Association of Nirmatrelvir/Ritonavir Treatment and COVID-19-Neutralizing Antibody Titers in a Longitudinal Health Care Worker Cohort

Nirmatrelvir/ritonavir (NMV/r) is used for the treatment of coronavirus disease 2019 (COVID-19) infection. However, rebound COVID-19 infections can occur after taking NMV/r. We examined neutralizing antibodies to the severe acute respiratory syndrome coronavirus 2 spike protein before and after infection in people who did and did not take NMV/r to determine if NMV/r impedes the humoral immune response.

Diet-induced obesity and diabetes enhance mortality and reduce vaccine efficacy for SARS-CoV-2

IMPORTANCE

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused a wide spectrum of diseases in the human population, from asymptomatic infections to death. It is important to study the host differences that may alter the pathogenesis of this virus. One clinical finding in coronavirus disease 2019 (COVID-19) patients is that people with obesity or diabetes are at increased risk of severe illness from SARS-CoV-2 infection. We used a high-fat diet model in mice to study the effects of obesity and type 2 diabetes on SARS-CoV-2 infection as well as how these comorbidities alter the response to vaccination. We find that diabetic/obese mice have increased disease after SARS-CoV-2 infection and they have slower clearance of the virus. We find that the lungs of these mice have increased neutrophils and that removing these neutrophils protects diabetic/obese mice from disease. This demonstrates why these diseases have increased risk of severe disease and suggests specific interventions upon infection.

Reduced SARS-CoV-2 mRNA vaccine immunogenicity and protection in mice with diet-induced obesity and insulin resistance

BACKGROUND

Obesity and type 2 diabetes mellitus (T2DM) are associated with an increased risk of severe outcomes from infectious diseases, including coronavirus disease 2019. These conditions are also associated with distinct responses to immunization, including an impaired response to widely used severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines.

OBJECTIVE

We sought to establish a connection between reduced immunization efficacy via modeling the effects of metabolic diseases on vaccine immunogenicity that is essential for the development of more effective vaccines for this distinct vulnerable population.

METHODS

A murine model of diet-induced obesity and insulin resistance was used to model the effects of comorbid T2DM and obesity on vaccine immunogenicity and protection.

RESULTS

Mice fed a high-fat diet (HFD) developed obesity, hyperinsulinemia, and glucose intolerance. Relative to mice fed a normal diet, HFD mice vaccinated with a SARS-CoV-2 mRNA vaccine exhibited significantly lower anti-spike IgG titers, predominantly in the IgG2c subclass, associated with a lower type 1 response, along with a 3.83-fold decrease in neutralizing titers. Furthermore, enhanced vaccine-induced spike-specific CD8+ T-cell activation and protection from lung infection against SARS-CoV-2 challenge were seen only in mice fed a normal diet but not in HFD mice.

CONCLUSIONS

The study demonstrated impaired immunity following SARS-CoV-2 mRNA immunization in a murine model of comorbid T2DM and obesity, supporting the need for further research into the basis for impaired anti-SARS-CoV-2 immunity in T2DM and investigation of novel approaches to enhance vaccine immunogenicity among those with metabolic diseases.

Pyronaridine tetraphosphate is an efficacious antiviral and anti-inflammatory active against multiple highly pathogenic coronaviruses

IMPORTANCE

Pyronaridine tetraphosphate is on the WHO Essential Medicine List for its importance as a widely available and safe treatment for malaria. We find that pyronaridine is a highly effective antiviral therapeutic across mouse models using multiple variants of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), and the highly pathogenic viruses SARS-CoV-1 and Middle East respiratory syndrome coronavirus responsible for previous coronavirus outbreaks. Additionally, we find that pyronaridine additively combines with current COVID-19 treatments such as nirmatrelvir (protease inhibitor in Paxlovid) and molnupiravir to further inhibit SARS-CoV-2 infections. There are many antiviral compounds that demonstrate efficacy in cellular models, but few that show this level of impact in multiple mouse models and represent a promising therapeutic for the current coronavirus pandemic as well as future outbreaks as well.

Diet Induced Obesity and Diabetes Enhance Mortality and Reduces Vaccine Efficacy for SARS-CoV-2

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), the causative agent of Coronavirus disease 2019 (COVID-19), emerged in Wuhan, China, in December 2019. As of October 2022, there have been over 625 million confirmed cases of COVID-19, including over 6.5 million deaths. Epidemiological studies have indicated that comorbidities of obesity and diabetes mellitus are associated with increased morbidity and mortality following SARS-CoV-2 infection. We determined how the comorbidities of obesity and diabetes affect morbidity and mortality following SARS-CoV-2 infection in unvaccinated and adjuvanted spike nanoparticle (NVX-CoV2373) vaccinated mice. We find that obese/diabetic mice infected with SARS-CoV-2 have increased morbidity and mortality compared to age matched normal mice. Mice fed a high-fat diet (HFD) then vaccinated with NVX-CoV2373 produce equivalent neutralizing antibody titers to those fed a normal diet (ND). However, the HFD mice have reduced viral clearance early in infection. Analysis of the inflammatory immune response in HFD mice demonstrates a recruitment of neutrophils that was correlated with increased mortality and reduced clearance of the virus. Depletion of neutrophils in diabetic/obese vaccinated mice reduced disease severity and protected mice from lethality. This model recapitulates the increased disease severity associated with obesity and diabetes in humans with COVID-19 and is an important comorbidity to study with increasing obesity and diabetes across the world.

Immunogenicity and protection of a variant nanoparticle vaccine that confers broad neutralization against SARS-CoV-2 variants

SARS-CoV-2 variants have emerged with elevated transmission and a higher risk of infection for vaccinated individuals. We demonstrate that a recombinant prefusion-stabilized spike (rS) protein vaccine based on Beta/B.1.351 (rS-Beta) produces a robust anamnestic response in baboons against SARS-CoV-2 variants when given as a booster one year after immunization with NVX-CoV2373. Additionally, rS-Beta is highly immunogenic in mice and produces neutralizing antibodies against WA1/2020, Beta/B.1.351, and Omicron/BA.1. Mice vaccinated with two doses of Novavax prototype NVX-CoV2373 (rS-WU1) or rS-Beta alone, in combination, or heterologous prime-boost, are protected from challenge. Virus titer is undetectable in lungs in all vaccinated mice, and Th1-skewed cellular responses are observed. We tested sera from a panel of variant spike protein vaccines and find broad neutralization and inhibition of spike:ACE2 binding from the rS-Beta and rS-Delta vaccines against a variety of variants including Omicron. This study demonstrates that rS-Beta vaccine alone or in combination with rS-WU1 induces antibody-and cell-mediated responses that are protective against challenge with SARS-CoV-2 variants and offers broader neutralizing capacity than a rS-WU1 prime/boost regimen alone. Together, these nonhuman primate and murine data suggest a Beta variant booster dose could elicit a broad immune response to fight new and future SARS-CoV-2 variants.

