The serological immunogenicity of the third and fourth doses of COVID-19 vaccine in patients with inflammatory rheumatic diseases on different biologic or targeted DMARDs: a Swedish nationwide study (COVID-19-REUMA)

Studies investigating the immunogenicity of additional COVID-19 vaccine doses in immunosuppressed patients with inflammatory rheumatic diseases (IRD) are still limited. The objective was to explore the antibody response including response to omicron virus subvariants (sBA.1 and sBS.2) after third and fourth COVID-19 vaccine doses in Swedish IRD patients treated with immunomodulating drugs compared to controls. Antibody levels to spike wild-type antigens (full-length protein and S1) and the omicron variants sBA.1 and sBA.2 (full-length proteins) were measured. A positive response was defined as having antibody levels over cut-off or ≥fourfold increase in post-vaccination levels for both antigens. Patients with arthritis, vasculitis, and other autoimmune diseases (n = 414), and controls (n = 61) receiving biologic/targeted synthetic disease-modifying anti-rheumatic drugs (DMARDs) with or without conventional synthetic DMARDs participated. Of these, blood samples were available for 370 patients and 52 controls after three doses, and 65 patients and 15 controls after four doses. Treatment groups after three vaccine doses were rituximab (n = 133), abatacept (n = 22), IL6r inhibitors (n = 71), JAnus Kinase inhibitors (JAK-inhibitors) (n = 56), tumor necrosis factor inhibitor (TNF-inhibitors) (n = 61), IL12/23/17 inhibitors (n = 27), and controls (n = 52). The percentage of responders after three and four vaccine doses was lower in rituximab-treated patients (59% and 57%) compared to controls (100%) (P < 0.001). After three doses, the percentage of responders in all other groups was 100%, including response to omicron sBA.1 and sBA.2. In rituximab-treated patients, higher baseline immunoglobulin G (IgG) and longer time-period between rituximab and vaccination predicted better response. In this Swedish nationwide study including IRD patients three and four COVID-19 vaccine doses were immunogenic in patients treated with IL6r inhibitors, TNF-inhibitors, JAK-inhibitors, and IL12/23/17-inhibitors but not in rituximab. As >50% of rituximab patients responded to vaccines including omicron subvariants, these patients should be prioritized for additional vaccine doses.

IMPORTANCE

Results from this study provide further evidence that additional doses of COVID-19 vaccines are immunogenic and result in satisfactory antibody response in a majority of patients with inflammatory rheumatic diseases (IRD) receiving potent immunomodulating treatments such as biological or targeted disease-modifying anti-rheumatic drugs (DMARDs) given as monotherapy or combined with traditional DMARDs. We observed that rituximab treatment, both as monotherapy and combined with csDMARDs, impaired antibody response, and only roughly 50% of patients developed a satisfactory antibody response including response to omicron subvariants after the third vaccine. In addition, higher IgG levels at the last rituximab course before the third vaccine dose and a longer time after the last rituximab treatment increased the chance of a satisfactory antibody response. These results indicate that rituximab-treated patients should be prioritized for additional vaccine doses.

CLINICAL TRIALS

EudraCT (European Union Drug Regulating Authorities Clinical Trials Database) with number 2021-000880-63.

Identification of circulating autoantibodies to non-modified proteins associated with ACPA status in early rheumatoid arthritis

OBJECTIVES

To discover autoantibodies to non-modified proteins associated with the presence/absence of anticitrullinated protein antibodies (ACPA) in rheumatoid arthritis (RA).

METHODS

The autoantibody repertoire of 80 ACPA negative and 80 ACPA positive RA subjects from the Swedish population-based Epidemiological Investigation of RA (EIRA) cohort was screened using a suspension bead array built on protein fragments earlier described as autoimmunity targets. Four autoantibodies positive in the initial screening were validated in another set of EIRA samples containing 317 ACPA-positive, 302 ACPA-negative and 372 age- and sex-matched controls. The relationship between the four autoantibodies and lung abnormalities on high-resolution computed tomography (HRTC) was examined in 93 early RA patients from LURA cohort. Association between the autoantibodies, smoking and MHC class II alleles was assessed by logistic regression analysis.

RESULTS

: Anti-ANOS1 and anti-MURC IgG levels were associated with ACPA-positive status (OR = 3.02; 95% CI 1.87-4.89; and OR = 1.86; 95% CI 1.16-2.97, respectively) and increased in ACPA-positive patients compared with controls. Anti-ANOS1 IgG was associated with smoking habit (OR = 2.11; 95% CI 1.22-3.69) and anti-MURC IgG with the presence of the MHC class II "shared-epitope" genes (OR = 1.95; 95% CI 1.11-3.46). Anti-TSPYL4 IgG was associated with ACPA-negative (OR = 0.41; 95% CI 0.19-0.89). Anti-TSPYL4 IgG and anti-MAP2K6 IgG levels were increased in the ACPA-negative patients compared with controls. Presence of anti-MAP2K6 IgG and anti-TSPYL4 IgG correlated negatively with HRCT-defined lung abnormalities.

CONCLUSIONS

These four autoantibodies may be useful in diagnostics and in predicting clinical phenotypes of RA.

Autoantibody Profiling and Anti-Kinesin Reactivity in ANCA-Associated Vasculitis

ANCA-associated vasculitides (AAV) are rare autoimmune diseases causing inflammation and damage to small blood vessels. New autoantibody biomarkers are needed to improve the diagnosis and treatment of AAV patients. In this study, we aimed to profile the autoantibody repertoire of AAV patients using in-house developed antigen arrays to identify previously unreported antibodies linked to the disease per se, clinical subgroups, or clinical activity. A total of 1743 protein fragments representing 1561 unique proteins were screened in 229 serum samples collected from 137 AAV patients at presentation, remission, and relapse. Additionally, serum samples from healthy individuals and patients with other type of vasculitis and autoimmune-inflammatory conditions were included to evaluate the specificity of the autoantibodies identified in AAV. Autoreactivity against members of the kinesin protein family were identified in AAV patients, healthy volunteers, and disease controls. Anti-KIF4A antibodies were significantly more prevalent in AAV. We also observed possible associations between anti-kinesin antibodies and clinically relevant features within AAV patients. Further verification studies will be needed to confirm these findings.

Autoantibodies against PIP4K2B and AKT3 Are Associated with Skin and Lung Fibrosis in Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is a rare autoimmune systemic disease that leads to decreased survival and quality of life due to fibrosis, inflammation, and vascular damage in the skin and/or vital organs. Early diagnosis is crucial for clinical benefit in SSc patients. Our study aimed to identify autoantibodies in the plasma of SSc patients that are associated with fibrosis in SSc. Initially, we performed a proteome-wide screening on sample pools from SSc patients by untargeted autoantibody screening on a planar antigen array (including 42,000 antigens representing 18,000 unique proteins). The selection was complemented with proteins reported in the literature in the context of SSc. A targeted antigen bead array was then generated with protein fragments representing the selected proteins and used to screen 55 SSc plasma samples and 52 matched controls. We found eleven autoantibodies with a higher prevalence in SSc patients than in controls, eight of which bound to proteins associated with fibrosis. Combining these autoantibodies in a panel could lead to the subgrouping of SSc patients with fibrosis. Anti-Phosphatidylinositol-5-phosphate 4-kinase type 2 beta (PIP4K2B)- and anti-AKT Serine/Threonine Kinase 3 (AKT3)-antibodies should be further explored to confirm their association with skin and lung fibrosis in SSc patients.

Array-Based Multiplex and High-Throughput Serology Assays

The detection of antibody responses using serological tests provides means to diagnose infections, follow disease transmission, and monitor vaccination responses. The coronavirus disease 2019 (COVID-19) pandemic, caused by the SARS-CoV-2 virus, highlighted the need for rapid development of robust and reliable serological tests to follow disease spreading. Moreover, the rise of SARS-CoV-2 variants emphasized the need to monitor their transmission and prevalence in the population. For this reason, multiplex and flexible serological assays are needed to allow for rapid inclusion of antigens representing new variants as soon as they appear. In this chapter, we describe the generation and application of a multiplex serological test, based on bead array technology, to detect anti-SARS-CoV-2 antibodies in a high-throughput manner, using only a few microliters of sample. This method is currently expanding to include a multi-disease antigen panel that will allow parallel detection of antibodies towards several infectious agents.

