Effects of fludarabine treatment on murine lupus nephritis

BXSB mice, a murine model of systemic lupus erythematosus (SLE), were treated with two different doses of fludarabine for a four-week period and examined two weeks after the final dose. Control mice were treated with saline or cyclophosphamide. Mice treated with fludarabine had a significant reduction in renal pathology compared to control mice. Fludarabine-treated mice also had an almost 10-fold increase in percentile of CD8+CD25+ T cells in the spleen and a smaller but significant increase in CD4+CD25+ cells. Mice treated with cyclophosphamide had a greater leucopenia compared to the other groups and a significant reduction in percentile of B220+ cells in peripheral blood and spleen. Serum autoantibody levels to dsDNA did not differ significantly among the groups, but were higher in 4/10 mice treated with fludarabine. Although few trials of fludarabine for human SLE have been conducted, additional studies may be warranted.

Activated STING in a vascular and pulmonary syndrome

BACKGROUND

The study of autoinflammatory diseases has uncovered mechanisms underlying cytokine dysregulation and inflammation.

METHODS

We analyzed the DNA of an index patient with early-onset systemic inflammation, cutaneous vasculopathy, and pulmonary inflammation. We sequenced a candidate gene, TMEM173, encoding the stimulator of interferon genes (STING), in this patient and in five unrelated children with similar clinical phenotypes. Four children were evaluated clinically and immunologically. With the STING ligand cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), we stimulated peripheral-blood mononuclear cells and fibroblasts from patients and controls, as well as commercially obtained endothelial cells, and then assayed transcription of IFNB1, the gene encoding interferon-β, in the stimulated cells. We analyzed IFNB1 reporter levels in HEK293T cells cotransfected with mutant or nonmutant STING constructs. Mutant STING leads to increased phosphorylation of signal transducer and activator of transcription 1 (STAT1), so we tested the effect of Janus kinase (JAK) inhibitors on STAT1 phosphorylation in lymphocytes from the affected children and controls.

RESULTS

We identified three mutations in exon 5 of TMEM173 in the six patients. Elevated transcription of IFNB1 and other gene targets of STING in peripheral-blood mononuclear cells from the patients indicated constitutive activation of the pathway that cannot be further up-regulated with stimulation. On stimulation with cGAMP, fibroblasts from the patients showed increased transcription of IFNB1 but not of the genes encoding interleukin-1 (IL1), interleukin-6 (IL6), or tumor necrosis factor (TNF). HEK293T cells transfected with mutant constructs show elevated IFNB1 reporter levels. STING is expressed in endothelial cells, and exposure of these cells to cGAMP resulted in endothelial activation and apoptosis. Constitutive up-regulation of phosphorylated STAT1 in patients' lymphocytes was reduced by JAK inhibitors.

CONCLUSIONS

STING-associated vasculopathy with onset in infancy (SAVI) is an autoinflammatory disease caused by gain-of-function mutations in TMEM173. (Funded by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases; ClinicalTrials.gov number, NCT00059748.).

Activated STING in a vascular and pulmonary syndrome

BACKGROUND

The study of autoinflammatory diseases has uncovered mechanisms underlying cytokine dysregulation and inflammation.

METHODS

We analyzed the DNA of an index patient with early-onset systemic inflammation, cutaneous vasculopathy, and pulmonary inflammation. We sequenced a candidate gene, TMEM173, encoding the stimulator of interferon genes (STING), in this patient and in five unrelated children with similar clinical phenotypes. Four children were evaluated clinically and immunologically. With the STING ligand cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), we stimulated peripheral-blood mononuclear cells and fibroblasts from patients and controls, as well as commercially obtained endothelial cells, and then assayed transcription of IFNB1, the gene encoding interferon-β, in the stimulated cells. We analyzed IFNB1 reporter levels in HEK293T cells cotransfected with mutant or nonmutant STING constructs. Mutant STING leads to increased phosphorylation of signal transducer and activator of transcription 1 (STAT1), so we tested the effect of Janus kinase (JAK) inhibitors on STAT1 phosphorylation in lymphocytes from the affected children and controls.

RESULTS

We identified three mutations in exon 5 of TMEM173 in the six patients. Elevated transcription of IFNB1 and other gene targets of STING in peripheral-blood mononuclear cells from the patients indicated constitutive activation of the pathway that cannot be further up-regulated with stimulation. On stimulation with cGAMP, fibroblasts from the patients showed increased transcription of IFNB1 but not of the genes encoding interleukin-1 (IL1), interleukin-6 (IL6), or tumor necrosis factor (TNF). HEK293T cells transfected with mutant constructs show elevated IFNB1 reporter levels. STING is expressed in endothelial cells, and exposure of these cells to cGAMP resulted in endothelial activation and apoptosis. Constitutive up-regulation of phosphorylated STAT1 in patients' lymphocytes was reduced by JAK inhibitors.

CONCLUSIONS

STING-associated vasculopathy with onset in infancy (SAVI) is an autoinflammatory disease caused by gain-of-function mutations in TMEM173. (Funded by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases; ClinicalTrials.gov number, NCT00059748.).

