Dengue virus (DENV) infection is a major and growing global health threat. The development of a safe and effective vaccine regardless of prior dengue immunity remains an unmet need. Virus-specific antibodies typically limit viral replication. In contrast, low-to-intermediate dengue-specific antibody titers can enhance viral replication and increase disease severity-a phenomenon known as antibody-dependent enhancement (ADE). ADE complicates dengue vaccine development; signals of ADE were observed in the CYD-TDV (Dengvaxia) vaccine trials but have not yet been reported for trials of TAK-003 (Qdenga). To better understand how prior immunity influences dengue infection outcomes, we developed a mechanistic within-host model of acute dengue infection dynamics that incorporates both humoral immunity and CD8+ T cells. Model simulations predict that severe disease is most likely when dengue-specific antibody titers are intermediate and dengue-specific CD8+ T-cell immunity is low at the time of infection. In our simulations, increasing pre-infection levels of CD8+ T-cell immunity reduces disease severity in a dose-dependent manner and can mitigate ADE. Our results suggest a mechanistic interaction between antibody levels and CD8+ T-cell immunity that may influence whether enhanced viral replication leads to severe disease. The model provides a possible explanation for why ADE is frequently observed in infections of nonhuman primates following passive antibody transfer, yet is less common during secondary infections in humans with memory CD8+ T cells. These findings may help interpret differences in reported clinical outcomes of dengue vaccine trials and highlight the importance of considering CD8+ T-cell responses in the design of future dengue vaccines.

Current influenza vaccines face challenges due to antigenic evolution of the circulating virus and waning immunity in humans. Here we investigated the durability of humoral immunity induced by an influenza vaccine based on AS03-adjuvanted chimeric hemagglutinin (cHA) in nonhuman primates (NHPs). Two groups of NHPs received two doses of a seasonal quadrivalent influenza vaccine, followed by sequential immunization with split virus cHA vaccines cH8/1N1, and cH5/1N1. One group received cHA immunizations with AS03 adjuvant. We monitored serum antibodies and long-lived plasma cells in bone marrow for nearly 2 years after the final vaccination. cHA vaccines induced stalk-specific antibody responses. The addition of AS03 enhanced both the magnitude and durability of humoral immunity by establishing long-lived plasma cells in the bone marrow and lymph nodes for nearly 2 years. Passive transfer of NHP serum provided protection against challenge with heterologous influenza A virus strains in mice. This study highlights the potential of the AS03-adjuvanted chimeric HA vaccine strategy to provide durable and broadly protective humoral immunity. The authors report that an AS03-adjuvanted chimeric hemagglutinin-based influenza vaccine induces persistent stalk-specific serum antibody and bone marrow plasma cell responses in nonhuman primates, offering promise for broader and durable flu protection.

Immunological memory is a defining feature of immunity, and a quantitative description of how it wanes would help better understand the processes underlying its maintenance and estimate the duration of protection after immunization. We analyzed the waning of antibodies to a panel of virus and vaccine antigens and found that a power-law model captured both the initial rapid decline and much slower subsequent waning. Importantly, accounting for the time post-immunization at which the waning was estimated reduced the difference between estimates for the rate of antibody waning to toxoid/protein vaccines and to live attenuated viruses. We found that protective levels of antibodies may be maintained for longer than previously estimated using exponential models fitted to data from the first decade following immunization. Our analyses indicate that the slow waning of antibodies over a time span of decades may be estimated from data from a shorter time frame of 2 to 3 years following immunization and stresses the importance of taking into account the time post-immunization at which antibody waning is estimated.

In vivo in infection, virions are constantly produced and die rapidly. In contrast, most antibody binding assays do not include such features. Motivated by this, we considered virions with n=100 binding sites in simple mathematical models with and without the production of virions. In the absence of viral production, at steady state, the distribution of virions by the number of sites bound is given by a binomial distribution, with the proportion being a simple function of antibody affinity (Kon/Koff) and concentration; this generalizes to a multinomial distribution in the case of two or more kinds of antibodies. In the presence of viral production, the role of affinity is replaced by an infection analog of affinity (IAA), with IAA=Kon/(Koff+dv+r), where dv is the virus decaying rate and r is the infection growth rate. Because in vivo dv can be large, the amount of binding as well as the effect of Koff on binding are substantially reduced. When neutralization is added, the effect of Koff is similarly small which may help explain the relatively high Koff reported for many antibodies. We next show that the n+2-dimensional model used for neutralization can be simplified to a 2-dimensional model. This provides some justification for the simple models that have been used in practice. A corollary of our results is that an unexpectedly large effect of Koff in vivo may point to mechanisms of neutralization beyond stoichiometry. Our results suggest reporting Kon and Koff separately, rather than focusing on affinity, until the situation is better resolved both experimentally and theoretically.

