Passive transfer of rabbit anti-mLAMC1-cterm IgG into neonatal mice does not reproduce the human disease.

<p>Rabbit IgG against the murine laminin γ1 C-terminus (mLAMC1-cterm) was not pathogenic when passively transferred into neonatal C57BL/6 mice. Injection of rabbit anti-mLAMC1-cterm IgG at a concentration of 10 mg/g body weight every second day for 10 days did not <u>induce</u> histopathological lesions on day 12 (<u>a</u>). Linear deposition of rabbit IgG at the DEJ was only observed in 2 of 8 mice (b), while staining of murine C3 was always negative (c). At day 12, in sera of all mice, rabbit IgG stained the basal keratinocytes at the DEJ of normal mouse skin (d), reacted with recombinant mLAMC1-cterm by ELISA (e) and immunoblotting (f, lanes 2–6) and with the 200 kDa p200 protein in extract of murine dermis (g, lanes 2–6). Polyclonal rabbit antibody H-190 against mLAMC1 (f, g, lane 1) and normal mouse serum (f, g, lane 7) was used as controls.</p

Passive transfer of rabbit anti-mLAMC1-cterm IgG into adult mice is not pathogenic.

<p>Rabbit IgG against the murine laminin γ1 C-terminus (mLAMC1-cterm) was not pathogenic when passively transferred into adult C57BL/6 and BALB/c mice. Injection of 15 mg rabbit anti-mLAMC1-cterm IgG every second day for 10 days did not result in clinical or histopathological (a, e) lesions on day 12. Linear deposition of rabbit IgG at the dermal-epidermal junction (DEJ) was only observed in 2 of 5 C57BL/6 (b) and one of 5 BALB/c mice (f), while staining of murine C3 was negative in all mice (c, g). At day 12, in sera of all 10 mice, rabbit IgG labeled the basal keratinocytes at the DEJ of normal mouse skin (d, h) and reacted with recombinant mLAMC1-cterm by ELISA (i) and immunoblotting (j, C57BL/6, lanes 1; BALB/c, lane 2) and the 200 kDa p200 protein in extract of murine dermis (k, C57BL/6 lane 1; BALB/c, lane 2). Normal mouse sera (j and k, C57BL/6, lane 3; BALB/c, lane 4) were used as controls.</p

A high concentration of rabbit anti-mLAMC1-cterm IgG is not pathogenic ex vivo.

<p>Rabbit IgG generated against the murine laminin γ1 C-terminus (mLAMC1-cterm) did not induce DES in cryosections of mouse skin. Rabbit anti-mLAMC1-cterm (a, lane 2; c, g; dilution 1∶1000) and commercial rabbit antibody H-190 against mLAMC1 (a, lane 1; b, f, dilution 1∶200) recognized the p200 protein by immunoblotting with extract of murine dermis (a) and labeled the DEJ of murine skin (b, c) but did not induce DES in cryosections of mouse skin (f, g). Of note, anti-mLAMC1-cterm rabbit IgG stained the basal layer of keratinocytes at the murine DEJ (b, c, inserts) in a similar pattern as seen with monoclonal anti-hLAMC1-antibody and hLAMC1-cterm-specific patient IgG (Fig. 3, c-f). Rabbit IgG against murine BP180 NC15A (e) and preimmune rabbit IgG (d, h) were used as positive and negative controls, respectively. Magnification: x400.</p

Human IgG specific to laminin γ1 is not pathogenic ex vivo.

<p>Using recombinant forms of the C-terminus of laminin γ1 (hLAMC1-cterm) and full length laminin γ1 (LAMC1-FL) IgG specific for hLAMC1-cterm (a, c; lane 3) and LAMC1-FL (b, lane 3; c lane 5 ) was generated from anti-p200 pemphigoid serum (a, b, c; lane 2), as well as serum depleted from anti-hLAMC1-cterm (a, c, lane 4) and LAMC1-FL reactivity (b, lane 4; c lane 6) reactivity, respectively, as shown by immunoblotting with recombinant hLAMC1-cterm (a), LAMC1-FL (b), and extract of human dermis<u>-</u>(c). Interestingly, serum depleted from anti-hLAMC1-cterm and LAMC1-FL reactivity, respectively, (a, b; lane 4) still labeled the p200 protein in dermal extract (c, lane 4, lane 6). Monoclonal antibody against LAMC1 (a, b, c; lane 1) and serum from a healthy volunteer (a, b; lane 5; c lane 7) were used as controls. Arrows indicate the positions of the proteins and bars the molecular weight markers (a, 34 kD and 26 kD; b, 200 kD; c, 200 kD). hLAMC1-cterm-specific (h, i) and LAMC1-FL-specific patients IgG (l, m) and the monoclonal anti-LAMC1 antibody (d, e) labeled the dermal-epidermal junction (DEJ) by indirect immunofluorescence (IF) microscopy but did not induce dermal-epidermal separation (DES). In contrast, serum depleted from reactivity against hLAMC1-cterm (j, k), and LAMC1-FL (n, o), respectively, as well as patient serum (f, g) resulted in DES (black triangles mark base of the split). While untouched patient serum (f) as well as serum depleted from anti-hLAMC1-cterm (j) and LAMC1-FL reactivity (n), respectively, stained the DEJ of human skin in a linear pattern, the monoclonal anti-hLAMC1-antibody (d), hLAMC1-cterm-specific patient<u>-</u>IgG (h), and hLAMC1-FL-specific patient IgG showed an additional staining of basal keratinocytes. Serum from a healthy volunteer was used as control (p, q). Magnification: x200.</p

Primer sequences for PCR amplification of cDNA fragments of human.