Carbohydrate fatty acid monosulphate: oil-in-water adjuvant enhances SARS-CoV-2 RBD nanoparticle-induced immunogenicity and protection in mice

Development of SARS-CoV-2 vaccines that protect vulnerable populations is a public health priority. Here, we took a systematic and iterative approach by testing several adjuvants and SARS-CoV-2 antigens to identify a combination that elicits antibodies and protection in young and aged mice. While demonstrating superior immunogenicity to soluble receptor-binding domain (RBD), RBD displayed as a protein nanoparticle (RBD-NP) generated limited antibody responses. Comparison of multiple adjuvants including AddaVax, AddaS03, and AS01B in young and aged mice demonstrated that an oil-in-water emulsion containing carbohydrate fatty acid monosulphate derivative (CMS:O/W) most effectively enhanced RBD-NP-induced cross-neutralizing antibodies and protection across age groups. CMS:O/W enhanced antigen retention in the draining lymph node, induced injection site, and lymph node cytokines, with CMS inducing MyD88-dependent Th1 cytokine polarization. Furthermore, CMS and O/W synergistically induced chemokine production from human PBMCs. Overall, CMS:O/W adjuvant may enhance immunogenicity and protection of vulnerable populations against SARS-CoV-2 and other infectious pathogens.

Sex-specific differences in oxidative stress markers and collagen expression in perioral skin wrinkling

Wrinkling is the hallmark of skin ageing. We previously reported that perioral wrinkling is more severe in females; however, the molecular basis is unknown. This study assessed sex differences in the molecular expression of key ageing regulators in perioral skin. Twelve subjects (n = 6 male/female) were enrolled in this cross-sectional study and biopsies were taken from the perioral and periocular regions. RNA expression of collagen I, collagen III, cysteine-rich angiogenic inducer 61 (CYR61) and insulin-like growth factor 1 (IGF-1) was assessed by qPCR. There was no difference between females' and males' Griffith's grades (6 and 5.67, respectively, p = 0.092) or periocular wrinkling grades (3.2 and 2.6, p = 0.421), but females had more severe perioral wrinkling grades than males (6.2 and 2.8, p = 0.020). Females not only expressed significantly more CYR61 (p = 0.018) in the perioral region than malesm but also expressed more collagen III (p = 0.016). There was no difference in collagen I (p = 0.115) or IGF-1 (p = 0.124) expression in the perioral region between sexes. In the periocular region, there were no significant differences between sexes in the expression of all four markers. The significant molecular differences in the perioral region between the sexes may contribute to the greater perioral skin wrinkling seen clinically in females.

Reduced SARS-CoV-2 mRNA vaccine immunogenicity and protection in mice with diet-induced obesity and insulin resistance

Background

Obesity and Type 2 Diabetes Mellitus (T2DM) are associated with an increased risk of severe outcomes from infectious diseases, including COVID-19. These conditions are also associated with distinct responses to immunization, including an impaired response to widely used SARS-CoV-2 mRNA vaccines.

Objective

To establish a connection between reduced immunization efficacy via modeling the effects of metabolic diseases on vaccine immunogenicity that is essential for the development of more effective vaccines for this distinct vulnerable population.

Methods

We utilized a murine model of diet-induced obesity and insulin resistance to model the effects of comorbid T2DM and obesity on vaccine immunogenicity and protection.

Results

Mice fed a high-fat diet (HFD) developed obesity, hyperinsulinemia, and glucose intolerance. Relative to mice fed a normal diet (ND), HFD mice vaccinated with a SARS-CoV-2 mRNA vaccine exhibited significantly lower anti-spike IgG titers, predominantly in the IgG2c subclass, associated with a lower type 1 response, along with a 3.83-fold decrease in neutralizing titers. Furthermore, enhanced vaccine-induced spike-specific CD8 + T cell activation and protection from lung infection against SARS-CoV-2 challenge were seen only in ND mice but not in HFD mice.

Conclusion

We demonstrate impaired immunity following SARS-CoV-2 mRNA immunization in a murine model of comorbid T2DM and obesity, supporting the need for further research into the basis for impaired anti-SARS-CoV-2 immunity in T2DM and investigation of novel approaches to enhance vaccine immunogenicity among those with metabolic diseases.

Capsule summary

Obesity and type 2 diabetes impair SARS-CoV-2 mRNA vaccine efficacy in a murine model.

SARS-CoV-2 Variant Spike and accessory gene mutations alter pathogenesis.. [PMID: 35677080 PMCID: PMC9176647 DOI: 10.1101/2022.05.31.494211]

The ongoing COVID-19 pandemic is a major public health crisis. Despite the development and deployment of vaccines against SARS-CoV-2, the pandemic persists. The continued spread of the virus is largely driven by the emergence of viral variants, which can evade the current vaccines through mutations in the Spike protein. Although these differences in Spike are important in terms of transmission and vaccine responses, these variants possess mutations in the other parts of their genome which may affect pathogenesis. Of particular interest to us are the mutations present in the accessory genes, which have been shown to contribute to pathogenesis in the host through innate immune signaling, among other effects on host machinery. To examine the effects of accessory protein mutations and other non-spike mutations on SARS-CoV-2 pathogenesis, we synthesized viruses where the WA1 Spike is replaced by each variant spike genes in a SARS-CoV-2/WA-1 infectious clone. We then characterized the in vitro and in vivo replication of these viruses and compared them to the full variant viruses. Our work has revealed that non-spike mutations in variants can contribute to replication of SARS-CoV-2 and pathogenesis in the host and can lead to attenuating phenotypes in circulating variants of concern. This work suggests that while Spike mutations may enhance receptor binding and entry into cells, mutations in accessory proteins may lead to less clinical disease, extended time toward knowing an infection exists in a person and thus increased time for transmission to occur.

