RAE1ε ligand expressed on pancreatic islets recruits NKG2D receptor-expressing cytotoxic T cells independent of T cell receptor recognition.

The mechanisms by which cytotoxic T lymphocytes (CTLs) enter and are retained in nonlymphoid tissue are not well characterized. With a transgenic mouse expressing the NKG2D ligand retinoic acid early transcript 1ε (RAE1ε) in ß-islet cells of the pancreas, we found that RAE1 expression was sufficient to induce the recruitment of adoptively transferred CTLs to islets. This was dependent on NKG2D expression by the CTLs and independent of antigen recognition. Surprisingly, the recruitment of CTLs resulted in the subsequent recruitment of a large number of endogenous lymphocytes. Whereas transgenic mice did not develop diabetes, RAE1 expression was sufficient to induce insulitis in older, unmanipulated transgenic mice that was enhanced by viral infection and pancreatic inflammation. These results demonstrate that the expression of an NKG2D ligand in islets is sufficient to recruit CTLs regardless of their antigen specificity and to induce insulitis.

NKG2D Promotes B1a Cell Development and Protection against Bacterial Infection.

NKG2D is a potent activating receptor that is expressed on cytotoxic immune cells such as CD8 T and NK cells, where it promotes cytotoxicity after binding stress ligands on infected or transformed cells. On NK cell precursors NKG2D modulates proliferation and maturation. Previously, we observed that NKG2D deficiency affects peripheral B cell numbers. In this study, we show that NKG2D regulates B1a cell development and function. We find that mice deficient for NKG2D have a strong reduction of B1a cell numbers. As a result, NKG2D-deficient mice produce significantly less Ag-specific IgM Abs upon immunization with T cell-independent Ags, and they are more susceptible to Gram-negative sepsis. Klrk1-/- B1a cells are also functionally impaired and they fail to provide protection against Francisella novicida upon adoptive transfer. Using mixed bone marrow chimeric mice, we show that the impact of NKG2D deficiency on B1a cell development is cell intrinsic. No changes in homeostatic turnover and homing of B cells were detectable, limiting the effects of NKG2D to modulation of the hematopoietic development of B1a cells. Using conditional ablation, we demonstrate that the effect of NKG2D on B1a cell development occurs at a developmental stage that precedes the common lymphoid progenitor. Our findings reveal an unexpected new role for NKG2D in the regulation of B1a cell development. The protective effects of this activating receptor therefore reach beyond that of cytotoxic cells, stimulating the immune system to fight bacterial infections by promoting development of innate-like B cells.

Altered NK cell development and enhanced NK cell-mediated resistance to mouse cytomegalovirus in NKG2D-deficient mice.

NKG2D is a potent activating receptor on natural killer (NK) cells and acts as a molecular sensor for stressed cells expressing NKG2D ligands such as infected or tumor-transformed cells. Although NKG2D is expressed on NK cell precursors, its role in NK cell development is not known. We have generated NKG2D-deficient mice by targeting the Klrk1 locus. Here we provide evidence for an important regulatory role of NKG2D in the development of NK cells. The absence of NKG2D caused faster division of NK cells, perturbation in size of some NK cell subpopulations, and their augmented sensitivity to apoptosis. As expected, Klrk1(-/-) NK cells are less responsive to tumor targets expressing NKG2D ligands. Klrk1(-/-) mice, however, showed an enhanced NK cell-mediated resistance to mouse cytomegalovirus infection as a consequence of NK cell dysregulation. Altogether, these findings provide evidence for regulatory function of NKG2D in NK cell physiology.

A dual function of NKG2D ligands in NK-cell activation.

NK-cell killing requires both the expression of activating receptor ligands and low MHC class I expression by target cells. Here we demonstrate that the expression of any of the murine ligands for the NK-cell activating receptor NKG2D results in a concomitant reduction in MHC class I expression. We show this both in tumor cell lines and in vivo. NK-cell lysis is enhanced by the decrease in MHC class I expression, suggesting the change is biologically relevant. These results demonstrate that NKG2D ligand expression on target cells not only allows for activating receptor recognition, but also actively reduces expression of the inhibitory ligand, MHC class I, leading to enhanced recognition and killing by NK cells.

Cutting edge: CD8+ T cell priming in the absence of NK cells leads to enhanced memory responses.

