Interpreting resting heart rate variability in complex populations: the role of autonomic reflexes and comorbidities.

PURPOSE: Resting heart rate variability (HRV) is an important biomarker linking mental health to cardiovascular outcomes. However, resting HRV is also impaired in autonomic neuropathy, a common and underdiagnosed complication of common medical conditions which is detected by testing autonomic reflexes. We sought to describe the relationship between autonomic reflex abnormalities and resting HRV, taking into consideration medical comorbidities and demographic variables. METHODS: Participants (n = 209) underwent a standardized autonomic reflex screen which was summarized as the Composite Autonomic Severity Score (CASS) and included measures of reflexive HRV, e.g., heart rate with deep breathing (HRDB). Resting HRV measures were: pNN50 (percentage of NN intervals that differ by > 50 ms) and cvRMSSD (adjusted root mean square of successive differences). RESULTS: In univariate analyses, lower resting HRV was associated with: older age, higher CASS, neuropathy on examination, hypertension, diabetes, chronic obstructive pulmonary disease, chronic kidney disease, and psychiatric disease. Adaptive regression spline analysis revealed that HRDB explained 27% of the variability in resting HRV for participants with values of HRDB in the normal range. Outside this range, there was no linear relationship because: (1) when HRDB was low (indicating autonomic neuropathy), resting HRV was also low with low variance; and (2) when HRDB was high, the variance in resting HRV was high. In multivariate models, only HRDB was significantly independently associated with cvRMSSD and pNN50. CONCLUSION: Subclinical autonomic neuropathy, as evidenced by low HRDB and other autonomic reflexes, should be considered as a potential confounder of resting HRV in research involving medically and demographically diverse populations.

Autonomic Neuropathy as a Predictor of Morbidity and Mortality in People Living With HIV: A Retrospective, Longitudinal Cohort Study.

Background and Objectives: HIV-associated autonomic neuropathy (HIV-AN) is common; however, its clinical effect is unclear. Previously, it was shown that the composite autonomic severity score is associated with markers of morbidity such as the Veterans Affair Cohort Study index. In addition, it is known that cardiovascular autonomic neuropathy due to diabetes is associated with poor cardiovascular outcomes. This study aimed to evaluate whether HIV-AN is predictive of important adverse clinical outcomes. Method: The electronic medical records of HIV-infected participants who underwent autonomic function tests at the Mount Sinai Hospital between April 2011 and August 2012 were reviewed. The cohort was stratified into those who had no or mild autonomic neuropathy (HIV-AN [-], CASS ≤3) and those with moderate or severe autonomic neuropathy (HIV-AN [+], CASS >3). The primary outcome was a composite of the incidence of death from any cause, new major cardiovascular or cerebrovascular event, or development of severe renal or hepatic disease. Time-to-event analysis was performed using Kaplan-Meier analysis and multivariate Cox proportional hazards regression models. Results: One hundred eleven of 114 participants had follow-up data (median follow-up for HIV-AN (-) was 94.00 months, and HIV-AN (+) was 81.29 months) and were included in the analysis. Participants were followed until March 1, 2020. The HIV-AN (+) group (N = 42) was significantly associated with the presence of hypertension, higher HIV-1 viral load, and more abnormal liver function. Seventeen (40.48%) events occurred in the HIV-AN (+) group, and 11 (15.94%) occurred in the HIV-AN (-) group. Six (14.29%) cardiac events occurred in the HIV-AN (+) group, whereas 1 (1.45%) occurred in the HIV-AN (-) group. The other subgroups of the composite outcome had a similar trend. The adjusted Cox proportional hazards model showed that the presence of HIV-AN predicted our composite outcome (HR 3.85, CI 1.61-9.20). Discussion: These findings suggest that HIV-AN is associated with the development of severe morbidity and mortality in people living with HIV. People living with HIV with autonomic neuropathy may benefit from closer cardiac, renal, and hepatic surveillance.

4-1BB functions as a survival factor in dendritic cells.

4-1BB (CD137) is expressed on dendritic cells (DCs) and its biological function has remained largely unresolved. By comparing 4-1BB-intact (4-1BB(+/+)) and 4-1BB-deficient (4-1BB(-/-)) DCs, we found that 4-1BB was strongly induced on DCs during the maturation and that DC maturation was normal in the absence of 4-1BB. However, DC survival rate was low in the absence of 4-1BB, which was due to the decreased Bcl-2 and Bcl-x(L) in 4-1BB(-/-) DCs compared with 4-1BB(+/+) DCs after DC maturation. Consistent with these results, 4-1BB(-/-) DCs showed an increased turnover rate in steady state and more severely decreased in spleen by injecting LPS compared with 4-1BB(+/+) DCs. When OVA-pulsed DCs were adoptively transferred to recipient mice along with OVA-specific CD4(+) T cells, 4-1BB(-/-) DCs did not properly migrate to the T cell zone in lymph nodes and poorly induced proliferation of CD4(+) T cells, although both DCs comparably expressed functional CCR7. Eventually, 4-1BB(-/-) DCs generated a reduced number of OVA-specific memory CD4(+) T cells compared with 4-1BB(+/+) DCs. To further assess the role of 4-1BB on DC longevity in vivo, 4-1BB(+/+) and 4-1BB(-/-) C57BL/6 were administrated with Propionibacterium acnes that develop liver granuloma by recruiting DCs. Number and size of granuloma were reduced in the absence of 4-1BB, but the inflammatory cytokine level was comparable between the mice, which implied that the granuloma might be reduced due to the decreased longevity of DCs. These results demonstrate that 4-1BB on DCs controls the duration, DC-T interaction, and, therefore, immunogenicity.

