Summary The airway epithelium develops into a treelike structure via branching morphogenesis. Here we show a critical role for localized differentiation of airway smooth muscle during epithelial bifurcation in the embryonic mouse lung. We found that during terminal bifurcation, changes in the geometry of nascent buds coincided with patterned smooth muscle differentiation. Evaluating spatiotemporal dynamics of α-smooth muscle actin (αSMA) in reporter mice revealed that αSMA-expressing cells appear at the basal surface of the future epithelial cleft prior to bifurcation, and then increase in density as they wrap around the bifurcating bud. Disrupting this stereotyped pattern of smooth muscle differentiation prevents terminal bifurcation. Our results reveal stereotyped differentiation of airway smooth muscle adjacent to nascent epithelial buds and suggest that localized smooth muscle wrapping at the cleft site is required for terminal bifurcation during airway branching morphogenesis.

IMPORTANCE Despite high prevalence of elevated blood pressure (BP) among medical inpatients, BP management guidelines are lacking for this population. The outcomes associated with intensifying BP treatment in the hospital are poorly studied.OBJECTIVES To characterize clinician response to BP in the hospital and at discharge and to compare short-and long-term outcomes associated with antihypertensive treatment intensification.DESIGN, SETTING, AND PARTICIPANTS This cohort study took place from January 1 to December 31, 2017, with 1 year of follow-up at 10 hospitals within the Cleveland Clinic Hospitals health care system. All adults admitted to a medicine service in 2017 were evaluated for inclusion. Patients with cardiovascular diagnoses were excluded. Demographic and BP characteristics were used for propensity matching.EXPOSURES Acute hypertension treatment, defined as administration of an intravenous antihypertensive medication or a new class of an oral antihypertensive treatment. MAIN OUTCOMES AND MEASURESThe association between acute hypertension treatment and subsequent inpatient acute kidney injury, myocardial injury, and stroke was measured. Postdischarge outcomes included stroke and myocardial infarction within 30 days and BP control up to 1 year. RESULTS Among 22 834 adults hospitalized for noncardiovascular diagnoses (mean [SD] age, 65.6 [17.9] years; 12 993 women [56.9%]; 15 963 White patients [69.9%]), 17 821 (78%) had at least 1 hypertensive BP recorded during their admission. Of these patients, 5904 (33.1%) were treated. A total of 8692 of 106 097 cases (8.2%) of hypertensive systolic BPs were treated; of these, 5747 (66%) were treated with oral medications. In a propensity-matched sample controlling for patient and BP characteristics, treated patients had higher rates of subsequent acute kidney injury (466 of 4520 [10.3%] vs 357 of 4520 [7.9%]; P < .001) and myocardial injury (53 of 4520 [1.2%] vs 26 of 4520 [0.6%]; P = .003). There was no BP interval in which treated patients had better outcomes than untreated patients. A total of 1645 of 17 821 patients (9%) with hypertension were discharged with an intensified antihypertensive regimen. Medication intensification at discharge was not associated with better BP control in the following year. CONCLUSIONS AND RELEVANCEIn this cohort study, hypertension was common among medical inpatients, but antihypertensive treatment intensification was not. Intensification of therapy without signs of end-organ damage was associated with worse outcomes.

Through multiple mechanisms, regulatory B cells (Breg) have been shown to play an important role in the development of allograft tolerance. However, a careful understanding of the role of antigen‐specificity in Breg‐mediated allograft tolerance has remained elusive. In experimental models of islet and cardiac transplantation, it has been established that Bregs can be induced in vivo by anti‐CD45RB ± anti‐TIM1antibody treatment, resulting in prolonged, Breg‐dependent allograft tolerance. The importance of Breg antigen recognition has been suggested but not confirmed through adoptive transfer experiments, using tolerant WT C57BL/6 animals challenged with either BALB/c or C3H grafts. However, the importance of receptor‐specificity has not been formally tested. Here, we utilize the novel ovalbumin‐specific B cell receptor transnuclear (OBI) mice in multiple primary tolerance and adoptive transfer experiments to establish that Breg‐dependent allograft tolerance relies on antigen recognition by B cells. Additionally, we identify that this Breg‐dependent tolerance relies on the function of transforming growth factor‐β. Together, these experiments mark important progress toward understanding how best to improve Breg‐mediated allograft tolerance.

Background: DBA/2J kidney allografts, but not heart allografts, are spontaneously accepted indefinitely in C57BL/6 (B6) mice, through regulatory tolerance mechanism dependent on Foxp3+ cells. In contrast, B6 kidneys are rejected within a week in DBA/2J recipients. We hypothesized that the tolerogenic difference of the kidneys might be due to differences in number or function of plasmacytoid dendritic cells (pDCs), since these cells are potent inducers of Foxp3+ cells.Methods: pDCs from murine bone marrow, native kidneys, and spontaneously accepted kidney allografts were analyzed using flow cytometry and immunohistochemical staining. Naïve T cells were co-cultured with pDCs in specific strain combinations and analyzed for FoxP3 induction and functionality. MEK/ERK and NFκB inhibitors were used to assess the Treg induction pathways. pDCs and T cell cultures were adoptively transferred prior to heterotopic heart transplantation to assess allograft survival.Results: DBA/2J pDCs were more potent in inducing Foxp3+ in B6 T cells than the reverse combination, correlating with survival of the kidney allografts. Foxp3 induction by pDCs in vitro was dependent on pDC viability, immaturity, and class II MHC mismatch, and blocked by MEK/ERK and NFκB inhibition. pDC-induced Foxp3+ T cells suppressed proliferation of B6 T cells in vitro, and adoptive transfer into B6 recipients two weeks prior to heterotopic DBA/2J heart transplantation resulted in prolonged allograft survival.Conclusions: These data suggest that pDC-induced Tregs are dependent on down-stream signaling effects and strain-dependent, MHC class II disparity with naïve T cells, which may explain organ and strain specific differences in spontaneous tolerance.

