The protein-protein interaction between leukocyte functional antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) is critical to lymphocyte and immune system function. Here, we report on the transfer of the contiguous, nonlinear epitope of ICAM-1, responsible for its association with LFA-1, to a small-molecule framework. These LFA-1 antagonists bound LFA-1, blocked binding of ICAM-1, and inhibited a mixed lymphocyte reaction (MLR) with potency significantly greater than that of cyclosporine A. Furthermore, in comparison to an antibody to LFA-1, they exhibited significant anti-inflammatory effects in vivo. These results demonstrate the utility of small-molecule mimics of nonlinear protein epitopes and the protein epitopes themselves as leads in the identification of novel pharmaceutical agents.

Purpose In the past, XLA was described as associated with several inflammatory conditions, but with adequate immune globulin treatment, these are presumed to have diminished. The actual prevalence is not known. Methods A web-based patient survey was conducted December 2011- February 2012. Respondents were recruited from the Immune Deficiency Foundation (IDF) patient database, online patient discussion forums and physician recruitment of patients. The questionnaire was developed jointly by IDF and by members of the USIDNET-XLA Disease Specific Working Group. Information regarding inflammatory conditions in patients with XLA was also obtained from the United States Immune Deficiency Network (USIDNET) Registry. Results Based on 128 unique patient survey responses, the majority of respondents (69 %) reported having at least one inflammatory symptom, with 53 % reporting multiple symptoms. However, only 28 % had actually been formally diagnosed with an inflammatory condition. Although 20 % reported painful joints and 11 % reported swelling of the joints, only 7 % were given a diagnosis of arthritis. Similarly, 21 % reported symptoms of chronic diarrhea and 17 % reported abdominal pain, however only 4 % had been diagnosed with Crohn’s disease. Data from the USIDNET Registry on 149 patients with XLA, revealed that 12 % had pain, swelling or arthralgias, while 18 % had been diagnosed with arthritis. Similarly, 7 % of these patients had abdominal pain and 9 % chronic diarrhea. Conclusions Although patients with XLA are generally considered to have a low risk of autoimmune or inflammatory disease compared to other PIDD cohorts, data from this patient survey and a national registry indicate that a significant proportion of patients with XLA have symptoms that are consistent with a diagnosis of arthritis, inflammatory bowel disease or other inflammatory condition. Documented diagnoses of inflammatory diseases were less common but still increased over the general population. Additional data is required to begin implementation of careful monitoring of patients with XLA for these conditions. Early diagnosis and proper treatment may optimize clinical outcomes for these patients.

The molecular chaperone cpn60 binds many unfolded proteins and facilitates their proper folding. Synthetic peptides have been used to probe the question of how cpn60 might recognize such a diverse set of unfolded proteins. Three hybrid peptides were synthesized encompassing portions of the bee venom peptide, apamin, and the sequence KWLAESVRAGK from an amphipathic helix in the NH 2 -terminal region of bovine rhodanese. Two disulfides connecting cysteine residues hold the peptides in stable helical conformations with unobstructed faces oriented away from the disulfides. Peptides were designed to present either a hydrophobic or hydrophilic face of the amphipathic helix that is similar to the one near the amino terminus of rhodanese. Aggregation of these peptides was detected by measuring 1,1-bis(4-anilino)napthalene-5,5-disulfonic acid (bisANS) fluorescence at increasing peptide concentrations, and aggregation was not apparent below 2 M. Thus, all experiments with the peptides were performed at a concentration of 1 M. Reducing agents cause these helical peptides to form random coils. Fluorescence anisotropy measurements of fluorescein-labeled peptide with the exposed hydrophobic face yielded a K d ‫؍‬ ϳ106 M for binding to cpn60, whereas there was no detectable binding of the reduced form. The peptide with the exposed hydrophilic face did not bind to cpn60 in either the oxidized or reduced states. Fluorescence experiments utilizing bisANS as a probe showed that binding of the helical hydrophobic peptide could induce the exposure of hydrophobic surfaces on cpn60, whereas the same peptide in its random coil form had no effect. Thus, binding to cpn60 is favored by a secondary structure that organizes and exposes a hydrophobic surface, a feature found in amphipathic helices. Further, the binding of a hydrophobic surface to cpn60 can induce further exposure of complementary surfaces on cpn60 complexes, thus amplifying interactions available for target proteins.

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