Ventilator Management in Extremely Preterm Infants

Advances in ventilation strategies for infants in the NICU have led to increased survival of extremely preterm infants. More than 75% of infants born at less than or equal to 27 weeks' gestation require initial mechanical ventilation for survival due to developmental immaturity of their lungs and respiratory drive. Various ventilators using different technologies and involving multiple management strategies are available for use in this population. Centers across the world have successfully used conventional, high-frequency oscillatory and high-frequency jet ventilation to manage respiratory failure in extremely preterm infants. This review explores the existing evidence for each mode of ventilation and the importance of individualizing ventilator management strategies when caring for extremely preterm infants.

Survival and short-term respiratory outcomes of <750 g infants initially intubated with 2.0 mm vs. 2.5 mm endotracheal tubes

OBJECTIVES

To compare survival and short-term respiratory outcomes of infants weighing <750 g initially intubated with 2.0 mm versus 2.5 mm endotracheal tube (ETT).

STUDY DESIGN

Retrospective, observational cohort study.

RESULTS

Of 149 inborn infants weighing <750 g admitted to the NICU, 69 (46%) were intubated with 2.0 mm ETT, 78 with 2.5 mm ETT (53%), and 2 infants never required intubation. Infants intubated with 2.0 mm ETT were more premature (median gestational age (GA) 23 weeks (22, 24) vs. 24 weeks (24, 25) p < 0.0001), smaller (median birth weight 545 g (450, 616) vs. 648 g (579, 700), p < 0.0001), and more frequently intubated at delivery (96% vs. 68%, p < 0.00001). Survival to discharge was similar 77%, 53/69 and 87%, 68/78 (p = 0.09). Adjusted for GA, there were no significant differences in ventilator days (p = 0.7338) or Grade 3 BPD.

CONCLUSIONS

Premature infants born at a median GA of 23 weeks and median birth weight of 545 g can be successfully managed with 2.0 mm ETT.

The gammaherpesvirus 68 viral cyclin facilitates expression of LANA

Gammaherpesviruses establish life-long infections within their host and have been shown to be the causative agents of devastating malignancies. Chronic infection within the host is mediated through cycles of transcriptionally quiescent stages of latency with periods of reactivation into detectable lytic and productive infection. The mechanisms that regulate reactivation from latency remain poorly understood. Previously, we defined a critical role for the viral cyclin in promoting reactivation from latency. Disruption of the viral cyclin had no impact on the frequency of cells containing viral genome during latency, yet it remains unclear whether the viral cyclin influences latently infected cells in a qualitative manner. To define the impact of the viral cyclin on properties of latent infection, we utilized a viral cyclin deficient variant expressing a LANA-beta-lactamase fusion protein (LANA::βla), to enumerate both the cellular distribution and frequency of LANA gene expression. Disruption of the viral cyclin did not affect the cellular distribution of latently infected cells, but did result in a significant decrease in the frequency of cells that expressed LANA::βla across multiple tissues and in both immunocompetent and immunodeficient hosts. Strikingly, whereas the cyclin-deficient virus had a reactivation defect in bulk culture, sort purified cyclin-deficient LANA::βla expressing cells were fully capable of reactivation. These data emphasize that the γHV68 latent reservoir is comprised of at least two distinct stages of infection characterized by differential LANA expression, and that a primary function of the viral cyclin is to promote LANA expression during latency, a state associated with ex vivo reactivation competence.

Gammaherpesviruses are ubiquitous viruses with oncogenic potential that establish latency for the life of the host. These viruses can emerge from latency through reactivation, a process that is controlled by the immune system. Control of viral latency and reactivation is thought to be critical to prevent γHV-associated disease. This study focuses on a virally-encoded cyclin that is required for reactivation from latency. By characterizing how the viral cyclin influences latent infection in pure cell populations, we find that the viral cyclin has a vital role in promoting viral gene expression during latency. This work provides new insight into the function of a virally encoded cyclin in promoting reactivation from latency.

Abstract A36: CXCL14-mediated antigen-specific CD8+ T-cell responses suppress HPV-positive head and neck cancer

