William R. Levis

CpG oligodeoxynucleotide-enhanced humoral immune response and production of antibodies to prion protein PrPSc in mice immunized with 139A scrapie-associated fibrils.

Prion diseases are characterized by conversion of the cellular prion protein (PrPC) to a protease‐resistant conformer, the srapie form of PrP (PrPSc). Humoral immune responses to nondenatured forms of PrPSc have never been fully characterized. We investigated whether production of antibodies to PrPSc could occur in PrP null (Prnp−/−) mice and further, whether innate immune stimulation with the TLR9 agonist CpG oligodeoxynucleotide (ODN) 1826 could enhance this process. Whether such stimulation could raise anti‐PrPSc antibody levels in wild‐type (Prnp+/+) mice was also investigated. Prnp−/− and Prnp+/+ mice were immunized with nondenatured 139A scrapie‐associated fibrils (SAF), with or without ODN 1826, and were tested for titers of PrP‐specific antibodies. In Prnp−/− mice, inclusion of ODN 1826 in the immunization regime increased anti‐PrP titers more than 13‐fold after two immunizations and induced, among others, antibodies to an N‐terminal epitope, which were only present in the immune repertoire of mice receiving ODN 1826. mAb 6D11, derived from such a mouse, reacts with the N‐terminal epitope QWNK in native and denatured forms of PrPSc and recombinant PrP and exhibits a Kd in the 10−11 M range. In Prnp+/+ mice, ODN 1826 increased anti‐PrP levels as much as 84% after a single immunization. Thus, ODN 1826 potentiates adaptive immune responses to PrPSc in 139A SAF‐immunized mice. These results represent the first characterization of humoral immune responses to nondenatured, infectious PrPSc and suggest methods for optimizing the generation of mAbs to PrPSc, many of which could be used for diagnosis and treatment of prion diseases.

Accelerated prion disease pathogenesis in Toll-like receptor 4 signaling-mutant mice.

ABSTRACT Prion diseases such as scrapie involve the accumulation of disease-specific prion protein, PrPSc, in the brain. Toll-like receptors (TLRs) are a family of proteins that recognize microbial constituents and are central players in host innate immune responses. The TLR9 agonist unmethylated CpG DNA was shown to prolong the scrapie incubation period in mice, suggesting that innate immune activation interferes with prion disease progression. Thus, it was predicted that ablation of TLR signaling would result in accelerated pathogenesis. C3H/HeJ (Tlr4Lps-d) mice, which possess a mutation in the TLR4 intracellular domain preventing TLR4 signaling, and strain-matched wild-type control (C3H/HeOuJ) mice were infected intracerebrally or intraperitoneally with various doses of scrapie inoculum. Incubation periods were significantly shortened in C3H/HeJ compared with C3H/HeOuJ mice, regardless of the route of infection or dose administered. At the clinical phase of disease, brain PrPSc levels in the two strains of mice showed no significant differences by Western blotting. In addition, compared with macrophages from C3H/HeOuJ mice, those from C3H/HeJ mice were unresponsive to fibrillogenic PrP peptides (PrP residues 106 to 126 [PrP106-126] and PrP118-135) and the TLR4 agonist lipopolysaccharide but not to the TLR2 agonist zymosan, as measured by cytokine production. These data confirm that innate immune activation via TLR signaling interferes with scrapie infection. Furthermore, the results also suggest that the scrapie pathogen, or a component(s) thereof, is capable of stimulating an innate immune response that is active in the central nervous system, since C3H/HeJ mice, which lack the response, exhibit shortened incubation periods following both intraperitoneal and intracerebral infections.

The role of the armadillo and sooty mangabey monkey in human leprosy.

Background  The armadillo was the first animal model of leprosy. Its role in the transmission of leprosy remains controversial. The sooty mangabey model of leprosy led to the discovery that rhesus monkeys were more susceptible to leprosy when coinfected with simian immunodeficiency virus (SIV), but that leprosy may play a protective role against acquired immunodeficiency syndrome (AIDS) mortality. Recently, molecular methods have been developed for leprosy and may help resolve the role of zoonoses in leprosy.

Deficient tumor necrosis factor-α production in lipoarabinomannan activated macrophages from toll-like receptor-4 deficient mice: Implication for mycobacterial susceptibility

Mice with a point mutation of toll-like receptor-4 (TLR-4) (C3H/HeJ) are hypo-responsive to LPS and more susceptible to mycobacterial infections than their control wild type (C3H/OuJ). We have previously shown that TLR-4-deficient mice produced NO in response to the mycobacterial product, ara-lipoarabinomannan (LAM), in the presence of either Interferon-beta (IFN-beta) or Interferon-gamma (IFN-gamma), with a dose response curve that produced levels of NO almost as high as those observed in C3H/OuJ mice at high concentrations of ara-LAM plus either IFN-beta or-gamma. We now report that tumor necrosis factor-alpha (TNF-alpha), an important cytokine for intracellular killing of mycobacteria, remains deficient in these C3H/HeJ mice compared to C3H/OuJ mice even at a high concentration of ara-LAM with either IFN-gamma or IFN-beta. In addition, TNF-alpha was further down regulated by taurine chloramine (Tau-Cl) in C3H/OuJ mice. The low level of TNF-alpha produced in the TLR-4-deficient (C3H/HeJ) mice was also further down regulated by Tau-Cl. These findings implicate the TLR-4 as an additional candidate locus for mycobacterial susceptibility, and provide a pathway for better understanding the molecular basis of this locus in the immunopathogenesis of mycobacterial infection.