Phage-like particle vaccines are highly immunogenic and protect against pathogenic coronavirus infection and disease

The response by vaccine developers to the COVID-19 pandemic has been extraordinary with effective vaccines authorized for emergency use in the United States within 1 year of the appearance of the first COVID-19 cases. However, the emergence of SARS-CoV-2 variants and obstacles with the global rollout of new vaccines highlight the need for platforms that are amenable to rapid tuning and stable formulation to facilitate the logistics of vaccine delivery worldwide. We developed a "designer nanoparticle" platform using phage-like particles (PLPs) derived from bacteriophage lambda for a multivalent display of antigens in rigorously defined ratios. Here, we engineered PLPs that display the receptor-binding domain (RBD) protein from SARS-CoV-2 and MERS-CoV, alone (RBDSARS-PLPs and RBDMERS-PLPs) and in combination (hCoV-RBD PLPs). Functionalized particles possess physiochemical properties compatible with pharmaceutical standards and retain antigenicity. Following primary immunization, BALB/c mice immunized with RBDSARS- or RBDMERS-PLPs display serum RBD-specific IgG endpoint and live virus neutralization titers that, in the case of SARS-CoV-2, were comparable to those detected in convalescent plasma from infected patients. Further, these antibody levels remain elevated up to 6 months post-prime. In dose-response studies, immunization with as little as one microgram of RBDSARS-PLPs elicited robust neutralizing antibody responses. Finally, animals immunized with RBDSARS-PLPs, RBDMERS-PLPs, and hCoV-RBD PLPs were protected against SARS-CoV-2 and/or MERS-CoV lung infection and disease. Collectively, these data suggest that the designer PLP system provides a platform for facile and rapid generation of single and multi-target vaccines.

Pyrimidine inhibitors synergize with nucleoside analogues to block SARS-CoV-2

The SARS-CoV-2 virus has infected more than 261 million people and has led to more than 5 million deaths in the past year and a half1 ( https://www.who.org/ ). Individuals with SARS-CoV-2 infection typically develop mild-to-severe flu-like symptoms, whereas infection of a subset of individuals leads to severe-to-fatal clinical outcomes2. Although vaccines have been rapidly developed to combat SARS-CoV-2, there has been a dearth of antiviral therapeutics. There is an urgent need for therapeutics, which has been amplified by the emerging threats of variants that may evade vaccines. Large-scale efforts are underway to identify antiviral drugs. Here we screened approximately 18,000 drugs for antiviral activity using live virus infection in human respiratory cells and validated 122 drugs with antiviral activity and selectivity against SARS-CoV-2. Among these candidates are 16 nucleoside analogues, the largest category of clinically used antivirals. This included the antivirals remdesivir and molnupiravir, which have been approved for use in COVID-19. RNA viruses rely on a high supply of nucleoside triphosphates from the host to efficiently replicate, and we identified a panel of host nucleoside biosynthesis inhibitors as antiviral. Moreover, we found that combining pyrimidine biosynthesis inhibitors with antiviral nucleoside analogues synergistically inhibits SARS-CoV-2 infection in vitro and in vivo against emerging strains of SARS-CoV-2, suggesting a clinical path forward.

An aluminum hydroxide:CpG adjuvant enhances protection elicited by a SARS-CoV-2 receptor binding domain vaccine in aged mice

Global deployment of vaccines that can provide protection across several age groups is still urgently needed to end the COVID-19 pandemic, especially in low- and middle-income countries. Although vaccines against SARS-CoV-2 based on mRNA and adenoviral vector technologies have been rapidly developed, additional practical and scalable SARS-CoV-2 vaccines are required to meet global demand. Protein subunit vaccines formulated with appropriate adjuvants represent an approach to address this urgent need. The receptor binding domain (RBD) is a key target of SARS-CoV-2 neutralizing antibodies but is poorly immunogenic. We therefore compared pattern recognition receptor (PRR) agonists alone or formulated with aluminum hydroxide (AH) and benchmarked them against AS01B and AS03-like emulsion-based adjuvants for their potential to enhance RBD immunogenicity in young and aged mice. We found that an AH and CpG adjuvant formulation (AH:CpG) produced an 80-fold increase in anti-RBD neutralizing antibody titers in both age groups relative to AH alone and protected aged mice from the SARS-CoV-2 challenge. The AH:CpG-adjuvanted RBD vaccine elicited neutralizing antibodies against both wild-type SARS-CoV-2 and the B.1.351 (beta) variant at serum concentrations comparable to those induced by the licensed Pfizer-BioNTech BNT162b2 mRNA vaccine. AH:CpG induced similar cytokine and chemokine gene enrichment patterns in the draining lymph nodes of both young adult and aged mice and enhanced cytokine and chemokine production in human mononuclear cells of younger and older adults. These data support further development of AH:CpG-adjuvanted RBD as an affordable vaccine that may be effective across multiple age groups.

Cluster analysis of circulating plasma biomarkers in prurigo nodularis reveals a distinct systemic inflammatory signature in African Americans

Patients with prurigo nodularis (PN) suffer from intractable itch and dramatic reduction in quality of life. While there is significant clinical heterogeneity in the presentation of PN, disease endotypes remain unknown. We assayed circulating plasma cytokine concentrations in PN patients (n=20) along with matched healthy controls and utilized an unsupervised machine learning algorithm to identify disease endotypes. We found two distinct clusters of PN patients with non-inflammatory (Cluster 1) and inflammatory (Cluster 2) plasma profiles. Cluster 2 had more African-Americans (82%, n=9 vs. 33%, n=3; P=0.028), higher worst-itch numeric rating scale scores (9.5±0.9 vs. 8.3±1.2; P=0.036), and lower quality of life as reflected by higher Dermatology Life Quality Index scores (21.9±6.4 vs. 13.0±4.1; P=0.015). In addition, Cluster 1 had a higher rate of myelopathy (67%, n=6 vs. 18%, n=2; P=0.028). Compared to Cluster 1, Cluster 2 had higher levels of IL-1α, IL-4, IL-5, IL-6, IL-10, IL-17A, IL-22, IL-25, and IFN-α. With population-level analysis, African-American PN patients had higher erythrocyte sedimentation rate, C-reactive protein, ferritin, eosinophils, and lower transferrin than Caucasian PN patients. These findings indicate discrete clusters of PN patients with plasma biomarker profiles corresponding to distinct demographic and clinical characteristics, potentially allowing for precision medicine approaches to treat PN.

