Fluid Shear Stress Promotes Osteoblast Proliferation and Suppresses Mitochondrial-Mediated Osteoblast Apoptosis Through the miR-214-3p-ATF4 Signaling Axis

MicroRNAs (miRNAs) play vital roles in bone metabolism and participate in the mechanically induced bone alterations. The underlying molecular mechanisms by which fluid shear stress (FSS) regulate the proliferative and apoptotic phenotypic changes of osteoblasts remain elusive. The study aimed to investigate the regulatory effects of FSS on osteoblast proliferative and apoptotic phenotypes and the roles of miR-214-3p-ATF4 (activating transcription factor 4) signaling axis in the mechanomodulation processes. FSS promoted the proliferative activity of osteoblasts and suppressed mitochondrial-mediated osteoblast apoptosis. FSS decreased miR-214-3p expression and increased ATF4 expression in MC3T3-E1 osteoblasts. MiR-214-3p inhibited osteoblast proliferative activity and promoted mitochondrial-mediated osteoblast apoptosis. Overexpression of miR-214-3p attenuated FSS-enhanced osteoblast proliferation and FSS-suppressed mitochondrial-mediated osteoblast apoptosis. We validated that ATF4 acted as a target gene of miR-214-3p. Moreover, miR-214 3p regulated osteoblast proliferation and apoptosis through targeting ATF4. Taken together, our study proved that FSS could suppress mitochondrial-mediated osteoblast apoptosis and promote osteoblast proliferation through the miR-214-3p-ATF4 signaling axis.

Evidence for Nonlinear Gluon Effects in QCD and Their Mass Number Dependence at STAR

The STAR Collaboration reports measurements of back-to-back azimuthal correlations of di-π^{0}s produced at forward pseudorapidities (2.6<η<4.0) in p+p, p+Al, and p+Au collisions at a center-of-mass energy of 200 GeV. We observe a clear suppression of the correlated yields of back-to-back π^{0} pairs in p+Al and p+Au collisions compared to the p+p data. The observed suppression of back-to-back pairs as a function of transverse momentum suggests nonlinear gluon dynamics arising at high parton densities. The larger suppression found in p+Au relative to p+Al collisions exhibits a dependence of the saturation scale Q_{s}^{2} on the mass number A. A linear scaling of the suppression with A^{1/3} is observed with a slope of -0.09±0.01.

Coherent Picture on the Pure Spin Transport between Ag/Bi and Ferromagnets

In a joint effort of both experiments and first-principles calculations, we resolve a hotly debated controversy and provide a coherent picture on the pure spin transport between Ag/Bi and ferromagnets. We demonstrate a strong inverse Rashba-Edelstein effect (IREE) at the interface in between Ag/Bi with a ferromagnetic metal (FM) but not with a ferromagnetic insulator. This is in sharp contrast to the previously claimed IREE at Ag/Bi interface or inverse spin Hall effect dominated spin transport. A more than one order of magnitude modulation of IREE signal is realized for different Ag/Bi-FM interfaces, casting strong tunability and a new direction for searching efficient spintronics materials.

[A nomogram based on systemic inflammation markers can predict adverse outcomes in patients with heart failure]

OBJECTIVE

To construct a nomogram based on systemic inflammation markers for assessing the risk of adverse outcomes in patients with heart failure (HF).

METHODS

We retrospectively collected the clinical data from 430 patients with HF hospitalized in our hospital from June, 2017 to June, 2019.The patients were randomized into derivation group (n=286) and validation group (n=144) at a 7:3 ratio using R software.The risk factors for adverse prognosis of HF were screened using COX regression analysis to establish the nomogram.The predictive accuracy of the nomogram was assessed using calibration curves.Decision curve analysis (DCA) and Kaplan-Meier curves were used to evaluate the clinical utility of the nomogram.

RESULTS

The results of COX multivariate regression analysis showed that age (P=0.030), body mass index (BMI, P=0.002), New York Heart Association classification (NYHA, P < 0.001), hypertension (P=0.004), lymphocyte count (P < 0.001), platelet-to-lymphocyte ratio (PLR, P=0.007), neutrophil-to-lymphocyte ratio (NLR, P < 0.001) and system inflammation response index (SIRI, P < 0.001) were prognostic factors for HF patients.The nomogram was constructed using these prognostic factors.The C-indexes of the derivation and validation cohorts were 0.719(95%CI: 0.680-0.758) and 0.732(95%CI: 0.693-0.771), respectively.The calibration curves showed a good concordance of the nomogram for predicting adverse outcomes in patients with HF.

