Good CARMA: Turning bad tumor-resident myeloid cells good with chimeric antigen receptor macrophages.

In religious philosophy, the concept of karma represents the effect of one's past and present actions on one's future. Macrophages are highly plastic cells with myriad roles in health and disease. In the setting of cancer, macrophages are among the most plentiful members of the immune microenvironment where they generally support tumor growth and restrain antitumor immunity. However, macrophages are not necessarily born bad. Macrophages or their immediate progenitors, monocytes, are induced to traffic to the tumor microenvironment (TME) and during this process they are polarized toward a tumor-promoting phenotype. Efforts to deplete or repolarize tumor-associated macrophages (TAM) for therapeutic benefit in cancer have to date disappointed. By contrast, genetic engineering of macrophages followed by their transit into the TME may allow these impressionable cells to mend their ways. In this review, we summarize and discuss recent advances in the genetic engineering of macrophages for the treatment of cancer.

Testing fractional doses of COVID-19 vaccines.

Due to the enormous economic, health, and social costs of the COVID-19 pandemic, there are high expected social returns to investing in parallel in multiple approaches to accelerating vaccination. We argue there are high expected social returns to investigating the scope for lowering the dosage of some COVID-19 vaccines. While existing evidence is not dispositive, available clinical data on the immunogenicity of lower doses combined with evidence of a high correlation between neutralizing antibody response and vaccine efficacy suggests that half or even quarter doses of some vaccines could generate high levels of protection, particularly against severe disease and death, while potentially expanding supply by 450 million to 1.55 billion doses per month, based on supply projections for 2021. An epidemiological model suggests that, even if fractional doses are less effective than standard doses, vaccinating more people faster could substantially reduce total infections and deaths. The costs of further testing alternative doses are much lower than the expected public health and economic benefits. However, commercial incentives to generate evidence on fractional dosing are weak, suggesting that testing may not occur without public investment. Governments could support either experimental or observational evaluations of fractional dosing, for either primary or booster shots. Discussions with researchers and government officials in multiple countries where vaccines are scarce suggests strong interest in these approaches.

Expansion of tumor-infiltrating and marrow-infiltrating lymphocytes from pediatric malignant solid tumors.

INTRODUCTION: The expansion of tumor-infiltrating lymphocytes (TIL) for adoptive cellular therapy is under investigation in many solid tumors of adulthood. Marrow-infiltrating lymphocytes (MIL) have demonstrated antitumor reactivity preclinically. Successful expansion of TIL/MIL has not been reported across pediatric solid tumor histologies. The objective of this study was to demonstrate successful expansion of TIL from pediatric solid tumors for translation in an adoptive cell therapy (ACT) treatment strategy. METHODS: A prospective study of TIL/MIL expansion was performed on solid tumors of pediatric patients undergoing standard-of-care procedures. TIL/MIL expansions were performed in the presence of high-dose interleukin 2. To demonstrate a full-scale expansion to clinically-relevant cell doses for TIL therapy, initial TIL culture was followed by a rapid expansion protocol for select patients. Expanded specimens were analyzed for phenotype by flow cytometry and for anti-tumor reactivity by the interferon-gamma release assay. RESULTS: Eighteen tumor samples were obtained. Initial TIL cultures were successfully generated from 14/18 samples (77.7%). A median of 5.52 × 107 (range: 2.5 × 106-3.23 × 108) cells were produced from initial cultures, with 46.9% expressing a CD3 phenotype (46.9%). Eight samples underwent rapid expansion, demonstrating a median 458-fold expansion and a CD3 phenotype of 98%. Initial MIL cultures were successfully generated from five samples, with a predominantly CD3 phenotype (45.2%). Sufficient tumor tissue was only available for seven TIL samples to be tested for reactivity; none demonstrated responsiveness to autologous tumor. CONCLUSIONS: TIL and MIL expansion from pediatric solid tumors was successful, including the full-scale expansion process. This data supports translation to an ACT-TIL treatment strategy in the pediatric population and thus a Phase I trial of ACT-TIL in pediatric high-risk solid tumors is planned.