Prurigo Nodularis Is Characterized by Systemic and Cutaneous T Helper 22 Immune Polarization

Prurigo nodularis (PN) is an understudied, chronic inflammatory skin disease that disproportionately affects African Americans and presents with intensely pruritic nodules of unknown etiology. To better characterize the immune dysregulation in PN, PBMCs and skin biopsies were obtained from patients with PN and healthy subjects (majority African American) matched by age, race, and sex. Flow cytometric analysis of functional T-cell response comparing patients with PN with healthy subjects identified increased γδT cells (CD3+CD4-CD8-γδTCR+) and Vδ2+ γδT enrichment. Activated T cells demonstrated uniquely increased IL-22 cytokine expression in patients with PN compared with healthy controls. CD4+ and CD8+ T cells were identified as the source of increased circulating IL-22. Consistent with these findings, RNA sequencing of lesional PN skin compared with nonlesional PN skin and biopsy site‒matched control skin demonstrated robust upregulation of T helper (Th) 22‒related genes and signaling networks implicated in impaired epidermal differentiation. Th22‒related cytokine upregulation remained significant, with stratifications by race and biopsy site. Importantly, the expression of the IL-22 receptors IL22RA1 and IL22RA2 was significantly elevated in lesional PN skin. These results indicate that both systemic and cutaneous immune responses in patients with PN are skewed toward a Th22/IL-22 profile. PN may benefit from immunomodulatory therapies directed at Th22‒mediated inflammation.

Pyrimidine biosynthesis inhibitors synergize with nucleoside analogs to block SARS-CoV-2 infection

The ongoing COVID-19 pandemic has highlighted the dearth of approved drugs to treat viral infections, with only ∼90 FDA approved drugs against human viral pathogens. To identify drugs that can block SARS-CoV-2 replication, extensive drug screening to repurpose approved drugs is underway. Here, we screened ∼18,000 drugs for antiviral activity using live virus infection in human respiratory cells. Dose-response studies validate 122 drugs with antiviral activity and selectivity against SARS-CoV-2. Amongst these drug candidates are 16 nucleoside analogs, the largest category of clinically used antivirals. This included the antiviral Remdesivir approved for use in COVID-19, and the nucleoside Molnupirivir, which is undergoing clinical trials. RNA viruses rely on a high supply of nucleoside triphosphates from the host to efficiently replicate, and we identified a panel of host nucleoside biosynthesis inhibitors as antiviral, and we found that combining pyrimidine biosynthesis inhibitors with antiviral nucleoside analogs synergistically inhibits SARS-CoV-2 infection in vitro and in vivo suggesting a clinical path forward.

Transcriptomic analysis of atopic dermatitis in African Americans is characterized by Th2/Th17-centered cutaneous immune activation

Atopic dermatitis (AD) often presents more severely in African Americans (AAs) and with greater involvement of extensor areas. To investigate immune signatures of AD in AAs with moderate to severe pruritus, lesional and non-lesional punch biopsies were taken from AA patients along with age-, race-, and sex-matched controls. Histology of lesional skin showed psoriasiform dermatitis and spongiotic dermatitis, suggesting both Th2 and Th17 activity. Gene Set Variation Analysis showed upregulation of Th2 and Th17 pathways in both lesional versus non-lesional and lesional versus control (p < 0.01), while Th1 and Th22 upregulation were observed in lesional versus control (p < 0.05). Evidence for a broad immune signature also was supported by upregulated Th1 and Th22 pathways, and clinically may represent greater severity of AD in AA. Furthermore, population-level analysis of data from TriNetX, a global federated health research network, revealed that AA AD patients had higher values for CRP, ferritin, and blood eosinophils compared to age-, sex-, and race-matched controls as well as white AD patients, suggesting broad systemic inflammation. Therefore, AA AD patients may feature broader immune activation than previously thought and may derive benefit from systemic immunomodulating therapies that modulate key drivers of multiple immune pathways.

Alum:CpG adjuvant enables SARS-CoV-2 RBD-induced protection in aged mice and synergistic activation of human elder type 1 immunity

Global deployment of vaccines that can provide protection across several age groups is still urgently needed to end the COVID-19 pandemic especially for low- and middle-income countries. While vaccines against SARS-CoV-2 based on mRNA and adenoviral-vector technologies have been rapidly developed, additional practical and scalable SARS-CoV-2 vaccines are needed to meet global demand. In this context, protein subunit vaccines formulated with appropriate adjuvants represent a promising approach to address this urgent need. Receptor-binding domain (RBD) is a key target of neutralizing antibodies (Abs) but is poorly immunogenic. We therefore compared pattern recognition receptor (PRR) agonists, including those activating STING, TLR3, TLR4 and TLR9, alone or formulated with aluminum hydroxide (AH), and benchmarked them to AS01B and AS03-like emulsion-based adjuvants for their potential to enhance RBD immunogenicity in young and aged mice. We found that the AH and CpG adjuvant formulation (AH:CpG) demonstrated the highest enhancement of anti-RBD neutralizing Ab titers in both age groups (∼80-fold over AH), and protected aged mice from the SARS-CoV-2 challenge. Notably, AH:CpG-adjuvanted RBD vaccine elicited neutralizing Abs against both wild-type SARS-CoV-2 and B.1.351 variant at serum concentrations comparable to those induced by the authorized mRNA BNT162b2 vaccine. AH:CpG induced similar cytokine and chemokine gene enrichment patterns in the draining lymph nodes of both young adult and aged mice and synergistically enhanced cytokine and chemokine production in human young adult and elderly mononuclear cells. These data support further development of AH:CpG-adjuvanted RBD as an affordable vaccine that may be effective across multiple age groups.

One Sentence Summary

Alum and CpG enhance SARS-CoV-2 RBD protective immunity, variant neutralization in aged mice and Th1-polarizing cytokine production by human elder leukocytes.