It is uncertain whether NK cells modulate T cell memory differentiation. By using a genetic model that allows the selective depletion of NK cells, we show in this study that NK cells shape CD8(+) T cell fate by killing recently activated CD8(+) T cells in an NKG2D- and perforin-dependent manner. In the absence of NK cells, the differentiation of CD8(+) T cells is strongly biased toward a central memory T cell phenotype. Although, on a per-cell basis, memory CD8(+) T cells generated in the presence or the absence of NK cells have similar functional features and recall capabilities, NK cell deletion resulted in a significantly higher number of memory Ag-specific CD8(+) T cells, leading to more effective control of tumors carrying model Ags. The enhanced memory responses induced by the transient deletion of NK cells may provide a rational basis for the design of new vaccination strategies.

Role of Cardiac Magnetic Resonance in Diagnosis and Treatment of Ball Thrombus in Left Atrium - Trust But Verify! - Case Report.

Male patient with left atrial cardiac mass was in need of a quick diagnosis for individualized and effective treatment. Transthoracic echocardiography showed presence of а giant left atrial cardiac mass with atypical location for thrombus. Cardiac Magnetic Resonance (CMR) Imaging was performed for histological discrimination, and showed a large cardiac mass wall attached in the left atrium, homogeneous, with diameter of 3.4cm x 3.2cm. Late Gadolinium Enhancement sequences revealed black avascular tissue without signal, confirming the characterization of a thrombus. The patient refused hospital initiation of low molecular weight heparin treatment and started treatment with Rivaroxaban. Six weeks later he presented with NYHA class II, almost complete dissolving of the thrombus on CMR scan. Seven months from the initial CMR scan, echocardiography screen was done showing complete absence of the left atrial mass. With this case report we have demonstrated the significance of the CMR as one step further in the precise diagnostics of cardiac masses, solving critical clinical dilemma.

Prevalence of congenital hypothyroidism in North Macedonia: data from a newborn screening program conducted for twenty years.

BACKGROUND: Congenital hypothyroidism (CH) is a common endocrine disorder that can be treated if timely detected by newborn screening, optimizing the developmental outcome in affected children. In the present study, we analyze the data of the national newborn thyroid screening program in North Macedonia collected over twenty years, including the CH prevalence as well as its geographical and ethnic variations. METHODS: The thyroid-stimulating hormone (TSH) was measured on a filter paper blood spot sample using the DELFIA fluoroimmunometric assay. A TSH value of 15 mIU/L whole blood was used as the cutoff point until 2010 and 10 mIU/L thereafter. RESULTS: Out of 377,508 screened live births, a total of 226 newborns with primary CH were detected, providing an overall prevalence of 6.0 per 10,000. Lowering the TSH cutoff led to an apparently increased prevalence of the transient CH, from 0.2 to 2.4 per 10,000 live births (p < 0.0001) with an impact on the overall prevalence of primary CH (from 4.0 to 7.1 per 10,000, p=0.0001). Taking ethnicity into account, the significantly highest primary CH prevalence of 11.3 per 10,000 live births was observed among the Roma neonates, with a predominance of permanent CH (75.5%). There were also regional differences in the prevalence of primary CH. The highest primary CH prevalence of 11.7 per 10,000 live births was observed in the Vardar region, together with the highest regional prevalence of the transient CH (3.2 per 10,000). The highest prevalence of permanent CH was observed in the Pelagonia region (6.6 per 10,000) where the largest percentage of the Roma population lives. CONCLUSIONS: The overall CH prevalence is high in North Macedonia, with substantial ethnic and geographical variations. Further analysis to elucidate the causes for the significant variations in the CH prevalence including environmental factors is warranted.

Predictive Admission Risk Factors, Clinical Features and Kidney Outcomes in Covid-19 Hospitalised Patients with Acute Kidney Injury.