Front-Line Memory T Cells Think Outside the T-box Mostly.

Tissue-resident memory T (Trm) cells patrol barrier tissues. In this issue of Immunity, Carbone and colleagues show that downregulation of T-box proteins Eomesodermin and T-bet is critical for their differentiation, but residual levels of T-bet are important for long-term Trm survival and function.

Nissen Fundoplication in Infants With Severe Bronchopulmonary Dysplasia: A Propensity-Matched Analysis.

INTRODUCTION: Bronchopulmonary dysplasia (BPD) is a common respiratory morbidity among premature infants. Nissen fundoplication may be performed on infants with BPD to protect the lungs from gastroesophageal reflux-related aspiration, but the indications and benefits associated with fundoplication are not well-defined. This study evaluated associations of Nissen with clinical outcomes in infants with severe BPD (sBPD), using propensity score matching to minimize bias and confounding. METHODS: Infants ≤31 wk gestational age with sBPD (grade 2-3) admitted to a single neonatal intensive care unit (NICU) between January 2016 and October 2021 were included. Patients with sBPD who underwent Nissen fundoplication during initial NICU admission were propensity score-matched at a 1:2 ratio with control patients who did not undergo Nissen (no-Nissen). Outcomes were compared, including time to freedom from respiratory support (defined as ≤2 L nasal cannula), time to initial NICU discharge, and incidence of hospital readmission or death within 1 y postdischarge. RESULTS: After propensity score matching, 18 Nissen infants were compared with 30 no-Nissen infants. The Nissen group trended toward longer time to freedom from respiratory support (median 105 versus 70 d, P = 0.09), and had longer initial hospital stays (188 versus 111 d, P = 0.002), more 1-y hospital readmissions (83% versus 50%, P = 0.04), and more tracheostomies (28% versus 0%, P = 0.005). Mortality during first-year postdischarge was similar (6% versus 10%, P = 1.0). CONCLUSIONS: Despite adjustment for confounding variables, Nissen fundoplication was associated with prolonged support and greater resource utilization among infants with sBPD. Prospective studies are needed to clarify indications for fundoplication in this population.

Firearm Injuries in Young Children: Surgical Resource Utilization and Implications for Prevention.

INTRODUCTION: Pediatric firearm injury prevention research in younger age groups is limited. This study evaluated a large multicenter cohort of younger children with firearm injuries, focusing on injury patterns and surgical resource utilization. METHODS: Children ≤15 y old sustaining firearm injuries between 2016 and 2021 and treated at 10 pediatric trauma centers in Florida were included. Individual cases were reviewed for demographics, shooting details, injury patterns, resource utilization, and outcomes. Patients were grouped by age into preschool (0-5 y), elementary school (6-10 y), middle school (11-13 y), and early high school (14-15 y). Multivariable logistic regression was used to identify predictors of death and critical resource utilization. RESULTS: A total of 489 children (80 preschool, 76 elementary school, 92 middle school, and 241 early high school) met inclusion criteria. Demographics, injury patterns, and resource utilization were similar across age groups. Assault and self-harm increased with age. Self-harm was implicated in 5% of cases but accounted for 18% of deaths. Hand surgery (i.e., below-elbow) procedures were common at 8%. Overall mortality was 10%, but markedly higher for self-harm injuries (47%). On multivariable regression, age and demographics were not predictive of death or critical resource utilization, but self-harm intent was a strong independent risk factor for both. CONCLUSIONS: This study suggests that given the age distribution and disproportionately high impact of self-harm injuries, behavioral health resources should be available to children at the middle school level or earlier. Hand surgery may represent an overlooked but frequently utilized resource to mitigate injury impact and optimize long-term function.

Measuring Pectus Excavatum Severity, External Caliper, or Cross-Sectional Imaging: Family Perceptions.

