Antimicrobial peptides from plants: stabilization of the γ core of a tomato defensin by intramolecular disulfide bond.

Cysteine-containing antimicrobial peptides of diverse phylogeny share a common structural signature, the γ core, characterized by a strong polarization of charges in two antiparallel ß sheets. In this work, we analyzed peptides derived from the tomato defensin SolyC07g007760 corresponding to the protein γ core and demonstrated that cyclization of the peptides, which results in segregation of positive charges to the turn region, produces peptides very active against Gram negative bacteria, such as Salmonella enterica and Helicobacter pylori. Interestingly, these peptides show very low hemolytic activity and thus represent a scaffold for the design of new antimicrobial peptides.

A novel synthetic peptide from a tomato defensin exhibits antibacterial activities against Helicobacter pylori.

Defensins are a class of cysteine-rich proteins, which exert broad spectrum antimicrobial activity. In this work, we used a bioinformatic approach to identify putative defensins in the tomato genome. Fifteen proteins had a mature peptide that includes the well-conserved tetradisulfide array. We selected a representative member of the tomato defensin family; we chemically synthesized its γ-motif and tested its antimicrobial activity. Here, we demonstrate that the synthetic peptide exhibits potent antibacterial activity against Gram-positive bacteria, such as Staphylococcus aureus A170, Staphylococcus epidermidis, and Listeria monocytogenes, and Gram-negative bacteria, including Salmonella enterica serovar Paratyphi, Escherichia coli, and Helicobacter pylori. In addition, the synthetic peptide shows minimal (<5%) hemolytic activity and absence of cytotoxic effects against THP-1 cells. Finally, SolyC exerts an anti-inflammatory activity in vitro, as it downregulates the level of the proinflammatory cytokines TNF-α and IFN-γ.

Early versus later onset childhood-onset systemic lupus erythematosus: Clinical features, treatment and outcome.

The objective of the study was to compare clinical features, treatment and disease outcome in patients with early versus later onset of childhood-onset systemic lupus erythematosus (cSLE). A retrospective matched cohort study of cSLE patients diagnosed between 1988 and 2008 and followed for a minimum of one year was conducted. Thirty-four pre-pubertal cSLE patients with disease onset prior to their 12th birthday were matched by ethnicity and year of diagnosis to 34 pubertal cSLE patients. The most common criteria at diagnosis in both groups were malar rash, arthritis, hematologic manifestations, and renal disease. After a mean follow-up of more than six years, a similar proportion of patients in the two groups were still prescribed corticosteroids (47% and 41%); patients in the early onset group required a significantly higher daily dose (0.6 mg/kg prednisone-equivalent versus 0.2 mg/kg, p < 0.05). There were no significant differences in organ involvement, disease activity and disease damage between the two groups, and severe complications occurred at similar rates. There were a greater number of admissions to the pediatric intensive care unit (PICU) in the early onset group (18 versus 5, p = 0.01), with time-to-event analysis demonstrating a significantly shorter disease duration from diagnosis to first PICU admission in the early onset group (p < 0.001). While a similar proportion of patients in the early and later onset groups required treatment with cyclophosphamide, patients in the early onset group received treatment earlier in their disease course (mean 13.7 versus 19.9 months, p < 0.001). Early onset cSLE leads to earlier and more frequent PICU admission, earlier use of cyclophosphamide, and higher corticosteroid dose at long-term follow-up.