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SUMMARYLyme disease is a tick-borne disease caused by bacteria of the genus Borrelia. The disease can initially manifest as an erythema migrans rash and, if able to evade the host immune defenses, can progress into a secondary stage chronic disease with debilitating physical or neurological manifestations1,2. The host factors that modulate susceptibility for Lyme disease have remained mostly unknown. Here we show a novel host defense mechanism against Lyme disease in humans. Using epidemiological and genetic data from FinnGen, we identify a common missense variant at the gene encoding for Secretoglobin family 1D member 2 (SCGB1D2) protein that increases the susceptibility for Lyme disease. The genetic variant changes proline at position 53 to leucine and is predicted as deleterious. Consequently, we validate the dysfunction of this protein variant using live Borrelia burgdorferi (Bb). Recombinant reference SCGB1D2 protein inhibits the growth of Bb twice as effectively as the recombinant SCGB1D2 P53L deleterious missense variant. Together, these data suggest that SCGB1D2 is a host defense factor present in the skin, sweat, and other secretions which protects against Bb infection. This finding provides a novel therapeutic avenue for drug development to prevent and treat Lyme disease.

CD47 is an important innate immune checkpoint through its interaction with its inhibitory receptor on macrophages, signal-regulatory protein α (SIRPα). Therapeutic blockade of CD47–SIRPα interactions is a promising immuno-oncology treatment that promotes clearance of cancer cells. However, CD47–SIRPα interactions also maintain homeostatic lymphocyte levels. In this study, we report that the mouse splenic marginal zone B cell population is dependent on intact CD47–SIRPα interactions and blockade of CD47 leads to the loss of these cells. This depletion is accompanied by elevated levels of monocyte-recruiting chemokines CCL2 and CCL7 and infiltration of CCR2+Ly6Chi monocytes into the mouse spleen. In the absence of CCR2 signaling, there is no infiltration and reduced marginal zone B cell depletion. These data suggest that CD47 blockade leads to clearance of splenic marginal zone B cells.

Background Borrelia burgdorferi is a bacterial spirochete that can cause Lyme disease after infecting a susceptible host. Immune responses to the bacteria are highly variable and host specific. The murine substrain, C3H/HeJ, is one of the most frequently utilized mouse models for Lyme disease. In this study, we sought to investigate the correlation of age with onset and severity of dermatitis, both in C3H/HeJ mice infected with B. burgdorferi as well as humans who have had a diagnosis of Lyme disease. Methods Female C3H/HeJ mice aged 6-8 weeks, 1 year, or 2 years were infected intraperitoneally with 105 B. burgdorferi. Dermatitis of the tail was evaluated by gross examination and histology. Human data via electronic health records of 342,499 Finnish individuals was tested and analyzed for associations between Lyme disease and atopic dermatitis. Results Dermatitis worsened over the course of untreated infection, with ulceration, hemorrhaging, flaking, hair loss, and dark lesions as well as spongiosis and acanthosis. These features of dermatitis were present in infected mice after 1 year of age. This relationship among Lyme disease, atopic dermatitis, and host age seen in the C3H/HeJ mouse model is consistent with a large pool (342,499) of human epidemiological data from Finland. We identified 5,248 individuals with Lyme disease and 17,233 with atopic dermatitis in FinnGen. Retrospective analysis shows Lyme disease is associated with atopic dermatitis (OR = 1.91 [1.68 -2.37], P < 2e−16). More visits due to Lyme disease complications (3 or more visits versus 1 visit) were associated with atopic dermatitis (OR = 2.19 [1.35-3.55], P = 0.0014) and risk of developing atopic dermatitis over time (HR=2.26 [1.54-3.95], P = 0.0017). Conclusion Data from mice and humans reveal a novel relationship among Lyme disease, age, and atopic dermatitis. Through defined pathological scoring, we demonstrate the onset of murine atopic dermatitis with B. burgdorferi infection, which is further exacerbated by host age at time of infection. In humans, a diagnosis of Lyme disease in FinnGen was associated with atopic dermatitis and further research is warranted to establish causation.

