No abstract

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects 15 to 30% of children and ~5% of adults in industrialized countries1. Although the pathogenesis of AD is not fully understood, the disease is mediated by an abnormal immunoglobulin E (IgE) immune response in the setting of skin barrier dysfunction2. Mast cells (MCs) contribute to IgE-mediated allergic disorders including AD3. Upon activation, MCs release their membrane-bound cytosolic granules leading to the release of multiple molecules that are important in the pathogenesis of AD and host defense4. More than 90% of AD patients are colonized with Staphylococcus aureus in the lesional skin whereas most healthy individuals do not harbor the pathogen5. Several Staphylococcal exotoxins (SEs) can act as superantigens and/or antigens in models of AD6. However, the role of these SEs in disease pathogenesis remains unclear. Here, we report that culture supernatants of S. aureus contain potent MC degranulation activity. Biochemical analysis identified δ-toxin as the MC degranulation-inducing factor produced by S. aureus. MC degranulation induced by δ-toxin depended on phosphoinositide 3-kinase (PI3K) and calcium (Ca2+) influx, but unlike that mediated by IgE crosslinking, it did not require the spleen tyrosine kinase (Syk). In addition, IgE enhanced δ-toxin-induced MC degranulation in the absence of antigen. Furthermore, S. aureus isolates recovered from AD patients produced high levels of δ-toxin. Importantly, skin colonization with S. aureus, but not a mutant deficient in δ-toxin, promoted IgE and IL-4 production, as well as inflammatory skin disease. Furthermore, enhancement of IgE production and dermatitis by δ-toxin was abrogated in KitW-sh/W-sh MC-deficient mice and restored by MC reconstitution. These studies identify δ-toxin as a potent inducer of MC degranulation and suggest a mechanistic link between S. aureus colonization and allergic skin disease.

Because cytotoxic T lymphocytes (CTL) may be important for preventing direct cell-to-cell transmission of human immunodeficiency virus (HIV), the agent responsible for acquired immunodeficiency syndrome, we have begun to investigate the epitope specificity and immune response (Ir) gene control of anti-HIV CTL responses in experimental animals. Mice were infected with a recombinant vaccinia virus expressing the HIV gpl60 envelope gene, and the primed lymphocytes were restimulated in vitro with a transfected histocompatible cell line expressing the same gene. Our results show that H-2d mice are CTL high responders and H-2k mice are low responders to the HIV gpl60 envelope protein under these conditions. Moreover, the H-2d mice respond predominantly to a single immunodominant site represented by a 15-residue synthetic peptide conforming to the amphipathic a-helix model of T-cell epitopes and seen by CD4-CD8+ CTL in association with the Dd class I major histocompatibility complex (MHC) molecules. The facts that CTL responses were detected in the context of only one of four class I MHC molecules tested and that the response was limited predominantly to a single epitope indicate that the CTL repertoire elicited by the HIV envelope protein in association with murine class

IMPORTANCE Our previous studies demonstrated that tumors significantly decrease in size and metabolic activity after delivery of 45 Gy of fractionated radiatiotherapy (RT), and that metabolic shrinkage is greater than anatomic shrinkage. This study aimed to determine whether 18F-fludeoxyglucose–positron emission tomography/computed tomography (FDG-PET/CT) acquired during the course of treatment provides an opportunity to deliver higher-dose radiation to the more aggressive areas of the tumor to improve local tumor control without increasing RT-induced lung toxicity (RILT), and possibly improve survival. OBJECTIVE To determine whether adaptive RT can target high-dose radiation to the FDG-avid tumor on midtreatment FDG-PET to improve local tumor control of locally advanced non–small-cell lung cancer (NSCLC). DESIGN, SETTING, AND PARTICIPANTS A phase 2 clinical trial conducted at 2 academic medical centers with 42 patients who had inoperable or unresectable stage II to stage III NSCLC enrolled from November 2008, to May 2012. Patients with poor performance, more than 10% weight loss, poor lung function, and/or oxygen dependence were included, providing that the patients could tolerate the procedures of PET scanning and RT. INTERVENTION Conformal RT was individualized to a fixed risk of RILT (grade >2) and adaptively escalated to the residual tumor defined on midtreatment FDG-PET up to a total dose of 86 Gy in 30 daily fractions. Medically fit patients received concurrent weekly carboplatin plus paclitaxel followed by 3 cycles of consolidation. MAIN OUTCOMES AND MEASURES The primary end point was local tumor control. The trial was designed to achieve a 20% improvement in 2-year control from 34% of our prior clinical trial experience with 63 to 69 Gy in a similar patient population. RESULTS The trial reached its accrual goal of 42 patients: median age, 63 years (range, 45–83 years); male, 28 (67%); smoker or former smoker, 39 (93%); stage III, 38 (90%). Median tumor dose delivered was 83 Gy (range, 63–86 Gy) in 30 daily fractions. Median follow-up for surviving patients was 47 months. The 2-year rates of infield and overall local regional tumor controls (ie, including isolated nodal failure) were 82% (95% CI, 62%–92%) and 62% (95% CI, 43%–77%), respectively. Median overall survival was 25 months (95% CI, 12–32 months). The 2-year and 5-year overall survival rates were 52% (95% CI, 36%–66%) and 30% (95% CI, 16%–45%), respectively. CONCLUSIONS AND RELEVANCE Adapting RT-escalated radiation dose to the FDG-avid tumor detected by midtreatment PET provided a favorable local-regional tumor control. The RTOG 1106 trial is an ongoing clinical trial to validate this finding in a randomized fashion. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01190527