It has been suggested that the novel selective phosphodiesterase 9 (PDE9) inhibitor may improve cardiac and renal function by blocking 3′,5′-cyclic guanosine monophosphate (cGMP) degradation. 5/6 nephrectomized (5/6Nx) rats were used to investigate the effects of the PDE9 inhibitor (BAY 73–6691) on the heart and kidney. Two doses of BAY 73–6691 (1 mg/kg/day and 5 mg/kg/day) were given for 95 days. The 5/6Nx rats developed albuminuria, a decrease in serum creatinine clearance (Ccr), and elevated serum troponin T levels. Echocardiographic data showed that 5/6 nephrectomy resulted in increased fractional shortening (FS), stroke volume (SV), and left ventricular ejection fraction (EF). However, 95 days of PDE9 inhibitor treatment did not improve any cardiac and renal functional parameter. Histopathologically, 5/6 nephrectomy resulted in severe kidney and heart damage, such as renal interstitial fibrosis, glomerulosclerosis, and enlarged cardiomyocytes. Telmisartan attenuated renal interstitial fibrosis and glomerulosclerosis as well as improved cardiomyocyte size. However, except for cardiomyocyte size and renal perivascular fibrosis, BAY 73–6691 had no effect on other cardiac and renal histologic parameters. Pathway enrichment analysis using RNA sequencing data of kidney and heart tissue identified chronic kidney disease pathways, such as phosphatidylinositol 3-kinase (PI3K)—protein kinase B (Akt) signaling pathway, complement and coagulation cascades, and nuclear factor kappa B (NF-κB) signaling pathway. PDE9i did not affect any of these disease-related pathways. Two dosages of the PDE9 inhibitor BAY 73–6691 known to be effective in other rat models have only limited cardio-renal protective effects in 5/6 nephrectomized rats.

Sclerostin (SOST) is produced by osteocytes and is known as a negative regulator of bone homeostasis. Parathyroid hormone (PTH) regulates calcium, phosphate as well as vitamin D metabolism, and is a strong inhibitor of SOST synthesis in vitro and in vivo. PTH has two methionine amino acids (positions 8 and 18) which can be oxidized. PTH oxidized at Met18 (Met18(ox)-PTH) continues to be bioactive, whereas PTH oxidized at Met8 (Met8(ox)-PTH) or PTH oxidized at Met8 and Met18 (Met8, Met18(di-ox)-PTH) has minor bioactivity. How non-oxidized PTH (n-oxPTH) and oxidized forms of PTH act on sclerostin synthesis is unknown. The effects of n-oxPTH and oxidized forms of PTH on SOST gene expression were evaluated in UMR106 osteoblast-like cells. Moreover, we analyzed the relationship of SOST with n-oxPTH and all forms of oxPTH in 516 stable kidney transplant recipients using an assay system that can distinguish in clinical samples between n-oxPTH and the sum of all oxidized PTH forms (Met8(ox)-PTH, Met18(ox)-PTH, and Met8, Met18(di-ox)-PTH). We found that both n-oxPTH and Met18(ox)-PTH at doses of 1, 3, 20, and 30 nmol/L significantly inhibit SOST gene expression in vitro, whereas Met8(ox)-PTH and Met8, Met18(di-ox)-PTH only have a weak inhibitory effect on SOST gene expression. In the clinical cohort, multivariate linear regression showed that only n-oxPTH, but not intact PTH (iPTH) nor oxPTH, is independently associated with circulating SOST after adjusting for known confounding factors. In conclusion, only bioactive PTH forms such as n-oxPTH and Met18(ox)-PTH, inhibit SOST synthesis.