Long-term follow-up after non-myeloablative transplant of bone and marrow in BXSB mice

We present long-term outcomes of BXSB mice after non-myeloablative bone marrow transplants using major histocompatability complex (MHC)-matched cells. Groups differed in sources of donor lymphocytes or mesenchymal stromal cells (MSC). Unfractionated marrow cells from green fluorescent protein (GFP) transgenic (Tg) mice (BMT group) or from RAG1−/− B6 mice (RAG group) were injected intravenously (i.v.) into irradiated (550 cGy) hosts. As a source of mesenchymal cells, bone chips from GFP-Tg were injected intraperitoneally alone (MSC group) or along with i.v. bone marrow cells (BMT + MSC group). Controls were untreated mice (UnTx) or mice exposed to radiation only (Rad Cont). At 62 weeks post-transplant, surviving mice were harvested for histopathology, flow cytometry and real time polymerase chain reaction (RT-PCR). The mice from BMT + MSC group had the best outcomes for survival rates (71.4% vs. 43.8%), renal scores (2.9% vs. 28.8% glomerular sclerosis) and percent splenic monocytes (4.2 vs. 11.3%) compared with mice from Rad Cont. Improvement in RAG and BMT groups was less prominent but were comparable with one another. Although MSC alone were not sufficient to control the renal pathology, it limited the expansion of CD4−CD8− T cell populations without a change in Foxp3 expression. The results suggest the importance of the innate immune system in disease pathogenesis and a role for MSC in immunomodulation.

Stem-like cells traffic from heart ex vivo, expand in vitro, and can be transplanted in vivo

BACKGROUND

Cells with stem cell surface markers have been identified in heart tissue. Early indications suggest that these are cardiac progenitor cells that could contribute to cardiac repair/regeneration. Clinically relevant therapeutic strategies based on these cells will require improved methods for their isolation and characterization of determinants of their mobilization, proliferation and differentiation.

METHODS

An ex vivo culture system was developed that promotes trafficking of progenitor-like cells from mouse ventricles to a culture surface. Cells that "trafficked" from cardiac tissue were phenotyped by flow cytometry and immunohistochemistry.

RESULTS

Morphologically distinct cells spontaneously trafficked from mouse ventricular tissue, adhered in culture, and proliferated for up to 4 weeks in Dulbecco's minimal essential media supplemented with fetal calf serum. After 4 weeks in culture, cell number declined. Co-culture with unfractionated bone marrow restored the proliferation of these trafficked cells. A significant population of the trafficked cells expressed a phenotype consistent with that of a myogenic progenitor such as: c-kit+, Sca-1+, CD45-, CD34-, CD90.2-, MyoD1-, desmin-, muscle-specific actin-, and, infrequently, myogenin+. An expanded population of trafficked cells from ventricles of mice expressing green fluorescent protein (GFP+) and containing cardiac-derived progenitor cells were injected into the pericardial space of GFP- mice. GFP+ cells trafficked throughout the heart but retained a primitive undifferentiated morphology. However, when injected into the pericardial space of Apo-E-deficient mice with coronary vasculopathy, progenitor-like cells trafficked into myocardium, and GFP+ cells differentiated into vessel-lining endothelial cells and, rarely, smooth muscle and cardiomyocytes.

CONCLUSIONS

Progenitor-like cells in the heart can be mobilized by tissue injury to spontaneously traffic from cardiac tissue and can expand in culture by co-culture with bone marrow. When re-infused by pericardiocentesis, these primitive cells traffic into heart, retain immature morphology, but are capable of undergoing injury-induced differentiation. The novel method described herein permits further characterization of cardiac-derived progenitor cells, which are a candidate for cardiac regeneration strategies.

Lupus headaches in childhood-onset systemic lupus erythematosus: relationship to disease activity as measured by the systemic lupus erythematosus disease activity index (SLEDAI) and disease damage

The Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) is the most commonly used measure of disease activity for children with systemic lupus erythematosus (SLE). For headaches to be scored in the SLEDAI as a symptom of active disease, they have to be nonresponsive to narcotic analgesia. This may affect the overall estimation of disease activity, especially because headaches are common among children with SLE and narcotic analgesia is rarely used for headache therapy in paediatrics. Moreover, the importance of headaches for the development of damage and their relation to other clinical parameters and outcomes has not been well described for children with SLE. We reviewed the medical charts of an inception cohort of children (n = 63) who were newly diagnosed with SLE. Information on headaches and other disease parameters was obtained. Disease activity and damage were measured using the SLEDAI and the Systemic Lupus International Collaboration Clinics/American College of Rheumatology Damage Index (SDI), respectively. It has been shown that the accumulated burden of active disease as measured by serial SLEDAI scores over time is one of the best predictors of eventual damage to children with SLE. New-onset or significant increase of severe and/or persistent headaches (LHA) were reported in 43% of the patients during a mean follow-up of 3.6 years. LHA occurred preferentially among patients with elevated levels of antiphospholipid antibodies (aPL) (P < 0.02) and only 6% of all LHA episodes were treated with narcotics and thus considered for the measurement of disease activity in the SLEDAI. LHA were unrelated to proxy-measures of disease activity, such as the need to intensify therapies. When used in children, the insensitivity of the SLEDAI to capture LHA did not seem to decrease the responsiveness of the SLEDAI to detect clinically important worsening of disease, or negatively impact on its ability to predict damage.

Nonmyeloablative allogeneic bone marrow transplantation for treatment of childhood overlap syndrome and small vessel vasculitis

A 13-year-old Caucasian female with a systemic connective tissue disease (overlap syndrome with pulmonary vasculitis) underwent nonmyeloablative allogeneic BMT after failure of prolonged combination immunosuppressives to induce remission. The procedure also included cotransplantation of donor bone chips as a source of stromal cells. The unique protocol allowed good engraftment of hematopoietic (>95%) and bone core stromal cells (>60%). The patient was clinically improved, stable, and off all immunosuppressive medications 36 months post-transplant. To our knowledge, this is the first pediatric nonmyeloablative BMT with cotransplantation of stromal cells solely for treatment of an autoimmune disease.