Engineering Protein Nanoparticles Functionalized with an Immunodominant Coxiella burnetii Antigen to Generate a Q Fever Vaccine

Coxiella burnetii is the causative agent of Q fever, for which there is yet to be an FDA-approved vaccine. This bacterial pathogen has both extra- and intracellular stages in its life cycle, and therefore both a cell-mediated (i.e., T lymphocyte) and humoral (i.e., antibody) immune response are necessary for effective eradication of this pathogen. However, most proposed vaccines elicit strong responses to only one mechanism of adaptive immunity, and some can either cause reactogenicity or lack sufficient immunogenicity. In this work, we aim to apply a nanoparticle-based platform toward producing both antibody and T cell immune responses against C. burnetii. We investigated three approaches for conjugation of the immunodominant outer membrane protein antigen (CBU1910) to the E2 nanoparticle to obtain a consistent antigen orientation: direct genetic fusion, high affinity tris-NTA-Ni conjugation to polyhistidine-tagged CBU1910, and the SpyTag/SpyCatcher (ST/SC) system. Overall, we found that the ST/SC approach yielded nanoparticles loaded with the highest number of antigens while maintaining stability, enabling formulations that could simultaneously co-deliver the protein antigen (CBU1910) and adjuvant (CpG1826) on one nanoparticle (CBU1910-CpG-E2). Using protein microarray analyses, we found that after immunization, antigen-bound nanoparticle formulations elicited significantly higher antigen-specific IgG responses than soluble CBU1910 alone and produced more balanced IgG1/IgG2c ratios. Although T cell recall assays from these protein antigen formulations did not show significant increases in antigen-specific IFN-γ production compared to soluble CBU1910 alone, nanoparticles conjugated with a CD4 peptide epitope from CBU1910 generated elevated T cell responses in mice to both the CBU1910 peptide epitope and whole CBU1910 protein. These investigations highlight the feasibility of conjugating antigens to nanoparticles for tuning and improving both humoral- and cell-mediated adaptive immunity against C. burnetii.

Rigorous benchmarking of T-cell receptor repertoire profiling methods for cancer RNA sequencing

The ability to identify and track T-cell receptor (TCR) sequences from patient samples is becoming central to the field of cancer research and immunotherapy. Tracking genetically engineered T cells expressing TCRs that target specific tumor antigens is important to determine the persistence of these cells and quantify tumor responses. The available high-throughput method to profile TCR repertoires is generally referred to as TCR sequencing (TCR-Seq). However, the available TCR-Seq data are limited compared with RNA sequencing (RNA-Seq). In this paper, we have benchmarked the ability of RNA-Seq-based methods to profile TCR repertoires by examining 19 bulk RNA-Seq samples across 4 cancer cohorts including both T-cell-rich and T-cell-poor tissue types. We have performed a comprehensive evaluation of the existing RNA-Seq-based repertoire profiling methods using targeted TCR-Seq as the gold standard. We also highlighted scenarios under which the RNA-Seq approach is suitable and can provide comparable accuracy to the TCR-Seq approach. Our results show that RNA-Seq-based methods are able to effectively capture the clonotypes and estimate the diversity of TCR repertoires, as well as provide relative frequencies of clonotypes in T-cell-rich tissues and low-diversity repertoires. However, RNA-Seq-based TCR profiling methods have limited power in T-cell-poor tissues, especially in highly diverse repertoires of T-cell-poor tissues. The results of our benchmarking provide an additional appealing argument to incorporate RNA-Seq into the immune repertoire screening of cancer patients as it offers broader knowledge into the transcriptomic changes that exceed the limited information provided by TCR-Seq.

Pharmacy undergraduate programs: Development of an adaptive curriculum for student success

Objectives

Applicants for graduate work in Pharmacy on paper appear competitive, but upon entering a Doctor of Pharmacy (PharmD) program many students struggle with course work, course load, and pharmacologic topics in their first-year studies. In addition to math and science, undergraduate candidates need to have skills that enable them to be adaptable and creative learners. The Pharmacy Undergraduate Program (PUP) at the University of Southern California (USC) has been attentive to these educational needs. In this manuscript we will show how our program has been successful in generating well-prepared and successful candidates for graduate programs (pharmaceutical, clinical, medical, and other) and employment in pharmaceutical fields.

Methods

A review of current student enrollments (N = 121), graduated student annual survey data (N = 50), student research data (N = 68), and ongoing course surveys have been used to detail information related to PUP.