CONCLUSION

The nomogram constructed based on the systemic inflammation markers and the conventional risk factors can predict adverse outcomes (mortality and readmission) in patients with HF.

p120 regulates E-cadherin expression in nasal epithelial cells in chronic rhinosinusitis

BACKGROUND

The epithelial barrier plays an important role in the regulation of immune homeostasis. The effect of the immune environment on E-cadherin has been demonstrated in previous studies. This discovery prompted new research on the targeting mechanism of E-cadherin in chronic rhinosinusitis (CRS).

METHODS

E-cadherin and p120 expression was determined by quantitative RT-PCR, and western blot. The interaction between E-cadherin and p120 was assessed by immunofluorescence staining and coimmunoprecipitation assays. Human nasal epithelial cells (HNECs) were cultured with submerged methods and transfected with p120-specific small interfering RNA. In other experiments, HNECs differentiated with the air-liquid interface (ALI) method were stimulated with various cytokines and Toll-like receptor (TLR) agonists. The barrier properties of differentiated HNECs were determined by assessing fluorescent dextran permeability.

RESULTS

E-cadherin and p120 expression was decreased in HNECs from patients with CRS, and the p120 protein expression level was positively correlated with that of E-cadherin. Two isoforms of p120 (p120-1 and p120-3) were expressed in HNECs, with p120-3 being the main isoform. Knocking down p120 in HNECs cultured under submerged conditions significantly reduced the E-cadherin protein expression. The Rac1 inhibitor NSC23766 reversed the protein expression of E-cadherin in p120 knockdown experiments. Inflammatory mediators, including IL-4, TNF-α, TGF- β, LPS and IFN-Î, reduced E-cadherin and p120 protein expression and increased paracellular permeability. Dexamethasone abolished the downregulation of E-cadherin and p120 caused by inflammatory mediators.

CONCLUSIONS

p120 is involved in regulating E-cadherin protein expression in CRS. Dexamethasone may alleviate the reduction in E-cadherin and p120 protein expression caused by inflammatory mediators.

[Genetic characteristics and prognostic analysis of 162 fetal cardiac abnormalities]

Objective: To analyze the type and characteristics of fetal cardiac abnormalities and their relationships with genetic abnormalities and clinical prognosis. Methods: The clinical data of 162 pregnant women with fetal cardiac abnormalities who came to the prenatal diagnosis center of Peking University First Hospital and performed genetic tests from February 2013 to February 2021 were reviewed. Genetic testing methods included chromosome karyotype analysis, array-based comparative genomic hybridization (aCGH) and pathogenic gene detection. Fetuses with isolated cardiac abnormalities and no fatal genetic abnormalities were assessed using the fetal cardiac birth defects clinical outcome score and followed up. Results: (1) Ultrasonography results: among the 162 fetuses, 86 cases (53.1%, 86/162) had isolated cardiac abnormalities, and 76 cases (46.9%, 76/162) had extra-cardiac abnormalities; single cardiac abnormalities were in 84 (51.9%,84/162) cases, and multiple cardiac abnormalities occurred in 78 cases (48.1%,78/162). (2) Genetic examination results: there were 39 cases (24.1%, 39/162) of pathogenic genetic abnormalities, including 35 cases (21.6%, 35/162) of pathogenic chromosome karyotype abnormality, 3 cases (1.9%, 3/162) of pathogenic copy number variant (CNV), and 1 case (0.6%, 1/162) of pathogenic gene variation. The detection rates of pathogenic genetic abnormalities were 16.3% (14/86) in fetuses with isolated cardiac abnormalities and 32.9% (25/76) in fetuses with cardiac abnormalities and extra-cardiac abnormalities, and the difference was statistically significant (χ²=6.094, P=0.014). The detection rate of genetic abnormalities was 28.6% (24/84) in the single cardiac abnormalities, among which ventricular septal defect was 36.7% (11/30), atrioventricular septal defect was 8/13, tetralogy of Fallot was 3/17, persistent trancus arteriosus was 1/1, cardiac tumor was 1/1; no genetic abnormality was detected in the other single cardiac abnormality types (22 cases in total). The main types of pathogenic genetic abnormalities were trisomy 21 (41.7%, 10/24) and trisomy 18 (41.7%, 10/24). (3) Pregnancy outcome and fetal prognosis: among 72 fetuses with isolated heart abnormalities without pathogenic genetic abnormalities, there were 4 cases of grade Ⅰ, all of which continued pregnancy; 39 cases of grade Ⅱ, with 21 cases induced labor, 18 cases continued pregnancy; 26 cases of grade Ⅲ, with 23 cases induced labor, 3 cases continued pregnancy; 3 cases of grade Ⅳ, all of which induced labor. Totally, there were 47 cases induced labor and 25 cases continued pregnancy, 24 cases (96.0%, 24/25) of which were alive. Conclusions: When fetal cardiac abnormalities are detected by prenatal ultrasound, comprehensive cardiac and extra-cardiac ultrasound assessment and further genetic testing are recommended. Fetuses excluded pathogenic genetic abnormalities and extra-cardiac abnormalities should perform clinical prognostic score evaluation through multidisciplinary collaboration, to improve maternal and fetal outcomes.