INTRODUCTION: Patients with pectus excavatum (PE) often undergo cross-sectional imaging (CSI) to quantify severity for insurance authorization before surgical repair. The modified percent depth (MPD), an external caliper-based metric, was previously validated to be similar to the pectus index and correction index. This study explored family perceptions of CSI and MPD with respect to value and costs. METHODS: This is a cross-sectional survey study including families of patients enrolled in an ongoing prospective multicenter study evaluating the use of MPD as an alternative to CSI for quantifying PE severity. Families of PE patients who underwent both MPD and CSI completed a survey to determine their perceptions of MPD and costs of CSI. Responses were described and associations were evaluated using chi squared, Wilcoxon rank-sum test and logistic regression as appropriate. Statistical significance was set to 0.05. RESULTS: There were 136 surveys completed for a response rate of 88%. Respondents were confident in MPD (86%) and confident in its similarity to CSI (76%). Families of females were less confident in the measurements than males (55% versus 80%, P = 0.02; odds ratio 0.30 (0.11, 0.83). Obtaining CSI required time off work/school in 90% and a copay in 60%. Nearly half (49%) of respondents reported CSI was a time/financial hardship. Increasing copay led to decreased reassurance in CSI (55%: copay > $100 versus 77%: lower copay/75%: no copay; P = 0.04). CONCLUSIONS: From the family perspective, MPD is valuable in assessing the severity of PE. Obtaining CSI was financially burdensome, particularly for those with higher copays. MPD measurements provide high value at low cost in assessing the severity of PE.

Investigation of the Synthesis and Energetic Properties of an ANTA-Based Energetic Plasticizer.

Energetic plasticizers are being sought for their use in energetic formulations when combined with explosives. An energetic plasticizer based on the insensitive highly explosive 3-amino-5-nitro-l,2,4-triazole (ANTA) was synthesized and characterized by spectroscopy, X-ray crystallography, thermal analyses, and safety testing. Lastly, density functional theory calculations were employed to examine the observed selectivity among the three nucleophilic ring nitrogen atoms of ANTA toward electrophiles such as ANTA acrylate; this selectivity was found to be a combination of steric, electronic, and hydrogen bonding effects.

Management of Pediatric Type III Tibial Shaft Fractures: A Cohort Study Utilizing the Trauma Quality Improvement Program Database.

BACKGROUND: Pediatric open tibial fractures represent a challenging subset of injuries with limited literature to guide management. For children, the epidemiology, management, and outcomes of tibial-shaft fractures have not been fully described. METHODS: A retrospective analysis of the Trauma Quality Improvement Program Data Bank from 2017-2020 was used to query demographics, injury patterns, and management strategies in pediatric open tibial fractures. Fractures were compared by age group (0-5, 6-12, 13-17 years) and type (I/II vs type III). A subgroup analysis was performed on patients with type III open fractures. RESULTS: A total of 3480 open tibial fractures were identified, 3049 were type I/II, and 431 were type III. Motor vehicle accidents (48%) were the most common mechanism of injury (P < 0.001). Subanalysis of 128 type IIIb/c tibial fractures revealed local flap reconstruction (25%) skin graft (25%), and free tissue transfer were the most common management strategies and soft-tissue coverage was achieved after 162 hours (interquartile range = 109-231). Negative pressure wound therapy was utilized in 63% of cases but used in isolation in only 23% of cases. Immediate fixation with intramedullary nailing was more frequently used in the 13-17 age group while plate fixation was more commonly used in younger age groups. CONCLUSIONS: Soft-tissue management patterns following open tibial shaft fractures mirror those seen in adult cohorts. The median time to achieve soft-tissue coverage exceeds the traditional 72-hour target advocated by Godina. Age-based variation is seen in orthopedic management of these fractures based on growth maintenance concerns.

Risk of Injury-Related Readmission Varies by Initial Presenting-Hospital Type Among Children at High Risk for Physical Abuse.