Results

Students who have graduated from PUP have been successful post-graduation. Graduates of PUP have gone on to PharmD programs 44% (22/50); medical school 16% (8/50); PhD programs 24% (12/50); full-time employment 6% (3/50); internship/volunteer positions 10% (5/50); taken a gap year 4% (2/50); and MS/MA program 2% (1/50).

Conclusions

PUP has been successful in helping the admission of our students into graduate degree programs related to pharmaceutical sciences and medicine. This success can be attributed to the dynamic nature of the course offerings and the creativity of the teaching faculty, which leads to students being well-prepared to tackle the rigors of their graduate studies after leaving the program.

pyTCR: A comprehensive and scalable solution for TCR-Seq data analysis to facilitate reproducibility and rigor of immunogenomics research

T cell receptor (TCR) studies have grown substantially with the advancement in the sequencing techniques of T cell receptor repertoire sequencing (TCR-Seq). The analysis of the TCR-Seq data requires computational skills to run the computational analysis of TCR repertoire tools. However biomedical researchers with limited computational backgrounds face numerous obstacles to properly and efficiently utilizing bioinformatics tools for analyzing TCR-Seq data. Here we report pyTCR, a computational notebook-based solution for comprehensive and scalable TCR-Seq data analysis. Computational notebooks, which combine code, calculations, and visualization, are able to provide users with a high level of flexibility and transparency for the analysis. Additionally, computational notebooks are demonstrated to be user-friendly and suitable for researchers with limited computational skills. Our tool has a rich set of functionalities including various TCR metrics, statistical analysis, and customizable visualizations. The application of pyTCR on large and diverse TCR-Seq datasets will enable the effective analysis of large-scale TCR-Seq data with flexibility, and eventually facilitate new discoveries.

Advancements in protein nanoparticle vaccine platforms to combat infectious disease

Infectious diseases are a major threat to global human health, yet prophylactic treatment options can be limited, as safe and efficacious vaccines exist only for a fraction of all diseases. Notably, devastating diseases such as acquired immunodeficiency syndrome (AIDS) and coronavirus disease of 2019 (COVID-19) currently do not have vaccine therapies. Conventional vaccine platforms, such as live attenuated vaccines and whole inactivated vaccines, can be difficult to manufacture, may cause severe side effects, and can potentially induce severe infection. Subunit vaccines carry far fewer safety concerns due to their inability to cause vaccine-based infections. The applicability of protein nanoparticles (NPs) as vaccine scaffolds is promising to prevent infectious diseases, and they have been explored for a number of viral, bacterial, fungal, and parasitic diseases. Many types of protein NPs exist, including self-assembling NPs, bacteriophage-derived NPs, plant virus-derived NPs, and human virus-based vectors, and these particular categories will be covered in this review. These vaccines can elicit strong humoral and cellular immune responses against specific pathogens, as well as provide protection against infection in a number of animal models. Furthermore, published clinical trials demonstrate the promise of applying these NP vaccine platforms, which include bacteriophage-derived NPs, in addition to multiple viral vectors that are currently used in the clinic. The continued investigations of protein NP vaccine platforms are critical to generate safer alternatives to current vaccines, advance vaccines for diseases that currently lack effective prophylactic therapies, and prepare for the rapid development of new vaccines against emerging infectious diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

Unique molecular signatures of antiviral memory CD8+ T cells associated with asymptomatic recurrent ocular herpes

The nature of antiviral CD8+ T cells associated with protective and pathogenic herpes simplex virus type 1 (HSV-1) infections remains unclear. We compared the transcriptome, phenotype, and function of memory CD8+ T cells, sharing the same HSV-1 epitope-specificities, from infected HLA-A*0201 positive symptomatic (SYMP) vs. asymptomatic (ASYMP) individuals and HLA-A*0201 transgenic rabbits. Compared to higher frequencies of multifunctional effector memory CD8+ TEM cells in ASYMP individuals, the SYMP individuals presented dysfunctional CD8+ TEM cells, expressing major exhaustion pathways. Compared to protected ASYMP HLA transgenic rabbits, the trigeminal ganglia of non-protected SYMP HLA transgenic rabbits had higher frequencies of dysfunctional tissue-resident CD8+ TRM cells. Moreover, blockade of T cell exhaustion pathways restored the function of CD8+ T cells, reduced virus reactivation, and diminished recurrent disease in HLA transgenic rabbits. These findings reveal unique molecular signatures of protective CD8+ T cells and pave the way for T-cell-based immunotherapy to combat recurrent ocular herpes.

