Patrick Arndt
· Associate ProfessorVerifiedUniversity of Minnesota · Internal Medicine
Active 1998–2025
About
Dr. Patrick Arndt is an Associate Professor in the Division of Endocrinology, Diabetes and Metabolism at the University of Minnesota. His research and clinical focus are dedicated to the quality improvement of pituitary perioperative patient care and the management of various pituitary disorders. As a key member of the Araki Lab, he contributes to advancing understanding and treatment of pituitary-related conditions, emphasizing patient care and research in this specialized area.
Research topics
- Internal medicine
- Medicine
- Immunology
Selected publications
The Role of Chemerin in Neutrophil Activation and Diseases of the Lung
Biomedicines · 2025-05-31 · 3 citations
reviewOpen access1st authorCorrespondingChemerin is an adipokine with complex biochemistry that undergoes proteolytic modification by components of the inflammatory, coagulation, and fibrinolytic systems, generating both active and inactive products. Chemerin has been found to have both pro- and anti-inflammatory properties, can regulate angiogenesis, and is involved in cancer pathogenesis. Although chemerin is a chemoattractant for macrophages, plasmacytoid dendritic cells, and natural killer cells, it does not induce neutrophil chemotaxis. In contrast, neutrophils appear to act on chemerin structure and localization to regulate the inflammatory response. A role for chemerin in several lung diseases, including airway disease, interstitial lung disease, and cancer, has begun to be explored, but its full role is yet to be fully understood. This review will discuss the role of chemerin in neutrophil activation and will examine what is currently known of the effect of chemerin in diseases of the lung.
Vaccines · 2024-07-19
articleOpen access(1) Background: Compared to medical personnel, SARS-CoV-2mRNA vaccination-related positive immunity rates, levels, and preservation over time in dialysis and kidney transplant patients are reduced. We hypothesized that COVID-19 pre-exposure influences both vaccination-dependent immunity development and preservation in a group-dependent manner. (2) Methods: We evaluated 2- and 9-month follow-up data in our observational Dia-Vacc study, exploring specific cellular (interferon-γ release assay = IGRA) and/or humoral immune responses (IgA/IgG/RBD antibodies) after two SARS-CoV-2mRNA vaccinations in 2630 participants, including medical personnel (301-MP), dialysis patients (1841-DP), and kidney transplant recipients (488-KTR). Study participants were also separated into COVID-19 pre-exposure (hybrid immunity) positive (n = 407) versus negative (n = 2223) groups. (3) Results: COVID-19 pre-exposure improved most vaccination-related positive immunity rates in KTR and DP at 2 months but not in MP, where rates reached almost 100% independent of hybrid immunity. In the COVID-19-negative study, patients' immunity faded between two and nine months, evaluated via the percentage of patients with an RBD antibody decrease >50%, and was markedly group- (MP-17.8%, DP-52.2%, and KTR-38.6%) and vaccine type-dependent. In contrast, in all patient groups with COVID-19, pre-exposure RBD antibody decreases of >50% were similarly rare (MP-4.3%, DP-7.2%, and KTR-0%) but still vaccine type-dependent, with numerically reduced numbers in mRNA-1273- versus BNT162b2mRNA-treated patients. Multivariable regression analysis of RBD antibody changes between two and nine months by interval scale categorization confirmed COVID-19 pre-exposure as a factor in inhibiting strong RBD Ab fading. COVID-19 pre-exposure in MP and DP also numerically reduced T-cell immunity fading. In DP, symptomatic (versus asymptomatic) COVID-19 pre-exposure was identified as a factor in reducing strong RBD Ab fading after vaccination. (4) Conclusions: After mRNA vaccination, immunity positivity rates in DP and KTR but not MP, as well as immunity preservation in MP/DP/KTR, are markedly improved via prior COVID-19 infection. In DP, prior symptomatic compared to asymptomatic COVID-19 disease was particularly effective in blocking immunity fading after mRNA vaccination.
