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Open Access Publications from the University of California

Scholarly Works (10 results)

  • Article
  • Peer Reviewed
UC San Diego Previously Published Works (2021)

Objective

To synthesize investigations into the role of lipid-mediated recruitment and activation of group 2 innate lymphoid cells (ILC2s) in aspirin-exacerbated respiratory disease (AERD).

Data sources

A comprehensive literature review of reports pertaining to cellular mechanisms, cytokine, and lipid mediators in AERD, as well as ILC2 activation and recruitment, was performed using PubMed and Google Scholar.

Study selections

Selections of studies were based on reports of lipid mediators in AERD, cytokine mediators in AERD, type 2 effector cells in AERD, platelets in AERD, AERD treatment, ILC2s in allergic airway disease, and ILC2 activation, inhibition, and trafficking.

Results

The precise mechanisms of AERD pathogenesis are not well understood. Greater levels of proinflammatory lipid mediators and type 2 cytokines are found in tissues derived from patients with AERD relative to controls. After pathognomonic cyclooxygenase-1 inhibitor reactions, proinflammatory mediator concentrations (prostaglandin D2 and cysteinyl leukotrienes) are rapidly increased, as are ILC2 levels in the nasal mucosa. The ILC2s, which potently generate type 2 cytokines in response to lipid mediator stimulation, may play a key role in AERD pathogenesis.

Conclusion

Although the literature suggests that lipid-mediated ILC2 activation may occur in AERD, there is a dearth of definitive evidence. Future investigations leveraging novel next-generation single-cell sequencing approaches along with recently developed AERD murine models will better define lipid mediator-induced ILC2 trafficking in patients with AERD.
    Cover page: Lipid-mediated innate lymphoid cell recruitment and activation in aspirin-exacerbated respiratory disease
    • Thesis
    • Peer Reviewed
    UC San Diego Electronic Theses and Dissertations (2024)

    The aim of this dissertation is to increase the understanding of the complex cellular communication network underlying skin immunity, with a focus on the role of fibroblasts. Dermal fibroblasts are appreciated for supporting tissue architecture and scar formation but have historically been ignored in terms of immunology. I begin this dissertation with a literature review on the topic of fibroblast immune function, which led to my innovative hypothesis that subsets of fibroblasts are critical for skin inflammation and host defense. To test my hypothesis, I performed an unbiased network analysis of mouse skin during Staphylococcus aureus infection and discovered CXCL12+ immune acting fibroblast (IAF) subsets with a dominant role in neutrophil communication. Subsequent experiments to characterize this novel cell population demonstrated that CXCL12+ IAFs predominantly reside in the reticular dermis, express adipocyte lineage markers, detect IL-17 and TNF⍺, and promote robust neutrophil recruitment through NFKBIZ-dependent release of CXCR2 ligands and CXCL12. Targeted deletion of Il17ra in mouse fibroblasts resulted in greatly reduced neutrophil recruitment and increased infection by S. aureus, demonstrating the significance of CXCL12+ IAFs. I next asked if CXCL12+ IAFs are involved in psoriasis, a human inflammatory skin disease responsive to drugs targeting IL-17 and TNF⍺. Using single-cell transcriptomics, analogous CXCL12+ IAFs were identified in human psoriatic skin. Importantly, therapeutic targeting of IL-17 decreased fibroblast expression of neutrophil chemokines, demonstrating that IL-17 inhibitors work, in part, by inhibiting CXCL12+ IAF communication with neutrophils. Finally, to characterize the cell-cell interactions underlying human neutrophilic dermatoses, I performed bulk, single-nuclei, and spatial transcriptomics on skin biopsies from patients with Sweet’s syndrome (SS), pustular psoriasis, and pyoderma gangrenosum. This analysis led to the identification interferon (IFN)-activated IAFs enriched in SS. To test the significance of the IFN signature, I performed experiments with cultured fibroblasts and found that type 1 IFN induced fibroblast expression of neutrophil chemokines, implicating IFN-activated IAFs in SS pathogenesis. In summary, this dissertation unveils the pivotal role of dermal IAFs in orchestrating skin immunity. Using a combination of bioinformatics, in vitro systems, murine models, and clinical samples, this work provides unprecedented insight into the intricate cellular communication network underlying skin inflammation and host defense. These findings contribute significantly to our understanding of immunology and lay the groundwork for the development of novel treatments for infectious and inflammatory diseases.