Tuning Subunit Vaccines with Novel TLR Triagonist Adjuvants to Generate Protective Immune Responses against Coxiella burnetii

Coxiella burnetii is an obligate intracellular bacterium and the causative agent of Q fever. C. burnetii is considered a potential bioterrorism agent because of its low infectious dose; resistance to heat, drying, and common disinfectants; and lack of prophylactic therapies. Q-Vax, a formalin-inactivated whole-bacteria vaccine, is currently the only prophylactic measure that is protective against C. burnetii infections but is not U.S. Food and Drug Administration approved. To overcome the safety concerns associated with the whole-bacteria vaccine, we sought to generate and evaluate recombinant protein subunit vaccines against C. burnetii To accomplish this, we formulated C. burnetii Ags with a novel TLR triagonist adjuvant platform, which used combinatorial chemistry to link three different TLR agonists together to form one adjuvanting complex. We evaluated the immunomodulatory activity of a panel of TLR triagonist adjuvants and found that they elicited unique Ag-specific immune responses both in vitro and in vivo. We evaluated our top candidates in a live C. burnetii aerosol challenge model in C56BL/6 mice and found that several of our novel vaccine formulations conferred varying levels of protection to the challenged animals compared with sham immunized mice, although none of our candidates were as protective as the commercial vaccine across all protection criteria that were analyzed. Our findings characterize a novel adjuvant platform and offer an alternative approach to generating protective and effective vaccines against C. burnetii.

Linked Toll-Like Receptor Triagonists Stimulate Distinct, Combination-Dependent Innate Immune Responses

Traditional vaccination strategies have failed to generate effective vaccines for many infections like tuberculosis and HIV. New approaches are needed for each type of disease. The protective immunity and distinct responses of many successful vaccines come from activating multiple Toll-like receptors (TLRs). Vaccines with multiple TLRs as adjuvants have proven effective in preclinical studies, but current research has not explored two important elements. First, few multi-TLR systems explore spatial organization-a critical feature of whole-cell vaccines. Second, no multi-TLR systems to date provide systematic analysis of the combinatorial space of three TLR agonists. Here, we present the first examination of the combinatorial space of several spatially defined triple-TLR adjuvants, by synthesizing a series of five triple-TLR agonists and testing their innate activity both in vitro and in vivo. The combinations were evaluated by measuring activation of immune stimulatory genes (Nf-κB, ISGs), cytokine profiles (IL12-p70, TNF-α, IL-6, IL-10, CCL2, IFN-α, IFN-β, IFN-γ), and in vivo cytokine serum levels (IL-6, TNF-α, IL12-p40, IFN-α, IFN-β). We demonstrate that linking TLR agonists substantially alters the resulting immune response compared to their unlinked counterparts and that each combination results in a distinct immune response, particularly between linked combinations. We show that combinations containing a TLR9 agonist produce more Th1 biasing immune response profiles, and that the effect is amplified upon conjugation. However, combinations containing TLR2/6 agonist are skewed toward T_H2 biasing profiles despite the presence of TLR9. These results demonstrate the profound effects that conjugation and combinatorial administration of TLR agonists can have on immune responses, a critical element of vaccine development.

A pathogen-free flow cytometry based opsonophagocytosis assay protocol to quantify antibody-mediated phagocytosis

An important function of antibodies is their ability to mark cells for phagocytosis and subsequent degradation in a process known as opsonization. When developing new vaccine candidates, it is critical to determine whether the antigen specific antibodies elicited in response to immunization have this function. Due to the high containment working constraints of several important human pathogens, it is not always possible to directly study this property using the pathogen of interest. Therefore, we sought to develop a pathogen-free, flow cytometry based assay to quantify the opsonizing activity of antibodies elicited in response to immunization. We studied this using vaccine candidates against Coxiella burnetii, the causative agent of Q-fever that is a potential bioterrorism agent. In our assay, fluorescent polystyrene beads were conjugated to C. burnetii proteins then incubated with the antibody-containing sera. The antibody-coated beads were incubated with macrophages and phagocytosis of the fluorescent beads was assayed by flow cytometry. This assay allows for rapid quantification of the opsonizing capacity of antigen specific antibodies elicited in response to immunization.

