Natural killer cells attenuate cytomegalovirus-induced hearing loss in mice

<div><p>Congenital cytomegalovirus (CMV) infection is the most common non-hereditary cause of sensorineural hearing loss (SNHL) yet the mechanisms of hearing loss remain obscure. Natural Killer (NK) cells play a critical role in regulating murine CMV infection via NK cell recognition of the Ly49H cell surface receptor of the viral-encoded m157 ligand expressed at the infected cell surface. This Ly49H NK receptor/m157 ligand interaction has been found to mediate host resistance to CMV in the spleen, and lung, but is much less effective in the liver, so it is not known if this interaction is important in the context of SNHL. Using a murine model for CMV-induced labyrinthitis, we have demonstrated that the Ly49H/m157 interaction mediates host resistance in the temporal bone. BALB/c mice, which lack functional Ly49H, inoculated with mCMV at post-natal day 3 developed profound hearing loss and significant outer hair cell loss by 28 days of life. In contrast, C57BL/6 mice, competent for the Ly49H/m157 interaction, had minimal hearing loss and attenuated outer hair cell loss with the same mCMV dose. Administration of Ly49H blocking antibody or inoculation with a mCMV viral strain deleted for the m157 gene rendered the previously resistant C57BL/6 mouse strain susceptible to hearing loss to a similar extent as the BALB/c mouse strain indicating a direct role of the Ly49H/m157 interaction in mCMV-dependent hearing loss. Additionally, NK cell recruitment to sites of infection was evident in the temporal bone of inoculated susceptible mouse strains. These results demonstrate participation of NK cells in protection from CMV-induced labyrinthitis and SNHL in mice.</p></div

Consequences of \u3ci\u3ein utero\u3c/i\u3e exposure to Zika virus in offspring of AG129 mice

Zika virus (ZIKV) can cause various diseases in offspring after congenital infection. The purpose of this study was to identify disease phenotypes in pups exposed to ZIKV in utero. Female interferon-α/β, -γ receptor knockout mice (AG129) were infected intraperitoneally with ZIKV 7.5 days’ post coitus (dpc). Viral RNA, antigen and infectious virus were detected in some, but not all, maternal and fetal tissues at various times during gestation. Fetuses of infected dams had significant intrauterine growth restriction (IUGR), which was more pronounced as females neared parturition. Pups born to infected dams were significantly smaller and had significantly shortened skull lengths, as determined by measurement with a caliper and by micro-CT analysis, as compared with age-matched controls. Growth rates of exposed pups after birth, however, was similar to sham-exposed offspring. Viral RNA was detected in pups of infected dams after birth. A lower survival rate was observed in neonates exposed to ZIKV in utero. A mortality rate of over 50%, attributed to consequences of ZIKV infection, occurred after birth in pups born to infected dams. A transient hearing loss was observed in some animals exposed to virus in utero. No motor deficits or cognitive deficits were detected using running wheel or viral paresis scoring assays. Abnormalities in offspring included smaller size, shorter skull length and increased neonatal mortality, while the only functional deficit we could detect was a low incidence of transient hearing loss

BDNF, NT-3 and Trk receptor agonist monoclonal antibodies promote neuron survival, neurite extension, and synapse restoration in rat cochlea ex vivo models relevant for hidden hearing loss.

Neurotrophins and their mimetics are potential treatments for hearing disorders because of their trophic effects on spiral ganglion neurons (SGNs) whose connections to hair cells may be compromised in many forms of hearing loss. Studies in noise or ototoxin-exposed animals have shown that local delivery of NT-3 or BDNF has beneficial effects on SGNs and hearing. We evaluated several TrkB or TrkC monoclonal antibody agonists and small molecules, along with BDNF and NT-3, in rat cochlea ex vivo models. The TrkB agonists BDNF and a monoclonal antibody, M3, had the greatest effects on SGN survival, neurite outgrowth and branching. In organotypic cochlear explants, BDNF and M3 enhanced synapse formation between SGNs and inner hair cells and restored these connections after excitotoxin-induced synaptopathy. Loss of these synapses has recently been implicated in hidden hearing loss, a condition characterized by difficulty hearing speech in the presence of background noise. The unique profile of M3 revealed here warrants further investigation, and the broad activity profile of BDNF observed underpins its continued development as a hearing loss therapeutic

Hearing loss in mCMV infected C57BL/6 mice after disruption of NK cell recognition signals.