OBJECTIVES: Children experiencing physical abuse may initially present to hospitals with underappreciated minor injuries, only to experience more severe injuries in the future. The objectives of this study were to 1) describe young children presenting with high-risk diagnoses for physical abuse, 2) characterize the hospitals to which they initially presented, and 3) evaluate associations of initial presenting-hospital type with subsequent admission for injury. METHODS: Patients aged younger than 6 years from the 2009-2014 Florida Agency for Healthcare Administration database with high-risk diagnoses (codes previously associated with >70% risk of child physical abuse) were included. Patients were categorized by the hospital type to which they initially presented: community hospital, adult/combined trauma center, or pediatric trauma center. Primary outcome was subsequent injury-related hospital admission within 1 year. Association of initial presenting-hospital type with outcome was evaluated with multivariable logistic regression, adjusting for demographics, socioeconomic status, preexisting comorbidities, and injury severity. RESULTS: A total of 8626 high-risk children met inclusion criteria. Sixty-eight percent of high-risk children initially presented to community hospitals. At 1 year, 3% of high-risk children had experienced subsequent injury-related admission. On multivariable analysis, initial presentation to a community hospital was associated with higher risk of subsequent injury-related admission (odds ratio, 4.03 vs level 1/pediatric trauma center; 95% confidence interval, 1.83-8.86). Initial presentation to a level 2 adult or combined adult/pediatric trauma center was also associated with higher risk for subsequent injury-related admission (odds ratio, 3.19; 95% confidence interval, 1.40-7.27). CONCLUSIONS: Most children at high risk for physical abuse initially present to community hospitals, not dedicated trauma centers. Children initially evaluated in high-level pediatric trauma centers had lower risk of subsequent injury-related admission. This unexplained variability suggests stronger collaboration is needed between community hospitals and regional pediatric trauma centers at the time of initial presentation to recognize and protect vulnerable children.

Investigation of a maxillary nerve block technique in guinea pigs (Cavia porcellus): A cadaveric study comparing two injectate volumes.

OBJECTIVE: To investigate and describe an extraoral approach to perform a maxillary nerve block in guinea pigs. STUDY DESIGN: Prospective, randomized, blinded, descriptive, cadaveric study. ANIMALS: A total of 14 adult guinea pig cadavers. METHODS: Two cadavers were used for anatomic dissection and determination of maxillary nerve block approach. A maxillary nerve block via infraorbital approach was then performed in 12 cadavers. A low volume (0.1 mL) or high volume (0.2 mL) of diluted methylene blue injectate was randomly assigned to the right or left side, with the other volume used for the contralateral side. The maxillary nerve was dissected after each injection by an investigator blinded to injectate volume. The region of dye distribution was identified, and the degree of staining assigned an accuracy score (0-2). Nerve coverage was considered adequate if ≥6 mm of circumferential staining was present. RESULTS: Accuracy evaluation indicated successful dye deposition in 10/12 [2 (0-2), median (range)] injections in the low volume group and 8/12 [2 (1-2)] injections in the high volume group. The majority (79.2%) of injections resulted in adequate nerve staining. There were no statistically significant differences between injectate volumes for accuracy (p = 0.64) or adequacy (p > 0.99) of staining. CONCLUSIONS: The infraorbital approach is a simple and practical method for maxillary nerve blockade in guinea pigs. An injectate volume of 0.1 mL results in adequate maxillary nerve coverage; however, additional studies are needed to assess the efficacy in clinical use.

Hematopoietic cell-mediated dissemination of murine cytomegalovirus is regulated by NK cells and immune evasion.

