A genome-wide CRISPR functional survey of the human phagocytosis molecular machinery

Phagocytosis, the process by which cells engulf large particles, plays a vital role in driving tissue clearance and host defense. Its dysregulation is connected to autoimmunity, toxic accumulation of proteins, and increased risks for infections. Despite its importance, we lack full understanding of all molecular components involved in the process. To create a functional map in human cells, we performed a genome-wide CRISPRko FACS screen that identified 716 genes. Mapping those hits to a comprehensive protein-protein interaction network annotated for functional cellular processes allowed retrieval of protein complexes identified multiple times and detection of missing phagocytosis regulators. In addition to known components, such as the Arp2/3 complex, the vacuolar-ATPase-Rag machinery, and the Wave-2 complex, we identified and validated new phagocytosis-relevant functions, including the oligosaccharyltransferase complex (MAGT1/SLC58A1, DDOST, STT3B, and RPN2) and the hypusine pathway (eIF5A, DHPS, and DOHH). Overall, our phagocytosis network comprises elements of cargo uptake, shuffling, and biotransformation through the cell, providing a resource for the identification of potential novel drivers for diseases of the endo-lysosomal system. Our approach of integrating protein-protein interaction offers a broadly applicable way to functionally interpret genome-wide screens.

[Pulmonary infection in neutropenia]

MEDICAL HISTORY AND CLINICAL COURSE: A 42-year-old patient with hairy cell leukemia had been treated for 3 years by a hematologist in private practice. Initially the patient received 1 course of cladribine upon which the disease went into complete remission. 6 weeks ago a relapse was diagnosed and combination therapy with cladibrin and rituximab was initiated. Now the patient presented to the emergency room with shortness of breath and pain when breathing.

INVESTIGATIONS, TREATMENT AND COURSE

In the chest x-ray, patchy infiltrates and pleural effusions were found on both sides. The subsequently performed computed tomography showed bilateral compactions with an Halo suspicious for fungal infiltrates. Upon admission to the hospital, an empirical antibiotic therapy with clarithromycin and piperacillin/tazobactam was initiated, which was later escalated to meropenem and linezolid. Additionally, an antifungal therapy with voriconazole was started and later switched to liposomal amphotericin B. At his admission, a positive aspergillus antigen could be detected in the microbiological laboratory. Under antimycotic treatment the aspergillus antigen was repeatedly negative. The patient presented with pronounced cytopenias and after a switch of therapy to vemurafenib and filgrastim, the hematopoiesis could only be stimulated insufficiently. The patient was transferred to the intensive care unit three days after admission with severe respiratory failure. He died on day 8 after admission. AUTOPSY AND DIAGNOSIS: Diagnosis was consistent with relapse of hairy cell leukemia with positive BRAF mutation and a bone marrow infiltration > 80 %. Autopsy revealed a significant hepato-splenomegaly, a lack of erythro-, granulo- and thrombopoiesis. Clots interspersed with fungal hyphae were found in both lungs and an infarction of the spleen with evidence of fungal hyphae was detected. The cultural findings post mortem on yeast or mold were negative.

CONCLUSION

Patients with refractory hairy cell leukemia and prolonged neutropenia are at increased risk for systemic fungal infections. Therefore, prohylactic antimycotic therapy should be considered early in this group of patients. The therapeutic approach of vemurafenib in treatment-refractory hairy cell leukemia is promising and offers an additional treatment option. In the present case, the patient could unfortunately not be stabilized due to the septic complications.

Anti-endothelial serum antibodies in a patient with Susac's syndrome

BACKGROUND

Susac's syndrome (SS) is a rare arteriopathy affecting the microvasculature of the brain, retina, and inner ear, resulting in encephalopathy, branch retinal artery occlusion and hearing loss. Anecdotal reports exist on SS being associated with a humoral immune response against endothelial cells. However, no original data has ever been published.

OBJECTIVE

To analyze serum and CSF from a patient with SS for the presence of CNS auto-antibodies and, if present, to further characterize such antibodies immunologically.

METHODS

Serum and CSF samples were examined by indirect immunofluorescence on adult mouse cerebrum, cerebellum, brain stem, and inner ear tissue sections, and IgG subclasses were determined.