Immunologic tolerance to solid organ and islet cell grafts has been achieved in various rodent models using antibodies directed at CD45RB and Tim-1. We have shown that this form of tolerance depends on regulatory B-cells. To elucidate further the mechanism by which Bregs induce tolerance we investigated the requirement of NK and NKT cells in this model. To do so, hyperglycemic B6, μMT, Beige or CD1d−/− mice received Balb/c islet grafts and treatment with the tolerance inducing regimen consisting of anti-CD45RB and anti –TIM1. B6 mice depleted of both NK and NKT cells by anti-NK1.1 antibody and mice deficient in NK activity (Beige) did not develop tolerance following dual antibody treatment. In contrast, transplant tolerance induction was successful in CD1d−/− recipients (deficient in NK-T cells), indicating that NK but not NKT cells are essential in B-cell dependent tolerance. In addition, reconstitution of Beige host with NK cells restored the ability to induce transplant tolerance with dual antibody treatment. Transfer of tolerance by B-cells from tolerant mice was also dependent on host Nk1.1+ cells. In conclusion, these results show that regulatory function of B-cells is dependent on NK cells in this model of transplantation tolerance.

The current liver allocation system may be disadvantaging younger adult recipients as it does not incorporate the donor-recipient age difference. Given the longer life expectancy of younger recipients, the influences of older donor grafts on their long-term prognosis should be elucidated. This study sought to reveal the long-term prognostic influence of the donor-recipient age difference in young adult recipients. Adult patients who received initial liver transplants from deceased donors between 2002 and 2021 were identified from the UNOS database. Young recipients (patients 45 years old or below) were categorized into 4 groups: donor age younger than the recipient, 0-9 years older, 10-19 years older, or 20 years older or above. Older recipients were defined as patients 65 years old or above.To examine the influence of the age difference in long-term survivors, conditional graft survival analysis was conducted on both younger and older recipients.Among 91,952 transplant recipients, 15,170 patients were 45 years old or below (16.5%); these were categorized into 6,114 (40.3%), 3,315 (21.9%), 2,970 (19.6%), and 2,771 (18.3%) for groups 1-4, respectively. Group 1 demonstrated the highest probability of survival, followed by groups 2, 3, and 4 for the actual graft survival and conditional graft survival analyses. In younger recipients who survived at least 5 years post-transplant, inferior long-term survival was observed when there was an age difference of 10 years or above (86.9% vs. 80.6%, logrank p < 0.01), whereas there was no difference in older recipients (72.6% vs. 74.2%, log-rank p = 0.89). In younger patients who are not in emergent need of a transplant, preferential allocation of younger aged donor offers would optimize organ utility by increasing postoperative graft survival time.

Epstein-Barr virus-related lymphoproliferative disease (EBV-LPD) rarely occurs in patients with acute lymphoblastic leukemia (ALL), who have not received hematopoietic transplantation. We describe EBV-LPD manifesting as facial lesions in two children with ALL in remission. One patient was a 16-year-old male with T-cell ALL with an EBV-positive angiocentric polymorphous lip lesion presenting as right-sided facial swelling. The other patient was a 12-year-old male with B-cell ALL with an EBV-positive polymorphous lymphoplasmacytic infiltrate presenting as bilateral dacryoadenitis. Neither patient had known primary immunodeficiencies. Both cases improved with immunosuppressant de-escalation. These cases suggest that immunosuppression induced by maintenance chemotherapy is sufficient to promote EBV-LPD.

Background Previous infection with SARS-CoV-2 provides strong protection against future infection. There is limited evidence on whether such protection extends to the Omicron variant. Methods This retrospective cohort study included 635,341 patients tested for SARS-CoV-2 via polymerase chain reaction (PCR) from 09 March 2020 to 01 March 2022. Patients were analyzed according to the wave in which they were initially infected. The primary outcome was reinfection during the Omicron period (20 December 2021, to 01 March 2022). We used a multivariable model to assess the effects of prior infection and vaccination on hospitalization. Results Among the patients tested during the Omicron wave, 30.6% tested positive. Protection of prior infection against reinfection with Omicron ranged from 18.0% (95% confidence interval [CI], 13.0-22.7) for patients infected in wave 1 to 69.2% (95% CI, 63.4-74.1) for those infected in the Delta wave. In adjusted models, previous infection reduced hospitalization by 28.5% (95% CI, 19.1-36.7), while full vaccination plus a booster reduced it by 59.2% (95% CI, 54.8-63.1).