Human papillomaviruses (HPVs) cause over 5% of all human cancer incidences, including a subset of head and neck squamous cell carcinoma (HNSCC), resulting in about half a million deaths every year. Persistent infection with high-risk HPV is necessary for development of HPV-associated malignancies. To establish persistence in the host, HPV must evade host antiviral defenses, including the innate and adaptive immune responses. As antiviral and antitumor immune responses share similar mechanisms, it is likely that HPV-induced immune suppression leads to immune evasion and survival of HPV-infected cancer cells. We have previously shown that expression of the chemokine CXCL14 is significantly downregulated by promoter methylation mediated by the HPV oncoprotein E7 during cancer progression. Restoration of CXCL14 expression in HPV-positive HNSCC cells dramatically suppresses tumor growth through an immune-dependent mechanism in mice. While CXCL14 recruits NK and CD8+ T cells to the tumor microenvironment, the roles of NK and T cells to enact the CXCL14-mediated tumor suppression remained undefined. To determine the roles of NK and CD8+ T cells, tumor growth was assessed in wild-type C57BL/6 mice depleted of NK or CD8+ T cells and CD8-knockout mice injected with the HPV-positive HNSCC cells re-expressing CXCL14. The results show that that CD8+ T cells are required for CXCL14-mediated tumor suppression. The antitumor CD8+ T-cell responses require antigen specificity as a transgenic model of mice with a restricted CD8+ T-cell receptor failed to control tumor growth. Counteracting the HPV-mediated downregulation of major histocompatibility complex class I (MHC-I), CXCL14 expression restores MHC-I expression on HPV-positive HNSCC cells. Furthermore, knockdown of MHC-I expression in CXCL14 expressing HNSCC cells results in loss of tumor suppression, defining a critical role for antigen presentation. These results suggest that CXCL14 expression drives antigen-specific CD8+ T-cell responses and suppresses tumor growth through the restoration of MHC-I expression in HPV-positive HNSCC. Our findings provide useful insight into the CXCL14-mediated antitumor mechanism that increases CD8+ T-cell recognition of tumor cells and could boost the efficacy of current immunotherapies.

Citation Format: Joseph A. Westrich, Daniel W. Vermeer, Stephanie Bonney, Alexa Silva, Jennifer N. Berger, Marianna Madeo, Louis Cicchini, John H. Lee, William C. Spanos, Dohun Pyeon. CXCL14-mediated antigen-specific CD8+ T-cell responses suppress HPV-positive head and neck cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A36.

CXCL14 suppresses human papillomavirus-associated head and neck cancer through antigen-specific CD8+ T-cell responses by upregulating MHC-I expression

Evasion of the host immune responses is critical for both persistent human papillomavirus (HPV) infection and associated cancer progression. We have previously shown that expression of the homeostatic chemokine CXCL14 is significantly downregulated by the HPV oncoprotein E7 during cancer progression. Restoration of CXCL14 expression in HPV-positive head and neck cancer (HNC) cells dramatically suppresses tumor growth and increases survival through an immune-dependent mechanism in mice. While CXCL14 recruits natural killer (NK) and T cells to the tumor microenvironment, the mechanism by which CXCL14 mediates tumor suppression through NK and/or T cells remained undefined. Here, we report that CD8⁺ T cells are required for CXCL14-mediated tumor suppression. Using a CD8⁺ T cell receptor transgenic model, we show that the CXCL14-mediated antitumor CD8⁺ T cell responses require antigen specificity. Interestingly, CXCL14 expression restores major histocompatibility complex class I (MHC-I) expression on HPV-positive HNC cells downregulated by HPV, and knockdown of MHC-I expression in HNC cells results in loss of tumor suppression even with CXCL14 expression. These results suggest that CXCL14 enacts antitumor immunity through restoration of MHC-I expression on tumor cells and promoting antigen-specific CD8⁺ T cell responses to suppress HPV-positive HNC.

Name and Characteristics of National Institutes of Health R01-Funded Pediatric Physician-Scientists: Hope and Challenges for the Vanishing Pediatric Physician-Scientists

This study describes the number and characteristics of physician-scientists who are funded by National Institutes of Health independent investigator awards.

Abstract A07: CXCL14 expression inhibits tumor growth by reversing human papillomavirus-mediated immune suppression

Human papillomaviruses (HPVs) are causally associated with over 5% of all human cancers including ~25% of head and neck cancers (HNC) and ~100% of cervical cancers (CxCa), resulting in approximately half a million deaths every year. Furthermore, HPV-positive HNC incidence is increasing at an epidemic rate. During decades of cancer progression, HPV persists, evades host immune surveillance, and continuously contributes to host cell transformation. However, little is known about the mechanisms of disease progression driven by HPV, particularly in the context of host immunity. We recently reported that expression of the chemokine CXCL14 is epigenetically repressed by the HPV oncoprotein E7 and that restoration of CXCL14 expression in HPV-positive HNC cells suppresses tumor growth in immunocompetent syngeneic mice, but not in immunodeficient Rag1-/- mice (PMID: 27143385). We also revealed that natural killer (NK), CD4+ T, and CD8+ T cell populations were significantly decreased in tumor-draining lymph nodes (TDLNs) compared to distal lymph nodes (dLNs) of tumor bearing mice. However, Cxcl14 expression restored NK, CD4+ T, and CD8+ T cell populations in the TDLNs to similar levels observed in the dLN. To better understand the mechanism by which CXCL14 induces antitumor immune responses, we performed a large scale immune cell profiling with dLNs and TDLNs from mice injected with HPV-positive mouse oropharyngeal epithelial cells with or without Cxcl14 expression. The multicolor flow cytometry results showed that B cell populations are significantly decreased in TDLNs by Cxcl14 expression, while populations of myeloid immune cells remain largely unchanged. To determine if NK or CD8+ T cells are necessary for tumor suppression by Cxcl14, we performed antibody-based depletion of NK or CD8+ T cell populations using anti-NK1.1 antibody (clone PK136) and anti-CD8a antibody (clone GK 2.43), respectively. The data revealed that both NK and CD8+ T cells are necessary for Cxcl14 to optimally function as a tumor suppressor. Interestingly, NK cell depletion showed two distinct groups of responders and non-responders to Cxcl14 expression, while all mice with CD8+ T cell depletion developed tumor. These results suggest that NK cells may play an important role in initiation of antitumor immune responses. In contrast, adoptive transfer of lymphocytes from Cxcl14 expressing mice does not suppress tumor growth, indicating that NK and CD8+ T cells are required but not sufficient for Cxcl14-mediated antitumor immunity. As we previously showed that Cxcl14 induces chemotaxis of NK and CD8+ T cells, the chemotactic function of Cxcl14 in the tumor microenvironment might be critical for induction of antitumor immune responses. Further, our analysis of The Cancer Genome Atlas (TCGA) data showed that CXCL14 methylation status inversely correlates to patient survival. Therefore, CXCL14 may be a key communicator for antitumor immunity in the HPV-infected tumor microenvironment and could be used as a prognostic and therapeutic tool for HPV-positive HNC and CxCa patients.