Journal of the American Society of Nephrology · 2024-10-01
articleBackground: Recent research has demonstrated that endothelial cells (EC) exhibit significant heterogeneity, displaying remarkable plasticity in both normal and pathophysiological conditions. However, the precise cellular responses of renal EC during injury and regeneration remain poorly understood. Therefore, we characterize the process of regeneration of renal EC using single-cell RNA sequencing (SC RNA-seq). This approach enables the identification of differentially expressed genes (DEG) at the single-cell level, which may facilitate the identification of potential regenerative gene patterns or niches within the renal endothelium. Methods: EC-specific injury was induced in Tie2-eGFP reporter mice (n=48) by renal arterial perfusion with ConcanavalinA (ConA)/anti-ConA serum. Ten mice served as sham-operated controls. Kidneys were harvested at 24h, 48h, 4 days, and 7 days post-injury induction. For SC RNA-seq more than 40,000 glomerular (gEC) and peritubular (pEC) endothelial cells were isolated and further separated using fluorescence-activated cell sorting (FACS). EC damage was evaluated by endomucin staining. Bioinformatic analyses of the SC RNAseq data were conducted using the Seurat, clusterProfiler, and venn.diagram packages for R. Results: EC injury (24 h) and remarkable regeneration (d4-d7) were observed in histology and SC RNA-seq data. In addition to known glomerular and peritubular endothelial subclusters, Gene Set Enrichment Analyses (GSEA) revealed several clusters with DEG associated with injury, a transition from injury to regeneration, remodeling, regeneration and proliferation. A strong resemblance between the regeneration cluster and the already known afferent arteriole-associated cluster was evident. 29% of the DEG of the regeneration cluster can also be found in the afferent arteriole associated cluster. A lot of these DEG are associated with regenerative processes. In contrast, only 1% of the regenerative cluster DEG can be found in the cluster linked with the EC of the efferent arteriole. Conclusion: In conclusion, our SC RNA-seq data illuminates the transcriptional changes that occur during injury and regeneration of renal EC. The analyses strongly suggest a role of the EC of afferent arteriole in initiating or transducing regeneration processes in the renal endothelium.
Journal of the American Society of Nephrology · 2024-10-01
articleBackground: Immediate early genes play a central role in the regulation of cell stress, cell proliferation and differentiation. Individual studies indicate that immediate early genes significantly influence vascular repair, of aortic and lung endothelial cells. Less is known about the regenerative mechanisms in renal endothelial cells. To test the relevance of mediated early genes in the kidney, renal endothelial injury was induced. Transcriptomic patterns of the endothelium were evaluated on a single-cell level to uncover potential mechanisms of renal vascular regeneration. Methods: For single-cell transcriptomics (scRNA), endothelial-specific injury was induced in Tie2 eGFP reporter mice (n=48) by renal arterial perfusion with Concanavalin A (ConA) /anti-ConA. Nineteen mice served as sham-operated controls. Kidneys were harvested 24 hours, 48 hours, 4 days, and 7 days after injury induction. For scRNA transcriptomics, cells were isolated from glomerular and extraglomerular renal tissue. Biopsies from 15 mice were used to perform 10x Xenium spatial transcriptomics. Endothelial cell damage was evaluated using periodic acid–Schiff and endomucin stainings. Results: Both endothelial cell injury (24h) and remarkable regeneration (d4-d7) were observed using glomerular injury evaluation. Following quality control measurements, 10 glomerular and 7 peritubular endothelial cell subclusters were identified. Based on scRNA transcriptomics, we identified cells which increased significantly with proportions of 6% (d2), 17% (d4), and 20% (d7), along with the detected healing process. Immediate early genes like Atf3, Erg1, Fos, and Junb were differentially expressed in these cell population. A similar pattern was observed in peritubular endothelial cells. With the help of spatial transcriptomics, findings were successfully confirmed. Conclusion: In summary, state-of-the-art transcriptomics allowed us to initially identify endothelial renal subpopulations expressing the immediate early genes, which potentially regulate the subsequent endothelial cell repair mediated by cell differentiation and proliferation. Next, gene expression has to be modified by depletion or overactivation to evaluate the participation of immediate early response genes in renal regenerative processes.