Borrelia burgdorferi is a bacterial spirochete that can cause Lyme disease (LD) after infecting a susceptible host. Immune responses to the bacteria are highly variable and host specific. The murine substrain, C3H/HeJ, is a frequently utilized model for LD. Interestingly, we observed dermatitis with flaky lesions of the tail skin on C3H/HeJ after a year of infection with B. burgdorferi. Female C3H/HeJ mice aged 6-8 weeks, 1 year, or 2 years were infected intraperitoneally with 105B. burgdorferi spirochetes. Mouse tails were evaluated by gross examination and histology either 2 months or 24 months post-infection. Dermatitis worsened over the course of untreated infection, with ulceration, hemorrhaging, flaking, hair loss, and dark lesions as well as spongiosis and acanthosis. These features of atopic dermatitis were present in infected mice after 1 year of age. This relationship among LD, atopic dermatitis, and host age seen in the C3H/HeJ mouse model is consistent with a large pool of human epidemiological data (342,499 individuals) from Finland. We identified 5,248 individuals with LD and 17,233 with atopic dermatitis in FinnGen. Retrospective analysis shows LD is associated with atopic dermatitis (OR = 1.91 [1.68 −2.37], P < 2e−16). Repeat visits for LD complications (3 or more visits versus 1 visit) were associated with atopic dermatitis (OR = 2.19 [1.35-3.55], P = 0.0014) and risk of developing atopic dermatitis over time (HR=2.26 [1.54-3.95], P = 0.0017). Data from mice and humans reveal a novel relationship among LD, age, and atopic dermatitis. Through defined pathological scoring, we demonstrate that the onset of murine Lyme disease associated atopic dermatitis is exacerbated by increased host age at time of B. burgdorferi infection. In humans, a diagnosis of Lyme disease in FinnGen was associated with atopic dermatitis and further research is warranted to establish causation.ETHICS APPROVAL/CONSENT TO PARTICIPATEAnimal studies were performed at the Stanford School of Medicine Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC) accredited Rodent Animal Facility (Palo Alto, CA). All procedures and care guidelines were approved by the Stanford University Administrative Panel on Laboratory Animal Care (Protocol #30109).Patients and control subjects in FinnGen provided informed consent for biobank research, based on the Finnish Biobank Act. Alternatively, separate research cohorts, collected prior the Finnish Biobank Act came into effect (in September 2013) and start of FinnGen (August 2017), were collected based on study-specific consents and later transferred to the Finnish biobanks after approval by Fimea (Finnish Medicines Agency), the National Supervisory Authority for Welfare and Health. Recruitment protocols followed the biobank protocols approved by Fimea. The Coordinating Ethics Committee of the Hospital District of Helsinki and Uusimaa (HUS) statement number for the FinnGen study is Nr HUS/990/2017.

Vaccination induced antibody and T-cell immune responses are important for systemic protection from COVID-19. Because SARS-CoV-2 infects and is transmitted by oral-pharyngeal mucosa, we wished to test mucosal antibodies elicited by natural infection or intramuscular vaccine injection. In a non-randomized observational study, we measured antibodies against the SARS-CoV-2 RBD in plasma and saliva from convalescent or vaccinated individuals and tested their neutralizing potential using a replication competent rVSV-eGFP-SARS-CoV-2. We found IgG and IgA anti-RBD antibodies as well as neutralizing activity in convalescent plasma and saliva. Two doses of mRNA vaccination (BNT162b2 or mRNA-1273) induced high levels of IgG anti-RBD in saliva, a subset of whom also had IgA, and significant neutralizing activity. We detected anti-RBD IgG and IgA with significant neutralizing potential in the plasma of single dose Ad26.COV2.S vaccinated individuals, and we detected slight amounts of anti-RBD antibodies in matched saliva. The role of salivary antibodies in protection against SARS-CoV-2 infection is unknown and merits further investigation. This study was not designed to, nor did it study the full kinetics of the antibody response or protection from infection, nor did it address variants of SARS-CoV-2.

Neutralizing activity found in the blood following intramuscular vaccination protects against systemic disease from SARS-CoV-2 infection. Mild breakthrough mucosal infections in vaccinated individuals can contribute to transmission chains of infection, and as such the contribution of intramuscular vaccination to mucosal immunity is important to understand. We assessed vesicular stomatitis virus (VSV) SARS-CoV-2 SPIKE protein neutralization activities as well as anti-viral spike and RBD IgG and IgA isotype antibody binding, in saliva from individuals who had recovered from SARS-CoV-2 infection and people who received immunization. The various vaccination strategies deployed globally showed key differences in the extent of neutralizing activity that could be measured. Even in subjects with significant peak activity 2–4 weeks following a second dose of mRNA vaccination, this neutralizing activity was transient and significantly reduced within 3–6 months. Among adenoviral vectors, ChAdOx1 elicited significantly more salivary neutralizing activity and antibody levels compared to Ad26.S. A large range of salivary neutralizing activity is induced following different intramuscular SARS-COV-2 vaccination strategies. All were orders of magnitude lower than neutralization levels observed in blood, and it remains to be determined if any of the observed neutralizing activity in the saliva can neutralize virus in the upper respiratory tract upon exposure. Based on studies where high levels of mucosal IgA antibodies were induced in response to stimulation with aerosol intranasal vaccines, such vaccines could be important in lowering transmission of SARS-COV-2. Supported by The Fairbairn Foundation and SPARK

