Inflammation and the Nervous System: The Connection in the Cornea in Patients with Infectious Keratitis

Purpose. To study the density and morphologic characteristics of epithelial dendritic cells, as correlated to subbasal corneal nerve alterations in acute infectious keratitis (IK) by in vivo confocal microscopy (IVCM). Methods. IVCM of the central cornea was performed prospectively in 53 eyes with acute bacterial (n = 23), fungal (n = 13), and Acanthamoeba (n = 17) keratitis, and in 20 normal eyes, by using laser in vivo confocal microscopy. Density and morphology of dendritic-shaped cells (DCs) of the central cornea, corneal nerve density, nerve numbers, branching, and tortuosity were assessed and correlated. It should be noted that due to the “in vivo” nature of the study, the exact identity of these DCs cannot be specified, as they could be monocytes or tissue macrophages, but most likely dendritic cells. Results. IVCM revealed the presence of central corneal DCs in all patients and controls. The mean DC density was significantly higher in patients with bacterial (441.1 ± 320.5 cells/mm2; P < 0.0001), fungal (608.9 ± 812.5 cells/mm2; P < 0.0001), and Acanthamoeba keratitis (1000.2 ± 1090.3 cells/mm2; P < 0.0001) compared with controls (49.3 ± 39.6 cells/mm2). DCs had an increased size and dendrites in patients with IK. Corneal nerves were significantly reduced in eyes with IK compared with controls across all subgroups, including nerve density (674.2 ± 976.1 vs. 3913.9 ± 507.4 μm/frame), total nerve numbers (2.7 ± 3.9 vs. 20.2 ± 3.3), main trunks (1.5 ± 2.2 vs. 6.9 ± 1.1), and branching (1.2 ± 2.0 vs. 13.5 ± 3.1; P < 0.0001). A strong association between the diminishment of corneal nerves and the increase of DC density was observed (r = −0.44; P < 0.0005). Conclusions. IVCM reveals an increased density and morphologic changes of central epithelial DCs in infectious keratitis. There is a strong and significant correlation between the increase in DC numbers and the decreased subbasal corneal nerves, suggesting a potential interaction between the immune and nervous system in the cornea

Corneal Epithelial Immune Dendritic Cell Alterations in Subtypes of Dry Eye Disease: A Pilot In Vivo Confocal Microscopic Study

Citation: Kheirkhah A, Rahimi Darabad R, Cruzat A, et al. Corneal epithelial immune dendritic cell alterations in subtypes of dry eye disease: a pilot in vivo confocal microscopic study. Invest Ophthalmol Vis Sci. 2015;56:7179-7185. DOI:10.1167/ iovs.15-17433 PURPOSE. To evaluate density and morphology of corneal epithelial immune dendritic cells (DCs) in different subtypes of dry eye disease (DED) using in vivo confocal microscopy (IVCM). METHODS. This retrospective study included 59 eyes of 37 patients with DED and 40 eyes of 20 age-matched healthy controls. Based on clinical tests, eyes with DED were categorized into two subtypes: aqueous-deficient (n ¼ 35) and evaporative (n ¼ 24). For all subjects, images of laser scanning in vivo confocal microscopy (IVCM) of the central cornea were analyzed for DC density and DC morphology (DC size, number of dendrites, and DC field). These DC parameters were compared among all dry eye and control groups. RESULTS. Compared with the controls, patients with DED had significantly higher DC density, larger DC size, higher number of dendrites, and larger DC field (all P &lt; 0.001). Comparison between aqueous-deficient and evaporative subtypes demonstrated that DC density was significantly higher in aqueous-deficient subtype (189.8 6 36.9 vs. 58.9 6 9.4 cells/mm 2 , P ¼ 0.001). However, there were no significant differences in morphologic parameters between DED subtypes. When aqueous-deficient DED with underlying systemic immune disease (Sjögren&apos;s syndrome and graft versus host disease) were compared with nonimmune conditions, the immunologic subgroup showed significantly higher DC density, DC size, and number of dendrites (all P &lt; 0.05). CONCLUSIONS. Corneal IVCM demonstrated differential changes in DC density and morphologic DC parameters between subtypes of DED. These changes, which reflect the degree of immune activation and inflammation in DED, can be used for clinical practice and endpoints in clinical trials. Keywords: dry eye disease, in vivo confocal microscopy, inflammation, dendritic cells D ry eye disease (DED) is one of the most commonly encountered ophthalmic disorders. It is a multifactorial disease of the ocular surface and tear film, characterized by symptoms of eye irritation, tear instability, and vision impairment. 1 In addition to evaluating symptoms, a variety of clinical tests are currently being used to diagnose DED, including the Schirmer&apos;s wetting test, tear break-up time (TBUT), tear osmolarity, and vital dye staining of the ocular surface by fluorescein, Rose Bengal and Lissamine Green. However, complex clinical features of the disease make the diagnosis a challenge in many cases. 2,3 Therefore, there remains a significant need for objective tests, which can be used to accurately diagnose DED and/or monitor therapeutic response in DED and its underlying changes. Recent studies have shown that the immune changes play an important role in the pathogenesis of DED. To evaluate changes in DCs in patients with DED, corneal in vivo confocal microscopy (IVCM) has lately been used. In vivo confocal microscopy is a noninvasive imaging modality that enables studying the cornea at a cellular level