Cytomegalovirus (CMV) causes clinically important diseases in immune compromised and immune immature individuals. Based largely on work in the mouse model of murine (M)CMV, there is a consensus that myeloid cells are important for disseminating CMV from the site of infection. In theory, such dissemination should expose CMV to cell-mediated immunity and thus necessitate evasion of T cells and NK cells. However, this hypothesis remains untested. We constructed a recombinant MCMV encoding target sites for the hematopoietic specific miRNA miR-142-3p in the essential viral gene IE3. This virus disseminated poorly to the salivary gland following intranasal or footpad infections but not following intraperitoneal infection in C57BL/6 mice, demonstrating that dissemination by hematopoietic cells is essential for specific routes of infection. Remarkably, depletion of NK cells or T cells restored dissemination of this virus in C57BL/6 mice after intranasal infection, while dissemination occurred normally in BALB/c mice, which lack strong NK cell control of MCMV. These data show that cell-mediated immunity is responsible for restricting MCMV to hematopoietic cell-mediated dissemination. Infected hematopoietic cells avoided cell-mediated immunity via three immune evasion genes that modulate class I MHC and NKG2D ligands (m04, m06 and m152). MCMV lacking these 3 genes spread poorly to the salivary gland unless NK cells were depleted, but also failed to replicate persistently in either the nasal mucosa or salivary gland unless CD8+ T cells were depleted. Surprisingly, CD8+ T cells primed after intranasal infection required CD4+ T cell help to expand and become functional. Together, our data suggest that MCMV can use both hematopoietic cell-dependent and -independent means of dissemination after intranasal infection and that cell mediated immune responses restrict dissemination to infected hematopoietic cells, which are protected from NK cells during dissemination by viral immune evasion. In contrast, viral replication within mucosal tissues depends on evasion of T cells.

Investigation into a Conformationally Locked (Z)-Azidoxime.

High nitrogen compounds find wide use in the development of new propellants and explosives as well as pharmaceutical chemistry as bioisosteres, bacterial stains, and antifungal agents. A class of underexplored high-nitrogen materials includes azidoximes and their 1-hydroxytetrazole isomers. Azidoximes possess an energetic azide group and are quite sensitive to impact, spark, and friction. Therefore, these materials are generated in situ and cyclized under mild acidic conditions to their 1-hydroxytetrazole isomers. Recently, we synthesized a novel 1,2,4-triazine-derived azidoxime; however, upon subjecting this material to established cyclization conditions, no reaction was observed, even after prolonged reaction times with heating. Additional 1,2,4-triazine-derived azidoximes also displayed a similar lack of reactivities. This observation led us to probe the reactivity of these materials with both a DFT investigation and crystallographically based electrostatic potential mapping. In all, the lack of reactivity toward cyclization was found to be due to an inability of 1,2,4-triazine-based azidoximes to isomerize into the reactive (E)-conformation, requiring an activation energy of 26.4 kcal mol-1.

Novel Technique for Cardiac Monitor Implantation in Pediatrics.

Implantable cardiac monitors (ICM) allow for symptom-rhythm correlation. Current manufacturer recommendations call for implantation of ICMs diagonally in the left anterior chest. Complications such as skin tenting and device erosion have occurred using this technique in pediatric patients. The purpose of this study was to assess the safety and efficacy of implanting ICMs via new vertical-parasternal technique (VP) compared to manufacturer-recommended diagonal technique (D) in pediatric patients. Single-center, IRB-approved retrospective study of pediatric patients that underwent ICM implantation from 01/01/2017 to 12/01/2021. All implants were performed after informed consent, under sterile conditions in the electrophysiology laboratory. Data collected included demographics, implant orientation (VP or D), complications, device type, presence of P-wave, and measurement of R-wave amplitude at implantation and follow-up. ICMs were implanted in 34 patients without congenital heart disease. Initial R-wave amplitude average for VP 1.00, D 0.99 (p = NS). Follow-up R-wave amplitude was 0.97 VP and 0.93 for D (p = NS). Median follow-up period for VP was 11 and for D was 20 months (p = NS). D cohort had only post-procedural complication due to skin tenting of the ICM in child < 2.5 years of age. No skin tenting, erosions, or complications occurred in the vertical-parasternal implant technique. Vertical-Parasternal ICM implantation is as safe and effective as the manufacturer-recommended diagonal implant. Short- and long-term data demonstrate an equivalent R-wave detection and no significant signal deterioration, even in very young children. No skin tenting, erosions, or complications occurred in the vertical parasternal implant technique.

Zio® XT Patches in Pediatrics During the COVID-19 Pandemic: Comparisons Between In-Person and Mail-Home Application.