Persistence of salivary antibody responses after COVID-19 vaccination is associated with oral microbiome variation in both healthy and people living with HIV

Coevolution of microbiome and immunity at mucosal sites is essential for our health. Whether the oral microbiome, the second largest community after the gut, contributes to the immunogenicity of COVID-19 vaccines is not known. We investigated the baseline oral microbiome in individuals in the COVAXID clinical trial receiving the BNT162b2 mRNA vaccine. Participants (n=115) included healthy controls (HC; n=57) and people living with HIV (PLHIV; n=58) who met the study selection criteria. Vaccine-induced Spike antibodies in saliva and serum from 0 to 6 months were assessed and comparative analyses were performed against the individual salivary 16S ASV microbiome diversity. High- versus low vaccine responders were assessed on general, immunological, and oral microbiome features. Our analyses identified oral microbiome features enriched in high- vs. low-responders among healthy and PLHIV participants. In low-responders, an enrichment of Gram-negative, anaerobic species with proteolytic activity were found including Campylobacter, Butyrivibrio, Selenomonas, Lachnoanaerobaculum, Leptotrichia, Megasphaera, Prevotella and Stomatobaculum. In high-responders, enriched species were mainly Gram-positive and saccharolytic facultative anaerobes: Abiotrophia, Corynebacterium, Gemella, Granulicatella, Rothia, and Haemophilus. Combining identified microbial features in a classifier using the area under the receiver operating characteristic curve (ROC AUC) yielded scores of 0.879 (healthy controls) to 0.82 (PLHIV), supporting the oral microbiome contribution in the long-term vaccination outcome. The present study is the first to suggest that the oral microbiome has an impact on the durability of mucosal immunity after Covid-19 vaccination. Microbiome-targeted interventions to enhance long-term duration of mucosal vaccine immunity may be exploited.

Exploring High-Throughput Immunoassays for Biomarker Validation in Rheumatic Diseases in the Context of the Human Proteome Project

Rheumatic diseases are high prevalence pathologies with different etiology and evolution and low sensitivity in clinical diagnosis. Therefore, it is necessary to develop an early diagnosis method which allows personalized treatment, depending on the specific pathology. The biology/disease initiative, at Human Proteome Project, is an integrative approach to identify relevant proteins in the human proteome associated with pathologies. A previously reported literature data mining analysis, which identified proteins related to osteoarthritis (OA), rheumatoid arthritis (RA), and psoriatic arthritis (PSA) was used to establish a systematic prioritization of potential biomarkers candidates for further evaluation by functional proteomics studies. The aim was to study the protein profile of serum samples from patients with rheumatic diseases such as OA, RA, and PSA. To achieve this goal, customized antibody microarrays (containing 151 antibodies targeting 121 specific proteins) were used to identify biomarkers related to early and specific diagnosis in a screening of 960 serum samples (nondepleted) (OA, n = 480; RA, n = 192; PSA, n = 288). This functional proteomics screening has allowed the determination of a panel (30 serum proteins) as potential biomarkers for these rheumatic diseases, displaying receiver operating characteristics curves with area under the curve values of 80-90%.

B cell repopulation dynamics and drug pharmacokinetics impact SARS-CoV-2 vaccine efficacy in anti-CD20-treated multiple sclerosis patients

BACKGROUND

Recent findings document a blunted humoral response to SARS-CoV-2 vaccination in patients on anti-CD20 treatment. Although most patients develop a cellular response, it is still important to identify predictors of seroconversion in order to optimize vaccine responses.

METHODS

We determined antibody responses after SARS-CoV-2 vaccination in a real-world cohort of multiple sclerosis patients (n = 94) treated with anti-CD20, mainly rituximab, with variable treatment duration (median 2.9; range 0.4-9.6 years) and time from last anti-CD20 infusion to vaccination (median 190; range 60-1032 days).

RESULTS

We find that presence of B cells and/or rituximab in blood predict seroconversion better than time since last infusion. Using multiple logistic regression, presence of >0.5% B cells increased probability for seroconversion with an odds ratio (OR) of 5.0 (CI 1.0-28.1, p = 0.055), while the corresponding OR for ≥ 6 months since last infusion was 1.45 (CI 0.20-10.15, p = 0.705). In contrast, detectable rituximab levels were negatively associated with seroconversion (OR 0.05; CI 0.002-0.392, p = 0.012). Furthermore, naïve and memory IgG⁺ B cells correlated with antibody levels. Although re-treatment with rituximab at four weeks or more after booster depleted spike-specific B cells, it did not noticeably affect the rate of decline in antibody titers. Interferon-γ and/or interleukin-13 T cell responses to the spike S1 domain were observed in most patients, but with no correlation to spike antibody levels.

CONCLUSIONS

These findings are relevant for providing individualized guidance to patients and planning of vaccination schemes, in turn optimizing benefit-risk with anti-CD20.

POS0255 PREDICTORS OF ANTIBODY RESPONSE TO COVID-19 VACCINE IN RITUXIMAB TREATED PATIENTS WITH INFLAMMATORY RHEUMATIC DISEASES. A SWEDISH NATIONWIDE STUDY (COVID19-REUMA)

Background

In line with other reports, our group showed that patients treated with rituximab had significant impaired antibody response compared to patients treated with other biologic and targeted and synthetic disease modifying anti-rheumatic drugs (csDMARD).

Objectives

To investigate predictors of response to COVID-19 vaccination (2 doses of mRNA vaccines, 2 doses of virus vector vaccines or combinations of these) in patients with inflammatory rheumatic diseases (IRD) treated with rituximab and controls.

Methods

Antibody levels to three antigens: Spike protein full length, Spike S1 and Nucleocapsid C-terminal fragment (to confirm previous COVID-19 infection) were measured in sera collected before vaccination and 2-12 weeks after the second vaccine using a multiplex bead-based serology assay. The antigen-specific cut-off was defined as the median fluorescence intensity signal plus 6x standard deviations across 12 pre-pandemic controls. A good vaccine response was defined as having antibodies over the cut-off level for both spike antigens. Proportion (%) responders was compared between patients and controls (Chi2 test).

Patients with IRD receiving last rituximab treatment within a mean (range) 193 (23-501) days before first vaccination participated. Individuals without IRD served as a control group. Predictors of a good vaccine response were explored using multivariate logistic regression analysis adjusted for age, sex, disease duration, diagnosis (systemic vasculitis/RA/JIA/other), concomitant csDMARD, rituximab dose and prednisolone dose. Hazard ratio (chanse) of a good antibody response in relation to time between the last rituximab treatment and vaccination was studied by Kaplan-Meier survival analysis.

Results

In total, 145 patients receiving rituximab and 61 controls were inclyded. Of these, 82 received rituximab as monotherapy (67% women; mean age 66 years, mean disease duration 13 years; 33% had RA/JIA and 60% vasculitis) and 63 received rituximab+csDMARD (62% women; mean age 66 years; mean disease duration 17 years; 76% had RA/JIA and 10 % vasculitis). Controls (n=61) were 74% women and mean age 49 years. Compared to controls, rituximab patients had lower antibody levels for both spike proteins (p<0.001). Proportion (%) responders among patients receiving rituximab as monotherapy (40.2%) and rituximab+DMARDs (25.4%) was significantly lower than in controls (98.4%) (p<0.001, Chi2). Higher age, concomitant csDMARD at vaccination and shorter time from last rituximab treatment predicted impaired antibody response (multivariate logistic regression model) (Table 1). Longer time between the last rituximab course and vaccination was associated with better antibody response (Figure 1).

Table 1.

Predictors of good antibody response to two doses of COVID-19 vaccine defined as antibodies over the cut-off level for both spike antigens

Bp-valueOR95% CIAge at vaccination (years)-0.040.0090.960.93-0.99Sex (male/female)-9.550.2090.580.24-1.36csDMARD at vaccination (yes/no)-1.080.0260.340.13-0.88Prednisolone (mg/dag)-0.100.1030.900.80-1.02Rituximab dos (1000 mg vs 500 mg)-0.010.3700.990.99-1.00Time between the last rituximab and vaccination (months)0.200.0011.311.11-1.55Diagnosis at vaccination (systemic vasculitis vs others)-0.510.3150.600.21-1.64Figure 1.

The chance of good antibody response following two doses of COVID-19 vaccine in relation to time between the last rituximab course and vaccination.

Conclusion

Patients with IRD getting vaccinated with two doses of COVID19 vaccine during the treatment with rituximab have the ability to develop antibody response although the response is impaired. For each month passed after the last rituximab course, the chance of good antibody response increases with 30%. Younger patients receiving rituximab as monotherapy and vaccinated preferably several months after the last rituximab treatment have the highest chance of achieving a good antibody response.

