Identification of human T-cell epitopes and highly immunogenic analog peptides on the non-typeable Haemophilus influenzae P6 outer membrane protein

Ishida, Yoshiya; Abe, Yusuke; Yanai, Mitsuru; Kobayashi, Hiroya; Harabuchi, Yasuaki

doi:10.1016/j.clim.2006.06.005

Cited by 6 publications

(3 citation statements)

References 40 publications

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“…The immunogenicity of P6 is facilitated by the presence of a CD4 helper T cell epitope [13], [24], [25]. The presentation of the epitope to P6-specific CD4 + T cells is likely enhanced by the presence of the lipid motif on the antigen when endocytosed by the APC upon recognition by TLR2.…”

Section: Discussionmentioning

confidence: 99%

Lipid Motif of a Bacterial Antigen Mediates Immune Responses via TLR2 Signaling

Lugade

Bianchi‐Smiraglia²,

Pradhan³

et al. 2011

PLoS ONE

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The cross-talk between the innate and the adaptive immune system is facilitated by the initial interaction of antigen with dendritic cells. As DCs express a large array of TLRs, evidence has accumulated that engagement of these molecules contributes to the activation of adaptive immunity. We have evaluated the immunostimulatory role of the highly-conserved outer membrane lipoprotein P6 from non-typeable Haemophilus influenzae (NTHI) to determine whether the presence of the lipid motif plays a critical role on its immunogenicity. We undertook a systematic analysis of the role that the lipid motif plays in the activation of DCs and the subsequent stimulation of antigen-specific T and B cells. To facilitate our studies, recombinant P6 protein that lacked the lipid motif was generated. Mice immunized with non-lipidated rP6 were unable to elicit high titers of anti-P6 Ig. Expression of the lipid motif on P6 was also required for proliferation and cytokine secretion by antigen-specific T cells. Upregulation of T cell costimulatory molecules was abrogated in DCs exposed to non-lipidated rP6 and in TLR2−/− DCs exposed to native P6, thereby resulting in diminished adaptive immune responses. Absence of either the lipid motif on the antigen or TLR2 expression resulted in diminished cytokine production from stimulated DCs. Collectively; our data suggest that the lipid motif of the lipoprotein antigen is essential for triggering TLR2 signaling and effective stimulation of APCs. Our studies establish the pivotal role of a bacterial lipid motif on activating both innate and adaptive immune responses to an otherwise poorly immunogenic protein antigen.

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Section: Discussionmentioning

confidence: 99%

Lipid Motif of a Bacterial Antigen Mediates Immune Responses via TLR2 Signaling

Lugade

Bianchi‐Smiraglia²,

Pradhan³

et al. 2011

PLoS ONE

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“…In a study by Beck-Sickinger et al (39), the epitopes of P6 were identified and localized within residues 31 to 46 and 59 to 70 and in the C-terminal part of P6, which partly overlapped the predicted T-and B-cell combined epitope P6-61 in our study; however, the lipopeptides containing the sequence pattern QILDAHAA (P6 residues 47 to 54) and the mouse B-cell epitope GEYV (P6 residues 43 to 46) induced high titers of anti-P6 antibodies (39), which were in line with that of P6-61 in the study. Ishida et al (40) established P6-specific CD4 ϩ T-cell lines restricted by the human histocompatibility leukocyte antigen (HLA)-DR9 molecule and revealed a human T-cell epitope on P6 and its core peptide sequence (p77 to 85; EYNIALGQR). Nomura et al (41) studied promiscuous peptides on the nontypeable H. influenzae outer membrane protein P6, identified that human B-cell epitope was located on p71 to 85, which could be recognized by T-cell lines (TCL) in the restriction of HLA-DR9, and induced a proliferative response.…”

Section: Discussionmentioning

confidence: 99%

Serum Concentrations of Antibodies against Outer Membrane Protein P6, Protein D, and T- and B-Cell Combined Antigenic Epitopes of Nontypeable Haemophilus influenzae in Children and Adults of Different Ages