Introduction: In COVID-19 patients, acute kidney injury (AKI) is recognized as a cause of high mortality. The aim of our study was to assess the rate and the predictors of AKI as well as survival among COVID-19 patients. Methods: We analyzed clinical and laboratory admission data, predictors of AKI and outcomes including the need for renal replacement therapy (RRT) and mortality at 30 days. Results: Out of 115 patients, 62 (53.9%) presented with AKI: 21 (33.9%) at stage 1, 7(11.3%) at stage 2, and 34 (54.8%) at stage 3. RRT was required in 22.6% of patients and was resolved in 76%. Pre-existing CKD was associated with a 13-fold risk of AKI (p= 0.0001). Low albumin (p = 0.017), thrombocytopenia (p = 0.022) and increase of creatine kinase over 350UI (p = 0.024) were independently associated with a higher risk for AKI. Mortality rates were significantly higher among patients who developed AKI compared to those without (59.6% vs 30.2%, p= 0.003). Low oxygen blood saturation at admission and albumin were found as powerful independent predictors of mortality (OR 0.937; 95%CI: 0.917 - 0.958, p = 0.000; OR 0.987; 95%CI: 0.885-0.991, p= 0.024, respectively). Longer survival was observed in patients without AKI compared to patients with AKI (22.01± 1.703 vs 16.69 ± 1.54, log rank p= 0.009). Conclusion: Renal impairment is significant in hospitalized COVID-19 patients. The severity of the disease itself is emphasized as main contributing mechanism in the occurrence of AKI, and lower blood saturation at admission is the strongest mortality predictor, surpassing the significance of the AKI itself.

Regulation of immune cell function and differentiation by the NKG2D receptor.

NKG2D is one of the most intensively studied immune receptors of the past decade. Its unique binding and signaling properties, expression pattern, and functions have been attracting much interest within the field due to its potent antiviral and anti-tumor properties. As an activating receptor, NKG2D is expressed on cells of the innate and adaptive immune system. It recognizes stress-induced MHC class I-like ligands and acts as a molecular sensor for cells jeopardized by viral infections or DNA damage. Although the activating functions of NKG2D have been well documented, recent analysis of NKG2D-deficient mice suggests that this receptor may have a regulatory role during NK cell development. In this review, we will revisit known aspects of NKG2D functions and present new insights in the proposed influence of this molecule on hematopoietic differentiation.

Plasmacytoid dendritic cells control dengue and Chikungunya virus infections via IRF7-regulated interferon responses.

Type I interferon (IFN-I) responses are critical for the control of RNA virus infections, however, many viruses, including Dengue (DENV) and Chikungunya (CHIKV) virus, do not directly activate plasmacytoid dendritic cells (pDCs), robust IFN-I producing cells. Herein, we demonstrated that DENV and CHIKV infected cells are sensed by pDCs, indirectly, resulting in selective IRF7 activation and IFN-I production, in the absence of other inflammatory cytokine responses. To elucidate pDC immunomodulatory functions, we developed a mouse model in which IRF7 signaling is restricted to pDC. Despite undetectable levels of IFN-I protein, pDC-restricted IRF7 signaling controlled both viruses and was sufficient to protect mice from lethal CHIKV infection. Early pDC IRF7-signaling resulted in amplification of downstream antiviral responses, including an accelerated natural killer (NK) cell-mediated type II IFN response. These studies revealed the dominant, yet indirect role of pDC IRF7-signaling in directing both type I and II IFN responses during arbovirus infections.

Growth parameters and nutritional status in relation to socioeconomic status of Macedonian adolescents.

AIM: To assess the anthropometric parameters of growth and nutritional status in relation to socioeconomic status (SES) of Macedonian adolescents. METHODS: The study included 546 adolescents from urban regions of the Republic of Macedonia, aged 14 to 15 years. Participants were measured with standard equipment and measurement technique according to the International Biological Programme. The following anthropometric indices were calculated: height-for-age (BH), weight-for-age (BW) and BMI-for-age (kg/m2). For measuring family wealth, the Family Affluence Scale (FAS) has been used. Adolescents were grouped into three SES groups. RESULTS: Age-specific differences were found for body height and weight in favour of 15-year-old males (p<0.05). There were no significant differences in height and weight among different SES groups. Female participants were more overweight in the high SES group (13.2%) and middle SES group (10.8%), compared to those in the low SES group (6.7%). According to the obtained results in females, the prevalence of obese and underweight females is higher in those with low SES. CONCLUSIONS: Male adolescents were found to be taller and heavier than female adolescents. Both male and female adolescents were taller and heavier in high SES group than those in other SES groups. There were no SES differences in prevalence of underweight, overweight and obesity among Macedonian school adolescents living in urban areas, except among females, those in the low SES group had a significantly higher prevalence of obesity than did those in the MSES and HSES groups.

Dermatoglyphics in patients with schizophrenia--findings in the Macedonian population.