Lyme disease, caused by the bacteria Borrelia burgdorferi, is the most common and rapidly growing vector-borne infectious disease in the United States and Europe. High variability in disease burden among Lyme patients suggests that individual immune responses may be key drivers of clinical presentation and patient outcomes. Use of high resolution flow-based immunosorbent profiling revealed that a subset of Lyme patients with persistent symptoms were producing high concentrations of IgE specific to B. burgdorferi. Comparing C57B/6 mice, which are tolerant to B. burgdorferi, and C3H/HeJ mice, which are susceptible to disease, we find high levels of IgE specific for B. burgdorferi in C3H/HeJ but not C57B/6 mice. Furthermore, IgE was found to target Borrelia peptidoglycan in both acute and chronic infection models. Histologic analysis of mouse Lyme arthritic ankle tissue showed mast cells, which release highly immunogenic effectors upon activation by bound IgE, degranulating at significantly higher rates compared to uninfected controls. Forced mast cell degranulation exacerbated Lyme arthritis in infected mice. This data suggests that a subset of Lyme patients with persistent symptoms may have developed an allergic response to conserved bacterial antigens from a B. burgdorferi infection, as opposed to an autoimmune type response. Inclusion of IgE reactivity in diagnostic testing and examination of pathological immune responses to bacterial antigens could assist clinicians in patient care and effective treatments. Research reported in this publication was supported by the Fairbairn family foundation; Bay Area Lyme Foundation; the Younger family foundation; the Robert J. Kleberg, Jr., and Helen C. Kleberg Foundation; the Virginia and D. K. Ludwig Fund for Cancer Research; M.C.T. was supported by Stanford Immunology training grant 5T32AI007290, and the NIH NRSA 1 F32 AI124558-01 award. L.B.T.D. was supported by a Stanford Diversifying Academia Recruiting Excellence fellowship. S.D.G was supported by the California Institute for Regenerative Medicine Bridges 2.0 Training Program grant EDUC2-08397. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

SARS-CoV-2 is a novel respiratory virus that has quickly spread across the globe. The virus uses a protein called Spike and its associated receptor binding domain (RBD) to interact with angiotensin converting enzyme-2 (ACE-2) on the surface of epithelial cells in the respiratory tract. Although a definite correlate of protection against COVID-19 has yet to emerge, many studies have quantified anti-Spike and anti-RBD IgG antibody (Ab) levels, as well as neutralizing Ab in the blood to ascertain immunity. This approach misses out on Ab that are produced in the upper respiratory tract (URT) mucosa – the site of viral encounter. Whether intramuscularly (i.m.) administered COVID-19 vaccines can promote immunity in the mucosa is not well understood. We recently completed a study where we showed that anti-Spike/RBD IgG could be detected in the saliva following i.m. vaccination with either two doses of mRNA vaccines (Pfizer or Moderna) or with a heterologous dosing of Astra Zeneca followed by an mRNA vaccine. Administration of a second dose of mRNA boosted the IgG but not IgA response, with only 30% of participants remaining positive for IgA at this timepoint. At 6 months post-dose 2, these participants had diminished anti-Spike/RBD IgG levels, although secretory component associated anti-Spike Ab were more stable. Examining two prospective cohorts we found that participants who experienced breakthrough infections with SARS-CoV-2 had lower levels of vaccine-induced serum anti-Spike/RBD IgA at 2–4 weeks post-dose 2 compared to participants who did not experience an infection, whereas IgG levels were comparable between groups. These data suggest that COVID-19 vaccines that elicit a durable IgA response may have utility in preventing infection. We received funding support from CIHR (Fund #15992), a COVID-19 Immunity Task force grant, an “Ontario Together” province of Ontario grant, a CIHR team grant to CoVARR-Net, a Donation from the Royal Bank of Canada (RBC) and a donation from the Krembil Foundation to the Sinai Health System Foundation.