Acknowledgements

Unrestricted research grants have been received from Roche and starting grants from The Swedish Rheumatism Association

Disclosure of Interests

Martina Frodlund: None declared, Katerina Chatzidionysiou Consultant of: consultancy fees from Eli Lilly, AbbVie and Pfizer., Anna Södergren: None declared, Eva Klingberg: None declared, Monika Hansson: None declared, Elisa Pin: None declared, Sophie Olsson: None declared, Anders Bengtsson: None declared, Lars Klareskog Grant/research support from: has eceived research grants from Pfizer, BMS, Affibody, Sonoma Biotherapeutics, Meliha C Kapetanovic Consultant of: have received consultancy fees from Abbvie, Pfizer and GSK, Grant/research support from: have received unrestricted research grants from Roche and Pfizer

Long-term SARS-CoV-2-specific and cross-reactive cellular immune responses correlate with humoral responses, disease severity, and symptomatology

Background

Cellular immune memory responses post coronavirus disease 2019 (COVID‐19) have been difficult to assess due to the risks of contaminating the immune response readout with memory responses stemming from previous exposure to endemic coronaviruses. The work herein presents a large‐scale long‐term follow‐up study investigating the correlation between symptomology and cellular immune responses four to five months post seroconversion based on a unique severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)‐specific peptide pool that contains no overlapping peptides with endemic human coronaviruses.

Methods

Peptide stimulated memory T cell responses were assessed with dual interferon‐gamma (IFNγ) and interleukin (IL)‐2 Fluorospot. Serological analyses were performed using a multiplex antigen bead array.

Results

Our work demonstrates that long‐term SARS‐CoV‐2‐specific memory T cell responses feature dual IFNγ and IL‐2 responses, whereas cross‐reactive memory T cell responses primarily generate IFNγ in response to SARS‐CoV‐2 peptide stimulation. T cell responses correlated to long‐term humoral immune responses. Disease severity as well as specific COVID‐19 symptoms correlated with the magnitude of the SARS‐CoV‐2‐specific memory T cell response four to five months post seroconversion.

Conclusion

Using a large cohort and a SARS‐CoV‐2‐specific peptide pool we were able to substantiate that initial disease severity and symptoms correlate with the magnitude of the SARS‐CoV‐2‐specific memory T cell responses.

Salivary IgG to SARS-CoV-2 indicates seroconversion and correlates to serum neutralization in mRNA-vaccinated immunocompromised individuals

BACKGROUND

Immunocompromised individuals are highly susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Whether vaccine-induced immunity in these individuals involves oral cavity, a primary site of infection, is presently unknown.

METHODS

Immunocompromised patients (n = 404) and healthy controls (n = 82) participated in a prospective clinical trial (NCT04780659) encompassing two doses of the mRNA BNT162b2 vaccine. Primary immunodeficiency (PID), secondary immunodeficiencies caused by human immunodeficiency virus (HIV) infection, allogeneic hematopoietic stem cell transplantation (HSCT)/chimeric antigen receptor T cell therapy (CAR-T), solid organ transplantation (SOT), and chronic lymphocytic leukemia (CLL) patients were included. Salivary and serum immunoglobulin G (IgG) reactivities to SARS-CoV-2 spike were measured by multiplex bead-based assays and Elecsys anti-SARS-CoV-2 S assay.

FINDINGS

IgG responses to SARS-CoV-2 spike antigens in saliva in HIV and HSCT/CAR-T groups were comparable to those of healthy controls after vaccination. The PID, SOT, and CLL patients had weaker responses, influenced mainly by disease parameters or immunosuppressants. Salivary responses correlated remarkably well with specific IgG titers and the neutralizing capacity in serum. Receiver operating characteristic curve analysis for the predictive power of salivary IgG yielded area under the curve (AUC) = 0.95 and positive predictive value (PPV) = 90.7% for the entire cohort after vaccination.

CONCLUSIONS

Saliva conveys vaccine responses induced by mRNA BNT162b2. The predictive power of salivary spike IgG makes it highly suitable for screening vulnerable groups for revaccination.

FUNDING

Knut and Alice Wallenberg Foundation, Erling Perssons family foundation, Region Stockholm, Swedish Research Council, Karolinska Institutet, Swedish Blood Cancer Foundation, PID patient organization of Sweden, Nordstjernan AB, Center for Medical Innovation (CIMED), Swedish Medical Research Council, and Stockholm County Council (ALF).

Covid-19 in patients with chronic lymphocytic leukemia: clinical outcome and B- and T-cell immunity during 13 months in consecutive patients

We studied clinical and immunological outcome of Covid-19 in consecutive CLL patients from a well-defined area during month 1-13 of the pandemic. Sixty patients (median age 71 y, range 43-97) were identified. Median CIRS was eight (4-20). Patients had indolent CLL (n = 38), had completed (n = 12) or ongoing therapy (n = 10). Forty-six patients (77%) were hospitalized due to severe Covid-19 and 11 were admitted to ICU. Severe Covid-19 was equally distributed across subgroups irrespective of age, gender, BMI, CLL status except CIRS (p < 0.05). Fourteen patients (23%) died; age ≥75 y was the only significant risk factor (p < 0.05, multivariate analysis with limited power). Comparing month 1-6 vs 7-13 of the pandemic, deaths were numerically reduced from 32% to 18%, ICU admission from 37% to 15% whereas hospitalizations remained frequent (86% vs 71%). Seroconversion occurred in 33/40 patients (82%) and anti-SARS-CoV-2 antibodies were detectable at six and 12 months in 17/22 and 8/11 patients, respectively. Most (13/17) had neutralizing antibodies and 19/28 had antibodies in saliva. SARS-CoV-2-specific T-cells (ELISpot) were detected in 14/17 patients. Covid-19 continued to result in high admission even among consecutive and young early- stage CLL patients. A robust and durable B and/or T cell immunity was observed in most convalescents.

SARS-CoV-2 induces a durable and antigen specific humoral immunity after asymptomatic to mild COVID-19 infection

Current SARS-CoV-2 serological assays generate discrepant results, and the longitudinal characteristics of antibodies targeting various antigens after asymptomatic to mild COVID-19 are yet to be established. This longitudinal cohort study including 1965 healthcare workers, of which 381 participants exhibited antibodies against the SARS-CoV-2 spike antigen at study inclusion, reveal that these antibodies remain detectable in most participants, 96%, at least four months post infection, despite having had no or mild symptoms. Virus neutralization capacity was confirmed by microneutralization assay in 91% of study participants at least four months post infection. Contrary to antibodies targeting the spike protein, antibodies against the nucleocapsid protein were only detected in 80% of previously anti-nucleocapsid IgG positive healthcare workers. Both anti-spike and anti-nucleocapsid IgG levels were significantly higher in previously hospitalized COVID-19 patients four months post infection than in healthcare workers four months post infection (p = 2*10-23 and 2*10-13 respectively). Although the magnitude of humoral response was associated with disease severity, our findings support a durable and functional humoral response after SARS-CoV-2 infection even after no or mild symptoms. We further demonstrate differences in antibody kinetics depending on the antigen, arguing against the use of the nucleocapsid protein as target antigen in population-based SARS-CoV-2 serological surveys.

Robust humoral and cellular immune responses and low risk for reinfection at least 8 months following asymptomatic to mild COVID-19

BACKGROUND

Emerging data support detectable immune responses for months after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and vaccination, but it is not yet established to what degree and for how long protection against reinfection lasts.

METHODS

We investigated SARS-CoV-2-specific humoral and cellular immune responses more than 8 months post-asymptomatic, mild and severe infection in a cohort of 1884 healthcare workers (HCW) and 51 hospitalized COVID-19 patients. Possible protection against SARS-CoV-2 reinfection was analyzed by a weekly 3-month polymerase chain reaction (PCR) screening of 252 HCW that had seroconverted 7 months prior to start of screening and 48 HCW that had remained seronegative at multiple time points.

RESULTS

All COVID-19 patients and 96% (355/370) of HCW who were anti-spike IgG positive at inclusion remained anti-spike IgG positive at the 8-month follow-up. Circulating SARS-CoV-2-specific memory T cell responses were detected in 88% (45/51) of COVID-19 patients and in 63% (233/370) of seropositive HCW. The cumulative incidence of PCR-confirmed SARS-CoV-2 infection was 1% (3/252) among anti-spike IgG positive HCW (0.13 cases per 100 weeks at risk) compared to 23% (11/48) among anti-spike IgG negative HCW (2.78 cases per 100 weeks at risk), resulting in a protective effect of 95.2% (95% CI 81.9%-99.1%).

