Cyclophosphamide treatment for hypertension and renal injury in an experimental model of systemic lupus erythematosus

Cardiovascular disease is the major cause of mortality among patients with the autoimmune disorder systemic lupus erythematosus (SLE). Our laboratory previously reported that immunosuppression with mycophenolate mofetil, a common therapy in patients with SLE, attenuates the development of hypertension in an experimental model of SLE. Cyclophosphamide (CYC) is another common therapy for patients with SLE that has contributed to improved disease management; however, its impact on the development of hypertension associated with SLE is not clear. We tested whether treatment with CYC (25 mg/kg, once/week, IP injection) for 4 weeks would attenuate hypertension in an established female mouse model of SLE with hypertension (30-week-old NZBWF1 females). Plasma anti-dsDNA IgG levels, pathogenic for the disease, were lower in CYC-treated SLE mice compared to vehicle-treated SLE mice, suggesting efficacy of the therapy to suppress aberrant immune system function. Mean arterial pressure (MAP) was assessed by carotid artery catheters in conscious mice. Treatment did not attenuate the development of hypertension when compared to vehicle-treated SLE mice; however, urinary albumin excretion was lower in CYC-treated animals. Corresponding with the reduction in autoantibodies, data suggest that CYC treatment lowered circulating CD45R+ B cells. Paradoxically, circulating CD11b+ Ly6G+ neutrophils were increased in CYC-treated SLE mice compared to vehicle treated. Estrus cycling data also suggest that CYC treatment had an impact on ovarian function that may be consistent with reduced circulating estrogen levels. Taken together, these data suggest that CYC treatment attenuates autoantibody production and renal disease during SLE, but that the potential to affect MAP may be blunted by the increase in circulating neutrophils and CYC's impact on ovarian function.

Clinical significance of myositis-specific autoantibody profiles in Japanese patients with polymyositis/dermatomyositis

Myositis-specific autoantibodies, such as anti-melanoma differentiation associated gene 5 (MDA5) and anti-anti-amino acyl-tRNA synthetases (ARS) antibodies, are associated with interstitial lung diseases (ILD), which determine the prognosis of polymyositis/dermatomyositis (PM/DM) patients. However, there is a paucity of data on the clinical correlation between anti-Sjögren syndrome-related antigen A (anti-SSA)/Ro52 antibodies in PM/DM. We investigated the prevalence of myositis-specific autoantibodies including anti-SSA/Ro52 antibody and assessed the clinical significance of these antibodies in patients with PM/DM.We retrospectively reviewed demographic data and clinical outcomes in patients with PM/DM. The study population comprised 24 patients with PM and 60 patients with DM. The presence of anti-myositis-specific antibodies (MDA5, ARS, Jo-1, SSA/Ro52) was determined by immunosorbent assay (ELISA).Anti-MDA5 antibody was detected in 18 patients with DM (n = 60). Anti-ARS/anti-SSA/Ro52 antibodies were detected in 31 and 39 patients with PM/DM (n = 84). Rapidly progressive ILD patients were mainly found in the anti-MDA5 antibody-positive DM group. During the follow-up period, 9 patients died. Kaplan-Meier analysis demonstrated that survival rates seem to be lower in DM patients with anti-MDA5 antibodies compared with those without anti-MDA5 antibodies. Furthermore, dual positivity for anti-SSA/Ro52 and anti-MDA5 antibodies was significantly higher in nonsurviving DM patients compared with survivors.Although the presence of anti-ARS or anti-MDA5 antibodies is a prognostic marker in patients with PM/DM, combined presence of anti-SSA/Ro52 and anti-MDA5 antibodies represent another marker for clinical outcome in DM patients. Our results suggest that anti-SSA/Ro52 antibody positivity in DM patients with anti-MDA5 antibody reveals a subgroup of DM patients with poor prognosis.

Ly6C(high) monocytes become alternatively activated macrophages in schistosome granulomas with help from CD4+ cells

Alternatively activated macrophages (AAM) that accumulate during chronic T helper 2 inflammatory conditions may arise through proliferation of resident macrophages or recruitment of monocyte-derived cells. Liver granulomas that form around eggs of the helminth parasite Schistosoma mansoni require AAM to limit tissue damage. Here, we characterized monocyte and macrophage dynamics in the livers of infected CX3CR1^GFP/+ mice. CX₃CR1-GFP⁺ monocytes and macrophages accumulated around eggs and in granulomas during infection and upregulated PD-L2 expression, indicating differentiation into AAM. Intravital imaging of CX₃CR1-GFP⁺ Ly6C^low monocytes revealed alterations in patrolling behavior including arrest around eggs that were not encased in granulomas. Differential labeling of CX₃CR1-GFP⁺ cells in the blood and the tissue showed CD4⁺ T cell dependent accumulation of PD-L2⁺ CX₃CR1-GFP⁺ AAM in the tissues as granulomas form. By adoptive transfer of Ly6C^high and Ly6C^low monocytes into infected mice, we found that AAM originate primarily from transferred Ly6C^high monocytes, but that these cells may transition through a Ly6C^low state and adopt patrolling behavior in the vasculature. Thus, during chronic helminth infection AAM can arise from recruited Ly6C^high monocytes via help from CD4⁺ T cells.