Journal of the American Society of Nephrology · 2024-10-01
article1st authorCorrespondingNephrology Dialysis Transplantation · 2023-06-01
articleOpen accessAbstract Background and Aims Immunity development and fading after SARS-CoV-2mRNA vaccination differently affects high risk populations such as dialysis or renal transplant patients compared to general population. We hypothesized that COVID-19 preexposure influences not only vaccination dependent development of immunity but also protects from immunity fading depending on vaccine type and patient group. Method We evaluated two and nine months follow up data in our observational DIA-Vacc study exploring specific cellular (interferon-γ release assay = IGRA) or/and humoral immune responses after 2x SARS-CoV-2mRNA vaccination in 2615 participants including medical personnel (300 MP), dialysis patients (1831 DP), kidney transplant recipients (484 KTR). Study participants were separated into COVID-19 preexposure positive (n = 405) versus negative (n = 2210) groups, where symptomatic or asymptomatic COVID-19 disease before start of vaccination was confirmed by clinical symptoms, PCR positivity and/or Spike S1/core antiSARS-CoV-2 antibodies. Results Two months (T2) after first vaccination, seroconversion and T-cell immunity success rates for MP and DP were excellent (86-100%) and independent on COVID-preexposure. In KTR, vaccination-related seroconversion rate on T2 almost doubled with COVID-preexposure (84% versus 45% without), a result consistent with all different antibody measurements (IgA, IgG, or receptor binding domain-RBD). Nine months after first vaccination in COVID-19 negative study patients, the percentage of patients with RBD-antibody fading results >50% remained low in MP (18%), high in DP (53%) and intermediate in KTR (39%). In contrast, in all patient groups with COVID-19 preexposure RBD-antibody fading reactions >50% within nine months after vaccination were almost vanished (4% in MP, 8% in DP and 0% in KTR). COVID-19 preexposure in DP also reduced T-cell immunity fading as measured by IGRA, where only 9% of patients showed a >50% titer decrease compared to 34% of DP without any COVID-19 preexposure. Similar results were also seen regarding vaccination dependent regulation of antiSARS-Cov-2 IgG antibodies dependent on COVID-19 preexposure. These results are also reflected by increased mean antibody titers for IgG- and RBD-antibodies nine months after vaccination in all COVID-19 preexposed compared to non-exposed groups. In addition, the degree of antibody fading after vaccination was not just dependent on COVID-19 preexposure status but also on mRNA vaccine type being used. In MP with COVID-preexposure, 22% of BNT162b2mRNA but 0% of 1273-mRNA vaccinated study participants experienced RBD-antibody fading >50% within nine months after vaccination start. This significant difference was even greater in COVID-19 preexposed DP, in whom vaccination with BNT162b2mRNA caused RBD-antibody fading >50% in 36% compared to 6% of 1273-mRNA treated DP. The patient number in the KTR group was not high enough for a vaccine type comparison. This vaccine dependent influence on antibody fading is consistent with our results in patient groups without COVID-19 preexposure. Conclusion Long term immunity time course is markedly modified via COVID-preexposure in a mRNA vaccine dependent matter. Hybrid immunity after COVID-19 preexposure almost completely lacks immunity fading between two and nine months especially in 1273-mRNA vaccinated MP, DP, or KTR. Immune monitoring shows great individual variability dependent on personal patient history and should be especially used for pandemic patient management in vulnerable groups such as DP and KTR.
Biomedicines · 2023-03-16 · 5 citations
reviewOpen access1st authorCorrespondingPleuroparenchymal fibroelastosis (PPFE) is a rare disease that is currently classified as an idiopathic interstitial pneumonia. Although originally described as an idiopathic disease, PPFE has now been identified as a rare complication following hematopoietic stem cell transplant (HSCT). Unlike other pulmonary complications after HSCT, PPFE occurs very late after transplant. Etiologies for PPFE after HSCT remain to be fully established. Infections and adverse effects to alkylating chemotherapy have been suggested as possible causes. In several cases, there is an association of PPFE with bronchiolitis obliterans syndrome after HSCT, suggesting that PPFE may be another manifestation of pulmonary chronic graft versus host disease after HSCT. Algorithms have been designed to assist in confirming a diagnosis of PPFE without the need for a surgical lung biopsy, however at present, no biomarker is established for the diagnosis or to predict the progression of disease. Presently, there is no current therapy for PPFE, but fortunately the disease progresses slowly in most patients.