The Zio® (Zio) XT Patch is a 14-day continuous ambulatory ECG monitor. During the Covid-19 pandemic, Zios were mailed directly to patients for self-application. The purpose of this study was to compare the percent artifact, a marker for quality, of in-clinic (IC) to mail-home (MH) applications in a pediatric population. A single-center, IRB-approved study of patients 0- < 21 years of age with Zios was studied for wear and artifact time filtered out based on iRhythm's proprietary algorithm. In total, 284 Zios were randomly selected and analyzed for total wear time and artifact. Of these, 149 were IC prior to 12/31/2019 and 135 MH patches prescribed after 1/1/2020. No significant difference was found for percent artifact between the IC (7.8%) and MH (8.3%) group. Average IC wear-time was 127 h compared to MH at 99 h (p = 0.02). In conclusion, application of Zio patches outside of the pediatric cardiology clinic offers equivalent artifact, a marker of quality, as those applied in clinic and should be consideration as a viable alternative.

Initial Counseling Prior to Palliation for Hypoplastic Left Heart Syndrome: 2021 vs 2011.

We sought to examine current practices and changes in practice regarding initial counseling for families of patients with hypoplastic left heart syndrome (HLHS) given the evolution of options and outcomes over time. Counseling (Norwood with Blalock-Taussig-Thomas shunt (NW-BTT), NW with right ventricle to pulmonary artery conduit (NW-RVPA), hybrid palliation, heart transplantation, or non-intervention/hospice (NI)) for patients with HLHS were queried via questionnaire of pediatric care professionals in 2021 and compared to identical questionnaire from 2011. Of 322 respondents in 2021 (39% female), 299 respondents were cardiologists (92.9%), 17cardiothoracic surgeons (5.3%), and 6 were nurse practitioners (1.9%). Respondents were largely from North America (96.9%). In 2021, NW-RVPA procedure was the preferred palliation for standard risk HLHS patient (61%) and was preferred across all US regions (p < 0.001). NI was offered as an option by 71.4% of respondents for standard risk patients and was the predominant strategy for patients with end-organ dysfunction, chromosomal abnormality, and prematurity (52%, 44%, and 45%, respectively). The hybrid procedure was preferred for low birth-weight infants (51%). In comparison to the identical 2011 questionnaire (n = 200), the NW-RVPA was endorsed more in 2021 (61% vs 52%, p = 0.04). For low birth-weight infants, hybrid procedure was more recommended than in 2011 (51% vs 21%, p < 0.001). The NW-RVPA operation is the most recommended strategy throughout the US for infants with HLHS. The hybrid procedure for low birth-weight infants is increasingly recommended. NI continues to be offered even in standard risk patients with HLHS.

Successful modified implantation of insertable cardiac monitor in a very young paediatric patient.

Insertable cardiac monitors are minimally invasive devices designed for implantation in the chest wall of patients to record heart rhythms and relate them to symptoms over prolonged periods. The Jot Dx™ (Abbott Laboratories, Abbott Park, IL, USA) is the latest Food and Drug Administration-cleared insertable cardiac monitor that is Bluetooth™ enabled allowing for near-immediate transmission of data from patients to physicians. We report on the first paediatric patient, in a patient weighing 11.7 kg, to undergo a modified, vertical, parasternal implantation of a Jot Dx™.

Mechanisms of Antiviral Cytotoxic CD4 T Cell Differentiation.