<p>F, forward primer; R, reverse primer.</p

Serum autoantibody reactivity in anti-p200 pemphigoid patients with overlapping fragments of laminin γ1 covering the whole molecule.

<p>Serum autoantibody reactivity in anti-p200 pemphigoid patients with overlapping fragments of laminin γ1 covering the whole molecule.</p

Schematic diagram of the 6 recombinant fragments of human laminin γ1 (hLAMC1) used in this study.

<p>The recombinant C-terminus (hLAMC1-cterm) was previously used as antigenic target in an ELISA for the diagnosis of anti-p200 pemphigoid <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041769#pone.0041769-Groth1" target="_blank">[8]</a>. Each recombinant fragment is fused with an N-terminal His-tag. Amino acid numbers are shown next to the fragments.</p

Anti-p200 pemphigoid patients’ sera induce dermal-epidermal separation ex vivo.

<p>Sera from anti-p200 pemphigoid patients recruit neutrophils to the dermal-epidermal junction (DEJ) and induce dermal-epidermal separation (DES) in cryosections of human skin. Anti-p200 pemphigoid sera (anti-p200 pemphigoid; b, e), but not from sera of healthy volunteers (HV; c, f), recruited leukocytes to the DEJ after 1 h of incubation (b, c) and induced DES after 3 h (e, f). As positive control for DES, IgG from a patient with bullous pemphigoid was used (BP a, d). Recruited neutrophils are marked by arrows, base of the split is marked by black triangles. All sections were stained with hematoxylin and eosin. Magnification, x200.</p

Immunization of mice with mLAMC1-cterm induces high serum levels of anti-mLAMC1-cterm antibodies but no skin lesions.

<p>Immunization of different mouse strains with the recombinant murine laminin γ1 C-terminus (mLAMC1-cterm) did induce high levels of anti-mLAMC1-cterm antibodies but no macro- or microscopic disease. Three different mouse strains (B57BL/6, BALB/c, and SJL; n = 5/strain) were immunized 4 times with 60 µg of recombinant mLAMC1-cterm in conjunction with TiterMax®. After 16 weeks, no clinical or histopathological changes (a, e, i) were seen. Deposition of mouse IgG at the dermal-epidermal junction (DEJ) was found in only 2 C56BL/6 mice (b). In all other mice, no IgG or C3 deposition was detected at the DEJ (f, j, c, g, k). In all mice, serum autoantibodies labeled the basal layer of keratinocytes at the murine DEJ (d, h, l) and reacted with recombinant mLAMC1-cterm by ELISA (m) and immunoblotting (n; C57BL/6, lane 1; BALB/c, lane 2; SJL, lane 3) and the 200 kDa p200 protein in extract of murine dermis (o; C57BL/6, lane 1; BALB/c, lane 2; SJL, lane 3). Serum of a mouse immunized with TiterMax® alone served as control (n and o; lane 4).</p

Persistent Autoantibody-Production by Intermediates between Short-and Long-Lived Plasma Cells in Inflamed Lymph Nodes of Experimental Epidermolysis Bullosa Acquisita

<div><p>Autoantibodies are believed to be maintained by either the continuous generation of short-lived plasma cells in secondary lymphoid tissues or by long-lived plasma cells localized in bone marrow and spleen. Here, we show in a mouse model for the autoimmune blistering skin disease epidermolysis bullosa acquisita (EBA) that chronic autoantibody production can also be maintained in inflamed lymph nodes, by plasma cells exhibiting intermediate lifetimes. After EBA induction by immunization with a mCOL7c-GST-fusion protein, antigen-specific plasma cells and CD4 T cells were analyzed. Plasma cells were maintained for months in stable numbers in the draining lymph nodes, but not in spleen and bone marrow. In contrast, localization of mCOL7c-GST -specific CD4 T cells was not restricted to lymph nodes, indicating that availability of T cell help does not limit plasma cell localization to this site. BrdU-incorporation studies indicated that pathogenic mCOL7c- and non-pathogenic GST-specific plasma cells resemble intermediates between short-and long-lived plasma cells with half-lives of about 7 weeks. Immunization with mCOL7c-GST also yielded considerable numbers of plasma cells neither specific for mCOL7c- nor GST. These bystander-activated plasma cells exhibited much shorter half-lives and higher population turnover, suggesting that plasma cell lifetimes were only partly determined by the lymph node environment but also by the mode of activation. These results indicate that inflamed lymph nodes can harbor pathogenic plasma cells exhibiting distinct properties and hence may resemble a so far neglected site for chronic autoantibody production.</p></div