[Investigation and analysis of the implementation status of "Diagnosis and therapy guideline of preterm birth (2014)"]

Objective: To understand the actual situation of the implementation of "Diagnosis and therapy guideline of preterm birth（2014）", "Guideline" for short, by front-line obstetricians, and to provide reference for the further update and supplement of the "Guideline". Methods: This study designed a structured questionnaire for the prominent problems in the prevention and treatment of preterm birth, which was determined by the expert team drafting the "Guideline". In October to November 2021, a cross-sectional survey was conducted among obstetricians, including members of the Perinatal Medicine Branch of Jiangsu Medical Association and the Obstetrics Subgroup,Chinese society of Obstetrics and Gynecology, Chinese Medical Association, on the implementation status of the "Guideline". The recommendations of the "Guideline" were used as standard answers to determine the implementation rate. A total of 328 valid questionnaires were collected. The total score of the questionnaire was 12 points. The questionnaire was divided into low executive ability group (<7 points) and high executive ability group (≥7 points) with a score of 7 as the threshold value, and the differences in baseline information such as hospital grade and professional title between the two groups were compared. Results: The score of 328 obstetricians was (7.6±1.6) points, including 250 (76.2%, 250/328) in the high execution group and 78 (23.8%, 78/328) in the low execution group. The execution rates of "the use of uterine contraction inhibitors for short courses"[97.0% (318/328)], "late umbilical cord breakage after birth of premature infants"[87.8% (288/328)] and "should preterm patients with intact membranes be treated with antibiotics"[86.6% (284/328)] were all over 80%, indicating good implementation. Multiple logistic regression analysis showed that hospital grade and professional title were independent factors influencing the performance of the "Guideline"(all P<0.05), and secondary hospitals had lower scores and worse execution than tertiary hospitals (OR=0.42, 95%CI: 0.23-0.77; P=0.005). Senior titles had higher scores and better execution than junior titles (OR=5.33, 95%CI: 2.35-12.07; P<0.001). When answering the question "gestational week at which premature infants could survive in your hospital", only 3.4% (11/328) answered 22 weeks, and 44.5% (146/328) answered 28 weeks, accounted for the highest proportion. The gestational week of surviving premature infants in tertiary hospitals was earlier than that in secondary hospitals (P<0.05). The gestational week of surviving premature infants answered by senior titles was earlier than that of junior titles (P<0.05). Conclusions: Obstetricians generally have a good implementation of the "Guideline", and their understanding of some recommended clauses in the guidelines needs to be improved. In the future, training of primary hospitals and physicians with junior titles should be strengthened.

Probing ^{93m}Mo Isomer Depletion with an Isomer Beam

The isomer depletion of ^{93m}Mo was recently reported [Chiara et al., Nature (London) 554, 216 (2018)NATUAS0028-083610.1038/nature25483] as the first direct observation of nuclear excitation by electron capture (NEEC). However, the measured excitation probability of 1.0(3)% is far beyond the theoretical expectation. In order to understand the inconsistency between theory and experiment, we produce the ^{93m}Mo nuclei using the ^{12}C(^{86}Kr,5n) reaction at a beam energy of 559 MeV and transport the reaction residues to a detection station far away from the target area employing a secondary beam line. The isomer depletion is expected to occur during the slowdown process of the ions in the stopping material. In such a low γ-ray background environment, the signature of isomer depletion is not observed, and an upper limit of 2×10^{-5} is estimated for the excitation probability. This is consistent with the theoretical expectation. Our findings shed doubt on the previously reported NEEC phenomenon and highlight the necessity and feasibility of further experimental investigations for reexamining the isomer depletion under low γ-ray background.