CCL28 Is Involved in Mucosal IgA Responses, Olfaction, and Resistance to Enteric Infections

CCL28 is a mucosal chemokine that has been involved in various responses, including IgA production. We have analyzed its production in human tissues using a comprehensive microarray database. Its highest expression is in the salivary gland, indicating that it is an important component of saliva. It is also expressed in the trachea, bronchus, and in the mammary gland upon onset of lactation. We have also characterized a Ccl28-/- mouse that exhibits very low IgA levels in milk, and the IgA levels in feces are also reduced. These observations confirm a role for the CCL28/CCR10 chemokine axis in the recruitment of IgA plasmablasts to the lactating mammary gland. CCL28 is also expressed in the vomeronasal organ. We also detected olfactory defects (anosmia) in a Ccl28-/- mouse suggesting that CCL28 is involved in the function/development of olfaction. Importantly, Ccl28-/- mice are highly susceptible to Salmonella enterica serovar Typhimurium in an acute model of infection, indicating that CCL28 plays a major role in innate immunity against Salmonella in the gut. Finally, microbiome studies revealed modest differences in the gut microbiota between Ccl28-/- mice and their cohoused wild-type littermates. The latter observation suggests that under homeostatic conditions, CCL28 plays a limited role in shaping the gut microbiome.

Identification of IL-40, a Novel B Cell-Associated Cytokine

We describe a novel B cell-associated cytokine, encoded by an uncharacterized gene (C17orf99; chromosome 17 open reading frame 99), that is expressed in bone marrow and fetal liver and whose expression is also induced in peripheral B cells upon activation. C17orf99 is only present in mammalian genomes, and it encodes a small (∼27-kDa) secreted protein unrelated to other cytokine families, suggesting a function in mammalian immune responses. Accordingly, C17orf99 expression is induced in the mammary gland upon the onset of lactation, and a C17orf99^-/- mouse exhibits reduced levels of IgA in the serum, gut, feces, and lactating mammary gland. C17orf99^-/- mice have smaller and fewer Peyer's patches and lower numbers of IgA-secreting cells. The microbiome of C17orf99^-/- mice exhibits altered composition, likely a consequence of the reduced levels of IgA in the gut. Although naive B cells can express C17orf99 upon activation, their production increases following culture with various cytokines, including IL-4 and TGF-β1, suggesting that differentiation can result in the expansion of C17orf99-producing B cells during some immune responses. Taken together, these observations indicate that C17orf99 encodes a novel B cell-associated cytokine, which we have called IL-40, that plays an important role in humoral immune responses and may also play a role in B cell development. Importantly, IL-40 is also expressed by human activated B cells and by several human B cell lymphomas. The latter observations suggest that it may play a role in the pathogenesis of certain human diseases.

Development of a tri-agonist compound library used to determine optimal adjuvanticity of a Q fever vaccine

Vaccines are one of the most successful treatments for disease. However, the development of more effective vaccines is still necessary for diseases, such as malaria and HIV. Recently, researchers have demonstrated that administering a target antigen with multiple immune agonists, especially Toll-like receptor (TLR) agonists, can enhance specific immune responses. Thus, suggesting that vaccines will require synergistic activity of multiple agonists to effectively activate the immune system and eliminate disease. In addition, vaccine development would greatly benefit from understanding the effect distinct combinations of immune agonists have on immune activity. This information would allow us to more rationally design vaccines that elicit directed and prolonged immune responses. Previously, we probed immune system responses by conjugating three TLR agonists together. Testing our construct in vitro and in vivo, we were able to modulate innate immune and antibody responses, suggesting downstream changes in immune signaling and adaptive immune activation. Here, we synthesized a library of tri-agonist compounds and examined how different covalently linked TLR agonist combinations affected immune activation via NF-kB activity and cytokine production. We are currently testing our constructs on a Q fever vaccination model, where Q fever is a current bioterrorism threat, to examine changes in T and B cell populations, antibody responses, and efficacy of the tri-agonist adjuvants. From our studies, these tri-agonist scaffolds can inform us about immune system signaling and activation in order to study immune activation mechanisms. Therefore, allowing us to potentially design more effective vaccines.

