Select gp120 V2 domain specific antibodies derived from HIV and SIV infection and vaccination inhibit gp120 binding to alpha4beta7

The GI tract is preferentially targeted during acute/early HIV-1 infection. Consequent damage to the gut plays a central role in HIV pathogenesis. The basis for preferential targeting of gut tissues is not well defined. Recombinant proteins and synthetic peptides derived from HIV and SIV gp120 bind directly to integrin alpha4beta7, a gut-homing receptor. Using both cell-surface expressed alpha4beta7 and a soluble alpha4beta7 heterodimer we demonstrate that its specific affinity for gp120 is similar to its affinity for MAdCAM (its natural ligand). The gp120 V2 domain preferentially engages extended forms of alpha4beta7 in a cation -sensitive manner and is inhibited by soluble MAdCAM. Thus, V2 mimics MAdCAM in the way that it binds to alpha4beta7, providing HIV a potential mechanism to discriminate between functionally distinct subsets of lymphocytes, including those with gut-homing potential. Furthermore, alpha4beta7 antagonists developed for the treatment of inflammatory bowel diseases, block V2 binding to alpha4beta7. A 15-amino acid V2 -derived peptide is sufficient to mediate binding to alpha4beta7. It includes the canonical LDV/I alpha4beta7 binding site, a cryptic epitope that lies 7-9 amino acids amino terminal to the LDV/I, and residues K169 and I181. These two residues were identified in a sieve analysis of the RV144 vaccine trial as sites of vaccine -mediated immune pressure. HIV and SIV V2 mAbs elicited by both vaccination and infection that recognize this peptide block V2-alpha4beta7 interactions. These mAbs recognize conformations absent from the beta- barrel presented in a stabilized HIV SOSIP gp120/41 trimer. The mimicry of MAdCAM-alpha4beta7 interactions by V2 may influence early events in HIV infection, particularly the rapid seeding of gut tissues, and supports the view that HIV replication in gut tissue is a central feature of HIV pathogenesis

Extracellular Vesicles from <i>Naegleria fowleri</i> Induce IL-8 Response in THP-1 Macrophage

Extracellular vesicles (EVs) released from pathogenic protozoans play crucial roles in host–parasite communication and disease pathogenesis. Naegleria fowleri is a free-living protozoan causing primary amoebic meningoencephalitis, a fatal disease in the central nervous system. This study aims to explore the roles of N. fowleri-derived EVs (Nf-EVs) in host–pathogen interactions using the THP-1 cell line as a model. The Nf-EVs were isolated from the N. fowleri trophozoite culture supernatant using sequential centrifugation and characterized by nanoparticle tracking analysis and transmission electron microscopy. The functional roles of Nf-EVs in the apoptosis and immune response induction of THP-1 monocytes and macrophages were examined by flow cytometry, quantitative PCR, and ELISA. Results showed that Nf-EVs displayed vesicles with bilayer membrane structure approximately 130–170 nm in diameter. The Nf-EVs can be internalized by macrophages and induce macrophage responses by induction of the expression of costimulatory molecules CD80, CD86, HLA-DR, and CD169 and the production of cytokine IL-8. However, Nf-EVs did not affect the apoptosis of macrophages. These findings illustrate the potential role of Nf-EVs in mediating the host immune cell activation and disease pathogenesis

Comparison of the expression of potential markers of relative pDCs maturation during acute DENV infection.

<p>(A) Representative histogram plots showing expression of the potential maturation markers on pDCs in blood samples from healthy subjects (solid black line, upper panel) and DENV-infected patients (solid black line, lower panel). The shaded grey histograms represent profiles obtained using isotype controls. The relative proportion of CD40 (B), CD80 (C), CD83 (D), and CD86 (E) -expressing pDCs were compared between healthy subjects and DENV-infected patients of both DF and DHF patients. The box plot shows the median value (horizontal line in the box). The box and whisker represent 25^th to 75^th, and 10^th to 90^th interquartile range, respectively. P values were determined by the Dunn’s post-test after Kruskal-Wallis test for comparison of three groups. (* p < 0.05 and ** p < 0.01).</p

Demographic characteristics of the study population.

<p>Demographic characteristics of the study population.</p

Comparison of the expression of potential markers of relative mDCs maturation during acute DENV infection.