Dengue is a global epidemic causing over 100 million cases annually. The clinical symptoms range from mild fever to severe hemorrhage and shock, including some fatalities. The current paradigm is that these severe dengue cases occur mostly during secondary infections due to antibody-dependent enhancement after infection with a different dengue virus serotype. India has the highest dengue burden worldwide, but little is known about disease severity and its association with primary and secondary dengue infections. To address this issue, we examined 619 children with febrile dengue-confirmed infection from three hospitals in different regions of India. We classified primary and secondary infections based on IgM:IgG ratios using a dengue-specific enzyme-linked immunosorbent assay according to the World Health Organization guidelines. We found that primary dengue infections accounted for more than half of total clinical cases (344 of 619), severe dengue cases (112 of 202) and fatalities (5 of 7). Consistent with the classification based on binding antibody data, dengue neutralizing antibody titers were also significantly lower in primary infections compared to secondary infections (P ≤ 0.0001). Our findings question the currently widely held belief that severe dengue is associated predominantly with secondary infections and emphasizes the importance of developing vaccines or treatments to protect dengue-naive populations.

Severe acute respiratory syndrome coronavirus 2 mRNA vaccination has reduced effectiveness in certain immunocompromised individuals. However, the cellular mechanisms underlying these defects, as well as the contribution of disease-induced cellular abnormalities, remain largely unexplored. In this study, we conducted a comprehensive serological and cellular analysis of patients with autoimmune systemic lupus erythematosus (SLE) who received the Wuhan-Hu-1 monovalent mRNA coronavirus disease 2019 vaccine. Our findings revealed that patients with SLE exhibited reduced avidity of anti-receptor-binding domain antibodies, leading to decreased neutralization potency and breadth. We also observed a sustained anti-spike response in IgD−CD27− ‘double-negative (DN)’ DN2/DN3 B cell populations persisting during memory responses and with greater representation in the SLE cohort. Additionally, patients with SLE displayed compromised anti-spike T cell immunity. Notably, low vaccine efficacy strongly correlated with higher values of a newly developed extrafollicular B and T cell score, supporting the importance of distinct B cell endotypes. Finally, we found that anti-BAFF blockade through belimumab treatment was associated with poor vaccine immunogenicity due to inhibition of naive B cell priming and an unexpected impact on circulating T follicular helper cells. SLE is a heterogeneous disorder that is characterized by different immune endotypes. Faliti et al. follow the immune memory responses upon mRNA COVID-19 vaccinations in a large cohort of patients with SLE. They note that skewed immune responses, such as lower seroconversion and neutralization, might be due to extrafollicular B and T cell biases in SLE endotypes.

BackgroundVitamin D binding protein (DBP) might increase substantially after ovarian stimulation and hence could be associated with IVF/ICSI outcomes because it determines the fraction of free bioavailable 25(OH) vitamin D. In this study, we aim to determine whether DBP is associated with E2 level after ovarian stimulation and IVF/ICSI outcomes.DesignPost-hoc analysis of a prospective observational cohort.SettingSingle-center study.Participants2569 women receiving embryo transfer.InterventionNone.Main outcome measuresThe main outcomes were oocyte and embryo quality as well as pregnancy outcomes.ResultsDBP concentration correlates with E2 on hCG day (=day of inducing ovulation with hCG; correlation coefficient r = 0.118, P<0.001) and E2 x-fold change to baseline level (r = 0.108, P<0.001). DBP is also positively correlated with total 25(OH)D (r = 0.689, R2 = 0.475, P<0.001) and inversely with free 25(OH)D (r=-0.424, R2=0.179, P<0.001), meaning that E2-stimulated DBP synthesis results in a decrease of free 25(OH)D during ovarian stimulation. However, such alteration does not affect IVF/ICSI outcomes when considering confounding factors, such as the number and quality of oocytes nor embryo quality as well as pregnancy outcomes.ConclusionDBP concentration correlates with the degree of E2 increase after ovarian stimulation. DBP is also positively correlated with total 25(OH)D and inversely with free 25(OH)D, suggesting that the proportion of free 25(OH)D decreases during ovarian stimulation caused by E2-stimulated DBP synthesis. However, such alteration does not affect clinical IVF/ICSI outcomes.