Human NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome activity is regulated by and potentially targetable through Bruton tyrosine kinase

BACKGROUND

The Nod-like receptor NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) and Bruton tyrosine kinase (BTK) are protagonists in innate and adaptive immunity, respectively. NLRP3 senses exogenous and endogenous insults, leading to inflammasome activation, which occurs spontaneously in patients with Muckle-Wells syndrome; BTK mutations cause the genetic immunodeficiency X-linked agammaglobulinemia (XLA). However, to date, few proteins that regulate NLRP3 inflammasome activity in human primary immune cells have been identified, and clinically promising pharmacologic targeting strategies remain elusive.

OBJECTIVE

We sought to identify novel regulators of the NLRP3 inflammasome in human cells with a view to exploring interference with inflammasome activity at the level of such regulators.

METHODS

After proteome-wide phosphoproteomics, the identified novel regulator BTK was studied in human and murine cells by using pharmacologic and genetic BTK ablation.

RESULTS

Here we show that BTK is a critical regulator of NLRP3 inflammasome activation: pharmacologic (using the US Food and Drug Administration-approved inhibitor ibrutinib) and genetic (in patients with XLA and Btk knockout mice) BTK ablation in primary immune cells led to reduced IL-1β processing and secretion in response to nigericin and the Staphylococcus aureus toxin leukocidin AB (LukAB). BTK affected apoptosis-associated speck-like protein containing a CARD (ASC) speck formation and caspase-1 cleavage and interacted with NLRP3 and ASC. S aureus infection control in vivo and IL-1β release from cells of patients with Muckle-Wells syndrome were impaired by ibrutinib. Notably, IL-1β processing and release from immune cells isolated from patients with cancer receiving ibrutinib therapy were reduced.

CONCLUSION

Our data suggest that XLA might result in part from genetic inflammasome deficiency and that NLRP3 inflammasome-linked inflammation could potentially be targeted pharmacologically through BTK.

Staphylococcus aureus alpha-toxin and Clumping Factor A are pathogenic and immunotherapeutic targets against a hematogenous implant-related biofilm infection

Infection is a major impediment to the long-term success of implantable medical devices. Treatment of these infections is complicated by bacteria biofilms, which form on the implants and block penetration of immune cells and antibiotics. Hematogenous implant-related infections following a transient bacteremia are particularly problematic because they can occur at any time in a previously stable implant. To evaluate alternative targeted immune-based therapies against these infections, we developed a hematogenous infection model in which an orthopaedic titanium implant was surgically placed in the legs of mice followed by an intravenous injection of Staphylococcus aureus 21 days later. This resulted in a marked propensity for a hematogenous implant-related infection comprised of septic arthritis, osteomyelitis with neutrophil abscess formation in the bone and biofilm formation on the implants in the surgical legs compared with sham surgical legs without implant placement or contralateral nonsurgical normal legs. Prophylaxis with two neutralizing human monoclonal antibodies directed against S. aureus virulence factors, secreted alpha-toxin (AT) and surface expressed clumping factor A (ClfA) inhibited biofilm formation in vitro and the hematogenous implant-related infection in vivo. Our findings suggest that AT and ClfA are important pathogenic factors that could be targeted as a novel immunotherapeutic against S. aureus hematogenous implant-related infections.

In vivo neutrophil recruitment by granulocyte chemotactic protein-2 is assisted by gelatinase B/MMP-9 in the mouse

Granulocyte chemotactic protein-2 (GCP-2) of the mouse is a potent neutrophil chemotactic and activating factor in vitro and in vivo. Gelatinase B/matrix metalloproteinase-9 is released from neutrophils within 1 h after stimulation with GCP-2. In vitro neutrophil chemotaxis by GCP-2 was not impaired by specific inhibitory monoclonal antibodies (mAb) against gelatinase B, indicating that gelatinase B is not involved in chemotaxis of neutrophils through polycarbonate filters. To investigate if gelatinase B degranulation is involved in in vivo cell migration toward GCP-2, experiments were performed with gelatinase B knockout mice. When mouse GCP-2 was injected intradermally in mice, a dose-dependent neutrophil chemotactic response was observed, and this cell migration was significantly impaired in young mice by genetic gelatinase B knockout. In adult vs. young gelatinase B-deficient mice, such compensatory mechanisms as higher basal neutrophil counts and less impairment of chemotaxis toward local GCP-2 injection were observed. These experiments prove the concept that gelatinase B release under pressure of GCP-2 is a relevant, but not exclusive, effector mechanism of neutrophil chemotaxis in vivo and that known mechanisms, other than the release of gelatinase B, allow for a full-blown chemotactic response and compensate for gelatinase B deficiency in adult life in the mouse.

Bimodal role of endogenous interleukin-6 in concanavalin A-induced hepatitis in mice

Acute concanavalin A (Con A)-induced hepatitis in mice is an animal model for hepatic injury induced by activated T cells. The evolution of hepatic involvement can be followed from hour to hour by measuring serum transaminase levels. We investigated the possible role of endogenous interleukin-6 (IL-6) in this model. We found serum IL-6 levels and splenic IL-6 mRNA during Con A-induced hepatitis to be significantly lower in interferon-gamma (IFN-gamma)-deficient mice, which are resistant against the Con A-induced syndrome, than in wild-type ones, suggesting that systemic IL-6 production favors development of hepatic injury. However, IL-6-deficient mice proved to be more susceptible to the disease than wild-type mice, indicating that endogenous IL-6 plays a predominantly hepatoprotective role. Experiments in which wild-type mice were treated with anti-IL-6 antibodies, before or after Con A challenge, allowed us to reconcile these contrasting observations. The antibody injections resulted in a biphasic alteration of serum IL-6 levels, initial neutralization being followed by rebound increased levels due to accumulation of IL-6 in the form of antigen-antibody complexes. The effect of antibody on disease severity differed depending on the time of injection. Antibody injection at 2.5 h post Con A resulted in delayed disease manifestation, whereas treatment initiated before Con A resulted in accelerated disease. We conclude that endogenous IL-6 plays a bimodal role. IL-6 present before Con A challenge as well as that induced in the very early phase after Con A injection triggers hepatoprotective pathways. Continuation of IL-6 production beyond this early phase, by some other pathway, seems to be harmful to hepatocytes.