Absence of salivary CCL28 in primary Sjögren's syndrome

CCL28 is a mucosa-associated epithelial-cell-produced chemokine involved in oral defense. We assessed the level of CCL28 in saliva of primary Sjögren's syndrome (pSS) patients in comparison with healthy controls and correlated it with IgA salivary levels. We included 30 non-smoker pSS patients and 30 non-smoker healthy controls paired by age (±5 years). Saliva samples were collected during the morning and kept frozen at -86 °C until the analysis. Fifty microliters of saliva was diluted 3:1 with water and analyzed for CCL28 salivary levels by ELISA method. The samples were tested in triplicate. IgA salivary levels were tested by ELISA method. We used descriptive statistics, Mann-Whitney U test and Kendall's tau correlation coefficients. pSS patients were mostly females (93.3 %), mean age 54.5 ± 13.3 years and median disease duration of 7.6 years (0.5-33). Patients with pSS had lower levels of salivary CCL28 when compared with controls [0 (0-1,272 pg/ml) vs. 94.4 (0-5,810) pg/ml, p < 0.0001]. pSS patients also had lower median levels of salivary IgA [72.55 μg/ml (0.40-297.4)] than controls [131.9 μg/ml (6.8-281.8)], although the latter results did not reach statistical significance (p = 0.51). Among the SS group, there was no correlation between CCL28 and IgA salivary levels nor between salivary IgA and disease duration, salivary flow, serum immunoglobulins or dental loss. CCL28 was absent in saliva of pSS patients; however, this finding did not correlate with salivary IgA levels.

METEORIN-LIKE is a cytokine associated with barrier tissues and alternatively activated macrophages

Cytokines are involved in many functions of the immune system including initiating, amplifying and resolving immune responses. Through bioinformatics analyses of a comprehensive database of gene expression (BIGE: Body Index of Gene Expression) we observed that a small secreted protein encoded by a poorly characterized gene called meteorin-like (METRNL), is highly expressed in mucosal tissues, skin and activated macrophages. Further studies indicate that Metrnl is produced by Alternatively Activated Macrophages (AAM) and M-CSF cultured bone marrow macrophages (M2-like macrophages). In the skin, METRNL is expressed by resting fibroblasts and IFNγ-treated keratinocytes. A screen of human skin-associated diseases showed significant over-expression of METRNL in psoriasis, prurigo nodularis, actinic keratosis and atopic dermatitis. METRNL is also up-regulated in synovial membranes of human rheumatoid arthritis. Taken together, these results indicate that Metrnl represents a novel cytokine, which is likely involved in both innate and acquired immune responses.

Cutting edge: GPR35/CXCR8 is the receptor of the mucosal chemokine CXCL17

Chemokines are chemotactic cytokines that direct the traffic of leukocytes and other cells in the body. Chemokines bind to G protein-coupled receptors expressed on target cells to initiate signaling cascades and induce chemotaxis. Although the cognate receptors of most chemokines have been identified, the receptor for the mucosal chemokine CXCL17 is undefined. In this article, we show that GPR35 is the receptor of CXCL17. GPR35 is expressed in mucosal tissues, in CXCL17-responsive monocytes, and in the THP-1 monocytoid cell line. Transfection of GPR35 into Ba/F3 cells rendered them responsive to CXCL17, as measured by calcium-mobilization assays. Furthermore, GPR35 expression is downregulated in the lungs of Cxcl17(-/-) mice, which exhibit defects in macrophage recruitment to the lungs. We conclude that GPR35 is a novel chemokine receptor and suggest that it should be named CXCR8.

CXCL17 is a major chemotactic factor for lung macrophages

Chemokines are a superfamily of chemotactic cytokines that direct the movement of cells throughout the body under homeostatic and inflammatory conditions. The mucosal chemokine CXCL17 was the last ligand of this superfamily to be characterized. Several recent studies have provided greater insight into the basic biology of this chemokine and have implicated CXCL17 in several human diseases. We sought to better characterize CXCL17's activity in vivo. To this end, we analyzed its chemoattractant properties in vivo and characterized a Cxcl17 (-/-) mouse. This mouse has a significantly reduced number of macrophages in its lungs compared with wild-type mice. In addition, we observed a concurrent increase in a new population of macrophage-like cells that are F4/80(+)CDllc(mid). These results indicate that CXCL17 is a novel macrophage chemoattractant that operates in mucosal tissues. Given the importance of macrophages in inflammation, these observations strongly suggest that CXCL17 is a major regulator of mucosal inflammatory responses.