CONCLUSIONS

The vast majority of anti-spike IgG positive individuals remain anti-spike IgG positive for at least 8 months regardless of initial COVID-19 disease severity. The presence of anti-spike IgG antibodies is associated with a substantially reduced risk of reinfection up to 9 months following asymptomatic to mild COVID-19.

Multiomics Profiling of Alzheimer's Disease Serum for the Identification of Autoantibody Biomarkers

New biomarkers of Alzheimer's disease (AD) with a diagnostic value in preclinical and prodromal stages are urgently needed. AD-related serum autoantibodies are potential candidate biomarkers. Here, we aimed at identifying AD-related serum autoantibodies using protein microarrays and mass spectrometry-based methods. To this end, an untargeted complementary screening using high-density (42,100 antigens) and low-density (384 antigens) planar protein-epitope signature tag (PrEST) arrays and an immunoprecipitation protocol coupled to mass spectrometry analysis were used for serum autoantibody profiling. From the untargeted screening phase, 377 antigens corresponding to 338 proteins were selected for validation. Out of them, IVD, CYFIP1, and ADD2 seroreactivity was validated using 128 sera from AD patients and controls by PrEST-suspension bead arrays, and ELISA or luminescence Halotag-based bead immunoassay using full-length recombinant proteins. Importantly, IVD, CYFIP1, and ADD2 showed in combination a noticeable AD diagnostic ability. Moreover, IVD protein abundance in the prefrontal cortex was significantly two-fold higher in AD patients than in controls by western blot and immunohistochemistry, whereas CYFIP1 and ADD2 were significantly down-regulated in AD patients. The panel of AD-related autoantigens identified by a comprehensive multiomics approach may provide new insights of the disease and should help in the blood-based diagnosis of Alzheimer's disease. Mass spectrometry raw data are available in the ProteomeXchange database with the access number PXD028392.

Identification of driver genes for critical forms of COVID-19 in a deeply phenotyped young patient cohort

[Figure: see text].

A cell-free high throughput assay for assessment of SARS-CoV-2 neutralizing antibodies

Highly accurate serological tests are key to assessing the prevalence of SARS-CoV-2 antibodies and the level of immunity in the population. This is important to predict the current and future status of the pandemic. With the recent emergence of new and more infectious SARS-CoV-2 variants, assays allowing for high throughput analysis of antibodies able to neutralize SARS-CoV-2 become even more important. Here, we report the development and validation of a robust, high throughput method, which enables the assessment of antibodies inhibiting the binding between the SARS-CoV-2 spike protein and angiotensin converting enzyme 2 (ACE2). The assay uses recombinantly produced spike-f and ACE2 and is performed in a bead array format, which allows analysis of up to 384 samples in parallel per instrument over seven hours, demanding only one hour of manual handling. The method is compared to a microneutralization assay utilising live SARS-CoV-2 and is shown to deliver highly correlating data. Further, a comparison with a serological method that measures all antibodies recognizing the spike protein shows that this type of assessment provides important insights into the neutralizing efficiency of the antibodies, especially for individuals with low antibody levels. This method can be an important and valuable tool for large-scale assessment of antibody-based neutralization, including neutralization of new spike variants that might emerge.

Development of humoral and cellular immunological memory against SARS-CoV-2 despite B cell depleting treatment in multiple sclerosis

B cell depleting therapies (BCDTs) are widely used as immunomodulating agents for autoimmune diseases such as multiple sclerosis. Their possible impact on development of immunity to severe acute respiratory syndrome virus-2 (SARS-CoV-2) has raised concerns with the coronavirus disease 2019 (COVID-19) pandemic. We here evaluated the frequency of COVID-19-like symptoms and determined immunological responses in participants of an observational trial comprising several multiple sclerosis disease modulatory drugs (COMBAT-MS; NCT03193866) and in eleven patients after vaccination, with a focus on BCDT. Almost all seropositive and 17.9% of seronegative patients on BCDT, enriched for a history of COVID-19-like symptoms, developed anti-SARS-CoV-2 T cell memory, and T cells displayed functional similarity to controls producing IFN-γ and TNF. Following vaccination, vaccine-specific humoral memory was impaired, while all patients developed a specific T cell response. These results indicate that BCDTs do not abrogate SARS-CoV-2 cellular memory and provide a possible explanation as to why the majority of patients on BCDTs recover from COVID-19.

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BCDT might blunt antibody responses after COVID-19 infection or vaccination

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Patients with no detectable B cells in the blood might still produce antibodies

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A majority of patients that do not develop antibodies still display a T cell response

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SARS-CoV-2 T-cells produce Th1 cytokines both in patients on BCDT and untreated

Differences in risk for SARS-CoV-2 infection among healthcare workers

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Clustering of SARS-CoV-2 exposure among HCWs in specific hospital wards was found.

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SARS-CoV-2 infection was most common among nurse assistants in COVID-19 wards.

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HCWs in wards with infectious diseases experience did not have increased risk.

Healthcare workers (HCWs) are a risk group for SARS-CoV-2 infection, but which healthcare work that conveys risk and to what extent such risk can be prevented is not clear. Starting on April 24th, 2020, all employees at work (n = 15,300) at the Karolinska University Hospital, Stockholm, Sweden were invited and 92% consented to participate in a SARS-CoV-2 cohort study. Complete SARS-CoV-2 serology was available for n = 12,928 employees and seroprevalences were analyzed by age, sex, profession, patient contact, and hospital department. Relative risks were estimated to examine the association between type of hospital department as a proxy for different working environment exposure and risk for seropositivity, adjusting for age, sex, sampling week, and profession. Wards that were primarily responsible for COVID-19 patients were at increased risk (adjusted OR 1.95 (95% CI 1.65–2.32) with the notable exception of the infectious diseases and intensive care units (adjusted OR 0.86 (95% CI 0.66–1.13)), that were not at increased risk despite being highly exposed. Several units with similar types of work varied greatly in seroprevalences. Among the professions examined, nurse assistants had the highest risk (adjusted OR 1.62 (95% CI 1.38–1.90)). Although healthcare workers, in particular nurse assistants, who attend to COVID-19 patients are a risk group for SARS-CoV-2 infection, several units caring for COVID-19 patients had no excess risk. Large variations in seroprevalences among similar units suggest that healthcare work-related risk of SARS-CoV-2 infection may be preventable.

Antibody responses after a single dose of ChAdOx1 nCoV-19 vaccine in healthcare workers previously infected with SARS-CoV-2

BACKGROUND

Recent reports demonstrate robust serological responses to a single dose of messenger RNA (mRNA) vaccines in individuals previously infected with SARS-CoV-2. Data on immune responses following a single-dose adenovirus-vectored vaccine expressing the SARS-CoV-2 spike protein (ChAdOx1 nCoV-19) in individuals with previous SARS-CoV-2 infection are however limited, and current guidelines recommend a two-dose regimen regardless of preexisting immunity.

METHODS

We compared RBD-specific IgG and RBD-ACE2 blocking antibodies against SARS-CoV-2 wild type and variants of concern following two doses of the mRNA vaccine BNT162b2 in SARS-CoV-2 naïve healthcare workers (n=65) and a single dose of the adenovector vaccine ChAdOx1 nCoV-19 in 82 healthcare workers more than (n=45) and less than (n=37) 11 months post mild SARS-CoV-2 infection at time of vaccination.

FINDINGS

The post-vaccine levels of RBD-specific IgG and neutralizing antibodies against the SARS-CoV-2 wild type and variants of concern including Delta lineage 1.617.2 were similar or higher in participants receiving a single dose of ChAdOx1 nCoV-19 vaccine post SARS-CoV-2 infection (both more than and less than 11 months post infection) compared to SARS-CoV-2 naïve participants who received two doses of BNT162b2 vaccine.

INTERPRETATION

Our data support that a single dose ChAdOx1 nCoV-19 vaccine that is administered up to at least 11 months post SARS-CoV-2 infection serves as an effective immune booster. This provides a possible rationale for a single-dose vaccine regimen.

FUNDING

A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

Persisting Salivary IgG Against SARS-CoV-2 at 9 Months After Mild COVID-19: A Complementary Approach to Population Surveys

Background

Declining humoral immunity in coronavirus disease 2019 (COVID-19) patients and possible reinfection have raised concern. Mucosal immunity, particularly salivary antibodies, may be short lived although long-term studies are lacking.