Chen

Shang

et al. 2016

Clin Vaccine Immunol

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e Nontypeable Haemophilus influenzae (NTHi) is one of the most common etiologies of acute otitis media, rhinosinusitis, and pneumonia. Outer membrane proteins (OMPs) are the main focus in new vaccine development against NTHi, as the H. influenzae type b (Hib) vaccine does not cover noncapsulated NTHi. The OMPs P6 and protein D are the most promising candidate antigens for an NTHi vaccine, and low antibody levels against them in serum may be correlated with infection caused by NTHi. In the current study, we measured the antibody titers against P6, protein D, and their T-and B-cell combined peptide epitopes in healthy individuals of different ages. We found that children <1 month old had the lowest antibody levels against NTHi P6, protein D, and their T-and B-cell combined antigenic epitopes. Antibody titers increased at ages 1 to 6 months, peaked at 7 months to 3 years, and remained high at 4 to 6 years. The antibody titers started to decrease after 6 years and were the lowest in the 21-to 30-year group. The geometric mean titers (GMTs) of T-and B-cell combined antigenic epitopes in P6 and protein D were positively correlated with those of the protein antigens. Among 12 peptides tested, P6-61, P6-123, and protein D-167 epitopes were better recognized than others in human serum. These findings might contribute to the development of an effective serotypeindependent vaccine for H. influenzae. Haemophilus influenzae is one of the normal inhabitants of the human nasopharynx and is responsible for pneumonia, acute otitis media (AOM), and acute rhinosinusitis (1-3). The presence or absence of a polysaccharide capsule segregates this bacterial species into two well-defined groups: one group of encapsulated strains and another group of noncapsulated strains, commonly referred to as nontypeable H. influenzae (NTHi) (3). Common infections caused by NTHi include otitis media in children and lower airway infections of chronic obstructive pulmonary disease in adults (4, 5). Vaccines composed of polysaccharide capsule conjugated to protein carriers have virtually eliminated infections caused by encapsulated H. influenzae type b, including meningitis and other systemic infections, in regions where the vaccines are widely administered (6, 7). However, these conjugate vaccines have no effect on infections caused by NTHi, and in regions with H. influenzae type b vaccination programs, nontypeable strains are now the most common cause of noninvasive H. influenzae infection, so that the development of the vaccine against NTHi is an urgent and challenging task (8-10).Since NTHi organisms are noncapsulated bacteria, the outer membrane proteins (OMPs) are the main targets for vaccine designers. Several research groups have identified conserved surface proteins and tested them as putative vaccines, and the conserved NTHi antigens with demonstrated preclinical protective capacity have been identified, among which P6 and protein D are the most widely studied (11)(12)(13)(14).Experimental data derived from humans and animal models indicate t...

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“…P6 plays a critical role in the structural integrity of the outer membrane as previous work has demonstrated that its absence increases sensitivity of the mutant NTHI strain to a panel of antimicrobial agents (Murphy et al, 2006). Although several studies have evaluated the potential of P6 as a vaccine antigen (Hotomi et al, 1998; Bertot et al, 2004; McMahon et al, 2005; Wu et al, 2005; Ishida et al, 2006; Nomura et al, 2008; Noda et al, 2010), there are no studies detailing its role in the initiation of inflammation during infection in vivo .…”

Section: Introductionmentioning

confidence: 99%

The Role of TLR2 and Bacterial Lipoprotein in Enhancing Airway Inflammation and Immunity

Lugade¹,

Bogner²,

Murphy³

et al. 2011

Front. Immun.

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Non-typeable Haemophilus influenzae (NTHI) colonizes the lower respiratory tract of patients with chronic obstructive pulmonary disease and also causes exacerbations of the disease. The 16-kDa lipoprotein P6 has been widely studied as a potential vaccine antigen due to its highly conserved expression amongst NTHI strains. Although P6 is known to induce potent inflammatory responses, its role in the pathogenesis of NTHI infection in vivo has not been examined. Additionally, the presence of an amino-terminal lipid motif on P6 serves to activate host Toll-like receptor 2 (TLR2) signaling. The role of host TLR2 and NTHI expression of the lipoprotein P6 on the induction of airway inflammation and generation of adaptive immune responses following chronic NTHI stimulation was evaluated with TLR2-deficient mice and a P6-deficient NTHI strain. Absence of either host TLR2 or bacterial P6 resulted in diminished levels of immune cell infiltration within lungs of mice exposed to NTHI. Pro-inflammatory cytokine secretion was also reduced in lungs that did not express TLR2 or were exposed to NTHI devoid of P6. Induction of specific antibodies to P6 was severely limited in TLR2-deficient mice. Although mice exposed to the P6-deficient NTHI strain were capable of generating antibodies to other surface antigens of NTHI, these levels were lower compared to those observed in mice exposed to P6-expressing NTHI. Therefore, cognate interaction between host TLR2 and bacterial P6 serves to enhance lung inflammation and elicit robust adaptive immune responses during NTHI exposure. Strategies to limit NTHI inflammation while simultaneously promoting robust immune responses may benefit from targeting the TLR2:P6 signaling axis.

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Identification of human T-cell epitopes and highly immunogenic analog peptides on the non-typeable Haemophilus influenzae P6 outer membrane protein

Cited by 6 publications

References 40 publications

Lipid Motif of a Bacterial Antigen Mediates Immune Responses via TLR2 Signaling

Lipid Motif of a Bacterial Antigen Mediates Immune Responses via TLR2 Signaling

Serum Concentrations of Antibodies against Outer Membrane Protein P6, Protein D, and T- and B-Cell Combined Antigenic Epitopes of Nontypeable Haemophilus influenzae in Children and Adults of Different Ages

The Role of TLR2 and Bacterial Lipoprotein in Enhancing Airway Inflammation and Immunity

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