Isthmin 1 is a secreted protein expressed in skin, mucosal tissues, and NK, NKT, and th17 cells

Using a comprehensive microarray database of human gene expression, we identified that in mammals, a secreted protein known as isthmin 1 (ISM1) is expressed in skin, mucosal tissues, and selected lymphocyte populations. ISM1 was originally identified in Xenopus brain during development, and it encodes a predicted ∼50-kDa protein containing a signal peptide, a thrombospondin domain, and an adhesion-associated domain. We confirmed the pattern of expression of ISM1 in both human and mouse tissues. ISM1 is expressed by DX5(+) lung lymphocytes that include NK and NKT-like cells, and is also expressed by some CD4(+) T cells upon activation but its expression increases significantly when CD4(+) T cells were polarized to the Th17 lineage in vitro. The presence of IFN-γ during CD4(+) T cell polarization inhibits ISM1 expression. Given that ISM1 has been reported to have anti-angiogenic properties, these observations suggest that ISM1 is a mediator of lymphocyte effector functions and may participate in both innate and acquired immune responses.

International Union of Basic and Clinical Pharmacology. [corrected]. LXXXIX. Update on the extended family of chemokine receptors and introducing a new nomenclature for atypical chemokine receptors

Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145-176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human Genome Nomenclature Committee.

CXCL17 is a mucosal chemokine elevated in idiopathic pulmonary fibrosis that exhibits broad antimicrobial activity

The mucosal immune network is a crucial barrier preventing pathogens from entering the body. The network of immune cells that mediates the defensive mechanisms in the mucosa is likely shaped by chemokines, which attract a wide range of immune cells to specific sites of the body. Chemokines have been divided into homeostatic or inflammatory depending upon their expression patterns. Additionally, several chemokines mediate direct killing of invading pathogens, as exemplified by CCL28, a mucosa-associated chemokine that exhibits antimicrobial activity against a range of pathogens. CXCL17 was the last chemokine ligand to be described and is the 17th member of the CXC chemokine family. Its expression pattern in 105 human tissues and cells indicates that CXCL17 is a homeostatic, mucosa-associated chemokine. Its strategic expression in mucosal tissues suggests that it is involved in innate immunity and/or sterility of the mucosa. To test the latter hypothesis, we tested CXCL17 for possible antibacterial activity against a panel of pathogenic and opportunistic bacteria. Our results indicate that CXCL17 has potent antimicrobial activities and that its mechanism of antimicrobial action involves peptide-mediated bacterial membrane disruption. Because CXCL17 is strongly expressed in bronchi, we measured it in bronchoalveolar lavage fluids and observed that it is strongly upregulated in idiopathic pulmonary fibrosis. We conclude that CXCL17 is an antimicrobial mucosal chemokine that may play a role in the pathogenesis of interstitial lung diseases.

Functional analysis of cGMP-dependent protein kinases I and II as mediators of NO/cGMP effects

NO and cGMP have emerged as important signal transduction mediators of the effects of certain hormones, inter-/intracellular signals, toxins and drugs. However, a major challenge is to define relevant criteria for determining which of the many NO and/or cGMP effects are dependent on cGMP-dependent protein kinases (cGKs). Important criteria include that: (1) the cell types/tissues investigated contain at least one form of cGK which is activated by the cGMP-elevating agent in the intact cell system; (2) specific activators/inhibitors of cGKs mimic/block the effects of cGMP-elevating agents in the intact cell system; and (3) the cGMP effect is absent or blunted in cGK-deficient systems, or can be reconstituted by the introduction of active cGKs. Previously, analysis of cGK activity in intact cells has been very difficult. However, the analysis of vasodilator-stimulated phosphoprotein (VASP) phosphorylation by polyclonal antibodies and newly developed monoclonal antibodies, each of which specifically recognize different phosphorylation sites, allows the quantitative measurement of cGK activity in intact cells. With the use of these methods, the properties of certain cGK mutants, cGK activators (cGMP, 8-Br-cGMP, 8-pCPT-cGMP) as well as various "specific cGK inhibitors" (KT 5823, Rp-8Br-PET-cGMPS, Rp-8-pCPT-cGMPS, H8 and H89) were investigated. Although these "specific cGK inhibitors" have been widely used to establish or rule out functional roles of cGKs, very few studies have actually addressed the efficiency/specificity of such compounds in intact cells. Our results demonstrate that these inhibitors are useful tools only when used in combination with other experimental approaches and biochemical evidence.