Methods

Using a multiplex bead-based array platform, we investigated antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins in 256 saliva samples from convalescent patients 1–9 months after symptomatic COVID-19 (n = 74, cohort 1), undiagnosed individuals with self-reported questionnaires (n = 147, cohort 2), and individuals sampled prepandemic (n = 35, cohort 3).

Results

Salivary IgG antibody responses in cohort 1 (mainly mild COVID-19) were detectable up to 9 months postrecovery, with high correlations between spike and nucleocapsid specificity. At 9 months, IgG remained in blood and saliva in most patients. Salivary IgA was rarely detected at this time point. In cohort 2, salivary IgG and IgA responses were significantly associated with recent history of COVID-19–like symptoms. Salivary IgG tolerated temperature and detergent pretreatments.

Conclusions

Unlike SARS-CoV-2 salivary IgA that appeared short lived, specific saliva IgG appeared stable even after mild COVID-19, as for blood serology. This noninvasive saliva-based SARS-CoV-2 antibody test with home self-collection may be a complementary alternative to conventional blood serology.

SARS-CoV-2 infections amongst personnel providing home care services for older persons in Stockholm, Sweden

BACKGROUND

In Sweden, home care services is a major external contact for older persons.

METHODS

Five home care service companies in Stockholm, Sweden, enrolled 405 employees to a study including serum IgG to SARS-CoV-2 and SARS-CoV-2 virus in throat swabs.

RESULTS

20.1% (81/403) of employees were seropositive, about twice as many as in a simultaneously enrolled reference population (healthcare workers entirely without patient contact, n = 3671; 9.7% seropositivity). 13/379 employees (3.4%) had a current infection (PCR positivity). Amongst these, 5 were also seropositive and 3 were positive with low amounts of virus. High amounts of virus and no antibodies (a characteristic for presymptomatic COVID-19) were present in 5 employees (1.3%).

CONCLUSIONS

Personnel providing home services for older persons appear to be a risk group for SARS-CoV-2. Likely presymptomatic employees can be readily identified by screening. Increased protection of employees and of the older persons they serve is warranted.

High Amounts of SARS-CoV-2 Precede Sickness Among Asymptomatic Health Care Workers

Background

Whether SARS-CoV-2 positivity among symptomatic subjects reflects past or future disease may be difficult to ascertain.

Methods

We tested a cohort of 9449 employees at work at the Karolinska University Hospital, Stockholm, Sweden for SARS-CoV-2 RNA and antibodies, linked the testing results to sick leave records and determined associations with past or future sick leave using multinomial logistic regression. ClinicalTrials.gov NCT04411576.

Results

Subjects with high amounts of SARS-CoV-2 virus, as indicated by the Cycle threshold (Ct) value in the PCR, had the highest risk for sick leave in the two weeks after testing (OR 11.97 (CI 95% 6.29-22.80)) whereas subjects with low amounts of virus had the highest risk for sick leave in the past three weeks before testing (OR 6.31 (4.38-9.08)). Only 2.5% of employees were SARS-CoV-2 positive while 10.5% were positive by serology and 1.2% were positive in both tests. Serology-positive subjects were not at excess risk for future sick leave (OR 1.06 (95% CI, 0.71-1.57)).

Conclusions

High amounts of SARS-CoV-2 virus, as determined using PCR Ct values, associates with development of sickness in the next few weeks. The results support the concept that PCR Ct may be informative when testing for SARS-CoV-2 is performed.

Systematic evaluation of SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay

Objective

The COVID-19 pandemic poses an immense need for accurate, sensitive and high-throughput clinical tests, and serological assays are needed for both overarching epidemiological studies and evaluating vaccines. Here, we present the development and validation of a high-throughput multiplex bead-based serological assay.

Methods

More than 100 representations of SARS-CoV-2 proteins were included for initial evaluation, including antigens produced in bacterial and mammalian hosts as well as synthetic peptides. The five best-performing antigens, three representing the spike glycoprotein and two representing the nucleocapsid protein, were further evaluated for detection of IgG antibodies in samples from 331 COVID-19 patients and convalescents, and in 2090 negative controls sampled before 2020.

Results

Three antigens were finally selected, represented by a soluble trimeric form and the S1-domain of the spike glycoprotein as well as by the C-terminal domain of the nucleocapsid. The sensitivity for these three antigens individually was found to be 99.7%, 99.1% and 99.7%, and the specificity was found to be 98.1%, 98.7% and 95.7%. The best assay performance was although achieved when utilising two antigens in combination, enabling a sensitivity of up to 99.7% combined with a specificity of 100%. Requiring any two of the three antigens resulted in a sensitivity of 99.7% and a specificity of 99.4%.

Conclusion

These observations demonstrate that a serological test based on a combination of several SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay.

POS0392 PRESENCE OF FOUR SERUM AUTOANTIBODIES ASSOCIATES WITH THE ACPA STATUS IN EARLY RHEUMATOID ARTHRITIS

Background:

The presence of anti-citrullinated protein antibodies (ACPAs) is a hallmark of rheumatoid arthritis (RA) that precede the development of the disease by years and is used for its clinical diagnosis. However, there are RA subjects that test negative for ACPA and thus the early diagnosis on these patients may be delayed. Furthermore, the presence or absence of ACPA in RA supports the hypothesis that on these two subsets of patients underlie different pathogenesis and clinical outcomes.

Objectives:

In this work, we searched for serum autoantibodies useful to assist the early diagnosis of ACPA-seronegative RA and its management.

Methods:

We profiled the serum autoantibody repertoire of 80 ACPA-seronegative and 80 ACPA-seropositive RA subjects from the Swedish population-based Epidemiological Investigation of RA (EIRA) cohort. A suspension bead array platform built on protein fragments within Human Protein Atlas and selected from an initial untargeted screening using arrays containing 2660 total antigens was employed to identify IgG and IgA serum autoantibodies. A validation phase on antigen suspension bead arrays was carried out on another set of samples from EIRA containing 386 ACPA-seropositive, 358 ACPA-seronegative and 372 randomly selected control subjects of the same age and sex. A sample-specific threshold based on 20 times the median absolute deviation plus the median of all signals was selected to determine the reactivity of samples. The Wilcoxon rank sum test and Fisher’s test were applied for the comparison of autoantibody levels and reactivity frequencies between the groups.

Results:

Our data revealed four antigens associated with the ACPA status (Table 1). Testis-specific Y-encoded-like protein 4 (TSPYL4) showed significantly higher IgG reactivity frequency in ACPA-seronegative subjects compared to ACPA-seropositive (8% vs. 3%; P<0.05). Significant differences at IgG autoantibody levels (P<0.05) were also observed between ACPA-seronegative subjects and controls for this specific antigen. Significantly higher IgG autoantibody levels (P<0.05) towards another antigen, dual specificity mitogen-activated protein kinase kinase 6 (MAP2K6), were also observed in ACPA-seronegative subjects compared to ACPA-seropositive and controls. In contrast, we found significantly higher IgG autoantibody levels (P<0.05) in ACPA-seropositive individuals compared to ACPA-seronegative and controls towards two antigens, anosmin-1 (ANOS-1) and muscle related coiled-coil protein (MURC). ANOS-1 shows also significantly higher IgG reactivity frequency in ACPA-seropositive individuals compared to ACPA-seronegative and controls (22%, 9% and 6% respectively; P<0.05). Interestingly, three out of the four antigens discovered to be associated with the ACPA status in early RA are highly expressed in lungs and heart, two of the main extraarticular sites affected in RA. No significant differences were observed at IgA levels for any of the antigens analyzed.

Table 1.

Scheme of the different phases of the study, the features within each phase and the results. The reactivity to four antigens allows to distinguish ACPA-seronegative (ACPA-), ACPA seropositive (ACPA+) and controls.

PhasesUntargeteddiscoveryTargeteddiscoveryTargetedvalidationNumber of samples80 ACPA-80 ACPA-358 ACPA-372 Controls80 ACPA+80 ACPA+386 ACPA+Antigen arrayplatformPlanararraysSuspensionbead array 1Suspensionbead array 2Number of antigens26606227Number of candidatebiomarkers6227 4 (TSPYL4,MAP2K6,ANOS1,MURC)

Conclusion:

Upon further validation in other early RA sample cohorts, our data suggest the measurement of these four autoantibodies may be useful for the early diagnosis of ACPA-seronegative RA and give insight into the pathogenesis of the different RA subsets.