<p>The effect of Ly49H receptor blockade on hearing loss was evaluated by examining distortion product otoacoustic emission (DPOAE) (A) and auditory brainstem response (ABR) (B) thresholds in post-natal day 28 (4 wks) and post-natal day 42 (6 wks) after intraperitoneal injection of IgG isotype control antibody or Ly49H blocking antibody and/or 200 pfu mCMV-GFP delivered by intracerebral injection on post-natal day 3. Statistically significant threshold differences were seen between the infected mice treated with the IgG isotype control antibody (N = 12 mice) and infected mice treated with the Ly49H blocking antibody 4 weeks post-injection (N = 8 mice) for DPOAE (<i>P</i> < 0.0001) and ABR (<i>P</i> = 0.0001) over the measured tone frequencies. Infected C57BL/6 mice treated with anti-Ly49H antibody and mCMV-GFP showed significant progressive hearing loss at 6 weeks after inoculation compared to thresholds 4 weeks after inoculation (<i>P</i> = 0.001 for DPOAE, <i>P</i> < 0.0001 for ABR). The effect of the mCMV-encoded m157 immunoevasin ligand on hearing loss was tested by comparing DPOAE (C) and ABR (D) in C57BL/6 mice after infection with either a virus deleted for the m157 gene (mCMV Δm157) or its parental wild type virus (mCMV WT1). Statistically significant threshold differences (<i>P</i> < 0.001) were seen between the mCMV WT1 and mCMV Δm157 treated C57BL/6 groups (<i>P</i> < 0.0001 for both DPOAE and ABR). Statistical differences between groups were determined using the Kruskal-Wallis test. ABR and DPOAE thresholds are presented as dB of sound pressure level (dB SPL) as a function of tone frequency in (kHz). Error bars represent standard error of the mean.</p

Hearing loss in mCMV-GFP infected BALB/c and C57BL/6 mice.

<p>Distortion product otoacoustic emission (DPOAE) (A) and auditory brainstem response (ABR) (B) thresholds of uninfected and infected mice were determined on post-natal day 28. Infected mice were treated with 200 pfu mCMV by intracerebral injection on post-natal day 3. Uninfected mice received the same volume of carrier by intracerebral injection on post-natal day 3. Statistically significant differences were seen between uninfected and infected BALB/c mice over the measured tone frequencies for both DPOAE and ABR thresholds (<i>P</i> < 0.0001, N = 6–7 mice per group) and between uninfected (N = 6) and infected (N = 12) C57BL/6 mice for DPOAE (<i>P</i> < 0.005), but not for ABR (<i>P</i> = 0.664). Statistically significant differences were also seen between infected BALB/c and C57BL/6 mice over the measured tone frequencies for both DPOAE and ABR thresholds (<i>P</i> < 0.0001). Statistical comparisons were performed using the Kruskal-Wallis test. ABR and DPOAE thresholds are presented as dB of sound pressure level (dB SPL) as a function of tone frequency in (kHz). Error bars represent standard error of the mean.</p

Ly49H blockade induces co-localization of mCMV-GFP infected cells and NK cells within the temporal bone.