Contralateral Clinically Unaffected Eyes of Patients With Unilateral Infectious Keratitis Demonstrate a Sympathetic Immune Response

Purpose To analyze the contralateral unaffected eyes of patients with microbial keratitis (MK) for any immune cell or nerve changes by laser in vivo confocal microscopy (IVCM). Methods A prospective study was performed on 28 patients with MK, including acute bacterial, fungal, and Acanthamoeba keratitis, as well as on their contralateral clinically unaffected eyes and on control groups, which consisted of 28 age-matched normal controls and 15 control contact lens (CL) wearers. Laser IVCM with the Heidelberg Retinal Tomograph 3/Rostock Cornea Module and Cochet-Bonnet esthesiometry of the central cornea were performed. Two masked observers assessed central corneal dendritiform cell density and subbasal corneal nerve parameters. Results The contralateral clinically unaffected eyes of patients with MK demonstrated significant diminishment in nerve density (15,603.8 ± 1265.2 vs. 24,102.1 ± 735.6 μm/mm2), total number of nerves (11.9 ± 1.0 vs. 24.9 ± 1.2/frame), number of branches (1.7 ± 0.2 vs. 19.9 ± 1.3/frame), and branch nerve length (5775.2 ± 757.1 vs. 12,715.4 ± 648.4 μm/mm2) (P < 0.001 for all parameters) compared to normal controls and CL wearers. Further, dendritiform cell density in the contralateral unaffected eyes was significantly increased as compared to that in controls (117.5 ± 19.9 vs. 24.2 ± 3.5 cells/mm2, P < 0.001). Conclusions We demonstrate a subclinical involvement in the contralateral clinically unaffected eyes in patients with unilateral acute MK. In vivo confocal microscopy reveals not only a diminishment of the subbasal corneal nerves and sensation, but also an increase in dendritiform cell density in the contralateral unaffected eyes of MK patients. These findings show bilateral immune alterations in a clinically unilateral disease

Degeneration and Regeneration of Subbasal Corneal Nerves after Infectious Keratitis

Purpose To investigate the longitudinal alterations of subbasal corneal nerves in patients with infectious keratitis (IK) during acute phase, cessation of treatment and recovery phase by in vivo confocal microscopy (IVCM). Design Prospective, longitudinal, case-control, single-center study. Subjects Fifty-six eyes of 56 patients with the diagnosis of bacterial (n=28), fungal (n=15), and Acanthamoeba (n=13) keratitis were included in the study. Thirty eyes of 30 normal volunteers constituted the control group. Methods Corneal sensation and serial IVCM of the central cornea were performed prospectively, by using the Heidelberg Retina Tomograph 3/Rostock Cornea Module (Heidelberg Engineering, Germany). IVCM images were assessed at 3 time points: at the first visit of the patient to the cornea service, at cessation of antimicrobial treatment, and up to six months after the resolution of infection. Main outcome measures Total nerve number and length, main nerve trunks, branching and corneal sensation were assessed during the follow-up period. Results Corneal nerves were significantly reduced during the acute phase in eyes with IK compared with controls across all subgroups, with total nerve length of 5.47 ± 0.69 vs. 20.59 ± 1.06 mm/mm2; p<0.0001. At the cessation of treatment, corneal nerves in patients with IK had regenerated, including total nerve length (8.49 ± 0.94; p=0.02) and nerve branch length (4.80 ± 0.37; p=0.005). During the recovery phase, after resolution of infection, corneal nerves further regenerated, including total nerve length (12.13 ± 1.97; p=0.005), main nerve trunk length (5.80 ± 1.00; p=0.01) and nerve branch length (6.33 ± 0.76; p=0.003) as compared to the acute phase, but were still significantly lower when compared to controls (p<0.05 for all parameters). Corneal degeneration and regeneration correlated with corneal sensation (r=0.47, p=0.0009). Conclusion Patients with IK, suffering from profound loss of corneal nerves during the acute phase of infection, demonstrate an increase of corneal nerve density during the first six months after the resolution of infection. However, despite significant nerve regeneration, corneal nerve density does not fully recover and remains low as compared to controls. By providing an objective methodology to monitor corneal re-innervation, IVCM adds potentially important findings that may have implications for clinical management and surgical planning

Inflammation and the Nervous System: The Connection in the Cornea in Patients with Infectious Keratitis

This study evaluates changes in dendritic cells and nerves in patients with infectious keratitis (IK) by in vivo confocal microscopy (IVCM). IVCM reveals an increased dendritic cell density in IK, correlating to decrease in subbasal corneal nerves