Bladder cancer is a carcinoma of the urothelial, or “umbrella,” cells that line the lumen of the urinary bladder. Technically, urothelial carcinoma includes tumors of the bladder, upper urinary tract (renal pelvis and ureters), and proximal urethra. Bladder cancer accounts for approximately 90% to 95% of urothelial carcinoma; bladder cancer comprises 75% pure urothelial carcinoma and 25% “variant” histology, adding complexity to the management of this disease. Bladder cancer can be categorized in several way, almost all bladder cancers originate in the urothelium, which is a 3- to 7-cell mucosal layer within the muscular bladder. Squamous cell carcinoma of the bladder can involve multiple sites; however, the lateral wall and trigone are more commonly involved by this tumor. All small cell carcinomas of the urinary system identified so far have been located in the urinary bladder, most commonly in the dome and vesical lateral wall. Radical cystectomy is a crucial surgical technique in managing MIBC, high-risk NMIBC, and treatment-refractory NMIBC. Despite a high perioperative mortality rate (5-10%), it now carries a 1-2% mortality rate due to improvements in surgical technique, intensive care medicine evolution, and antibiotic availability.

Introduction Patients with B cell malignancies remain at high risk of morbidity and mortality from respiratory viruses like SARS-CoV-2. These patients often receive B cell-depleting agents in combination with chemotherapy as part of their cancer treatment, impairing their subsequent capacity to generate antibody responses to infection and vaccination. However, less is known about the effects of these aggressive treatments on already acquired humoral immunity in this population. Objective To determine the effect of frontline chemoimmunotherapy with anti-CD20 antibodies on established antibody titers against SARS-CoV-2, measles, and rubella over time in patients with newly diagnosed aggressive B cell non-Hodgkin lymphoma (aNHL). Methods Patients with a new diagnosis of aNHL were enrolled after informed consent. Serial blood samples were obtained before, during, and up to 1 year after treatment with regimens containing an anti-CD20 antibody + multiagent chemotherapy. IgG binding titers against the SARS-CoV-2 nucleocapsid (N) protein and the spike protein of several SARS-CoV-2 variants were measured with a multiplex assay. Live virus neutralization titers against SARS-CoV-2 variants over time were also measured. IgG titers against measles and rubella were measured by ELISA. Antibody decay half-lives were calculated using exponential model. Clinical information was abstracted from the electronic medical record and correlated with antibody responses. Results A total of 42 individuals were enrolled (33 with aNHL, 9 healthy donor controls). For the aNHL group, mean age was 59.7, 51.5% were male, and 39.4% non-white. Mean number of vaccine doses was 3 with a mean of 199 days between last vaccine and cycle 1 of lymphoma-directed therapy. All patients received rituximab as their anti-CD20 antibody and only 2 patients did not receive an anthracycline. Before treatment (baseline), 56.5% of aNHL patients did not show anti-N antibodies to indicate prior infection. Greater variability in IgG binding titers against wild-type (WT) spike protein and significantly lower neutralization titers were observed in aNHL at baseline vs controls (mean titer 1227 vs 1822 AU/mL, p<0.05). Median binding titers against BA.5 and XBB.1.5 spike was 5.3- and 8.3-fold lower than WT, respectively (vs 4.0- and 7.2-fold in control, respectively). Median anti-WT spike binding titers decreased by 2.5-, 3.4-, and 6.1-fold after 3-, 9- , and 12-months from initiation of chemoimmunotherapy, respectively while titers in controls decreased 1.1-fold over a similar period. After excluding 2 patients with very low anti-WT spike titers before aNHL treatment, the half-life for anti-WT spike was 192 days in aNHL patients vs 444 days in controls (p<0.001). No statistically significant increase in anti-spike titers was seen in the 16 patients who received an additional SARS-CoV-2 vaccine within the first year of treatment initiation. Multivariable analyses for factors associated with more rapid decay will be presented. Antibody titers vs SARS-CoV-2 are known to wane over time. Thus, to determine the effect of aNHL treatment on long-term humoral immunity, IgG titers against measles and rubella were measured, as these antibodies show remarkable stability over time in healthy individuals, and the likelihood of infection while on study was low. Baseline titers against measles and rubella did not differ significantly between controls and aNHL patients. Anti-measles and rubella titers showed <2-fold decrease during the study period in aNHL patients and no decline in control. Conclusion In patients with newly diagnosed aNHL, preexisting antibody titers vs SARS-CoV-2, measles, and rubella, were largely preserved during lymphoma-directed treatment. However, an accelerated rate of decay was observed for anti-spike IgG during the first year after completion of aNHL therapy. Neutralization activity against newer SARS-CoV-2 variants was low throughout the study period. Our data highlight the need for new mechanisms to protect these immunocompromised patients against current and emerging SARS-CoV-2 strains.