Role of interferon-gamma and nitric oxide in pulmonary edema and death induced by lipopolysaccharide

Mice given lipopolysaccharide (LPS) intravenously developed lung edema, which was maximum after 6 h. Tumor necrosis factor, interleukin 12 (IL-12), IL-6, and interferon-gamma (IFN-gamma) appeared in the serum, and levels of nitrogen oxide (NO) derivatives were increased in serum and bronchoalveolar fluid. Mice pretreated with neutralizing anti-IFN-gamma antibodies had lower serum levels of IFN-gamma, and fewer died. However, levels of other cytokines and NO derivatives as well as lung edema were unchanged. If IFN-gamma and LPS were given together, pulmonary edema was less, but levels of cytokines and NO derivatives in serum were raised, and the mortality was greater. IFN-gamma receptor knockout mice had more edema after LPS, but were less sensitive to the lethal effects. Treatment with anti-IL-12 antibody inhibited IFN-gamma induction and reduced mortality, but had no effect on the lung edema; exogenous IL-12 also failed to affect edema, but boosted serum cytokine levels and increased the mortality. Aminoguanidine, an inhibitor of NO synthase, protected against pulmonary edema, but did not modify the lethal effects of LPS. Clearly, in this model, early pulmonary edema and lethality are not directly related, and induced IFN-gamma has no role in causing early lung edema, but augments other events that result in death.

Stable Escherichia coli-Clostridium acetobutylicum shuttle vector for secretion of murine tumor necrosis factor alpha

Recombinant plasmids were constructed to secrete mouse tumor necrosis factor alpha (mTNF-alpha) from Clostridium acetobutylicum. The shuttle plasmids contained the clostridial endo-beta1, 4-glucanase (eglA) promoter and signal sequence that was fused in frame to the mTNF-alpha cDNA. The construction was first tested in Escherichia coli and then introduced in C. acetobutylicum DSM792 by electroporation. Controls confirmed the presence and stability of the recombinant plasmids in this organism. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and an in vitro cytotoxic assay were used to monitor expression and secretion of mTNF-alpha during growth. Significant levels of biologically active mTNF-alpha were measured in both lysates and supernatants. The present report deals with investigations on the elaboration of a gene transfer system for cancer treatment using anaerobic bacteria.

Role of endogenous interleukin-12 (IL-12) in induced and spontaneous relapses of experimental autoimmune encephalomyelitis in mice

Actively induced, chronic relapsing experimental autoimmune encephalomyelitis (CREAE) was studied in SJL/J and in Biozzi ABH mice. In Biozzi ABH mice, relapses occurred spontaneously with high frequency. In SJL/J mice, spontaneous relapses occurred infrequently; however they could be induced reproducibly by reimmunization. In both models, moderately increased levels of serum IL-12(p40) were consistently found shortly before primary attacks, but irregularly at later times. Injections of anti-IL-12 antibody inhibited disease development in both SJL/J and in Biozzi ABH mice. The time window during which treatment needed to be initiated in order to be effective, ranged from before induction until shortly before the symptoms of primary attacks emerged. Such treatment inhibited not only the first attack but also the spontaneous or induced relapses. Most significantly, anti-IL-12 antibody given during remission of primary disease inhibited actively re-induced relapses in SJL/J, but not spontaneous relapses in Biozzi ABH mice. These results indicate that endogenous IL-12 favours EAE development by crucially affecting the active induction process, but that a second burst of IL-12 production may not be necessary for triggering spontaneous relapses.

Imaging findings in diffuse axonal injury after closed head trauma

Even in patients with closed head trauma, brain parenchyma can be severely injured due to disruption of axonal fibers by shearing forces during acceleration, deceleration, and rotation of the head. In this article we review the spectrum of imaging findings in patients with diffuse axonal injuries (DAI) after closed head trauma. Knowledge of the location and imaging characteristics of DAI is important to radiologists for detection and diagnosis. Common locations of DAI include: cerebral hemispheric gray-white matter interface and subcortical white matter, body and splenium of corpus callosum, basal ganglia, dorsolateral aspect of brainstem, and cerebellum. In the acute phase, CT may show punctate hemorrhages. The true extent of brain involvement is better appreciated with MR imaging, because both hemorrhagic and non-hemorrhagic lesions (gliotic scars) can be detected. The MR appearance of DAI lesions depends on several factors, including age of injury, presence of hemorrhage or blood-breakdown products (e. g., hemosiderin), and type of sequence used. Technical aspects in MR imaging of these patients are discussed. Non-hemorrhagic lesions can be detected with fluid attenuated inversion recovery (FLAIR), proton-density-, or T2-weighted images, whereas gradient echo sequences with long TE increase the visibility of old hemorrhagic lesions.

Evaluation of a novel subtilisin inhibitor gene and mutant derivatives for the expression and secretion of mouse tumor necrosis factor alpha by Streptomyces lividans

In order to evaluate the expression and secretion signals of the highly secreted subtilisin inhibitor of Streptomyces venezuelae CBS762.70 (VSI) for the production of heterologous proteins by Streptomyces lividans, mouse tumor necrosis factor alpha (mTNF) was chosen as a model protein. The mTNF cDNA was fused to the vsi signal sequence. The analysis of secretion by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and biological activity measurements revealed an efficient translocation of mTNF. Up to 300 mg of secreted biologically active mTNF per liter could be obtained in shaken-flask cultures. By analyzing the effects of mutations in the N region of the VSI signal peptide on secretion, we found that decreasing the +3 charge of the wild-type protein to +2 resulted in a 3- to 10-fold increase in secretion.

Chronic relapsing experimental autoimmune encephalomyelitis (CREAE) in mice: enhancement by monoclonal antibodies against interferon-gamma

Experimental autoimmune encephalomyelitis (EAE) is a T cell-mediated inflammatory and demyelinating disorder of the central nervous system. Depending on the experimental conditions, it takes an acute monophasic or a chronic relapsing-remitting course. We have previously reported that the incidence and severity of acute EAE in mice are reduced by administration of interferon (IFN)-gamma and augmented by treatment with neutralizing antibodies against IFN-gamma. Here, we investigated the role of IFN-gamma in chronic relapsing models of EAE (CREAE) in SJL/J and Biozzi ABH mice. Spontaneous relapses in Biozzi mice as well as induced relapses in SJL/J mice were facilitated by administration of neutralizing monoclonal antibody (mAb) against IFN-gamma in the disease-free interval. The enhancing effect of anti-IFN-gamma mAb given before and during the primary attack did not carry over to the relapses. However, early administration of IFN-gamma in Biozzi mice, which developed spontaneous relapses in a high proportion, provided partial protection not only against the first attack, but also against subsequent relapses. Administration of exogenous IFN-gamma during the remission phase provided some protection against subsequent relapses. These results indicate that in both types of relapses, IFN-gamma is produced and does provide a certain degree of protection against disease progression.