Comparison of the Utility of High-Resolution CT-DWI and T2WI-DWI Fusion Images for the Localization of Cholesteatoma

BACKGROUND AND PURPOSE

Cholesteatoma is an aggressive disease that may lead to hearing impairment. This study aimed to compare the utility of high-resolution CT and TSE-DWI fusion images with that of T2WI and TSE-DWI fusion images in the localization of middle ear cholesteatoma.

MATERIALS AND METHODS

Seventy-one patients with middle ear cholesteatoma were retrospectively recruited. High-resolution CT, T2WI with fat suppression, and TSE-DWI scans were obtained, and image fusion was performed using a 3D reconstruction postprocessing workstation to form CT-DWI and T2WI-DWI fusion images. The quality of the 2 fused images was subjectively evaluated using a 5-point Likert scale with the horizontal semicircular canal transverse position as the reference. Receiver operating characteristic analysis was performed, and the diagnostic efficacies of CT-DWI and T2WI-DWI fusion images in localizing middle ear cholesteatoma were calculated.

RESULTS

The overall quality of T2WI-DWI fusion images was slightly higher than that of CT-DWI fusion images (P < .001), and the semicircular canal was slightly less clear on T2WI-DWI than on CT-DWI (P < .001). No statistical difference was found in the diagnostic confidence between them. In the localization of middle ear cholesteatoma, the accuracy, sensitivity, and specificity of T2WI-DWI fusion images and CT-DWI fusion images were equivalent for involvement of the attic, tympanic cavity, mastoid antrum, and mastoid process, with no statistically significant differences.

CONCLUSIONS

T2WI-DWI fusion images could replace CT-DWI in the preoperative selection of surgical options for middle ear cholesteatoma.

AB0227 TREATMENT SEQUENCING PATTERNS AND COMPARATIVE EFFICACY IN PATIENTS WITH RHEUMATOID ARTHRITIS FROM A REAL-WORLD SETTING

Background

The European League Against Rheumatism (EULAR)1 recently provided updated guidelines regarding the initiation and modification of disease-modifying antirheumatic drug (DMARD) therapy in patients with Rheumatoid Arthritis (RA). Therefore, real-world evidence studies are warranted to provide insights into first-line DMARD utilization and durability of response in the second-line setting.

Objectives

To analyze RA treatment patterns in real-world data and compare durability of response between second-line DMARDs + anti-TNF (TNFi) therapies vs. TNFi monotherapy.

Methods

Electronic health records (EHRs) from a large health system in the Northeast US were used to identify RA patients. Lines of therapy were defined based on confirmed prescriptions for DMARDs and TNFi therapies. Time to next treatment (TTNT) was the primary outcome to estimate durability of response. Time-to-event analyses were performed using Kaplan-Meier and log-rank test methods. In addition, a Cox Proportional-Hazards (CoxPH) model was used to evaluate covariates as independent predictors of disease progression.

Results

Our study cohort consisted of 8,040 patients who had at least one line of therapy for RA. Conventional synthetic DMARDs (csDMARDs) were the predominant first line of therapy in this dataset (71.3%), followed by TNFi alone (11.1%) or TNFi combined with csDMARD (9.1%) (Figure 1).

For patients who had csDMARD as their first line of therapy, 22.93% progressed to second line treatment. Among them 36.2% patients were TNFi with or without in combination with csDMARDs. In the second-line, TNFi + csDMARDs were associated with a longer TTNT (median time: 13.1 months vs 6.1 months, P < 0.005) compared to TNFi monotherapy. The multiple variable CoxPH model (adjusted for age, gender, and race) demonstrated that second-line TNFi + csDMARDs had a lower hazard rate when compared to TNFi monotherapy (HR = 0.74, 95% CI: 0.36 - 1.12, p < 0.005).

Conclusion

We demonstrated the first comprehensive treatment sequencing patterns in RA from a real-world setting. As a second-line therapy for patients with inadequate response to csDMARDS, the TNFi + csDMARDs combination may improve duration of response when compared to TNFi monotherapy. Results from this study will inform future sequencing strategies to improve patient outcomes.