Characters from table content including title and footnotes:

Disclosure of Interests:

None declared

Immunoglobulin A Autoreactivity toward Brain Enriched and Apoptosis-Regulating Proteins in Saliva of Athletes after Acute Concussion and Subconcussive Impacts

The diagnosis and management of concussion is hindered by its diverse clinical presentation and assessment tools reliant on subjectively experienced symptoms. The biomechanical threshold of concussion is also not well understood, and asymptomatic concussion or "subconcussive impacts" of variable magnitudes are common in contact sports. Concerns have risen because athletes returning to activity too soon have an increased risk of prolonged recovery or long-term adverse health consequences. To date, little is understood on a molecular level regarding concussion and subconcussive impacts. Recent research suggests that neuroinflammatory mechanisms may serve an important role subsequent to concussion and possibly to subconcussive impacts. These studies suggest that autoantibodies may be a valuable tool for detection of acute concussion and monitoring for changes caused by cumulative exposure to subconcussive impacts. Hence, we aimed to profile the immunoglobulin (Ig)A autoantibody repertoire in saliva by screening a unique sport-related head trauma biobank. Saliva samples (n = 167) were donated by male and female participants enrolled in either the concussion (24-48 h post-injury) or subconcussion (non-concussed participants having moderate or high cumulative subconcussive impact exposure) cohorts. Study design included discovery and verification phases. Discovery aimed to identify new candidate autoimmune targets of IgA. Verification tested whether concussion and subconcussion cohorts increased IgA reactivity and whether cohorts showed similarities. The results show a significant increase in the prevalence of IgA toward protein fragments representing 5-hydroxytryptamine receptor 1A (HTR1A), serine/arginine repetitive matrix 4 (SRRM4) and FAS (tumor necrosis factor receptor superfamily member 6) after concussion and subconcussion. These results may suggest that concussion and subconcussion induce similar physiological effects, especially in terms of immune response. Our study demonstrates that saliva is a potential biofluid for autoantibody detection in concussion and subconcussion. After rigorous confirmation in much larger independent study sets, a validated salivary autoantibody assay could provide a non-subjective quantitative means of assessing concussive and subconcussive events.

False Positive Results in SARS-CoV-2 Serological Tests for Samples From Patients With Chronic Inflammatory Diseases

Patients with chronic inflammatory diseases are often treated with immunosuppressants and therefore are of particular concern during the SARS-CoV-2 pandemic. Serological tests will improve our understanding of the infection and immunity in this population, unless they tests give false positive results. The aim of this study was to evaluate the specificity of SARS-Cov-2 serological assays using samples from patients with chronic inflammatory diseases collected prior to April 2019, thus defined as negative. Samples from patients with multiple sclerosis (MS, n=10), rheumatoid arthritis (RA, n=47) with or without rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (anti-CCP2) and systemic lupus erythematosus (SLE, n=10) with or without RF, were analyzed for SARS-CoV-2 antibodies using 17 commercially available lateral flow assays (LFA), two ELISA kits and one in-house developed IgG multiplex bead-based assay. Six LFA and the in-house validated IgG assay correctly produced negative results for all samples. However, the majority of assays (n=13), gave false positive signal for samples from patients with RA and SLE. This was most notable in samples from RF positive RA patients. No false positive samples were detected in any assay using samples from patients with MS. Poor specificity of commercial serological assays could possibly be, at least partly, due to interfering antibodies in samples from patients with chronic inflammatory diseases. For these patients, the risk of false positivity should be considered when interpreting results of the SARS-CoV-2 serological assays.

Fluid proteomics of CSF and serum reveal important neuroinflammatory proteins in blood-brain barrier disruption and outcome prediction following severe traumatic brain injury: a prospective, observational study

BACKGROUND

Severe traumatic brain injury (TBI) is associated with blood-brain barrier (BBB) disruption and a subsequent neuroinflammatory process. We aimed to perform a multiplex screening of brain enriched and inflammatory proteins in blood and cerebrospinal fluid (CSF) in order to study their role in BBB disruption, neuroinflammation and long-term functional outcome in TBI patients and healthy controls.

METHODS

We conducted a prospective, observational study on 90 severe TBI patients and 15 control subjects. Clinical outcome data, Glasgow Outcome Score, was collected after 6-12 months. We utilized a suspension bead antibody array analyzed on a FlexMap 3D Luminex platform to characterize 177 unique proteins in matched CSF and serum samples. In addition, we assessed BBB disruption using the CSF-serum albumin quotient (QA), and performed Apolipoprotein E-genotyping as the latter has been linked to BBB function in the absence of trauma. We employed pathway-, cluster-, and proportional odds regression analyses. Key findings were validated in blood samples from an independent TBI cohort.

RESULTS

TBI patients had an upregulation of structural CNS and neuroinflammatory pathways in both CSF and serum. In total, 114 proteins correlated with QA, among which the top-correlated proteins were complement proteins. A cluster analysis revealed protein levels to be strongly associated with BBB integrity, but not carriage of the Apolipoprotein E4-variant. Among cluster-derived proteins, innate immune pathways were upregulated. Forty unique proteins emanated as novel independent predictors of clinical outcome, that individually explained ~ 10% additional model variance. Among proteins significantly different between TBI patients with intact or disrupted BBB, complement C9 in CSF (p = 0.014, ΔR2 = 7.4%) and complement factor B in serum (p = 0.003, ΔR2 = 9.2%) were independent outcome predictors also following step-down modelling.

CONCLUSIONS

This represents the largest concomitant CSF and serum proteomic profiling study so far reported in TBI, providing substantial support to the notion that neuroinflammatory markers, including complement activation, predicts BBB disruption and long-term outcome. Individual proteins identified here could potentially serve to refine current biomarker modelling or represent novel treatment targets in severe TBI.

Antibodies to SARS-CoV-2 and risk of past or future sick leave

The extent that antibodies to SARS-CoV-2 may protect against future virus-associated disease is unknown. We invited all employees (n = 15,300) at work at the Karolinska University Hospital, Stockholm, Sweden to participate in a study examining SARS-Cov-2 antibodies in relation to registered sick leave. For consenting 12,928 healthy hospital employees antibodies to SARS-CoV-2 could be determined and compared to participant sick leave records. Subjects with viral serum antibodies were not at excess risk for future sick leave (adjusted odds ratio (OR) controlling for age and sex: 0.85 [95% confidence interval (CI) (0.85 (0.43-1.68)]. By contrast, subjects with antibodies had an excess risk for sick leave in the weeks prior to testing [adjusted OR in multivariate analysis: 3.34 (2.98-3.74)]. Thus, presence of viral antibodies marks past disease and protection against excess risk of future disease. Knowledge of whether exposed subjects have had disease in the past or are at risk for future disease is essential for planning of control measures.Trial registration: First registered on 02/06/20, ClinicalTrials.gov NCT04411576.

Lynch syndrome and Muir-Torre phenotype associated with a recurrent variant in the 3'UTR of the MSH6 gene

A MSH6 3'UTR variant (c.*23_26dup) was found in 13 unrelated families consulted for Lynch/Muir-Torre Syndrome. This variant, which is very rare in the genomic databases, was absent in healthy controls and strongly segregated with the disease in the studied pedigrees. All tumors were defective for MSH2/MSH6/MSH3 proteins expression, but only MSH2 somatic pathogenic mutations were found in 5 of the 12 sequenced tumors. Moreover, we had no evidence of MSH6 transcript decrease in carriers, whereas MSH2 transcript was downregulated. Additional evaluations performed in representative carriers, including karyotype, arrayCGH and Linked-Reads whole genome sequencing, failed to evidence any MSH2 germline pathogenic variant. Posterior probability of pathogenicity for MSH6 c.*23_26dup was obtained from a multifactorial analysis incorporating segregation and phenotypic data and resulted >0.999, allowing to classify the variant as pathogenic (InSiGHT Class 5). Carriers shared a common haplotype involving MSH2/MSH6 loci, then a cryptic disease-associated variant, linked with MSH6 c.*23_26dup, cannot be completely excluded. Even if it is not clear whether the MSH6 variant is pathogenic per se or simply a marker of a disease-associated MSH2/MSH6 haplotype, all data collected on patients and pedigrees prompted us to manage the variant as pathogenic and to offer predictive testing within these families.