      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2022)
      The term fibroblast has been used generally to describe spindle-shaped stromal cells of mesenchymal origin that produce extracellular matrix, establish tissue structure, and form scar. Current evidence has found that cells with this morphology are highly heterogeneous with some fibroblastic cells actively participating in both innate and adaptive immune defense. Detailed analysis of barrier tissues such as skin, gut, and lung now show that some fibroblasts directly sense pathogens and other danger signals to elicit host defense functions including antimicrobial activity, leukocyte recruitment, and production of cytokines and lipid mediators relevant to inflammation and immunosuppression. This review will synthesize current literature focused on the innate immune functions performed by fibroblasts at barrier tissues to highlight the previously unappreciated importance of these cells in immunity.
        Cover page: Essential immune functions of fibroblasts in innate host defense
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2017)

        Background

        Aspirin-exacerbated respiratory disease (AERD) is characterized by tissue eosinophilia and mast cell activation, including abundant production of prostaglandin D2 (PGD2). Group 2 innate lymphoid cells (ILC2s), which promote tissue eosinophilia and mast cell responses, undergo chemotaxis and cytokine production in response to PGD2, but it is unknown whether ILC2s are active in patients with AERD.

        Objective

        We sought to determine whether ILC2 numbers change in peripheral blood and the nasal mucosa during COX-1 inhibitor-induced reactions in patients with AERD.

        Methods

        Blood and nasal scrapings were collected at baseline, during reactions, and after completion of ketorolac/aspirin challenge/desensitization in 12 patients with AERD. ILC2s and eosinophils were quantitated by means of flow cytometry. Urine was also collected, and quantification of PGD2 metabolite and leukotriene E4 levels was done by using ELISA. Baseline and nonsteroidal anti-inflammatory drug reaction clinical data were correlated with cell changes.

        Results

        ILC2 numbers significantly increased in nasal mucosal samples and decreased in blood at the time of COX-1 inhibitor reactions in 12 patients with AERD. These changes were not observed in 2 patients without AERD. Furthermore, eosinophil numbers decreased in blood concurrently with significant increases in urinary PGD2 metabolite and leukotriene E4 levels. The magnitude of increases in nasal mucosal ILC2 numbers positively correlated with maximum symptom scores during challenges. Furthermore, blood ILC2 numbers during the reaction correlated with time for the reaction to resolve, possibly reflecting reaction severity.