References

[1]Smolen, Josef S., Robert B. M. Landewé, Johannes W. J. Bijlsma, Gerd R. Burmester, Maxime Dougados, Andreas Kerschbaumer, Iain B. McInnes, et al. 2020. “EULAR Recommendations for the Management of Rheumatoid Arthritis with Synthetic and Biological Disease-Modifying Antirheumatic Drugs: 2019 Update.” Annals of the Rheumatic Diseases 79 (6): 685–99.

Disclosure of Interests

Lei Ai: None declared, Mitchell Higashi: None declared, Kyeryoung Lee: None declared, Zongzhi Liu: None declared, Lan Jin: None declared, Kalpana Raja: None declared, Yun Mai: None declared, Tomi Jun: None declared, William Oh Consultant of: Janssen

Pfizer, Aviva Beckmann: None declared, Emilio Schadt: None declared, Zachary Schadt: None declared, Rick Wallsten: None declared, Ediz Calay: None declared, Andrew Kasarskis: None declared, Qi Pan: None declared, Eric Schadt Speakers bureau: Eli Lilly, Consultant of: SAB of Eli Lilly

Celgene, Xiaoyan Wang: None declared

Circulating myeloid-derived suppressors cells correlate with clinicopathological characteristics and outcomes undergoing neoadjuvant chemoimmunotherapy in non-small cell lung cancer

PURPOSE

Myeloid-derived suppressors cells (MDSCs) are heterogeneous immunosuppressive cells, closely related to the development, efficacy and prognosis in various tumors. The relationship between clinicopathological characteristics, efficacy of neoadjuvant chemoimmunotherapy (NCIO) and circulating MDSCs in patients with non-small cell lung cancer (NSCLC) was investigated in this study.

METHODS

This study analyzed the clinical data of patients diagnosed at Department of Thoracic Surgery, Beijing Chest Hospital from November 2020 to August 2021. MDSCs and T cells subgroups were measured in fresh peripheral blood mononuclear cells(PBMCs) at baseline. Flow cytometry was used to detect MDSCs and T cells subgroups.

RESULTS

A total of 78 patients with NSCLC and 20 patients with benign nodule underwent direct surgery. 23 patients with NSCLC scheduled to accept NCIO before surgery. NSCLC had elevated levels of total MDSCs, PMN-MDSCs and M-MDSCs compared to patients with benign nodule. MDSCs subgroups were correlated to the pTNM stage in NSCLC patients. The frequency of total MDSCs were moderately positively correlated with regulatory T cells (Tregs)(r = 0.3597, P < 0.01) and negatively correlated with CD4 + T cells(r = 0.2714, P < 0.05). The baseline levels of total MDSCs, PMN-MDSCs and Tregs in pCR patients were significantly decreased than those of non-pCR patients (P < 0.05).

CONCLUSION

Circulating MDSCs were increased in NSCLC patients. MDSC subgroups were related to pTNM stage in NSCLC patients. Total MDSCs were positively correlated with Tregs levels and negatively correlated with CD4 + T cells in peripheral blood. The level of MDSCs and Tregs in peripheral blood may have potential value in predicting pathological response in NSCLC.

[Impact of C2-femoral heads center and sacroiliac fixation on the occurrence of post-operative proximal junctional kyphosis in adults with spinal deformity]

Objective: To analyze the relationship between post-operative proximal junctional kyphosis (PJK) and C₂-femoral heads center (C₂-FH), pelvic fixation in adult spinal deformity (ASD) patients, so as to provide a reference for the preoperative decision-making and the postoperative intervention timely. Methods: It was a retrospective study that analyzed 34 cases of ASD patients who underwent posterior pedicle screw fixation in Nanjing Drum Tower Hospital between January 2017 and May 2017. ASD patients were divided into two groups according to fixation options: the sacroiliac fixation group and the non-sacroiliac fixation group. The spine-pelvis parameters were evaluated on full-length X ray films of spine at preoperatively, 2 weeks postoperatively and the last follow-up, and the incidence of PJK was recorded. Results: A total of 34 ASD patients (3 males and 31 females) were included in this study, with an average age of (58±6) years. The mean follow-up period was (2.9±1.0) years (2.0-4.0 years). The age, follow-up time and various spine-pelvis parameters showed no significant differences between the two groups (all P>0.05). The immediate postoperative C₂-FH in the sacroiliac fixation group was significantly lower than that in the non-sacroiliac fixation group [(-69.46±30.85) mm vs (-31.62±15.31) mm, P<0.001]. The incidence of PJK was as high as 50.0% (8/16) in patients with sacroiliac fixation, but it was only 22% (4/18) in patients without sacroiliac fixation (P=0.016). At the last follow-up, the C₂-FH of both groups were both higher than -20 mm (both were approximately -15 mm, P=0.976), indicating that the C₂-FH was compensated in both groups. Due to the loss of the distal compensation ability, the incidence of PJK in the sacroiliac fixation group was higher than that in the non-sacroiliac fixation group. Due to the fixation of pelvis and most of lumbar spine, no significant differences were found in lumbar lordosis (LL), pelvic tilt (PT) and sacral slope (SS) at the last follow-up in both groups when compared with those after the operation (all P>0.05); while the thoracic kyphosis (TK) and cervical lordosis (CL) increased significantly (both P<0.05) to compensate C₂-FH at the last follow-up. Conclusion: It's demonstrated that C₂-FH< -2 cm and pelvic fixation are high risk factors of PJK in ASD patients. It is suggested that both global sagittal balance and pelvic fixation should be considered in decision-making and corrective surgery, rather than only focusing on spine-pelvic parameters.