Nephrology Dialysis Transplantation · 2023-06-01
articleOpen accessAbstract Background and Aims SARS-CoV-2mRNA vaccination related seroconversion rates are reduced in dialysis (DP) and kidney transplant patients (KTR). Recently, we demonstrated that established vaccination related immunity (via positive seroconversion) fades faster in DP and at a lesser extent in KTR compared to medical personnel (MP).[1] We hypothesized that a longer follow up period might be able to profoundly show immunity fading differences specific to different patient groups and identify strong fading risk factors that are relevant for patient management especially in vulnerable groups. Method We evaluated nine months follow up data in our observational Dia-Vacc study exploring specific cellular (interferon-γ release assay) or/and humoral immune responses after 2x SARS-CoV-2mRNA vaccination in 880 participants including healthy MP (125), DP (595), KTR (111), and apheresis patients (49-AP) with positive seroconversion (de novo IgA or IgG antibody positivity by ELISA) after eight weeks. Results Nine months after first vaccination, receptor binding domain (RBD) antibodies were still positive in 90 % of MP, 86 % of AP, but only 55 %/48 % of DP/KTR, respectively. Seroconversion remained positive in 100 % of AP and 99·2 % of MP, but 86 %/81 % of DP/KTR, respectively. Compared to MP, DP but not KTR or AP were at risk for a strong RBD decline, while KTR kept lowest RBD values over time (see Fig. 1 and Table 1). By multivariate analysis, BNT162b2mRNA versus 1273-mRNA vaccine type was an independent risk factor for a strong decline of RBD antibodies. Within the DP group, only time on dialysis was another (inverse) risk factor for the DP group. Compared to humoral immunity, T-cell immunity decline was less prominent. Conclusion While seroconverted KTR reach lowest RBD values over time, DP are at specific risk for a strong decline of RBD antibodies after successful SARS-CoV-2mRNA vaccination, which also depends on the vaccine type being used. Therefore, booster vaccinations for DP should be considered earlier compared to normal population.
Vaccine · 2023-12-18 · 6 citations
articleThe Lancet Regional Health - Europe · 2022 · 29 citations
- Medicine
- Immunology
- Internal medicine
Background: Vulnerable dialysis and kidney transplant patients show impaired seroconversion rates compared to medical personnel eight weeks after SARS-CoV-2mRNA vaccination. Methods: IgA or IgG antibody positivity by ELISA) after eight weeks. Findings: < 0·001). Within the DP but not KTR group male gender, peritoneal dialysis, short time on dialysis, BNT162b2mRNA vaccine, immunosuppressive drug use and diabetes mellitus were independent risk factors for a strong decline of IgG or RBD antibodies. The percentage of cellular immunity decline was similar in all groups. Interpretation: Both vulnerable DP and KTR groups are at risk for a strong decline for IgG and RBD antibodies. In KTR, antibody titres peak at a markedly lower level and accelerated antibody decline is mixed with a delayed/increasing IgG, RBD-IgG, or cellular immune response in a 16% fraction of patients. In both populations, immune monitoring should be used for early timing of additional booster vaccinations. Funding: This study was funded by the Else Kröner Fresenius Stiftung, Bad Homburg v. d. H., grant number Fördervertrag EKFS 2021_EKSE.27.
Recent grants
NIH · $618k · 2006
NIH · $1.3M · 2013
Frequent coauthors
- 35 shared
G. Scott Worthen
Children's Hospital of Philadelphia
- 34 shared
Christian Hugo
TU Dresden
- 32 shared
Scott K. Young
Pulmonary and Critical Care Associates
- 31 shared
Jerry A. Nick
National Jewish Health
- 31 shared
Julian Stumpf
TU Dresden
- 28 shared
Jan Sradnick
- 24 shared
Jonathan G. Lieber
- 23 shared
Michael B. Fessler
Triangle
Labs
Awards & honors
- American Thoracic Society
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