RESULTS

Anti-endothelial antibodies were found at a titre of 1:960 in serum but not CSF. Antibodies belonged to the complement activating IgG1 subclass. Glucocorticoid treatment resulted in a decrease of titres (1:480), though the antibodies remained clearly detectable.

CONCLUSION

Our finding of anti-endothelial cell antibodies in a patient with SS is important in the light of previous pathological data suggesting that SS is associated with endothelial damage. Larger serological studies are now warranted to assess systematically the frequency and relevance of auto-antibodies in SS.

[Time-torque diagrams of self-cutting osteosynthesis screws of various lengths in fracture tests in aluminum]

Tapping screws of the Medicon system were checked for their mechanical strength by a time-torque curve and a new measurement system. To simulate a real situation three types of screws were applied. The predrill was 80% of the kernel diameter. The percentage of demolition was significantly higher with longer screws because there was a typical tilting of screws in aluminium. All tested screws had double the minimum fracture moment of 43 Ncm. Fracture of the screws occurred at about triple the torque of the maximal moment in the bones.

[Tensile strength studies of self-cutting titanium osteosynthesis screws]

The tapping screws of the Medicon Osteosynthese System applied in the jaw and facial area were checked for their mechanical sturdiness. Screwing tests with bones and aluminium were carried out. The minimum fracture moment, the moment transferrable by the screw slot and the required moment for a tight seat of the Osteosynthese plate on the bone surface were calculated. The screws and plates are of titanium alloy TiA16V4 (US standard) for implantats. In a sample taken at random of test screws the fracture moments were measured and examined. All the screws support considerable loads and the fracture moments are almost 20% higher that the minimum fracture moment for TiA16V4 screws specified in DIN 267, part 18.

[Optimizing titanium osteosynthesis miniplates. Some basic considerations]

Most recently there seems to be a general turning away from the use of rectangular osteosynthesis miniplates in the treatment of maxillofacial fractures and in plastic surgery. Meanwhile a novel design based on circular arcs and connecting bars has been successfully employed. Its particular two-dimensional shape allows three-dimensional deformation without damaging the plates or the openings required for screw insertion. Apart from a reduced plate-bearing area and an increased torsional stability during adaptation to the bone surface, this new plate geometry and the complete system excells by its high tissue compatibility. This later characteristic is attributable to the choice of the bioinert material titanium, which has been processed into a special alloy.

[Automation for the orthodontics model analysis using a digital caliper]

1. The discussed program structure is a common one and is transferable to other computer systems. 2. The structure is independent from computer language and thus is usable with various computer languages. 3. This proposal for automation is helpful in treatment planning but it cannot substitute the orthodontists diagnostic work. 4. Because of the modular structure the program can be used for daily practice as well as for extensive scientific works. 5. The program can be included totally or partly in other programs and used as an integral part of existing programs.

[Basic geometrical principles of profile harmony as an aid in planning and simulating maxillofacial surgery]

Dividing the facial profile into three sectors according to the principle of the golden section with one circle around the auditory meatus as the center provides a basis for a harmonic profile. An additional important factor for the general harmony of the profile is the nose. Based on a great number of measurements, computer programs allow preoperative profile simulations and the assessment of surgical feasibility. As numbers and the resulting numerical relationships play a fundamental role in the classification of the human body, it is possible to express beauty in terms of geometry. It is, however, only at certain definite numerical relationships of these three facial sectors to each other that a harmonic profile of the human head is produced. The resulting constructive ideals of beauty provide aids and guidelines in plastic surgery.

[Torque measurement of self-threading bone screws. Test procedure for new surgical screws]

Different systems of self-cutting screws are tested by a measuring instrument to test the torsional strain. Modern methods of measuring techniques are applied to get results of the torsional force and the torque by screwing into the bones. To get a self-cutting screw system several methods of biomechanical properties must be applied. A variety of quality tests, of biomechanical screws, are used, before performing the operations, that flaws may be detected.

[Comparative studies on stability of titanium and V4A osteosynthesis screws]

Three years of clinical use and testing provided clear support to the advantages of the self-tapping titanium splithole screws. Although having rather flat heads these screws afford a fast grip with the screw driver blade. In addition to this, the pin offers good axial guidance and adhesion of the screw. The cylindrical design of the screw equator improves the fit of the screw in the chuck of the screw driver. The spherical shape of the lower half of the screw head increases the circular contact to the osteosynthesis plate, which is particularly favorable in the case of a minor angular error.