We have identified the low MW 27 kD heat shock protein as a major phosphoprotein constituent of smooth muscle and have investigated its potential role in agonist induced smooth muscle contraction. The neuropeptides bombesin and substance P, which are present in neurons of the anorectal region, induce contraction of isolated smooth muscle cells from this region by activating different intracellular pathways. Substance P-induced contraction is 1,4,5-inositol trisphosphate (IP3)/calmodulin dependent, while contraction induced by bombesin is mediated by a protein kinase C (PKC)-dependent pathway. The sustained contraction induced by bombesin or exogenous PKC was blocked by preincubation of cells with monoclonal antibodies to hsp27, while the transient contraction induced by substance P or IP3 was unaffected by the antibodies. Preincubation with isotype matched control antibodies had no inhibitory effect on contraction induced in response to the agents used. These data support a novel role for hsp27 in the non calmodulin mediated sustained contraction induced by bombesin or PKC.

authors request that the following correction be noted. Mutant 49 of the Tac receptor subunit in which Thr-85, Thr-86 were replaced by Ala-85, Gly-86 was also modified at the C terminus of the polypeptide chain. The oligonucleotide used in the mutation reaction apparently hybridized with the single-stranded template at the correct location surrounding Thr-85, Thr-86 and also at a site after the codon for Gln-202. As a consequence, the C-terminal region of the mutant 49 protein differed markedly from that of the native molecule. The mutant protein bound to affinity supports coupled with interleukin 2 and the anti-Tac monoclonal antibody, but was defective for expression on the cell surface. Examination of a new mutant of the Tac protein in which Thr-85 and Thr-86 were replaced by Ala and Gly, respectively, but in which the remaining sequence was identical to that of the native protein, indicates that this substitution has no effect on cell-surface expression. Moreover Correction. In the article "Helper T-cell antigenic site identification in the acquired immunodeficiency syndrome virus gp120 envelope protein and induction of immunity in mice to the native protein using a 16-residue synthetic peptide" by

T-lymphocyte immunity is likely to be an important component of the immune defence against the AIDS virus, because helper T cells are necessary for the antibody response as well as the cytotoxic response. We have previously predicted two antigenic sites of the viral envelope protein gp120 likely to be recognized by T lymphocytes, based on their ability to fold as amphipathic helices, and have demonstrated that these are recognized by T cells of mice immunized with gp120 (ref. 1). A peptide corresponding to one of these sites can also be induce immunity in mice to the whole gp120 protein. Because many clinically healthy seropositive blood donors have already lost their T-cell proliferative response to specific antigen, we tested the response to these synthetic peptides of lymphocytes from 14 healthy human volunteers who had been immunized with a recombinant vaccinia virus containing the AIDS viral envelope gene and boosted with a recombinant fragment. Eight of the 14 responded to one peptide, and four to the other peptide, not included in the boost. These antigenic sites recognized by human T cells may be useful components of a vaccine against AIDS. We also found a correlation between boosting with antigen-antibody complexes (compared to free antigen) and higher stimulation indices, suggesting a more effective method of immunization.

In summary, our results using the model protein antigen myoglobin indicated, in concordance with others, that helper T lymphocytes recognize a limited number of immunodominant antigenic sites of any given protein. Such immunodominant sites are the focus of a polyclonal response of a number of different T cells specific for distinct but overlapping epitopes. Therefore, the immunodominance does not depend on the fine specificity of any given clone of T cells, but rather on other factors, either intrinsic or extrinsic to the structure of the antigen. A major extrinsic factor is the MHC of the responding individual, probably due to a requirement for the immunodominant peptides to bind to the MHC of presenting cells in that individual. In looking for intrinsic factors, we noted that both immunodominant sites of myoglobin were amphipathic helices, i.e., helices having hydrophilic and hydrophobic residues on opposite sides. Studies with synthetic peptides indicated that residues on the hydrophilic side were necessary for T-cell recognition. However, unfolding of the native protein was shown to be the apparent goal of processing of antigen, presumably to expose something not already exposed on the native molecule, such as the hydrophobic sides of these helices. We propose that such exposure is necessary to interact with something on the presenting cell, such as MHC or membrane, where we have demonstrated the presence of antigenic peptides by blocking of presentation of biotinylated peptide with avidin. The membrane may serve as a short-term memory of peptides from antigens encountered by the presenting cell, for dynamic sampling by MHC molecules to be available for presentation to T cells. These ideas, together with the knowledge that T-cell recognition required only short peptides and therefore had to be based only on primary or secondary structure, not tertiary folding of the native protein, led us to propose that T-cell immunodominant epitopes may tend to be amphipathic structures. An algorithm to search for potential amphipathic helices from sequence information identified 18 of 23 known immunodominant T-cell epitopes from 12 proteins (p less than 0.001). Another statistical approach confirmed the importance of amphipathicity and also supported the importance of helical structure that had been proposed by others. It suggested that peptides able to form a stable secondary structure, especially a helix, more commonly formed immunodominant epitopes. We used this approach to predict potential immunodominant epitopes for induction of T-cell immunity in proteins of clinical relevance, such as the malarial circumsporozoite protein and the AIDS viral envelope.(ABSTRACT TRUNCATED AT 400 WORDS)