-AA), and hepatocyte growth factor (HGF) in glial and retinal pigment epithelial (RPE) cells of epiretinal membranes from proliferative vitreoretinopathy (PVR).

METHODS

A total of 37 PVR membranes, of various stages, underwent fluorescent immunohistochemisty and confocal laser scanning microscopy to localize CTGF, HGF, and PDGF-AA in RPE and glial cells.

RESULTS

Numerous RPE, and relatively fewer glial cells, were found in all stages of PVR. CTGF immunoreactivity increased from early to late stage PVR and was principally expressed by RPE cells in early stage, and by glial cells in late stage PVR. HGF, expressed by both RPE and glial cells, was principally expressed in mid-stage PVR. PDGF-AA, expressed by both cell types, demonstrated a uniform level of staining throughout all stages of PVR.

CONCLUSIONS

RPE and glial cells contribute to the expression of CTGF, HGF, and PDGF-AA during PVR, but with specific developmental patterns. PDGF-AA is expressed uniformly throughout all stages of PVR, while HGF expression peaks during mid stage, and CTGF expression is highest during late stage PVR. These results allow for the development of stage-specific therapeutics for PVR that may allow targeting of the early proliferative and/or the late tractional stages of PVR.

Human immunodeficiency virus 1 Nef suppresses CD40-dependent immunoglobulin class switching in bystander B cells

Immunoglobulin class switching from immunoglobulin M (IgM) to IgG and IgA is central to immunity against viruses and requires the activation of B cells by T cells via CD154 (CD40 ligand) and cytokines. These molecules limit their signaling activity in immune cells by turning on negative feedback proteins, including IkappaB and SOCS. We show here that negative factor (Nef) protein, an immunosuppressive human immunodeficiency virus 1 protein expressed and released by infected cells, penetrates B cells both in vivo and in vitro. Nef suppressed immunoglobulin class-switch DNA recombination by inducing IkappaBalpha and SOCS proteins, which blocked CD154 and cytokine signaling via NF-kappaB and STAT transcription factors. Thus, human immunodeficiency virus 1 may evade protective T cell-dependent IgG and IgA responses by 'hijacking' physiological feedback inhibitors in B cells via Nef.

Brain volume measurements in patients with human T-cell lymphotropic virus-1–associated tropical spastic paraparesis

Human T-cell lymphotropic virus (HTLV)-1 is associated with a chronic progressive neurologic disease known as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) that affects 0.2% to 3% of HTLV-1-infected people. The authors aimed at exploring, in vivo, whether brain volume reduction occurs in patients with HAM/TSP through the use of magnetic resonance imaging (MRI). T1 pre/postcontrast spin echo-weighted images (WIs) and T2WIs of the brain were obtained in 19 HAM/TSP patients and 14 age-and sex-matched healthy volunteers. Both patients and healthy individuals were imaged at a 1.5-Tesla magnet by employing a conventional head coil. Focal T1 and T2 abnormalities were calculated and two measurements of brain parenchyma fraction (BPF) were obtained by using SIENAx (Structural Image Evaluation,using Normalisation, of Atrophy; University of Oxford, Oxford, UK) and MIPAV (Medical Image Processing, Analysis, and Visualization; National Institutes of Health, Bethesda, USA) from T1WIs. No significant differences in BPF were found between patients and healthy subjects when using either SIENAx or MIPAV. Analysis of individual patients detected that BPF was lower by 1 standard deviation (SD) relative to patients' average BPF in one patient. The authors conclude that reductions in BPF do not occur frequently in patients with HAM/TSP. However, the authors believe that one individual case of significant brain atrophy raises the question as to whether atrophy selectively targets the spinal cord of HAM/TSP patients or may involve the brain as well. A larger patient population analyzing regional brain volume changes could be helpful in determining whether brain atrophy is a marker of disease in patients with HAM/TSP.

Topical vitamins, minerals and botanical ingredients as modulators of environmental and chronological skin damage

Ageing skin is characterized by fine lines, wrinkles, lentigines, dyspigmentation and increased coarseness. Topical preparations alleged to combat these changes abound in the over-the-counter market. Some of the most popular ingredients used in these products are vitamins, minerals and botanical extracts. Proposed mechanisms for antiageing effects on skin range from antioxidant properties to improved collagen synthesis or protection from collagen breakdown. Despite the media attention and consumer popularity that these ingredients have generated, there have been few scientific studies to support these claims. In this report, we review recent published studies on the most common of these ingredients for the topical photoprotection and the treatment of ageing skin.

Pathological examination of sentinel lymph node in breast cancer: potential problems and possible solutions

Sentinel lymph node (SLN) biopsy has emerged during the last few years as a viable option for staging the axilla in the treatment of breast carcinoma. This procedure can potentially identify patients who would be helped by full axillary lymph node dissection (the SLN-positive cases), and those who would not (the SLN-negative cases). Review of the literature confirms the promise of SLN; however, the possible problems in the pathological handling of SLN, including the microscopic misinterpretation of benign structures and "spurious" immunohistochemical staining, need wider recognition.