Understanding the waning of vaccine-induced protection is important for both immunology and public health. Population heterogeneities in underlying (pre-vaccination) susceptibility and vaccine response can cause measured vaccine effectiveness (mVE) to change over time, even in the absence of pathogen evolution and any actual waning of immune responses. We use multi-scale agent-based models parameterized using epidemiological and immunological data, to investigate the effect of these heterogeneities on mVE as measured by the hazard ratio. Based on our previous work, we consider the waning of antibodies according to a power law and link it to protection in two ways: (1) motivated by correlates of risk data and (2) using a within-host model of stochastic viral extinction. The effect of the heterogeneities is given by concise and understandable formulas, one of which is essentially a generalization of Fisher’s fundamental theorem of natural selection to include higher derivatives. Heterogeneity in underlying susceptibility accelerates apparent waning, whereas heterogeneity in vaccine response slows down apparent waning. Our models suggest that heterogeneity in underlying susceptibility is likely to dominate. However, heterogeneity in vaccine response offsets <10% to >100% (median of 29%) of this effect in our simulations. Our study suggests heterogeneity is more likely to ‘bias’ mVE downwards towards the faster waning of immunity but a subtle bias in the opposite direction is also plausible.

BACKGROUND:Genetic-guided P2Y12 inhibitor selection has been proposed to reduce ischemic events by identifying CYP2C19 loss-of-function (LOF) carriers at increased risk with clopidogrel treatment after percutaneous coronary intervention (PCI). A prespecified analysis of TAILOR-PCI (Tailored Antiplatelet Therapy Following PCI) evaluated the effect of genetic-guided P2Y12 inhibitor therapy on cumulative ischemic and bleeding events. OBJECTIVES:Here, the authors detail a prespecified analysis of cumulative endpoints. The primary endpoint was cumulative incidence rate of ischemic events at 12 months. Cumulative incidence of major and minor bleeding was a secondary endpoint. Cox proportional hazards models as adapted by Wei, Lin, and Weissfeld were used to estimate the effect of this strategy on all observed events. METHODS:The TAILOR-PCI trial was a prospective trial including 5,302 post-PCI patients with acute and stable coronary artery disease (CAD) who were randomized to genetic-guided P2Y12 inhibitor or conventional clopidogrel therapy. In the genetic-guided group, LOF carriers were prescribed ticagrelor, whereas noncarriers received clopidogrel. TAILOR-PCI's primary analysis was time to first event in LOF carriers. RESULTS:Among 5,276 patients (median age 62 years; 25% women; 82% acute CAD; 18% stable CAD), 1,849 were LOF carriers (903 genetic-guided; 946 conventional therapy). The cumulative primary endpoint was significantly reduced in the genetic-guided group compared with the conventional therapy (HR: 0.61; 95% CI: 0.41-0.89; P = 0.011) with no significant difference in cumulative incidence of major or minor bleeding (HR: 1.36; 95% CI: 0.67-2.76; P = 0.39). CONCLUSIONS:Among CYP2C19 LOF carriers undergoing PCI, a genetic-guided strategy resulted in a statistically significant reduction in cumulative ischemic events without a significant difference in bleeding. (Tailored Antiplatelet Therapy Following PCI [TAILOR-PCI]; NCT01742117).

Novel mRNA vaccines have resulted in a reduced number of SARS-CoV-2 infections and hospitalizations. Yet, there is a paucity of studies regarding their effectiveness on immunocompromised autoimmune subjects. In this study, we enrolled subjects naïve to SARS-CoV-2 infections from two cohorts of healthy donors (HD, n=56) and systemic lupus erythematosus (SLE, n=69). Serological assessments of their circulating antibodies revealed a significant reduction of potency and breadth of neutralization in the SLE group, only partially rescued by a 3rd booster dose. Immunological memory responses in the SLE cohort were characterized by a reduced magnitude of spike-reactive B and T cell responses that were strongly associated with poor seroconversion. Vaccinated SLE subjects were defined by a distinct expansion and persistence of a DN2 spike-reactive memory B cell pool and a contraction of spike-specific memory cTfh cells, contrasting with the sustained germinal center (GC)-driven activity mediated by mRNA vaccination in the healthy population. Among the SLE-associated factors that dampened the vaccine responses, treatment with the monoclonal antibody anti-BAFF/Belimumab (a lupus FDA-approved B cell targeting agent) profoundly affected the vaccine responsiveness by restricting the de novo B cell responses and promoting stronger extra-follicular (EF)-mediated responses that were associated with poor immunogenicity and impaired immunological memory. In summary, this study interrogates antigen-specific responses and characterized the immune cell landscape associated with mRNA vaccination in SLE. The identification of factors associated with reduced vaccine efficacy illustrates the impact of SLE B cell biology on mRNA vaccine responses and provides guidance for the management of boosters and recall vaccinations in SLE patients according to their disease endotype and modality of treatment.