[Effect evaluation of "Smoking cessation: Doctor first"program in China]

Objective: To evaluate the effect of "Smoking cessation: Doctor first" program on smoking medical staff. Methods: From December 2016 to September 2019, 1 747 smoking medical staff from 54 units of China Tobacco Cessation Alliance were enrolled into"Smoking cessation: Doctor first"program. Demographic characteristics, smoking characteristics, degree of tobacco dependence, willingness to quit smoking and other related factors were collected during the baseline survey. Multivariate logistic regression model was used to analyze the related factors of willingness to quit. The subjects were given intensive smoking cessation intervention from October 2017 to September 2019, including education on the hazards of smoking, methods of smoking cessation and giving smoking cessation drugs. After intervention, the subjects were investigated about their smoking cessation progress and the effect of the project was evaluated. Results: The subjects were (41±11) years old, 91.9% (1 609/1 747) were male and 62.2% (1 086/1 747) were daily smokers. The main reasons for smoking included the influence of friends [697 (39.9%)], the need for social entertainment [629 (36.0%)], the relief of mental stress [589 (33.7%)] and the refreshment [459 (26.3%)]. At baseline, 52.9% (885/1 672) and 43.2% (755/1 747) smokers had intention to quit smoking and had planned to quit within one year, respectively. Multivariate logistic regression model analysis showed that: low education level [OR (95%CI) of high school and junior high school and below were 2.42 (1.61, 3.63) and 1.57 (1.18, 2.11)], daily smoking [OR (95%CI): 1.38 (1.06, 1.78)], thinking quitting smoking is not important [OR (95%CI): 4.15 (3.33, 5.18)] and having no quitting experience [OR (95%CI): 3.21 (2.53, 4.05)] were associated with no intention to quit smoking. After intensive smoking cessation intervention, 81.0% (1 415/1 747) smokers started to quit and 36.6% (518/1 415) quit smoking with drugs, both higher than the baseline level (all P values<0.001). By the end of the program, 60.2% (852/1 415) of the medical staff had quit smoking successfully. Conclusion: "Smoking cessation: Doctor first"program can improve the willingness to quit and the proportion of using smoking cessation drugs of medical staff.

Measurements of Proton High-Order Cumulants in sqrt[s_{NN}]=3 GeV Au+Au Collisions and Implications for the QCD Critical Point

We report cumulants of the proton multiplicity distribution from dedicated fixed-target Au+Au collisions at sqrt[s_{NN}]=3.0  GeV, measured by the STAR experiment in the kinematic acceptance of rapidity (y) and transverse momentum (p_{T}) within -0.5<y<0 and 0.4<p_{T}<2.0  GeV/c. In the most central 0%-5% collisions, a proton cumulant ratio is measured to be C_{4}/C_{2}=-0.85±0.09 (stat)±0.82 (syst), which is 2σ below the Poisson baseline with respect to both the statistical and systematic uncertainties. The hadronic transport UrQMD model reproduces our C_{4}/C_{2} in the measured acceptance. Compared to higher energy results and the transport model calculations, the suppression in C_{4}/C_{2} is consistent with fluctuations driven by baryon number conservation and indicates an energy regime dominated by hadronic interactions. These data imply that the QCD critical region, if created in heavy-ion collisions, could only exist at energies higher than 3 GeV.