DNA polymerase mu gene expression in B-cell non-Hodgkin's lymphomas: an analysis utilizing in situ hybridization

DNA polymerase mu (pol mu) is a novel error-prone DNA repair enzyme bearing significant structural homology with terminal deoxynucleotidyltransferase. Whereas other human error-prone DNA polymerases identified thus far show no preferential lymphoid tissue distribution, the highest levels of pol mu mRNA have been detected in peripheral lymphoid tissues, particularly germinal center B cells. Conceivably, up-regulation of the pol mu gene may be biologically significant in lymphomagenesis, especially in the development of B-cell non-Hodgkin's lymphomas (B-NHLs), because of enhanced error-prone DNA repair activities. To explore this possibility, we generated a digoxigenin-labeled riboprobe to pol mu mRNA and used the probe and in situ hybridization to examine the expression pattern of the pol mu gene in formalin-fixed, paraffin-embedded tissue sections of 37 B-NHLs. This included eight chronic lymphocytic leukemia/small lymphocytic lymphomas, six mantle cell lymphomas, seven follicular lymphomas, nine diffuse large B-cell lymphomas, three splenic marginal zone lymphomas, two Burkitt's lymphomas, and two precursor B-lymphoblastic lymphomas. We also correlated the pol mu mRNA expression levels with the tumor proliferation index, which was assessed in each case by image analysis of Ki-67 immunostained slides. Nineteen of 21 (90%) B-NHLs arising from postgerminal center B cells (follicular lymphomas, diffuse large B-cell lymphomas, splenic marginal zone lymphomas, and Burkitt's lymphomas) exhibited high expression of pol mu mRNA. In contrast, only 2 of 16 (13%) B-NHLs arising from pregerminal center B cells (chronic lymphocytic leukemia/small lymphocytic lymphomas, mantle cell lymphomas, and precursor B-lymphoblastic lymphomas) expressed significant levels of pol mu mRNA. Pol mu gene expression did not seem to correlate with the proliferation index, especially because a significant level of pol mu mRNA was not detected in either case of precursor B-lymphoblastic lymphomas. In conclusion, pol mu gene expression is highly associated with B-NHLs of postgerminal center B-cell derivation. Furthermore, the expression level is independent of the proliferation rate and thus is unrelated to the biological aggressiveness of the tumors. These findings, along with the error-prone nature of the enzyme, suggest that up-regulation of pol mu gene expression may be a contributing factor to the pathogenesis of a subset of B-NHLs through DNA repair-associated genomic instability.

Intraepidermal cytokeratin 7 immunoreactive cells in the non-neoplastic nipple may represent interepithelial extension of lactiferous duct cells

AIMS

The interpretation of cytokeratin 7 (CK7)-positive cells in the epidermis of the nipple has been controversial. These cells have been described in Paget's disease of the nipple, and they have also been cited as benign 'Toker' cells or as Merkel cells. Having observed CK7+ cells in histologically unremarkable nipple biopsies, we sought to assess the distribution of CK7+ cells in Paget's disease of the nipple and in histologically unremarkable nipple.

METHODS AND RESULTS

Representative sections from 37 cases of Paget's disease of the nipple and 32 cases of histologically unremarkable nipple were obtained. The histologically unremarkable nipple sections were taken from prophylactic mastectomies (n=17) and from autopsies of patients who did not have breast cancer (n=15). CK7 immunostaining was performed on sections from formalin-fixed paraffin blocks. Sequential sections were immunostained with antibodies to low-molecular weight cytokeratin-CAM 5.2 and HER-2/neu. CK7+ cells were present in the epidermis around the opening of the lactiferous ducts in Paget's disease (95%) and in histologically unremarkable nipple (45%) cases. CK7+ cells diminished in number with increasing distance from the orifice of the lactiferous ducts. The lactiferous duct epithelium in Paget's disease and in histologically unremarkable nipple was CK7+ in all specimens when this element was present. CAM5.2 immunostaining had a similar but weaker pattern of reactivity. HER-2/neu reactivity was seen in 68% cases of Paget's disease and was negative in all cases of histologically unremarkable nipple. Tumour cells in two cases of Paget's disease were CK7-. In one of these, the underlying breast carcinoma was also CK7-, the only CK7- tumour in this series. In the other case, the normal lactiferous duct was CK7+ and no underlying carcinomatous tissue was available to study.

CONCLUSIONS

The presence of CK7+ cells does not equate to Paget's disease of the nipple. Intraepidermal CK7+ cells in the non-neoplastic nipple can be a manifestation of interepithelial extension of benign lactiferous duct cells. The increased presence of CK7+ cells in Paget's disease probably results either from neoplastic transformation of native intraepithelial lactiferous duct cells or form direct extension/migration of neoplastic cells into the nipple. The distribution of CK7 immunoreactive cells in the nipple epidermis can be helpful in the diagnosis of Paget's disease of the nipple.