        Conclusions

        ILC2s are recruited to the nasal mucosa during COX-1 inhibitor-induced reactions in patients with AERD, correlating with enhanced production of prostaglandins and leukotrienes.
          Cover page: Group 2 innate lymphoid cells are recruited to the nasal mucosa in patients with aspirin-exacerbated respiratory disease
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2024)
          The skin provides an essential barrier for host defense through rapid action of multiple resident and recruited cell types, but the complex communication network governing these processes is incompletely understood. To define these cell-cell interactions more clearly, we performed an unbiased network analysis of mouse skin during invasive S. aureus infection and revealed a dominant role for CXCL12+ fibroblast subsets in neutrophil communication. These subsets predominantly reside in the reticular dermis, express adipocyte lineage markers, detect IL-17 and TNFα, and promote robust neutrophil recruitment through NFKBIZ-dependent release of CXCR2 ligands and CXCL12. Targeted deletion of Il17ra in mouse fibroblasts resulted in greatly reduced neutrophil recruitment and increased infection by S. aureus. Analogous human CXCL12+ fibroblast subsets abundantly express neutrophil chemotactic factors in psoriatic skin that are subsequently decreased upon therapeutic targeting of IL-17. These findings show that CXCL12+ dermal immune acting fibroblast subsets play a critical role in cutaneous neutrophil recruitment and host defense.
            Cover page: CXCL12+ dermal fibroblasts promote neutrophil recruitment and host defense by recognition of IL-17
            • Article
            • Peer Reviewed
            UC San Diego Previously Published Works (2021)
            As the number of human microbiome studies expand, it is increasingly important to identify cost-effective, practical preservatives that allow for room temperature sample storage. Here, we reanalyzed 16S rRNA gene amplicon sequencing data from a large sample storage study published in 2016 and performed shotgun metagenomic sequencing on remnant DNA from this experiment. Both results support the initial findings that 95% ethanol, a nontoxic, cost-effective preservative, is effective at preserving samples at room temperature for weeks. We expanded on this analysis by collecting a new set of fecal, saliva, and skin samples to determine the optimal ratio of 95% ethanol to sample. We identified optimal collection protocols for fecal samples (storing a fecal swab in 95% ethanol) and saliva samples (storing unstimulated saliva in 95% ethanol at a ratio of 1:2). Storing skin swabs in 95% ethanol reduced microbial biomass and disrupted community composition, highlighting the difficulties of low biomass sample preservation. The results from this study identify practical solutions for large-scale analyses of fecal and oral microbial communities.IMPORTANCE Expanding our knowledge of microbial communities across diverse environments includes collecting samples in places far from the laboratory. Identifying cost-effective preservatives that will enable room temperature storage of microbial communities for sequencing analysis is crucial to enabling microbiome analyses across diverse populations. Here, we validate findings that 95% ethanol efficiently preserves microbial composition at room temperature for weeks. We also identified the optimal ratio of 95% ethanol to sample for stool and saliva to preserve both microbial load and composition. These results provide rationale for an accessible, nontoxic, cost-effective solution that will enable crowdsourcing microbiome studies, such as The Microsetta Initiative, and lower the barrier for collecting diverse samples.
              Cover page: Evaluation of the Effect of Storage Methods on Fecal, Saliva, and Skin Microbiome Composition
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (2019)
              We demonstrate that unconventional ST2- and CD127-negative ILC2 populations are present in mouse lung and are induced by Alternaria, suggesting commonly used ILC2 identification practices do not accurately enumerate the total burden of type 2 cytokine producing ILC2s.
                Cover page: Unconventional ST2- and CD127-negative lung ILC2 populations are induced by the fungal allergen Alternaria alternata
                • Article
                • Peer Reviewed
                UC San Diego Previously Published Works (2023)
                During inflammation, the skin deploys antimicrobial peptides (AMPs) yet during allergic inflammation it becomes more susceptible to Staphylococcus aureus. To understand this contradiction, single-cell sequencing of Il4ra-/- mice combined with skin microbiome analysis reveals that lower production of AMPs from interleukin-4 receptor α (IL-4Rα) activation selectively inhibits survival of antibiotic-producing strains of coagulase-negative Staphylococcus (CoNS). Diminished AMPs under conditions of T helper type 2 (Th2) inflammation enable expansion of CoNS strains without antibiotic activity and increase Staphylococcus aureus (S. aureus), recapitulating the microbiome on humans with atopic dermatitis. This response is rescued in Camp-/- mice or after topical steroids, since further inhibition of AMPs enables survival of antibiotic-producing CoNS strains. In conditions of Th17 inflammation, a higher expression of host AMPs is sufficient to directly inhibit S. aureus survival. These results show that antimicrobials produced by the host and commensal bacteria each act to control S. aureus on the skin.
                  Cover page: Competition between skin antimicrobial peptides and commensal bacteria in type 2 inflammation enables survival of S. aureus.
                  • Article
                  • Peer Reviewed
                  UC San Diego Previously Published Works (2022)
                  Innate immune defense against deep tissue infection by Staphylococcus aureus is orchestrated by fibroblasts that become antimicrobial when triggered to differentiate into adipocytes. However, the role of this process in noninfectious human diseases is unknown. To investigate the potential role of adipogenesis by dermal fibroblasts in acne, a disorder triggered by Cutibacterium acnes, single-cell RNA sequencing was performed on human acne lesions and mouse skin challenged by C. acnes. A transcriptome consistent with adipogenesis was observed within specific fibroblast subsets from human acne and mouse skin lesions infected with C. acnes. Perifollicular dermal preadipocytes in human acne and mouse skin lesions showed colocalization of PREF1, an early marker of adipogenesis, and cathelicidin (Camp), an antimicrobial peptide. This capacity of C. acnes to specifically trigger production of cathelicidin in preadipocytes was dependent on TLR2. Treatment of wild-type mice with retinoic acid (RA) suppressed the capacity of C. acnes to form acne-like lesions, inhibited adipogenesis, and enhanced cathelicidin expression in preadipocytes, but lesions were unresponsive in Camp-/- mice, despite the anti-adipogenic action of RA. Analysis of inflamed skin of acne patients after retinoid treatment also showed enhanced induction of cathelicidin, a previously unknown beneficial effect of retinoids in difficult-to-treat acne. Overall, these data provide evidence that adipogenic fibroblasts are a critical component of the pathogenesis of acne and represent a potential target for therapy.
                    Cover page: Antimicrobial production by perifollicular dermal preadipocytes is essential to the pathophysiology of acne
                    • Article
                    • Peer Reviewed
                    UC San Diego Previously Published Works (2021)
                    Inflammatory disorders of the skin are frequently associated with inflammatory bowel diseases (IBDs). To explore mechanisms by which these organs communicate, we performed single-cell RNA-Seq analysis on fibroblasts from humans and mice with IBD. This analysis revealed that intestinal inflammation promoted differentiation of a subset of intestinal stromal fibroblasts into preadipocytes with innate antimicrobial host defense activity. Furthermore, this process of reactive adipogenesis was exacerbated if mouse skin was inflamed as a result of skin wounding or infection. Since hyaluronan (HA) catabolism is activated during skin injury and fibroblast-to-adipocyte differentiation is dependent on HA, we tested the hypothesis that HA fragments could alter colon fibroblast function by targeted expression of human hyaluronidase-1 in basal keratinocytes from mouse skin. Hyaluronidase expression in the skin activated intestinal stromal fibroblasts, altered the fecal microbiome, and promoted excessive reactive adipogenesis and increased inflammation in the colon after challenge with dextran sodium sulfate. The response to digested HA was dependent on expression of TLR4 by preadipocytes. Collectively, these results suggest that the association between skin inflammation and IBD may be due to recognition by mesenchymal fibroblasts in the colon of HA released during inflammation of the skin.
                      Cover page: Skin inflammation activates intestinal stromal fibroblasts and promotes colitis
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