Biology subjects

Skerry, C.

Publications and source records attributed to Skerry, C..

4 recordsLinked to original sources

bioRxiv2025

A dual role for PGLYRP1 in host defense and immune regulation during B. pertussis infection

Bordetella pertussis, the etiologic agent of whooping cough, remains a serious public health concern despite widespread vaccination. Improved therapeutics and vaccines are urgently needed to treat and prevent pertussis disease. Host recognition of bacterial peptidoglycan (PGN), including B. pertussis extracellular PGN fragment tracheal cytotoxin (TCT), shapes the immune response to infection. Peptidoglycan recognition proteins (PGLYRPs) are a conserved family of innate immune molecules which bind bacterial PGN. While they function as immune signaling receptors in arthropods (termed PGRPs in arthropods), PGLYRPs in mammals have thus far been primarily recognized for their bactericidal activity. Previously thought to function only as antimicrobial peptides in mammals, the immune modulatory roles of this family of peptidoglycan recognition proteins are beginning to gain greater appreciation. Peptidoglycan recognition protein 1 (PGLYRP1) is a secreted antimicrobial protein. However, its role in mammalian host defenses and immune signaling during infection with Gram-negative pathogens, such as B. pertussis, remain largely unknown. Here, we identify a dual role for PGLYRP1 in modulating host immune responses to B. pertussis. Using knockout mice, single-cell and bulk transcriptomics and functional assays, we show that PGLYRP1 contributes to host antibacterial responses to B. pertussis. PGLYRP1 also dampens inflammatory responses and paradoxically inhibits bacterial killing later in infection. Mechanistically, PGLYRP1 enhances nucleotide oligomerization domain (NOD)-1 signaling in response to TCT while suppressing NOD2- and triggering receptor expressed on myeloid cells-1 (TREM-1)-mediated inflammatory pathways. TCT-bound PGLYRP1 selectively impairs TREM-1 activation compared to PGNs from other bacteria, revealing a novel bacterial immune evasion strategy. These findings demonstrate that B. pertussis co-opts PGLYRP1 to temper inflammation and alter immune signaling, revealing a novel immune evasion mechanism of manipulating the availability and structure of their exogenous peptidoglycan, revealing implications for host-pathogen evolution, vaccine design and host-directed therapeutics.

microbiology↗

bioRxiv2025

B. pertussis tracheal cytotoxin biases NOD signaling to suppress IL-1 mediated inflammation and evade adaptive immunity

Bordetella pertussis releases the monomeric peptidoglycan (PGN) fragment tracheal cytotoxin (TCT) due to inefficient recycling by the permease AmpG. Releasing this PGN is metabolically costly and potentially immune alarming and the benefits to B. pertussis are unclear. While TCT has been characterized as a potent NOD1 agonist capable of causing the extrusion of ciliated cells, in vitro, the consequences of its release have yet to be studied in vivo. Here we show that selective PGN release by B. pertussis biases host PGN sensing toward NOD1 and away from NOD2, suppressing IL-1{beta}-driven inflammation and blunting adaptive immune recruitment. Mice infected with a TCT over-releasing strain (TCT(+)) exhibit reduced pulmonary immunopathology relative to wild type (WT) and a TCT-under-releasing strain (TCT(-)), despite similar bacterial burdens. NOD reporter assays demonstrate that TCT release enhances NOD1 activation and inversely correlates with NOD2 activation. Bulk transcriptomic analysis of infected lungs shows that B. pertussis PGN release dampens pro-inflammatory transcriptional programs. Single-cell transcriptomic determined Nod2 expression is limited to inflammatory myeloid subsets. IL-1 family genes were highly enriched in Nod2- but not Nod1 expressing alveolar macrophages. Upstream regulator analysis predicted IL-1{beta} as a major driver of B. pertussis inflammation, which was enhanced by the absence of PGN release. Flow cytometry shows that PGN release skews macrophages polarization toward M2 and away from M1 in a NOD1 dependent manner. Finally, extracellular release of PGN and subsequent reduced IL-1 production facilitated the suppression fibroblast chemokine programs (e.g., CXCL13, CCL19), diminished recruitment of B and T cells, reduced iBALT formation, and limited immune memory development. Conversely, IL-1R1 deficiency impairs adaptive recruitment and bacterial clearance despite similar innate infiltration. Together, these data suggest PGN release by B. pertussis is an immune-evasion strategy, favoring NOD1 activation over NOD2, reducing IL-1-dependent fibroblast reprogramming, and curtailing chemokine-driven adaptive responses. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/669383v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@ada335org.highwire.dtl.DTLVardef@1b61a0eorg.highwire.dtl.DTLVardef@68c66eorg.highwire.dtl.DTLVardef@bb6e54_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 8.C_FLOATNO Graphic Abstract B. pertussis can produce both NOD1 and NOD2 activating PGNs. Release of TCT promotes NOD1 activation and diminishes NOD2 activation. NOD2 activation in myeloid cells drives M1 polarization of macrophages and IL-1 family cytokine production. IL-1 family cytokines skew fibroblasts towards an inflammatory phenotype, leading to chemokine release, extracellular remodeling, and recruitment of lymphocytes. Therefore, TCT release tempers long-term immunity to B. pertussis. C_FIG