The human secretome

The proteins secreted by human cells (collectively referred to as the secretome) are important not only for the basic understanding of human biology but also for the identification of potential targets for future diagnostics and therapies. Here, we present a comprehensive analysis of proteins predicted to be secreted in human cells, which provides information about their final localization in the human body, including the proteins actively secreted to peripheral blood. The analysis suggests that a large number of the proteins of the secretome are not secreted out of the cell, but instead are retained intracellularly, whereas another large group of proteins were identified that are predicted to be retained locally at the tissue of expression and not secreted into the blood. Proteins detected in the human blood by mass spectrometry-based proteomics and antibody-based immunoassays are also presented with estimates of their concentrations in the blood. The results are presented in an updated version 19 of the Human Protein Atlas in which each gene encoding a secretome protein is annotated to provide an open-access knowledge resource of the human secretome, including body-wide expression data, spatial localization data down to the single-cell and subcellular levels, and data about the presence of proteins that are detectable in the blood.

Multiplexed analysis of the secretin-like GPCR-RAMP interactome

Receptor activity-modifying proteins (RAMPs) have been shown to modulate the functions of several G protein-coupled receptors (GPCRs), but potential direct interactions among the three known RAMPs and hundreds of GPCRs have never been investigated. Focusing mainly on the secretin-like family of GPCRs, we engineered epitope-tagged GPCRs and RAMPs, and developed a multiplexed suspension bead array (SBA) immunoassay to detect GPCR-RAMP complexes from detergent-solubilized lysates. Using 64 antibodies raised against the native proteins and 4 antibodies targeting the epitope tags, we mapped the interactions among 23 GPCRs and 3 RAMPs. We validated nearly all previously reported secretin-like GPCR-RAMP interactions, and also found previously unidentified RAMP interactions with additional secretin-like GPCRs, chemokine receptors, and orphan receptors. The results provide a complete interactome of secretin-like GPCRs with RAMPs. The SBA strategy will be useful to search for additional GPCR-RAMP complexes and other interacting membrane protein pairs in cell lines and tissues.

Identification of a Novel Autoimmune Peptide Epitope of Prostein in Prostate Cancer

There is a demand for novel targets and approaches to diagnose and treat prostate cancer (PCA). In this context, serum and plasma samples from a total of 609 individuals from two independent patient cohorts were screened for IgG reactivity against a sum of 3833 human protein fragments. Starting from planar protein arrays with 3786 protein fragments to screen 80 patients with and without PCA diagnosis, 161 fragments (4%) were chosen for further analysis based on their reactivity profiles. Adding 71 antigens from literature, the selection of antigens was corroborated for their reactivity in a set of 550 samples using suspension bead arrays. The antigens prostein (SLC45A3), TATA-box binding protein (TBP), and insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) showed higher reactivity in PCA patients with late disease compared with early disease. Because of its prostate tissue specificity, we focused on prostein and continued with mapping epitopes of the 66-mer protein fragment using patient samples. Using bead-based assays and 15-mer peptides, a minimal peptide epitope was identified and refined by alanine scanning to the KPxAPFP. Further sequence alignment of this motif revealed homology to transmembrane protein 79 (TMEM79) and TGF-beta-induced factor 2 (TGIF2), thus providing a reasoning for cross-reactivity found in females. A comprehensive workflow to discover and validate IgG reactivity against prostein and homologous targets in human serum and plasma was applied. This study provides useful information when searching for novel biomarkers or drug targets that are guided by the reactivity of the immune system against autoantigens.

A pilot study exploring the molecular architecture of the tumor microenvironment in human prostate cancer using laser capture microdissection and reverse phase protein microarray

The cross-talk between tumor epithelium and surrounding stromal/immune microenvironment is essential to sustain tumor growth and progression and provides new opportunities for the development of targeted treatments focused on disrupting the tumor ecology. Identification of novel approaches to study these interactions is of primary importance. Using laser capture microdissection (LCM) coupled with reverse phase protein microarray (RPPA) based protein signaling activation mapping we explored the molecular interconnection between tumor epithelium and surrounding stromal microenvironment in 18 prostate cancer (PCa) specimens. Four specimen-matched cellular compartments (normal-appearing epithelium and its adjacent stroma, and malignant epithelium and its adjacent stroma) were isolated for each case. The signaling network analysis of the four compartments unraveled a number of molecular mechanisms underlying the communication between tumor cells and stroma in the context of the tumor microenvironment. In particular, differential expression of inflammatory mediators like IL-8 and IL-10 by the stroma cells appeared to modulate specific cross-talks between the tumor cells and surrounding microenvironment.

Immunocapture strategies in translational proteomics

Aiming at clinical studies of human diseases, antibody-assisted assays have been applied to biomarker discovery and toward a streamlined translation from patient profiling to assays supporting personalized treatments. In recent years, integrated strategies to couple and combine antibodies with mass spectrometry-based proteomic efforts have emerged, allowing for novel possibilities in basic and clinical research. Described in this review are some of the field's current and emerging immunocapture approaches from an affinity proteomics perspective. Discussed are some of their advantages, pitfalls and opportunities for the next phase in clinical and translational proteomics.

HSP-90 inhibitor ganetespib is synergistic with doxorubicin in small cell lung cancer

Small cell lung cancer (SCLC) at advanced stage is considered an incurable disease. Despite good response to initial chemotherapy, the responses in SCLC patients with metastatic disease are of short duration and resistance inevitably occurs. Although several target-specific drugs have altered the paradigm of treatment for many other cancers, we have yet to witness a revolution of the same magnitude in SCLC treatment. Anthracyclines, such as doxorubicin, have definite activity in this disease, and ganetespib has shown promising activity in preclinical models but underwhelming activity as a single agent in SCLC patients. Using SCLC cell lines, we demonstrated that ganetespib (IC50: 31 nM) was much more potent than 17-allylamino-17-demethoxygeldanamycin (17-AAG), a geldanamycin derivative (IC50: 16 μM). Ganetespib inhibited SCLC cell growth via induction of persistent G2/M arrest and Caspase 3-dependent cell death. MTS assay revealed that ganetespib synergized with both doxorubicin and etoposide, two topoisomerase II inhibitors commonly used in SCLC chemotherapy. Expression of receptor-interacting serine/threonine-protein kinase 1 (RIP1), a protein that may function as a pro-survival scaffold protein or a pro-death kinase in TNFR1-activated cells, was induced by doxorubicin and downregulated by ganetespib. Depletion of RIP1 by either RIP1 small interfering RNA (siRNA) or ganetespib sensitized doxorubicin-induced cell death, suggesting that RIP1 may promote survival in doxorubicin-treated cells and that ganetespib may synergize with doxorubicin in part through the downregulation of RIP1. In comparison to ganetespib or doxorubicin alone, the ganetespib+doxorubicin combination caused significantly more growth regression and death of human SCLC xenografts in immunocompromised mice. We conclude that ganetespib and doxorubicin combination exhibits significant synergy and is efficacious in inhibiting SCLC growth in vitro and in mouse xenograft models. Our preclinical study suggests that ganetespib and doxorubicin combination therapy may be an effective strategy for SCLC treatment, which warrants clinical testing.

Pilot phase I/II personalized therapy trial for metastatic colorectal cancer: evaluating the feasibility of protein pathway activation mapping for stratifying patients to therapy with imatinib and panitumumab

This nonrandomized phase I/II trial assessed the efficacy/tolerability of imatinib plus panitumumab in patients affected by metastatic colorectal cancer (mCRC) after stratification to treatment by selection of activated imatinib drug targets using reverse-phase protein array (RPPA). mCRC patients presenting with a biopsiable liver metastasis were enrolled. Allocation to the experimental and control arms was established using functional pathway activation mapping of c-Kit, PDGFR, and c-Abl phosphorylation by RPPA. The experimental arm received run-in escalation therapy with imatinib followed by panitumumab. The control arm received panitumumab alone. Seven patients were enrolled in the study. For three of the seven patients, sequential pre- and post-treatment biopsies were used to evaluate the effect of the therapeutic compounds on the drug targets and substrates. A decrease in the activation level of the drug targets and downstream substrates was observed in two of three patients. Combination therapy increased the activation of the AKT-mTOR pathway and several receptor tyrosine kinases. This study proposes a novel methodology for stratifying patients to personalized treatment based on the activation level of the drug targets. This workflow provides the ability to monitor changes in the signaling pathways after the administration of targeted therapies and to identify compensatory mechanisms.

Preparation and use of reverse protein microarrays

Reverse-phase protein array (RPPA) is a multiplex, high-throughput proteomic technique for profiling the activation status of signal transduction pathways involved in cancer survival and progression, potentially allowing for identification of new biomarkers and drug targets. On RPPA, the entire patient proteome is immobilized on a spot and single proteins can be quantified across a set of samples, spotted on the same array, with high specificity and sensitivity. Array immunostaining and signal amplification systems are used to generate a signal proportional to the concentration of the analyte. Dedicated scanners and software are used to detect spots, measure intensity, subtract background, normalize signal, and generate a numeric value as output. The generated output file is then analyzed using several different bioinformatic and biostatistical tools. In this unit, the RPPA procedure is described in depth, from sample handling and preparation to data analysis, with particular emphasis on tissue sample analysis.