IgA antibodies against phenolic glycolipid I from Mycobacterium leprae in serum of leprosy patients and contacts: Subclass distribution and relation to disease activity

The anti-PGL-I IgA response against phenolic glycolipid I (PGL-I) a specific surface antigen of Mycobacterium leprae, was demonstrated to be essentially of the IgA1 subclass in sera from leprosy patients and contacts. Anti-PGL-I IgA1 mean levels were found to increase significantly from the tuberculoid toward the lepromatous pole of the leprosy disease spectrum, thus resembling the predominating anti-PGL-I IgM response. Furthermore, anti-PGL-I IgA1 values were shown to increase significantly with increasing bacillary load, measured as bacillary index (BI) from skin biopsies. However, a number of BI negative leprosy patients recorded elevated anti-PGL-I IgA1 levels possibly reflecting a persistence of disease activity. Three of 28 household or family contacts of leprosy patients were detected seropositive for anti-PGL-I IgA1. Thus, our results suggest that anti-PGL-I IgA1 may be considered as an additional parameter for the early detection of infection with M. leprae.

Molecular Origin of Endemic Leprosy in New York City

We report an indigenous case of leprosy in New York City in an immunocompetent patient who was infected with a Mycobacterium leprae genotype that is consistent with an exogenous origin. Physicians in the eastern United States should be alerted that, although most patients who develop leprosy in the United States are foreign born, native-born Americans are also susceptible to the infection.

Leprosy is teaching us the immunopathogenesis of inflammatory skin disease

To the Editor: Czarnowicki et al have reported that severe atopic dermatitis is characterized by expansion of circulating TH2 and TH22, but not TH17, within the skin-homing population. The TH22 subset has been discovered in leprosy, with increased IL-22 in TH2 anergic lepromatous leprosy and decreased IL-22 in TH1 tuberculoid leprosy with intact cell-mediated immunity. The increase in IL-22 at the TH2 lepromatous pole corresponds to the increase in IL-22 in TH2 atopic dermatitis versus TH1 psoriasis. 1 TH22 is well established in both TH1 psoriasis and TH2 atopic dermatitis. 3

Quantiferon-Gold Tuberculosis Test Cannot Detect Latent Tuberculosis in Patients With Leprosy

Five of 10 paucibacillary leprosy patients were Quantiferon Gold (Q-G) positive with negative chest X-rays. Forty multibacillary leprosy patients were negative. Reports have shown 100% cross-reactivity of ESAT6 and CFP10 between Mycobacterium leprae and Mycobacterium tuberculosis. The Q-G test cannot detect latent tuberculosis in patients with leprosy.

Antiviral immunotherapy: emerging approaches with relevance to cutaneous disease

Recent developments in the characterization of the receptors and pathways of the innate immune system, and of the mechanisms of activation of adaptive immunity, have opened new possibilities for modulation of the immune response to eradicate neoplasms and to overcome resistant viral infections. The discovery of numerous and varied pattern recognition receptors and their ligands have helped to explain the success of older therapies, and paved the way for the novel immunomodulator, imiquimod, which demonstrates the practical applicability of immunomodulation to cutaneous disease. In this review we summarize current knowledge on the mechanisms of activation of innate immunity to viral disease, available therapies and agents in development for cutaneous antiviral immunomodulation, and the implications of the current restructuring of the understanding of cell-mediated immunity, the desired end point of innate immunomodulation, on future immunomodulatory modalities.

Diphencyprone Treatment of Alopecia Areata: Postulated Mechanism of Action and Prospects for Therapeutic Synergy with RNA Interference

Diphencyprone (DPCP) is a potent topical sensitizing agent that has been used since the late 1970s by physicians for the treatment of alopecia areata (AA), viral warts (human papillomavirus) and cutaneous metastases of melanoma. Although to date the compound is not approved as a drug by the FDA or EMA, physicians have continued to use DPCP because of its proven effects in these dermatological conditions. The use of the drug has been highly variable because of differences in compounding, and as a result, the literature reports vary widely in the concentrations used for sensitization and challenge treatment with DPCP. The efficacy of DPCP has generally been ascribed to immunological reactions by the host. Inducing inflammation with a contact sensitizer is counterintuitive to treating AA, an autoimmune disorder. We have hypothesized that the bodys attempt to downregulate the inflammation caused by the contact sensitizer may also ameliorate AA. Studies using microarray and miRNA profiling may provide information about how DPCP induces inflammation in human skin at different times. Gene targets and microRNAs identified through these data may be modulated by an RNA interference approach to enhance DPCP efficacy and response rates. In addition, this approach may result in the discovery and development of drugs that are more potent and selective for the treatment of AA.