Macrophages will adopt different characteristics based on different types of inflammatory responses. During infection by parasitic helminths such as Schistosoma mansoni, macrophages adopt an “alternatively activated” or M2 phenotype (AAM). These AAM are important for protecting liver hepatocytes from damage caused by the parasite eggs. Here, we examine the cellular source of AAM in the liver of mice infected with S. mansoni. We find that AAM during S. mansoni infection come from monocytes and not from tissue resident macrophages. Monocytes can be separated into Ly6C^high and Ly6C^low monocyte subsets. We demonstrate that it is the Ly6C^high monocytes that are the precursors of AAM in the liver granulomas, but they might adopt the behavior of Ly6C^low monocytes in response to schistosome eggs. Additionally, these Ly6C^High monocytes require help from CD4⁺ T cells in order to differentiate into AAM or to maintain this phenotype.

Development of Murine Plasmacytoid Dendritic Cells Defined by Increased Expression of an Inhibitory NK Receptor, Ly49Q

Plasmacytoid dendritic cells (PDCs) are defined in mice by a unique combination of markers: CD11c, B220, and Ly6C/G. We have reported previously that PDCs express Ly49Q, a lectin-type killer cell inhibitory receptor. We now find that different expression levels of Ly49Q define sequential developmental stages of PDCs in bone marrow. Although PDCs in spleen and lymph nodes express high levels of Ly49Q, a significant portion of CD11c(+)B220(+) PDCs in bone marrow lack Ly49Q, as well as the CD4 and MHC II. Purified Ly49Q(-) marrow PDCs spontaneously up-regulate Ly49Q after overnight culture without cell proliferation and acquire most features of typical PDCs in spleen. When exposed to TLR ligands, such as CpG-oligodeoxynucleotide and hemagglutinating virus of Japan (Sendai virus), Ly49Q(-) PDCs increase CD86 and MHC class II expression but produce less IFN-alphabeta, IL-6, and IL-12p70 than Ly49Q(+) PDCs, although they are able to produce comparable amounts of TNF-alpha. However, interestingly, Ly49Q(-) PDCs do not produce TNF-alpha in response to the TLR2 ligand, Pam3SCK(4), whereas Ly49Q(+) PDCs did. Therefore, Ly49Q is a new marker to identify a precursor form of PDCs that participates in innate immunity.

A murine model of antimetabolite-based, submyeloablative conditioning for bone marrow transplantation: biologic insights and potential applications

OBJECTIVE

Nonmyeloablative conditioning regimens for marrow transplantation are desirable in many settings. Because repeated doses of the antimetabolite 5-fluorouracil (5-FU) decreases marrow long-term repopulating ability (LTRA) upon transplantation into lethally irradiated hosts, we hypothesized that mice given sequential doses of 5-FU (termed paired dose 5-FU) may permit substantial syngeneic marrow engraftment.

METHODS

C57Bl/6 or X-linked chronic granulomatous disease (X-CGD) mice were administered 5-FU (150 mg/kg) on days -5 and -1. Assessment of host marrow phenotype and repopulating ability occurred on day 0. Transplantation of syngeneic donor marrow occurred on day 0 or day +15.

RESULTS

We confirmed that the number of Sca-1+lin- cells and the LTRA of marrow from paired dose 5-FU-treated animals were diminished. C57Bl/6 hosts conditioned with paired doses of 5-FU followed by transplantation of 20 x 10(6) fresh B6.SJL marrow cells on day 0 displayed 44.9% +/- 7.1% donor chimerism 2 months posttransplant, and 34.4% +/- 8.6% donor chimerism 6 months posttransplant. In contrast, paired dose 5-FU-conditioned hosts transplanted with similar numbers of donor cells on day +15 exhibited only 3.4% +/- 1.2% donor chimerism at 2 months. Paired dose 5-FU-conditioned X-CGD hosts transplanted with MSCV-m91Neo-transduced X-CGD marrow averaged 6.6% +/- 2.3% (range, 4%-10%) NADPH oxidase-reconstituted neutrophils 12-16 months after transplant.

CONCLUSION

These findings support the concept that impairment of host stem cell competitiveness may be an important mechanism for permitting engraftment of donor cells, and suggest that only a brief period of modest host stem cell impairment may be necessary to achieve substantial donor cell engraftment.