4-1BB triggers IL-13 production from T cells to limit the polarized, Th1-mediated inflammation.

4-1BB (CD137) triggering typically induces Th1 response by increasing IFN-gamma from T cells upon TCR ligation. We found recently that 4-1BB costimulation increased the expression of IL-13 from CD4(+) T cells, as well as CD8(+) T cells. The enhanced IL-13 expression by agonistic anti-4-1BB treatment was mediated via MAPK1/2, PI-3K, JNK, mammalian target of rapamycin, NF-AT, and NF-kappaB signaling pathways. The signaling for IL-13 induction was similar to that of IFN-gamma production by anti-4-1BB treatment in T cells. When the anti-4-1BB-mediated IL-13 expression was tested in an in vivo viral infection model such as HSV-1 and vesicular stomatitis virus, 4-1BB stimulation enhanced IL-13 expression of CD4(+) T, rather than CD8(+) T cells. Although IL-13 was enhanced by anti-4-1BB treatment, the increased IL-13 did not significantly alter the anti-4-1BB-induced Th1 polarization of T cells--increase of T-bet and decrease of GATA-3. Nevertheless, anti-4-1BB treatment polarized T cells excessively in the absence of IL-13 and even became detrimental to the mice by causing liver inflammation. Therefore, we concluded that IL-13 was coinduced following 4-1BB triggering to maintain the Th1/2 balance of immune response.

Immune Myopathy With Perimysial Pathology Associated With Interstitial Lung Disease and Anti-EJ Antibodies.

OBJECTIVES: We report a case of immune myopathy with perimysial pathology associated with anti-glycyl-transfer RNA synthetase (anti-EJ) antibody and an excellent treatment response. METHODS: Chart review. RESULTS: A 36-year-old woman presented with 3 months of fatigue, weight loss, progressive weakness in a scapuloperoneal distribution, and dysphagia. Nerve conduction studies, electromyography, and ultrasound suggested an irritable myopathy. She had marked elevations of creatine kinase and positive anti-glycyl-transfer RNA synthetase (anti-EJ) antibodies. A left biceps muscle biopsy revealed inflammation of the perimysium and surrounding perimysial blood vessels with focal fragmentation of the perimysium. Further evaluation revealed interstitial lung disease. Treatment with prednisone and mycophenolate mofetil led to marked clinical improvement of her symptoms. CONCLUSIONS: Our case adds to the growing spectrum of inflammatory myopathies and highlights the importance of performing a comprehensive, multisystem workup.

Adult stem cells from the hyaluronic acid-rich node and duct system differentiate into neuronal cells and repair brain injury.

The existence of a hyaluronic acid-rich node and duct system (HAR-NDS) within the lymphatic and blood vessels was demonstrated previously. The HAR-NDS was enriched with small (3.0-5.0 µm in diameter), adult stem cells with properties similar to those of the very small embryonic-like stem cells (VSELs). Sca-1(+)Lin(-)CD45(-) cells were enriched approximately 100-fold in the intravascular HAR-NDS compared with the bone marrow. We named these adult stem cells "node and duct stem cells (NDSCs)." NDSCs formed colonies on C2C12 feeder layers, were positive for fetal alkaline phosphatase, and could be subcultured on the feeder layers. NDSCs were Oct4(+)Nanog(+)SSEA-1(+)Sox2(+), while VSELs were Oct4(+)Nanog(+)SSEA-1(+)Sox2(-). NDSCs had higher sphere-forming efficiency and proliferative potential than VSELs, and they were found to differentiate into neuronal cells in vitro. Injection of NDSCs into mice partially repaired ischemic brain damage. Thus, we report the discovery of potential adult stem cells that may be involved in tissue regeneration. The intravascular HAR-NDS may serve as a route that delivers these stem cells to their target tissues.

Blockade of the 4-1BB (CD137)/4-1BBL and/or CD28/CD80/CD86 costimulatory pathways promotes corneal allograft survival in mice.

To explore the roles of 4-1BB (CD137) and CD28 in corneal transplantation, we examined the effect of 4-1BB/4-1BB ligand (4-1BBL) and/or CD28/CD80/CD86 blockade on corneal allograft survival in mice. Allogeneic corneal transplantation was performed between two strains of wild-type (WT) mice, BALB/c and C57BL/6 (B6), and between BALB/c and B6 WT donors and various gene knockout (KO) recipients. Some of the WT graft recipients were treated intraperitoneally with agonistic anti-4-1BB or blocking anti-4-1BBL monoclonal antibody (mAb) on days 0, 2, 4 and 6 after transplantation. Transplanted eyes were observed over a 13-week period. Allogeneic grafts in control WT B6 and BALB/c mice treated with rat immunoglobulin G showed median survival times (MST) of 12 and 14 days, respectively. Allogeneic grafts in B6 WT recipients treated with anti-4-1BB mAb showed accelerated rejection, with an MST of 8 days. In contrast, allogeneic grafts in BALB/c 4-1BB/CD28 KO and B6 CD80/CD86 KO recipients had significantly prolonged graft survival times (MST, 52.5 days and 36 days, respectively). Treatment of WT recipients with anti-4-1BB mAb resulted in enhanced cellular proliferation in the mixed lymphocyte reaction and increased the numbers of CD4(+) CD8(+) T cells, and macrophages in the grafts, which correlated with decreased graft survival time, whereas transplant recipients with costimulatory receptor deletion showed longer graft survival times. These results suggest that the absence of receptors for the 4-1BB/4-1BBL and/or CD28/CD80/CD86 costimulatory pathways promotes corneal allograft survival, whereas triggering 4-1BB with an agonistic mAb enhances the rejection of corneal allografts.