Attenuated liver fibrosis in the absence of B cells
Tatiana I. Novobrantseva, Gerard R. Majeau, Aldo Amatucci, Sophia Kogan, Ian Brenner, Stefano Casola, Mark J. Shlomchik, Victor Koteliansky, Paula S. Hochman, Alexander Ibraghimov
Tatiana I. Novobrantseva, Gerard R. Majeau, Aldo Amatucci, Sophia Kogan, Ian Brenner, Stefano Casola, Mark J. Shlomchik, Victor Koteliansky, Paula S. Hochman, Alexander Ibraghimov
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Research Article Immunology

Attenuated liver fibrosis in the absence of B cells

Abstract

Analysis of mononuclear cells in the adult mouse liver revealed that B cells represent as much as half of the intrahepatic lymphocyte population. Intrahepatic B cells (IHB cells) are phenotypically similar to splenic B2 cells but express lower levels of CD23 and CD21 and higher levels of CD5. IHB cells proliferate as well as splenic B cells in response to anti-IgM and LPS stimulation in vitro. VDJ gene rearrangements in IHB cells contain insertions of N,P region nucleotides characteristic of B cells maturing in the adult bone marrow rather than in the fetal liver. To evaluate whether B cells can have an impact on liver pathology, we compared CCl4-induced fibrosis development in B cell–deficient and wild-type mice. CCl4 caused similar acute liver injury in mutant and wild-type mice. However, following 6 weeks of CCl4 treatment, histochemical analyses showed markedly reduced collagen deposition in B cell–deficient as compared with wild-type mice. By analyzing mice that have normal numbers of B cells but lack either T cells or immunoglobulin in the serum, we established that B cells have an impact on fibrosis in an antibody- and T cell–independent manner.

Authors

Tatiana I. Novobrantseva, Gerard R. Majeau, Aldo Amatucci, Sophia Kogan, Ian Brenner, Stefano Casola, Mark J. Shlomchik, Victor Koteliansky, Paula S. Hochman, Alexander Ibraghimov

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Collagen production by T6-HSC can be stimulated by B cell–derived solubl...
Collagen production by T6-HSC can be stimulated by B cell–derived soluble factors. T6-HSC cells were seeded at 25% confluence in a 96-well plate in RPMI, 5% FBS, penicillin, streptomycin. After 24 hours, an equal volume of B cell–conditioned medium was added with [3H]-thymidine (to measure proliferation) or with [3H]-proline (to measure de novo collagen synthesis). After 18 hours, the amount of incorporated 3H was quantified. Collagen synthesis per cell is expressed in arbitrary units; we took the ratio of radioactive counts of [3H]-proline/radioactive counts of [3H]-thymidine, considering this ratio equal to 1 in the absence of TGF-β. Each treatment was performed in triplicate. A representative experiment out of 3 is shown. (A) Human TGF-β that is recognized by rat TGF-β receptor was added at different concentration to the culture of T6-HSC cells. [3H]-thymidine incorporation is shown in red. Collagen synthesis as assessed by the rate of [3H]-proline incorporation is shown in blue. T6-HSC proliferation (B) and collagen synthesis relative to cell number as assessed by the ratio of [3H]-proline/[3H]-thymidine incorporation (C) is measured in medium alone (M), with LPS, and with supernatant of B cells cultured with LPS (S). B cells were cultured for 3.5 days prior to harvesting supernatant. Red and blue bars show a mean from triplicate values; error bars show standard deviation.