Aims: To investigate all-cause mortality (ACM) attributable to insulin treated diabetes mellitus through propensity score (PS)-weighting with and without novel confounders identified by Random Survival Forest (a machine learning approach). Methods: Prospective clinic encounter data was obtained from 1517 females with Type 2 diabetes (mean age 63±12 years) from Barranquilla, Colombia (2003 – 2016, censored August 2017) for a median 10-year mortality follow-up. Risk variables of importance for ACM were identified on RSF screening. Survival was compared in retrospective cohorts, identified by baseline treatment with glucose-lowering therapy, and balanced for confounders through PS-weighting with and without RSF variables using multivariable Cox regression. Results: RSF screening identified new risk variables (e.g., recruitment year, parity, reproductive lifespan) for ACM in women receiving insulin. The unweighted risk estimate showed a nonsignificant increased risk for ACM [HR 1.32 (.9, 2), p=0.2] compared to noninsulin treated women. After balancing for risk covariates in the compared cohorts, PS showed no significant effect of insulin on all-cause mortality [HR 95% CI 0.83 (0.5, 1.4) p=0.5] whereas PS-weighted analyses incorporating RSF novel variables approached conservative ACM estimates [HR 95% CI 0.56 (0.3, 1.0) p=0.07)]. The estimated ACM risk from active smoking was also more conservative with RSF weighting. Conclusion: In this observational study, insulin treatment appeared to be a surrogate for higher-risk women with diabetes mellitus. RSF-augmented PS analysis showed that insulin treatment may potentially be associated with a survival advantage compared to non-insulin treatment in older female diabetics.

Developing accurate and reliable methods to estimate vaccine protection is a key goal in immunology and public health. While several statistical methods have been proposed, their potential inaccuracy in capturing fast intra-seasonal waning of vaccine-induced protection needs to be rigorously investigated. To compare statistical methods for vaccine effectiveness (VE) estimation, we generated simulated data using a multiscale agent-based model of an epidemic with an acute viral infection and differing extents of VE waning. We extended the previously proposed framework for VE measures based on the observational data richness to assess changes of vaccine-induced protection with time. While VE measures based on hard-to-collect information (e.g. exact timing of exposures) were accurate, usually VE studies rely on time-to-infection data and the Cox proportional hazard model. We found that its extension utilizing scaled Schoenfeld residuals, previously proposed for capturing VE waning, was unreliable in capturing both the degree of waning and its functional form and identified the mathematical factors contributing to this unreliability. We showed that partitioning time and including a time-vaccine interaction term in the Cox model significantly improved estimation of VE waning, even in the case of dramatic, rapid waning. We also proposed how to optimize the partitioning scheme. Using simulated data, we compared different measures of VE for capturing the intra-seasonal waning of vaccine-induced protection. We propose an extension of the Cox model based on including a time-vaccine interaction term with further optimization of partitioning time. These findings may guide future analysis of VE waning in observational data.