Individualized therapy for metastatic colorectal cancer

Systemic therapeutic efficacy is central to determining the outcome of patients with metastatic colorectal cancer (CRC). In these patients, there is a critical need for predictive biomarkers to optimize efficacy whilst minimizing toxicity. The integration of a new generation of molecularly targeted drugs into the treatment of CRC, coupled with the development of sophisticated technologies for individual tumours as well as patient molecular profiling, underlines the potential for personalized medicine. In this review, we focus on the latest progress made within the genomic and proteomic fields, concerning predictive biomarkers for individualized therapy in metastatic CRC.

The role of proteomics in prostate cancer research: biomarker discovery and validation

PURPOSE

Prostate Cancer (PCa) represents the second most frequent type of tumor in men worldwide. Incidence increases with patient age and represents the most important risk factor. PCa is mostly characterized by indolence, however in a small percentage of cases (3%) the disease progresses to a metastatic state. To date, the most important issue concerning PCa research is the difficulty in distinguishing indolent from aggressive disease. This problem frequently results in low-grade PCa patient overtreatment and, in parallel; an effective treatment for distant and aggressive disease is not yet available.

RESULT

Proteomics represents a promising approach for the discovery of new biomarkers able to improve the management of PCa patients. Markers more specific and sensitive than PSA are needed for PCa diagnosis, prognosis and response to treatment. Moreover, proteomics could represent an important tool to identify new molecular targets for PCa tailored therapy. Several possible PCa biomarkers sources, each with advantages and limitations, are under investigation, including tissues, urine, serum, plasma and prostatic fluids. Innovative high-throughput proteomic platforms are now identifying and quantifying new specific and sensitive biomarkers for PCa detection, stratification and treatment. Nevertheless, many putative biomarkers are still far from being applied in clinical practice.

CONCLUSIONS

This review aims to discuss the recent advances in PCa proteomics, emphasizing biomarker discovery and their application to clinical utility for diagnosis and patient stratification.

MUTYH c.933+3A>C, associated with a severely impaired gene expression, is the first Italian founder mutation in MUTYH-Associated Polyposis

MUTYH variants are differently distributed in geographical areas of the world. In MUTYH-associated polyposis (MAP) patients from North-Eastern Italy, c.933+3A>C (IVS10+3A>C), a transversion causing an aberrant splicing process, accounts for nearly 1/5 of all mutations. The aim of this study was to verify whether its high frequency in North-Eastern Italy is due to a founder effect and to clarify its impact on MUTYH transcripts and protein. Haplotype analysis and age estimate performed on members of eleven Italian MAP families and cancer-free controls provided evidence that c.933+3A>C is a founder mutation originated about 83 generations ago. In addition, the Italian haplotype associated with the c.933+3A>C was also found in German families segregating the same mutation, indicating it had a common origin in Western Europe. Altogether c.933+3A>C and the two common Caucasian mutations p.Tyr179Cys and p.Gly396Asp represent about 60% of MUTYH alterations in MAP patients from North-Eastern Italy, suggesting the opportunity to perform targeted molecular screening for these variants in the diagnostic setting. Expression analyses performed on lymphoblastoid cell lines supported the notion that MUTYH c.933+3A>C alters splicing causing the synthesis of a non functional protein. However, some primary transcripts escape aberrant splicing, producing traces of full-length transcript and wild-type protein in a homozygote; this is in agreement with clinical findings that suggest a relatively mild phenotypic effect for this mutation. Overall, these data, that demonstrate a founder effect and further elucidate the splicing alterations caused by the MUTYH c.933+3A>C mutation, have important implications for genetic counseling and molecular diagnosis of MAP.

Correlation of VEGFR activation within the tumor-associated stroma with an aggressive colon cancer phenotype

e14151

Background: The tumour microenvironment, and especially the stroma surrounding the tumor cells, is an important target for cancer therapy. Previous results published by our group showed that colon cancer (CC) patients with a high (>50%) intra-tumor stroma ratio had poor prognosis compared to patients with low intra-tumor stroma ratios. In order to evaluate the contribution of the underpinning signalling and molecular architecture of the tumor associated stroma (TAS) to this aggressive phenotype, we utilized laser capture microdissection (LCM) coupled to broad-scale protein pathway activation mapping using reverse phase protein microarrays (RPMA). Such analysis could identify new stromal-based targeted treatment options through the identification of activated pathways within the TAS of patients with aggressive CC. Methods: CC stage II and III tissue specimens were scored for the amount of stroma and a stroma-high and a stroma-low group were defined. Correspondent frozen tumor specimens were selected for a pilot study (n=30; 15 high and 15 low TAS) and subjected to LCM to enrich for TAS cells. RPMA was performed on the resultant lysates whereby an initial set of 30 total and phospho-proteins, known to be involved in stroma proliferation and activation, were analyzed. Results: Unsupervised hierarchical clustering analysis showed partial grouping of stroma high and stroma low samples with phosphorylation of VEGFR-2 being significantly higher in the stroma high group compared to the stroma low (p=0.030). Conclusions: These preliminary results reveal the potential presence of biochemical derangements in the TAS of tumors from patients with aggressive CC with increased activation of VEGFR-2. Considering the central role this protein plays in angiogenesis and cell migration, these results suggest that anti-VEGFR targeted therapy could be considered for a pre-stratified group of patients with aggressive tumors with high recurrence rates. Ongoing expanded pathway analysis with additional signalling proteins including downstream signalling components of VEGFR are being conducted in order to validate this pilot finding and identify new TAS related signalling derangements.

Somatic mosaicism in a patient with Lynch syndrome

Genetic mosaicism is the presence of genetically different cell populations within an individual and can be associated with a milder disease phenotype. We describe a somatic mosaicism in a Lynch syndrome patient with a MLH1 gene mutation (c.1050delA). Since she was the sister of a heterozygous proposita, the mosaicism appeared to be caused by reversion of an inherited mutation and not a de novo mutation. In order to better understand her cancer risk, we tested different tissues to quantify the amount of mutated allele in several districts. The mosaicism was analyzed using DNA sequencing, primer extension, and dHPLC. The MLH1 mutation was present in somatic cells representative of the three embryonic layers and its percentage was > or =80% in both blood and tissues. Since this patient had a relevant quota of mutated cells, a significantly milder phenotype is not expected.

Serum antibody response to lytic and latent Epstein-Barr virus antigens in undifferentiated nasopharyngeal carcinoma patients from an area of nonendemicity

Epstein-Barr virus (EBV)-associated undifferentiated carcinoma of the nasopharyngeal type (UCNT) is highly prevalent in southeast China, where immunoglobulin A (IgA) antibodies to viral capsid antigen and early antigen (EA) represent important markers, routinely used to assist in diagnosing this malignancy. Our study aimed at determining the EBV serological profiles of 78 UCNT patients from Italy, an area of nonendemicity for this tumor, using different assays specific for both lytic and latent EBV antigens. Serum IgA against both EA and EBNA1 and IgG and IgA to the latent membrane protein 1 (LMP1), to EA, and to the EBV transactivator ZEBRA protein were assessed. These serological responses were then evaluated according to the clinicopathologic parameters at diagnosis. The sensitivities of the IgG assays were 37.7% for LMP1, 73.6% for EA, and 61.0% for ZEBRA. EA/EBNA1 IgA reactivity was 84.4%, and a high association (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.7 to 4.0) with UCNT was observed. When EBV serological reactivities were analyzed according to the tumor, node, and metastasis staging system (TNM), a statistically significant association was found between N stage and IgG antibody rates for EA (OR, 3.6; 95% CI, 1.2 to 10.9) and ZEBRA (OR, 2.6; 95% CI, 1.2 to 5.5) and between M stage and IgG antibody rates for ZEBRA (OR, 7.1; 95% CI, 3.2 to 16.0) and LMP1 (OR, 14.0; 95% CI, 1.8 to 110.9). Our results show that no single serological marker allows the detection of all UCNT cases. EA/EBNA1 IgA represents a reliable marker for diagnosis, with a high predictive value also in areas where UCNT is not endemic, such as Italy. The analysis of serological results according to TNM classification is consistent with a progressive impairment of humoral immune response to EBV as the disease advances and may be used to improve the accuracy of diagnosis.