<p>Green fluorescent protein expressed in mCMV-GFP infected cells and red fluorescent protein expressed in NK cells were visualized in cochlear cryosections from NK1.1-tdTomato knock-in mouse temporal bones harvested 3 days post-injection using anti-GFP (green) and anti-RFP antibodies (red). Representative images of 3–4 cochleae examined per group are shown for NK1.1-tdTomato knock-in mice injected with anti-Ly49H antibody only (A), mCMV-GFP only (B), or both (C). Panel D depicts a higher magnification of the auditory nerve region indicated by * in panel B. Panel E depicts a higher magnification of the spiral ganglion region indicated by * in panel C. Scale bars indicate 500 μm in panels A, B, and C and 100 μm in panels D and E. st = scala tympani.</p

Management of coronary disease in patients with advanced kidney disease

BACKGROUND Clinical trials that have assessed the effect of revascularization in patients with stable coronary disease have routinely excluded those with advanced chronic kidney disease. METHODS We randomly assigned 777 patients with advanced kidney disease and moderate or severe ischemia on stress testing to be treated with an initial invasive strategy consisting of coronary angiography and revascularization (if appropriate) added to medical therapy or an initial conservative strategy consisting of medical therapy alone and angiography reserved for those in whom medical therapy had failed. The primary outcome was a composite of death or nonfatal myocardial infarction. A key secondary outcome was a composite of death, nonfatal myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. RESULTS At a median follow-up of 2.2 years, a primary outcome event had occurred in 123 patients in the invasive-strategy group and in 129 patients in the conservative-strategy group (estimated 3-year event rate, 36.4% vs. 36.7%; adjusted hazard ratio, 1.01; 95% confidence interval [CI], 0.79 to 1.29; P=0.95). Results for the key secondary outcome were similar (38.5% vs. 39.7%; hazard ratio, 1.01; 95% CI, 0.79 to 1.29). The invasive strategy was associated with a higher incidence of stroke than the conservative strategy (hazard ratio, 3.76; 95% CI, 1.52 to 9.32; P=0.004) and with a higher incidence of death or initiation of dialysis (hazard ratio, 1.48; 95% CI, 1.04 to 2.11; P=0.03). CONCLUSIONS Among patients with stable coronary disease, advanced chronic kidney disease, and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of death or nonfatal myocardial infarction

Health status after invasive or conservative care in coronary and advanced kidney disease

BACKGROUND In the ISCHEMIA-CKD trial, the primary analysis showed no significant difference in the risk of death or myocardial infarction with initial angiography and revascularization plus guideline-based medical therapy (invasive strategy) as compared with guideline-based medical therapy alone (conservative strategy) in participants with stable ischemic heart disease, moderate or severe ischemia, and advanced chronic kidney disease (an estimated glomerular filtration rate of &lt;30 ml per minute per 1.73 m2 or receipt of dialysis). A secondary objective of the trial was to assess angina-related health status. METHODS We assessed health status with the Seattle Angina Questionnaire (SAQ) before randomization and at 1.5, 3, and 6 months and every 6 months thereafter. The primary outcome of this analysis was the SAQ Summary score (ranging from 0 to 100, with higher scores indicating less frequent angina and better function and quality of life). Mixed-effects cumulative probability models within a Bayesian framework were used to estimate the treatment effect with the invasive strategy. RESULTS Health status was assessed in 705 of 777 participants. Nearly half the participants (49%) had had no angina during the month before randomization. At 3 months, the estimated mean difference between the invasive-strategy group and the conservative-strategy group in the SAQ Summary score was 2.1 points (95% credible interval, 120.4 to 4.6), a result that favored the invasive strategy. The mean difference in score at 3 months was largest among participants with daily or weekly angina at baseline (10.1 points; 95% credible interval, 0.0 to 19.9), smaller among those with monthly angina at baseline (2.2 points; 95% credible interval, 122.0 to 6.2), and nearly absent among those without angina at baseline (0.6 points; 95% credible interval, 121.9 to 3.3). By 6 months, the between-group difference in the overall trial population was attenuated (0.5 points; 95% credible interval, 122.2 to 3.4). CONCLUSIONS Participants with stable ischemic heart disease, moderate or severe ischemia, and advanced chronic kidney disease did not have substantial or sustained benefits with regard to angina-related health status with an initially invasive strategy as compared with a conservative strategy