Prevention of acute autoimmune encephalomyelitis and abrogation of relapses in murine models of multiple sclerosis by the protease inhibitor D-penicillamine

The in vitro activity of gelatinase B, an enzyme whose appearance in the cerebrospinal fluid is associated with inflammatory diseases of the central nervous system, was dose-dependently inhibited by the antirheumatic D-penicillamine. Inhibition of gelatinase B in electrophoretically pure preparations and in cell culture supernatants and human body fluids was obtained at dosages reached in the circulation of patients treated with a peroral dosis of 750 mg D-penicillamine per day. In mice, developing acute demyelination, D-penicillamine significantly reduced the mortality and morbidity rates of experimental allergic encephalomyelitis (EAE). In chronic relapsing EAE in Biozzi AB/H mice, an animal model for relapses in multiple sclerosis (MS), it attenuated the exacerbations, even when the treatment was started after the primary full-blown disease had developed. We infer protease inhibition as the mechanism of action of D-penicillamine and suggest that its use may be effective as peroral treatment for MS.

Efficient secretion of biologically active mouse tumor necrosis factor alpha by Streptomyces lividans

We have studied the production of mouse tumor necrosis factor alpha (mTNF) with Streptomyces lividans as host. mTNF cDNA was fused to the alpha-amylase-encoding gene (aml) of Streptomyces venezuelae ATCC15068 at 12 amino acids (aa) downstream from the signal-peptidase cleavage site so that the aa surrounding this processing site were conserved. S. lividans containing this construct secreted mTNF at moderately high levels (1-10 micrograms/ml) as a biologically active compound of high specific activity (1 x 10(8) units/mg protein). No unprocessed pre-protein and virtually no processed protein could be detected in the cell lysates. N-terminal aa sequence analysis indicated microheterogeneity (-3 to -6 forms) at the N-terminal site of secreted mTNF. It was demonstrated that this microheterogeneity was due to aminopeptidase activity.

Essential role for natural killer cells in the lethal lipopolysaccharide-induced Shwartzman-like reaction in mice

Observations in our laboratory have provided evidence that interferon-gamma (IFN-gamma) is a key regulator of inflammatory responses to bacterial lipopolysaccharide (LPS) (Heremans et al., J. Exp. Med. 1990. 171: 1853): treatment of mice with neutralizing monoclonal antibody against IFN-gamma was found to completely prevent lethal shock reactions, in particular the generalized Shwartzman reaction, whereas treatment with IFN-gamma sensitized the mice to the development of such reactions. Since activated T cells and natural killer (NK) cells are the main if not the only potential source of LPS-induced IFN-gamma, we investigated the relative importance of these cells in the development of the generalized Shwartzman-like reaction in mice by depleting them selectively with relevant monoclonal antibodies. Treatment with antibodies directed against the CD4+ T cells subset was not effective in protecting mice. Anti-CD8 antibody did attenuate the reaction to some extent. However, markedly reduced mortality was seen in mice which were depleted of NK cells by systemic administration of polyclonal anti-asialo GM1 or monoclonal anti-NK1.1 antibodies. Failure of T cells to promote the Shwartzman reaction was also evidenced by the observation that thymus-less nude mice, which are deficient in T cells, were more rather than less sensitive to the reaction. Approximately 20 times less LPS was needed to induce the lethal reaction in these mice than in NMRI mice and 58 times more anti-IFN-gamma antibody was required to block mortality. Nu/nu mice reportedly have an over-active NK cell compartiment. IFN-gamma production by these cells in LPS-treated mice may account for the augmented sensitivity. Our data suggest that NK cells may be the most important source of endogenous IFN-gamma which mediates the LPS-induced lethal reactions in mice.

Modification of the anti-CD3-induced cytokine release syndrome by anti-interferon-gamma or anti-interleukin-6 antibody treatment: protective effects and biphasic changes in blood cytokine levels

Anti-interferon-gamma (IFN-gamma) antibodies were found to protect mice against pathological changes induced by injection of anti-CD3 antibody: incidence of diarrhea, severity of hypothermia and mortality rates were dramatically reduced. In anti-IFN-gamma antibody-treated mice, IFN-gamma blood levels were significantly reduced at 1.5 h post anti-CD3 challenge, but more elevated levels were found from 4 to 24 h. This rebound-like IFN-gamma response coincided with more profound hypoglycemia. Tumor necrosis factor and interleukin (IL)-6 levels were not affected by anti-IFN-gamma treatment. Exogenous IFN-gamma, administered within 3 h (but not later) of the anti-CD3 challenge made the syndrome worse. Furthermore, inter-mouse strain differences in sensitivity to the anti-CD3 syndrome correlated with the ability of the strain to produce IFN-gamma. Anti-IL-6 antibodies provided only marginal protection against hypothermia and mortality, but did markedly reduce hypoglycemia. Levels of biologically active IL-6 in serum were not influenced by anti-IL-6 antibody treatment during the first few hours after anti-CD3 challenge, but were significantly increased at later times. The data provide evidence that endogenous IFN-gamma is a critical element in the early phase of the anti-CD3 syndrome; endogenous IL-6, while possibly being involved in hypoglycemia, seems of lesser importance for the outcome of the syndrome.