Cytotoxic CD4 T lymphocytes (CD4-CTL) are important in antiviral immunity. For example, we have previously shown that in mice, CD4-CTL are important to control ectromelia virus (ECTV) infection. How viral infections induce CD4-CTL responses remains incompletely understood. We demonstrate here that not only ECTV but also vaccinia virus and lymphocytic choriomeningitis virus induce CD4-CTL, though the response to ECTV is stronger. Using ECTV, we also demonstrate that in contrast to CD8-CTL, CD4-CTL differentiation requires constant virus replication and ceases once the virus is controlled. We also show that major histocompatibility complex class II molecules on CD11c+ cells are required for CD4-CTL differentiation and for mousepox resistance. Transcriptional analysis indicated that antiviral CD4-CTL and noncytolytic T helper 1 (Th1) CD4 T cells have similar transcriptional profiles, suggesting that CD4-CTL are terminally differentiated classical Th1 cells. Interestingly, CD4-CTL and classical Th1 cells expressed similar mRNA levels of the transcription factors ThPOK and GATA-3, necessary for CD4 T cell linage commitment, and Runx3, required for CD8 T cell development and effector function. However, at the protein level, CD4-CTL had higher levels of the three transcription factors, suggesting that further posttranscriptional regulation is required for CD4-CTL differentiation. Finally, CRISPR/Cas9-mediated deletion of Runx3 in CD4 T cells inhibited CD4-CTL but not classical Th1 cell differentiation in response to ECTV infection. These results further our understanding of the mechanisms of CD4-CTL differentiation during viral infection and the role of posttranscriptionally regulated Runx3 in this process. IMPORTANCE While it is well established that cytotoxic CD4 T cells (CD4-CTLs) directly contribute to viral clearance, it remains unclear how CD4-CTL are induced. We now show that CD4-CTLs require sustained antigen presentation and are induced by CD11c-expressing antigen-presenting cells. Moreover, we show that CD4-CTLs are derived from the terminal differentiation of classical T helper 1 (Th1) subset of CD4 cells. Compared to Th1 cells, CD4-CTLs upregulate protein levels of the transcription factors ThPOK, Runx3, and GATA-3 posttranscriptionally. Deletion of Runx3 in differentiated CD4 T cells prevents induction of CD4-CTLs but not classical Th1 cells. These results advance our knowledge of how CD4-CTLs are induced during viral infection.

α2ß1 Integrin Is Required for Optimal NK Cell Proliferation during Viral Infection but Not for Acquisition of Effector Functions or NK Cell-Mediated Virus Control.

NK cells play an important role in antiviral resistance. The integrin α2, which dimerizes with integrin ß1, distinguishes NK cells from innate lymphoid cells 1 and other leukocytes. Despite its use as an NK cell marker, little is known about the role of α2ß1 in NK cell biology. In this study, we show that in mice α2ß1 deficiency does not alter the balance of NK cell/ innate lymphoid cell 1 generation and slightly decreases the number of NK cells in the bone marrow and spleen without affecting NK cell maturation. NK cells deficient in α2ß1 had no impairment at entering or distributing within the draining lymph node of ectromelia virus (ECTV)-infected mice or at becoming effectors but proliferated poorly in response to ECTV and did not increase in numbers following infection with mouse CMV (MCMV). Still, α2ß1-deficient NK cells efficiently protected from lethal mousepox and controlled MCMV titers in the spleen. Thus, α2ß1 is required for optimal NK cell proliferation but is dispensable for protection against ECTV and MCMV, two well-established models of viral infection in which NK cells are known to be important.

STING Sensing of Murine Cytomegalovirus Alters the Tumor Microenvironment to Promote Antitumor Immunity.

CMV has been proposed to play a role in cancer progression and invasiveness. However, CMV has been increasingly studied as a cancer vaccine vector, and multiple groups, including ours, have reported that the virus can drive antitumor immunity in certain models. Our previous work revealed that intratumoral injections of wild-type murine CMV (MCMV) into B16-F0 melanomas caused tumor growth delay in part by using a viral chemokine to recruit macrophages that were subsequently infected. We now show that MCMV acts as a STING agonist in the tumor. MCMV infection of tumors in STING-deficient mice resulted in normal recruitment of macrophages to the tumor, but poor recruitment of CD8+ T cells, reduced production of inflammatory cytokines and chemokines, and no delay in tumor growth. In vitro, expression of type I IFN was dependent on both STING and the type I IFNR. Moreover, type I IFN alone was sufficient to induce cytokine and chemokine production by macrophages and B16 tumor cells, suggesting that the major role for STING activation was to produce type I IFN. Critically, viral infection of wild-type macrophages alone was sufficient to restore tumor growth delay in STING-deficient animals. Overall, these data show that MCMV infection and sensing in tumor-associated macrophages through STING signaling is sufficient to promote antitumor immune responses in the B16-F0 melanoma model.