Interleukin-3 supports expansion of long-term multilineage repopulating activity after multiple stem cell divisions in vitro

Although long-term repopulating hematopoietic stem cells (HSC) can self-renew and expand extensively in vivo, most efforts at expanding HSC in vitro have proved unsuccessful and have frequently resulted in compromised rather than improved HSC grafts. This has triggered the search for the optimal combination of cytokines for HSC expansion. Through such studies, c-kit ligand (KL), flt3 ligand (FL), thrombopoietin, and IL-11 have emerged as likely positive regulators of HSC self-renewal. In contrast, numerous studies have implicated a unique and potent negative regulatory role of IL-3, suggesting perhaps distinct regulation of HSC fate by different cytokines. However, the interpretations of these findings are complicated by the fact that different cytokines might target distinct subpopulations within the HSC compartment and by the lack of evidence for HSC undergoing self-renewal. Here, in the presence of KL+FL+megakaryocyte growth and development factor (MGDF), which recruits virtually all Lin(-)Sca-1(+)kit(+) bone marrow cells into proliferation and promotes their self-renewal under serum-free conditions, IL-3 and IL-11 revealed an indistinguishable ability to further enhance proliferation. Surprisingly, and similar to IL-11, IL-3 supported KL+FL+MGDF-induced expansion of multilineage, long-term reconstituting activity in primary and secondary recipients. Furthermore, high-resolution cell division tracking demonstrated that all HSC underwent a minimum of 5 cell divisions, suggesting that long-term repopulating HSC are not compromised by IL-3 stimulation after multiple cell divisions. In striking contrast, the ex vivo expansion of murine HSC in fetal calf serum-containing medium resulted in extensive loss of reconstituting activity, an effect further facilitated by the presence of IL-3. (Blood. 2000;96:1748-1755)

Structural and phylogenetic characterization of human SLURP-1, the first secreted mammalian member of the Ly-6/uPAR protein superfamily

Members of the Ly-6/uPAR protein family share one or several repeat units of the Ly-6/uPAR domain that is defined by a distinct disulfide bonding pattern between 8 or 10 cysteine residues. The Ly-6/uPAR protein family can be divided into two subfamilies. One comprises GPI-anchored glycoprotein receptors with 10 cysteine residues. The other subfamily includes the secreted single-domain snake and frog cytotoxins, and differs significantly in that its members generally possess only eight cysteines and no GPI-anchoring signal sequence. We report the purification and structural characterization of human SLURP-1 (secreted mammalian Ly-6/uPAR related protein 1) from blood and urine peptide libraries. SLURP-1 is encoded by the ARS (component B)-81/s locus, and appears to be the first mammalian member of the Ly-6/uPAR family lacking a GPI-anchoring signal sequence. A phylogenetic analysis based on the SLURP-1 primary protein structure revealed a closer relationship to the subfamily of cytotoxins. Since the SLURP-1 gene maps to the same chromosomal region as several members of the Ly-6/uPAR subfamily of glycoprotein receptors, it is suggested that both biologically distinct subfamilies might have co-evolved from local chromosomal duplication events.

Gene gun-mediated IL-12 gene therapy induces antitumor effects in the absence of toxicity: a direct comparison with systemic IL-12 protein therapy

Using three murine tumor models, we compared the antitumor efficacy and certain physiological effects of an in vivo interleukin-12 (IL-12) gene therapy protocol and a systemic IL-12 protein therapy protocol. An IL-12 cDNA gene construct was administered in situ into skin tissue via gene gun delivery, and recombinant IL-12 protein was administered subcutaneously at a dose of 1 microgram/mouse/treatment. Both treatment regimes induced a comparable level of regression of established intradermal MethA sarcomas. In B16 melanoma and P815 mastocytoma models, antitumor efficacy of IL-12 protein therapy appeared to be slightly higher than that of IL-12 gene therapy; however, the protein therapy protocol in this comparative study resulted in a high level of mortality of mice. It was also demonstrated that IL-12 gene therapy, in contrast to the IL-12 protein therapy, was not associated with weight loss, splenomegaly, increased Ly6 antigen expression in the spleen, or visible signs of toxicity, such as fur ruffling and lethargy. Moreover, serum levels of interferon-gamma (IFN-gamma) induced in response to IL-12 gene therapy were 300-1000 times lower than those induced by the systemic IL-12 protein administration. Together, these results suggest that gene gunmediated in vivo delivery of IL-12 cDNA may be considered as a safer alternative to IL-12 protein therapy for certain human cancers.

Structural characterization of an Lyt-2/3 homolog expressed on Bufo regularis lymphocytes

Two alloantisera and a monoclonal antibody (mAb 53-6.7) of proven specificities to the murine Lyt-2/3 macromolecule labeled, in indirect immunofluorescent assays, a distinct lymphocyte population in the toad, Bufo regularis. Lyt-2/3 antigenic activities expressed by B. regularis lymphocytes have been solubilized and purified by mAb 53-6.7 affinity chromatography and found to be associated with a single 67 kDa macromolecule in SDS-PAGE. Upon reduction, this macromolecule resolved into 38 kDa, 34 kDa and 28 kDa subunits corresponding to the alpha, alpha' and beta subunits of the murine Lyt-2/3 complex. Comparisons based on the S delta Q index of differences in amino acid compositions of HPLC-purified alpha- and alpha'-subunits of the amphibian Lyt-2/3 molecule indicated a significant structural relatedness to their murine counterpart as well as to the human CD8 polypeptide. Our observations point to an early phylogenetic emergence of Lyt-2/3 as an important component of the T cell cytolytic apparatus during vertebrate evolution.