Background:25-hydroxyvitamin D (25(OH)D) and potentially also 1,25-dihydroxyvitamin D (1,25(OH)2D) inhibits the synthesis of parathyroid hormone (PTH) in the chief cells of the parathyroid gland. Clinical studies showing a negative correlation between (25(OH)D and PTH are in good agreement with these findings in basic science studies. However, PTH was measured in these studies with the currently clinically used 2nd or 3rd generation intact PTH (iPTH) assay systems. iPTH assays cannot distinguish between oxidized forms of PTH and non-oxidized PTH. Oxidized forms of PTH are the by far most abundant form of PTH in the circulation of patients with impaired kidney function. Oxidation of PTH causes a loss of function of PTH. Given that the clinical studies done so far were performed with an PTH assay systems that mainly detect oxidized forms of PTH, the real relationship between bioactive non-oxidized PTH and 25(OH)D as well as 1,25(OH)2D is still unknown.Methods:To address this topic, we compared for the first time the relationship between 25(OH)D as well as 1,25(OH)2D and iPTH, oxPTH as well as fully bioactive n-oxPTH in 531 stable kidney transplant recipients in the central clinical laboratories of the Charité. Samples were assessed either directly (iPTH) or after oxPTH (n-oxPTH) was removed using a column that used anti-human oxPTH monoclonal antibodies, a monoclonal rat/mouse parathyroid hormone antibody (MAB) was immobilized onto a column with 500 liters of plasma samples. Spearman correlation analysis and Multivariate linear regression were used to evaluate the correlations between the variables.Results:There was an inverse correlation between 25(OH)D and all forms of PTH, including oxPTH (iPTH: r=-0.197, p<0.0001; oxPTH: r=-0.203, p<0.0001; n-oxPTH: r=-0.146, p=0.001). No significant correlation was observed between 1,25(OH)2D and all forms of PTH. Multiple linear regression analysis considering age, PTH (iPTH, oxPTH and n-oxPTH), serum calcium, serum phosphor, serum creatinine, fibroblast growth factor 23 (FGF23), osteoprotegerin (OPG), albumin, and sclerostin as confounding factors confirmed these findings. Subgroup analysis showed that our results are not affected by sex and age.Conclusion:In our study, all forms of PTH are inversely correlated with 25-hydroxyvitamin D (25(OH)D). This finding would be in line with an inhibition of the synthesis of all forms of PTH (bioactive n-oxPTH and oxidized forms of PTH with minor or no bioactivity) in the chief cells of the parathyroid glad.

Antibodies and humoral memory are key components of the adaptive immune system. We consider and computationally model mechanisms by which humoral memory present at baseline might increase rather than decrease infection load; we refer to this effect as EI-HM (enhancement of infection by humoral memory). We first consider antibody dependent enhancement (ADE) in which antibody enhances the growth of the pathogen, typically a virus, and typically at intermediate 'Goldilocks' levels of antibody. Our ADE model reproduces ADE in vitro and enhancement of infection in vivo from passive antibody transfer. But notably the simplest implementation of our ADE model never results in EI-HM. Adding complexity, by making the cross-reactive antibody much less neutralizing than the de novo generated antibody or by including a sufficiently strong non-antibody immune response, allows for ADE-mediated EI-HM. We next consider the possibility that cross-reactive memory causes EI-HM by crowding out a possibly superior de novo immune response. We show that, even without ADE, EI-HM can occur when the cross-reactive response is both less potent and 'directly' (i.e. independently of infection load) suppressive with regard to the de novo response. In this case adding a non-antibody immune response to our computational model greatly reduces or completely eliminates EI-HM, which suggests that 'crowding out' is unlikely to cause substantial EI-HM. Hence, our results provide examples in which simple models give qualitatively opposite results compared to models with plausible complexity. Our results may be helpful in interpreting and reconciling disparate experimental findings, especially from dengue, and for vaccination.

An ideal vaccine both attenuates virus growth and disease in infected individuals and reduces the spread of infections in the population, thereby generating herd immunity. Although this strategy has proved successful by generating humoral immunity to measles, yellow fever and polio, many respiratory viruses evolve to evade pre-existing antibodies1. One approach for improving the breadth of antiviral immunity against escape variants is through the generation of memory T cells in the respiratory tract, which are positioned to respond rapidly to respiratory virus infections2-6. However, it is unknown whether memory T cells alone can effectively surveil the respiratory tract to the extent that they eliminate or greatly reduce viral transmission following exposure of an individual to infection. Here we use a mouse model of natural parainfluenza virus transmission to quantify the extent to which memory CD8+ T cells resident in the respiratory tract can provide herd immunity by reducing both the susceptibility of acquiring infection and the extent of transmission, even in the absence of virus-specific antibodies. We demonstrate that protection by resident memory CD8+ T cells requires the antiviral cytokine interferon-γ (IFNγ) and leads to altered transcriptional programming of epithelial cells within the respiratory tract. These results suggest that tissue-resident CD8+ T cells in the respiratory tract can have important roles in protecting the host against viral disease and limiting viral spread throughout the population.