Citation Format: Joseph A. Westrich, Louis Cicchini, Daniel W. Vermeer, Jennifer N. Berger, Eric T. Clambey, John H. Lee, Dohun Pyeon. CXCL14 expression inhibits tumor growth by reversing human papillomavirus-mediated immune suppression. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A07.

Compliance of Parenting Magazines Advertisements with American Academy of Pediatrics Recommendations

This study examined 3218 advertisements from the two parenting magazines with highest circulation in the United States. The authors compared each advertisement for a product for use by children, against all the published recommendations of the American Academy of Pediatrics (AAP) on topics such as toy safety, helmet use, age-defined choking hazards, infant sleep safety, and others. Any advertisement with images or products which went against a published AAP recommendation was deemed as non-adherence and was categorized according to the statement it contradicted. Nearly one in six (15.7%) of the advertisements contained example(s) of non-adherence to AAP recommendations, with twelve categories of offense represented. Categories ranked by overall share from most to least include: non-Food and Drug Administration (FDA) approved medical treatments, age-defined choking hazards, vitamins, cold medicine, formula, oral care, screen time, toy/playground safety, infant sleep, nutrition, water safety, and fall risk. Given that repeated exposure to messages in advertisements has been associated with changes in health decision-making, and parents often turn to parenting magazines for advice and ideas regarding their children, the publishers might consider screening the content in order to prevent confusing and potentially dangerous messages from being disseminated in the media.

Myeloid Cell Arg1 Inhibits Control of Arthritogenic Alphavirus Infection by Suppressing Antiviral T Cells

Arthritogenic alphaviruses, including Ross River virus (RRV) and chikungunya virus (CHIKV), are responsible for explosive epidemics involving millions of cases. These mosquito-transmitted viruses cause inflammation and injury in skeletal muscle and joint tissues that results in debilitating pain. We previously showed that arginase 1 (Arg1) was highly expressed in myeloid cells in the infected and inflamed musculoskeletal tissues of RRV- and CHIKV-infected mice, and specific deletion of Arg1 from myeloid cells resulted in enhanced viral control. Here, we show that Arg1, along with other genes associated with suppressive myeloid cells, is induced in PBMCs isolated from CHIKV-infected patients during the acute phase as well as the chronic phase, and that high Arg1 expression levels were associated with high viral loads and disease severity. Depletion of both CD4 and CD8 T cells from RRV-infected Arg1-deficient mice restored viral loads to levels detected in T cell-depleted wild-type mice. Moreover, Arg1-expressing myeloid cells inhibited virus-specific T cells in the inflamed and infected musculoskeletal tissues, but not lymphoid tissues, following RRV infection in mice, including suppression of interferon-γ and CD69 expression. Collectively, these data enhance our understanding of the immune response following arthritogenic alphavirus infection and suggest that immunosuppressive myeloid cells may contribute to the duration or severity of these debilitating infections.

Mosquito-transmitted chikungunya virus (CHIKV), Ross River virus (RRV), and related alphaviruses cause epidemics involving millions of persons, such as on-going CHIKV outbreaks in the Caribbean and Central and South America. Infection with these viruses results in severe pain due to inflammation of musculoskeletal tissues that can persist for months and even years. There are no specific therapeutics or licensed vaccines for these viruses. Suppressive myeloid cells have been shown to inhibit anti-pathogen immune responses, including T cell responses, which can promote chronic disease. We showed previously that a gene associated with suppressive myeloid cells, arginase 1 (Arg1), was induced in musculoskeletal tissues and macrophages of mice infected with RRV or CHIKV, and mice that lacked Arg1 expression in myeloid cells had reduced viral loads at late times post-infection. Here, we demonstrate that Arg1 is induced in PBMCs isolated from CHIKV-infected patients, and Arg1 expression is associated with viral loads. Moreover, we found that Arg1-expressing myeloid cells inhibit the activation and function of antiviral T cells in RRV-infected mice. These studies underscore the role of suppressive myeloid cells in modulating the T cell response to arthritogenic alphaviruses and provide a therapeutic target to enhance viral clearance and potentially limit chronic disease.