microbiology↗

bioRxiv2023

Tick hemocytes have pleiotropic roles in microbial infection and arthropod fitness

Uncovering the complexity of systems in non-model organisms is critical for understanding arthropod immunology. Prior efforts have mostly focused on Dipteran insects, which only account for a subset of existing arthropod species in nature. Here, we describe immune cells or hemocytes from the clinically relevant tick Ixodes scapularis using bulk and single cell RNA sequencing combined with depletion via clodronate liposomes, RNA interference, Clustered Regularly Interspaced Short Palindromic Repeats activation (CRISPRa) and RNA-fluorescence in situ hybridization (FISH). We observe molecular alterations in hemocytes upon tick infestation of mammals and infection with either the Lyme disease spirochete Borrelia burgdorferi or the rickettsial agent Anaplasma phagocytophilum. We predict distinct hemocyte lineages and reveal clusters exhibiting defined signatures for immunity, metabolism, and proliferation during hematophagy. Furthermore, we perform a mechanistic characterization of two I. scapularis hemocyte markers: hemocytin and astakine. Depletion of phagocytic hemocytes affects hemocytin and astakine levels, which impacts blood feeding and molting behavior of ticks. Hemocytin specifically affects the c-Jun N-terminal kinase (JNK) signaling pathway, whereas astakine alters hemocyte proliferation in I. scapularis. Altogether, we uncover the heterogeneity and pleiotropic roles of hemocytes in ticks and provide a valuable resource for comparative biology in arthropods.

immunology↗

bioRxiv2020

Pharmacological targeting of host chaperones protects from pertussis toxin in vitro and in vivo

Whooping cough is caused by Bordetella pertussis that releases pertussis toxin (PT) which comprises enzyme A-subunit PTS1 and binding/transport B-subunit. After receptor-mediated endocytosis, PT reaches the endoplasmic reticulum from where unfolded PTS1 is transported to the cytosol. PTS1 ADP-ribosylates G-protein -subunits resulting in increased cAMP signaling. Here, the role of target cell chaperones Hsp90, Hsp70, cyclophilins and FK506-binding proteins for cytosolic PTS1-uptake is characterized in detail. PTS1 specifically and directly interacts with chaperones in vitro and in cells. Specific pharmacological chaperone inhibition protects CHO-K1, human primary airway basal cells and a fully differentiated airway epithelium from PT-intoxication by reducing cytosolic PTS1-amounts without affecting cell binding or enzyme activity. PT is internalized by human airway epithelium secretory but not ciliated cells and leads to increase of apical surface liquid. Cyclophilin-inhibitors reduced leukocytosis in infant mouse model of pertussis, indicating their promising potential for developing novel therapeutic strategies against whooping cough.

pharmacology and toxicology↗