<p>(A) Representative histogram plots showing maturation markers on mDCs on blood samples from healthy subjects (solid black line, upper panel) and DENV-infected patients (solid black line, lower panel). The shaded grey histograms represent profiles obtained using isotype controls. The relative proportion of CD40 (B), CD80 (C), CD83 (D), and CD86 (E) -expressing mDCs were compared on samples from healthy subjects and DENV-infected patients, DF and DHF patients. The box plot shows the median value (horizontal line in the box). The box and whisker represent 25^th to 75^th, and 10^th to 90^th interquartile range, respectively. P values were determined by the Dunn’s post-test after Kruskal-Wallis test for comparison of three groups. (** p < 0.01 and **** p < 0.0001).</p

Comparison of the relative proportion of mDC subsets in DENV infected patients.

<p>Distribution of each of the three mDC subsets as a percentage of total DCs during acute DENV was analyzed from 64 DENV-infected samples and 14 healthy subjects (A). The relative proportion (%) of CD16⁺ mDCs (B), CD1b⁺ mDCs (C) and CD141⁺ mDCs (D) as a percentage of total mDCs in DENV-infected patients were compared with those of healthy subjects. The box plot shows the median value (horizontal line in the box). The box and whisker represent 25^th to 75^th, and 10^th to 90^th interquartile range, respectively. P values were determined by the Mann-Whitney U test for comparison between two groups. (* p < 0.05, *** p <0.001 and **** p < 0.0001).</p

Kinetic changes of the maturation markers on mDCs during acute DENV infection.

<p>Expression of CD40 (A), CD80 (B), CD83 (C) and CD86 (D) -expressing mDCs were determined at different days of fever ranging from febrile day-2 (D-2) and day-1 (D-1) to defervescence day 0 (D0) and day+1 (D+1) and to afebrile day+2 (D+2). Data are median and interquartile range. P values were determined by the Dunn’s post-test after Kruskal-Wallis test for comparison of the three groups. The median of relative proportion on samples from healthy subjects are denoted by a dashed line.</p

Kinetic changes of DC subsets during acute DENV infection.

<p>The kinetics of the relative proportion of mDCs (A), pDCs (B), DN (C), CD16⁺ mDCs (D), CD1b⁺ mDCs (E), and CD141⁺ mDCs (F) on samples from DENV-infected patients were determined at different days of fever ranging from febrile day-2 (D-2) and day-1 (D-1) to defervescence day 0 (D0) and day+1 (D+1) and to afebrile day+2 (D+2). Data are median and interquartile range. P values were determined by the Dunn’s post-test after Kruskal-Wallis test for comparison of the three groups. The median of relative proportion on samples from healthy subjects are denoted by a dashed line.</p

Comparison of the relative proportion and MFI of CD33-expressing mDCs and pDCs during acute DENV infection.

<p>The relative proportion of CD33-expressing mDCs (A) and pDCs (B) were compared between three groups, healthy subjects, DF and DHF patients. The relative proportion of CD33-expressing CD16⁺ mDCs in DENV-infected patients were compared with healthy individuals (C). The MFI of CD33 on mDCs (D), pDCs (E), CD16⁺ mDCs (F), CD1b⁺ mDCs (G), CD141⁺ mDCs (H) were compared between healthy subjects and DENV-infected patients. The box plot shows the median value (horizontal line in the box). The box and whisker represent 25^th to 75^th, and 10^th to 90^th interquartile range, respectively. P values were determined by the Dunn’s post-test after Kruskal-Wallis test for comparison of three groups or Mann-Whitney U test for comparison between two groups. (* p < 0.05, ** p < 0.01, *** p < 0.001 and **** p < 0.0001).</p

Comparison of the relative proportion of mDCs, pDCs and DN subset in blood samples from DENV infected patients and healthy subjects.

<p>The mean of relative proportion (%) of mDCs, pDCs, and DN were analyzed in blood samples from 68 DENV-infected samples and 14 healthy returned subjects (A). The relative proportion of mDCs (B) pDCs (C) and DN subsets (D) were compared between healthy and DENV-infected patients. The relative proportion of mDCs (E), pDCs (F) and DN subsets (G) were compared between DF and DHF patients. The box plot shows the median value (horizontal line in the box). The box and whisker represent 25^th to 75^th, and 10^th to 90^th interquartile range, respectively. P values were determined by the Mann-Whitney U test for comparison of two groups. (* p < 0.05, *** p < 0.001 and **** p < 0.0001).</p