Increased circulating interleukin-6 (IL-6) activity in endotoxin-challenged mice pretreated with anti-IL-6 antibody is due to IL-6 accumulated in antigen-antibody complexes

Mice pretreated with monoclonal anti-interleukin-6 (IL-6) antibody and then challenged with lipopolysaccharide (LPS), paradoxically develop higher levels of circulating biological IL-6 activity, as measured by the hybridoma growth promotion assay, than mice similarly challenged but not pretreated with antibody. Here we provide evidence that this increased biological activity was entirely accounted for by the presence of increased amounts of IL-6 protein, which could be isolated by immunoaffinity chromatography and subsequently visualized after gel electrophoresis. Chromatography on a protein G matrix and a sandwich ELISA allowed to demonstrate that all IL-6 present in the serum was in the form of antigen-antibody complexes. Serum samples of antibody-treated animals which contained the highest biological activity typically contained near equimolar concentrations of IL-6 and antibody. In vitro neutralization tests with pure antibody and IL-6 demonstrated that, with both antibodies tested, more than 1000-fold molar excess of antibody is needed for neutralization in the hybridoma growth assay. It is concluded that increased biological activity in serum of the anti-IL-6 antibody-treated mice is due to sequestration of the endogenous IL-6 in the form of antigen-antibody complexes which, due to the lack of sufficient antibody excess, produce nearly full activity in the hybridoma growth assay.

Protective effect of anti-interleukin (IL)-6 antibody against endotoxin, associated with paradoxically increased IL-6 levels

Two rat monoclonal antibodies (6B4 and 20F3) against mouse interleukin (IL)-6 were studied for their effects on the generalized Shwartzman reaction and on cytokine production elicited by endotoxin injections. Both antibodies were found to protect mice against the generalized Shwartzman reaction. Production of interferon and tumor necrosis factor in these animals, as assessed from serum levels, were not consistently affected by the antibody treatment, although rather increased levels were occasionally noted. Paradoxically, however, endotoxin-induced serum levels of IL-6 in anti-IL-6-treated mice were consistently found to be markedly increased and also to persist for longer time periods. The more vigorous and persistent response may have been due to slower elimination, increased synthesis, or a combination of both. Endogenous production of IL-6 in mice may be sufficiently large to supersede the neutralizing potential of an excess of antibody, as was evident from the fact that ascites fluid of the anti-IL-6-producing 6B4 hybridoma was biologically active in the IL-6 assay.

Murine interferon-gamma/interleukin-1 fusion proteins used as antigens for the generation of hybridomas producing monoclonal anti-interleukin-1 antibodies

In several biological systems interferon-gamma (IFN-gamma) and interleukin-1 (IL-1) act synergistically. We therefore examined whether it would be possible to construct IFN-gamma/IL-1 hybrid proteins that would be more active than the individual components. Hybrid proteins were examined that consisted of the amino-terminal 118 residues of mouse IFN-gamma and the 156 or 152 carboxyl-terminal residues of mouse IL-1 alpha or IL-1 beta, respectively. They were obtained by ligation of the respective coding sequences and expression of the fused genes under control of the PL promotor in Escherichia coli. Both the IFN-gamma/IL-1 alpha and the IFN-gamma/IL-1 beta fusion proteins were purified by affinity chromatography on an anti-IFN-gamma monoclonal antibody column. Analysis of biological activities showed that these fusion proteins were less active than the individual cytokines. Specific antiviral activity of the IFN-gamma/IL-1 beta hybrids was less than 0.1% that of IFN-gamma and D10.G4.1 T-cell proliferative (IL-1) activity amounted to 0.1% that of mouse IL-1. Affinity-purified preparations of the IFN-gamma/IL-1 alpha hybrid were found to contain variable proportions of a Mr 14,000 degradation product possessing IFN-gamma activity, whereas the undegraded Mr 30,000 fusion protein, while being devoid of detectable IFN-gamma activity, did possess IL-1 activity (1%). Serum from rats immunized with the IFN-gamma/IL-1 alpha hybrid contained high levels of IL-1 alpha-binding and -neutralizing antibodies and IFN-gamma-binding antibodies, but no detectable levels of IFN-gamma-neutralizing antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon gamma, a mediator of lethal lipopolysaccharide-induced Shwartzman-like shock reactions in mice

The involvement of cytokines in the pathogenesis of a generalized, Shwartzman-like lethal inflammatory response to bacterial lipopolysaccharides (LPS) was studied by testing the ability of cytokines or neutralizing anticytokine antibodies to modify the course of the syndrome. The reaction was elicitable in non-SPF NMRI mice by two consecutive injections of S. marcescens LPS: a first injection in the footpad, followed after 24 h by an intravenous dose; the size and route of the preparatory LPS dose were found to be critical. Treatment with mAbs against IFN-gamma was found to completely prevent the reaction. Treatment with IFN-gamma on the other hand, rendered the mice more sensitive to elicitation of the reaction. In contrast, systemic administration of IFN-alpha/beta exerted a desensitizing effect. The role of endogenous cytokines in the pathogenesis of this generalized Shwartzman reaction was also documented by a study of the cytokine levels in the serum of the mice. In comparisons between mice given lethal and nonlethal induction schedules, a good correlation was found between mortality rates and height of IFN or TNF levels, but no correlation was seen with IL-6 levels. Also, in mice that were protected by anti-IFN-gamma antibody, serum IFN and TNF were undetectable, whereas IL-6 levels were as high as in unprotected mice. These data provide evidence that among the cytokines that govern the inflammatory response to LPS, endogenous IFN-gamma occupies a key position. These findings therefore also open perspectives for clinical application of IFN-gamma antagonists.

Anti-interferon-gamma antibody protects mice against the generalized Shwartzman reaction

A generalized Shwartzman reaction was found to occur in non-SPF-NMRI mice given a local injection of S. marcescens lipopolysaccharide (LPS) in the footpad, followed, with an interval of 24 h, by an i.v. injection. The reaction occurred several hours after the second injection. It was characterized by disseminated subcutaneous bleedings at the mouth, anus, conjuctiva, nose tip and tail end. Most mice died within 24-48 h. The size of the LPS dose given in the footpad (5 micrograms) was found to be critical in that the reaction failed to occur with higher as well as lower doses. The reaction was found to be completely absent in mice that had received one or more systemic injections of monoclonal antibodies with neutralizing potential for murine interferon-gamma (IFN-gamma). Mice treated with control preparations, including a monoclonal antibody with binding but no neutralizing activity for murine IFN-gamma, remained sensitive to induction of the reaction. These observations assign a crucial role to endogenous IFN-gamma in the elicitation of the generalized Shwartzman reaction and open perspectives for the prevention or therapy of clinical conditions related to the Shwartzman reaction by the use of antibodies to IFN-gamma.