UNLABELLED: The human palms and soles are textured with skin different to that of the other body surface. Instead of sebaceous glands or hairs, there are sweat glands opening into epidermal ridges. They are variously oriented, thus forming different patterns. The aim of the study was to assess some dermatoglyphic patterns, the TRC and the a-b ridge count in a sample of patients and a control group of healthy examinees. MATERIAL AND METHOD: 59 male and 50 female patients with schizophrenia and 60 healthy male and 50 female individuals as a control group were included in the study. Hand prints were taken using the method of Cummins and Midlo; pattern types were determined and classified using the Henry classification. An analysis of pattern frequency in schizophrenia compared to the normal controls was conducted. RESULTS: The patterns most frequently present are loops (ulnar) with greater incidence and whorls with smaller incidence in patients with schizophrenia compared to the healthy individuals. The number of arches is higher in male patients and lower in female patients. Complex patterns are rare. TRC in females has lower values found in patients. The a-b ridge count has significant difference in male and female patients; higher values in male and lower in female patients. CONCLUSION: There is some association between the frequency of certain dermatoglyphic characteristicss and schizophrenia. Our findings form a useful database for the dermatoglyphic marks present in patients with schizophrenia and healthy subjects of Macedonian nationality.

NKG2D signaling on CD8⁺ T cells represses T-bet and rescues CD4-unhelped CD8⁺ T cell memory recall but not effector responses.

CD4-unhelped CD8(+) T cells are functionally defective T cells primed in the absence of CD4(+) T cell help. Given the co-stimulatory role of natural-killer group 2, member D protein (NKG2D) on CD8(+) T cells, we investigated its ability to rescue these immunologically impotent cells. We demonstrate that augmented co-stimulation through NKG2D during priming paradoxically rescues memory, but not effector, CD8(+) T cell responses. NKG2D-mediated rescue is characterized by reversal of elevated transcription factor T-box expressed in T cells (T-bet) expression and recovery of interleukin-2 and interferon-γ production and cytolytic responses. Rescue is abrogated in CD8(+) T cells lacking NKG2D. Augmented co-stimulation through NKG2D confers a high rate of survival to mice lacking CD4(+) T cells in a CD4-dependent influenza model and rescues HIV-specific CD8(+) T cell responses from CD4-deficient HIV-positive donors. These findings demonstrate that augmented co-stimulation through NKG2D is effective in rescuing CD4-unhelped CD8(+) T cells from their pathophysiological fate and may provide therapeutic benefits.

The intraepithelial T cell response to NKG2D-ligands links lymphoid stress surveillance to atopy.

Epithelial cells respond to physicochemical damage with up-regulation of major histocompatibility complex-like ligands that can activate the cytolytic potential of neighboring intraepithelial T cells by binding the activating receptor, NKG2D. The systemic implications of this lymphoid stress-surveillance response, however, are unknown. We found that antigens encountered at the same time as cutaneous epithelial stress induced strong primary and secondary systemic, T helper 2 (T(H)2)-associated atopic responses in mice. These responses required NKG2D-dependent communication between dysregulated epithelial cells and tissue-associated lymphoid cells. These data are germane to uncertainty over the afferent induction of T(H)2 responses and provide a molecular framework for considering atopy as an important component of the response to tissue damage and carcinogenesis.

Cytomegalovirus immunoevasin reveals the physiological role of "missing self" recognition in natural killer cell dependent virus control in vivo.

Cytomegaloviruses (CMVs) are renowned for interfering with the immune system of their hosts. To sidestep antigen presentation and destruction by CD8(+) T cells, these viruses reduce expression of major histocompatibility complex class I (MHC I) molecules. However, this process sensitizes the virus-infected cells to natural killer (NK) cell-mediated killing via the "missing self" axis. Mouse cytomegalovirus (MCMV) uses m152 and m06 encoded proteins to inhibit surface expression of MHC I molecules. In addition, it encodes another protein, m04, which forms complexes with MHC I and escorts them to the cell surface. This mechanism is believed to prevent NK cell activation and killing by restoring the "self" signature and allowing the engagement of inhibitory Ly49 receptors on NK cells. Here we show that MCMV lacking m04 was attenuated in an NK cell- and MHC I-dependent manner. NK cell-mediated control of the infection was dependent on the presence of NK cell subsets expressing different inhibitory Ly49 receptors. In addition to providing evidence for immunoevasion strategies used by CMVs to avoid NK cell control via the missing-self pathway, our study is the first to demonstrate that missing self-dependent NK cell activation is biologically relevant in the protection against viral infection in vivo.